bims-cagime 2024-12-29 papers

bims-cagime

Biomed News

on Cancer, aging and metabolism

Issue of 2024–12–29
37 papers selected by
Kıvanç Görgülü, Technical University of Munich

Cell membranes sustain phospholipid imbalance via cholesterol asymmetry.
Leucine Aminopeptidase LyLAP enables lysosomal degradation of membrane proteins.
Ubiquitin-mediated recruitment of the ATG9A-ATG2 lipid transfer complex drives clearance of phosphorylated p62 aggregates.
Tuft cells transdifferentiate to neural-like progenitor cells in the progression of pancreatic cancer.
Reconsidering the selectivity of bulk autophagy: cargo hitchhiking specifies cargo for degradation.
Characterization of a Cancer-Induced Bone Pain Model for Use as a Model of Cancer Cachexia.
Senolysis by ABT-263 is associated with inherent apoptotic dependence of cancer cells derived from the non-senescent state.
Targeted degradation of oncogenic KRASG12V triggers antitumor immunity in lung cancer models.
Liver Cancer Neuroscience: Regulating Liver Tumors via Selective Hepatic Vagotomy.
Limiting serine availability during tumor progression promotes muscle wasting in cancer cachexia.
Organoids, tissue slices and organotypic cultures: advancing our understanding of pancreatic ductal adenocarcinoma through in vitro and ex vivo models.
Impairment of lipid homeostasis causes lysosomal accumulation of endogenous protein aggregates through ESCRT disruption.
Effects of Aging on Glucose and Lipid Metabolism in Mice.
Pan-KRAS inhibitors BI-2493 and BI-2865 display potent anti-tumor activity in tumors with KRAS wild-type allele amplification.
Caveolin-1 regulates context-dependent signaling and survival in Ewing Sarcoma.
Peripheral, central, and chemotherapy-induced neuropathic changes in pancreatic cancer.
Diet therapy abates mutant APC and KRas effects by reshaping plasma membrane cholesterol nanodomains.
Membrane structure-responsive lipid scramblase activity of the TMEM63/OSCA family.
Targeting senescent cells for the treatment of age-associated diseases.
Extensive molecular profiling of KRAS wild-type as compared to KRAS mutated pancreatic ductal adenocarcinoma on 318 patients.
Cost-effective and simple flow cytometry quantification of receptor-mediated autophagy using fluorescent tagging.
RNA sensing induced by chromosome missegregation augments anti-tumor immunity.
Heat-Induced Phosphatidylserine Changes Drive HSPA1A's Plasma Membrane Localization.
Deciphering Colorectal Cancer-Hepatocyte Interactions: A Multiomic Platform for Interrogation of Metabolic Crosstalk in the Liver-Tumor Microenvironment.
Influence of the glycocalyx on the size and mechanical properties of plasma membrane-derived vesicles.
The many paths ascending to ferroptosis.
Preventing excessive autophagy protects from the pathology of mtDNA mutations in Drosophila melanogaster.
A neurodegenerative cellular stress response linked to dark microglia and toxic lipid secretion.
Global versus local matrix remodeling drives rotational versus invasive collective migration of epithelial cells.
Reprogramming tumor-associated macrophages with lipid nanosystems reduces PDAC tumor burden and liver metastasis.
50 years since the concept of homeoviscous adaptation.
Identification of the mammalian VPS4A as a selective lipophagy receptor.
Controlled Lipid Domain Positioning and Polarization in Confined Minimal Cell Models.
Thoughts for the future.
A Miniaturized In Vivo Fluorescence Microscopy Method for Monitoring Circulating Tumor Cells in Freely Moving Animals.
Generation of a selective senolytic platform using a micelle-encapsulated Sudan Black B conjugated analog.
Inflammation switches the chemoattractant requirements for naive lymphocyte entry into lymph nodes.

bioRxiv. 2024 Dec 09. pii: 2023.07.30.551157. [Epub ahead of print]

Cell membranes sustain phospholipid imbalance via cholesterol asymmetry.

Milka Doktorova, Jessica L Symons, Xiaoxuan Zhang, Hong-Yin Wang, Jan Schlegel, Joseph H Lorent, Frederick A Heberle, Erdinc Sezgin, Edward Lyman, Kandice R Levental, Ilya Levental.

  Membranes are molecular interfaces that compartmentalize cells to control the flow of nutrients and information. These functions are facilitated by diverse collections of lipids, nearly all of which are distributed asymmetrically between the two bilayer leaflets. Most models of biomembrane structure and function often include the implicit assumption that these leaflets have similar abundances of phospholipids. Here, we show that this assumption is generally invalid and investigate the consequences of lipid abundance imbalances in mammalian plasma membranes (PM). Using quantitative lipidomics, we discovered that cytoplasmic leaflets of human erythrocyte membranes have >50% overabundance of phospholipids compared to exoplasmic leaflets. This imbalance is enabled by an asymmetric interleaflet distribution of cholesterol, which regulates cellular cholesterol homeostasis. These features produce unique functional characteristics, including low PM permeability and resting tension in the cytoplasmic leaflet that regulates protein localization. These largely overlooked aspects of membrane asymmetry represent an evolution of classic paradigms of biomembrane structure and physiology.

Keywords:  cholesterol; lipid asymmetry; lipid diffusion; membrane packing; membrane structure; peripheral protein; permeability; phospholipid; plasma membrane; protein-membrane interactions

DOI:  https://doi.org/10.1101/2023.07.30.551157
bioRxiv. 2024 Dec 14. pii: 2024.12.13.628212. [Epub ahead of print]

Leucine Aminopeptidase LyLAP enables lysosomal degradation of membrane proteins.

Aakriti Jain, Isaac Heremans, Gilles Rademaker, Tyler C Detomasi, Grace A Hernandez, Justin Zhang, Suprit Gupta, Teresa von Linde, Mike Lange, Martina Spacci, Peter Rohweder, Dashiell Anderson, Y Rose Citron, James A Olzmann, David W Dawson, Charles S Craik, Guido Bommer, Rushika M Perera, Roberto Zoncu.

Proteolysis of hydrophobic helices is required for complete breakdown of every transmembrane protein trafficked to the lysosome and sustains high rates of endocytosis. However, the lysosomal mechanisms for degrading hydrophobic domains remain unknown. Combining lysosomal proteomics with functional genomic data mining, we identify Lysosomal Leucine Aminopeptidase (LyLAP; formerly Phospholipase B Domain-Containing 1) as the hydrolase most tightly associated with elevated endocytic activity. Untargeted metabolomics and biochemical reconstitution demonstrate that LyLAP is not a phospholipase, but a processive monoaminopeptidase with strong preference for N-terminal leucine - an activity necessary and sufficient for breakdown of hydrophobic transmembrane domains. LyLAP is upregulated in pancreatic ductal adenocarcinoma (PDA), which relies on macropinocytosis for nutrient uptake, and its ablation led to buildup of undigested hydrophobic peptides, which compromised lysosomal membrane integrity and inhibited PDA cell growth. Thus, LyLAP enables lysosomal degradation of membrane proteins, and may represent a vulnerability in highly endocytic cancer cells.
One sentence summary: LyLAP degrades transmembrane proteins to sustain high endocytosis and lysosomal membrane stability in pancreatic cancer.

DOI: https://doi.org/10.1101/2024.12.13.628212
Mol Biol Cell. 2024 Dec 24. mbcE24030101

Ubiquitin-mediated recruitment of the ATG9A-ATG2 lipid transfer complex drives clearance of phosphorylated p62 aggregates.

D G Broadbent, C M McEwan, D Jayatunge, E G Kaminsky, T M Tsang, D M Poole, B C Naylor, J C Price, J C Schmidt, J L Andersen.

Autophagy is an essential cellular recycling process that maintains protein and organelle homeostasis. ATG9A vesicle recruitment is a critical early step in autophagy to initiate autophagosome biogenesis. The mechanisms of ATG9A vesicle recruitment are best understood in the context of starvation-induced non-selective autophagy, whereas less is known about the signals driving ATG9A vesicle recruitment to autophagy initiation sites in the absence of nutrient stress. Here we demonstrate that loss of ATG9A, or the lipid transfer protein ATG2, leads to the accumulation of phosphorylated p62 aggregates in nutrient replete conditions. Furthermore, we show that p62 degradation requires the lipid scramblase activity of ATG9A. Lastly, we present evidence that poly-ubiquitin is an essential signal that recruits ATG9A and mediates autophagy foci assembly in nutrient replete cells. Together, our data support a ubiquitin-driven model of ATG9A recruitment and autophagosome formation during basal autophagy. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].

DOI: https://doi.org/10.1091/mbc.E24-03-0101
Dev Cell. 2024 Dec 19. pii: S1534-5807(24)00725-1. [Epub ahead of print]

Tuft cells transdifferentiate to neural-like progenitor cells in the progression of pancreatic cancer.

Daniel J Salas-Escabillas, Megan T Hoffman, Sydney M Brender, Jacee S Moore, Hui-Ju Wen, Simone Benitz, Erick T Davis, Daniel Long, Allison M Wombwell, Ella Rose D Chianis, Brittany L Allen-Petersen, Nina G Steele, Rosalie C Sears, Ichiro Matsumoto, Kathleen E DelGiorno, Howard C Crawford.

  Pancreatic ductal adenocarcinoma (PDA) is partly initiated through the transdifferentiation of acinar cells to metaplasia, which progresses to neoplasia and cancer. Tuft cells (TCs) are chemosensory cells not found in the normal pancreas but arise in cancer precursor lesions and diminish during progression to carcinoma. These metaplastic TCs (mTCs) suppress tumor progression through communication with the tumor microenvironment, but their fate during progression is unknown. To determine the fate of mTCs during PDA progression, we created a dual recombinase lineage trace model, wherein a pancreas-specific FlpO was used to induce tumorigenesis, while a tuft-cell specific Pou2f3CreERT/+ driver was used to induce expression of a tdTomato reporter. We found that mTCs in carcinoma transdifferentiate into neural-like progenitor cells (NRPs), a cell type associated with poor survival in patients. Using conditional knockout and overexpression systems, we found that Myc activity in mTCs is necessary and sufficient to induce this tuft-to-neuroendocrine transition (TNT).

Keywords:  cellular plasticity; lineage trace; metaplasia; transdifferentiation

DOI:  https://doi.org/10.1016/j.devcel.2024.12.003
Autophagy. 2024 Dec 27.

Reconsidering the selectivity of bulk autophagy: cargo hitchhiking specifies cargo for degradation.

Eigo Takeda, Alexander I May, Yoshinori Ohsumi.

  Bulk macroautophagy/autophagy, typically induced by starvation, is generally thought to non-selectively isolate cytosolic components for degradation. However, a detailed analysis of bulk autophagy cargo has not been conducted. We recently employed mass spectrometry to analyze the contents of isolated autophagic bodies. In this process, we uncovered Hab1 (Highly enriched in Autophagic Bodies 1), a novel protein, that is preferentially delivered via autophagy. Hab1 is a receptor protein that binds Atg8-PE and ribosomes at its N- and C-termini, respectively. We found that ribosome-bound Hab1 is preferentially delivered to the vacuole by "'hitchhiking'" on phagophores/isolation membranes formed during bulk autophagy. This hitchhiking mechanism confers selectivity to bulk autophagy.

Keywords:  Atg8; Hab1; Saccharomyces cerevisiae; hitchhiking; ribosome

DOI:  https://doi.org/10.1080/15548627.2024.2447209
Curr Issues Mol Biol. 2024 Nov 23. 46(12): 13364-13382

Characterization of a Cancer-Induced Bone Pain Model for Use as a Model of Cancer Cachexia.

Takuya Hasegawa, Kohichi Kawahara, Koji Sato, Yoshihisa Asano, Takehiko Maeda.

  Cancer cachexia is a debilitating syndrome characterized by progressive weight loss, muscle wasting, and systemic inflammation. Despite the prevalence and severe consequences of cancer cachexia, effective treatments for this syndrome remain elusive. Therefore, there is a greater need for well-characterized animal models to identify novel therapeutic targets. Certain manifestations of cachexia, such as pain and depression, have been extensively studied using animal models of cancer-induced bone pain (CIBP). In contrast, other aspects of cachexia have received less attention in these models. To address this issue, we established the CIBP model by injecting Lewis lung carcinoma into the intramedullary cavity of the femur, observed cachexia-related symptoms, and demonstrated the utility of this model as a preclinical platform to study cancer cachexia. This model accurately recapitulates key features of cancer cachexia, including weight loss, muscle atrophy, adipose tissue depletion, CIBP, and anxiety. These findings suggest that psychological factors, in addition to physiological and metabolic factors, play significant roles in cancer cachexia development. Our model offers a valuable resource for investigating the underlying mechanisms of cancer cachexia and for developing innovative therapeutic strategies that target physical and psychological components.

Keywords:  animal model; cancer cachexia; nutritional impact symptoms

DOI:  https://doi.org/10.3390/cimb46120797
Cell Death Differ. 2024 Dec 21.

Senolysis by ABT-263 is associated with inherent apoptotic dependence of cancer cells derived from the non-senescent state.

Fleur Jochems, Chrysiida Baltira, Julie A MacDonald, Veerle Daniels, Abhijeet Mathur, Mark C de Gooijer, Olaf van Tellingen, Anthony Letai, René Bernards.

Cellular senescence is a stress response that cells can employ to resist cell death. Senescent cells rely on anti-apoptotic signaling for their survival, which can be targeted by senolytic agents, like the BCL-XL, BCL-2, BCL-W inhibitor ABT-263. However, the response to ABT-263 of senescent cancer cells ranges from highly sensitive to refractory. Using BH3 profiling, we identify here apoptotic blocks in cancer cells that are resistant to this senolytic treatment and discover a correlation between mitochondrial apoptotic priming and cellular sensitivity to ABT-263 in senescence. Intriguingly, ABT-263 sensitivity correlates with overall mitochondrial apoptotic priming, not only in senescence but also in the parental state. Moreover, we confirm that ABT-263 exposure increases dependency on MCL-1, which is most enhanced in ABT-263 sensitive cells. ABT-263 resistant cells however upregulate MCL-1, while sensitive cells exhibit low levels of this anti-apoptotic protein. Overall, our data indicate that the response of senescent cells to ABT-263 is predetermined by the mitochondrial apoptotic priming state of the parental cells, which could serve as a predictive biomarker for response to senolytic therapy.

DOI: https://doi.org/10.1038/s41418-024-01439-7
J Clin Invest. 2024 Dec 24. pii: e174249. [Epub ahead of print]

Targeted degradation of oncogenic KRASG12V triggers antitumor immunity in lung cancer models.

Dezhi Li, Ke Geng, Yuan Hao, Jiajia Gu, Saurav Kumar, Annabel T Olson, Christina C Kuismi, Hye Mi Kim, Yuanwang Pan, Fiona Sherman, Asia M Williams, Yiting Li, Fei Li, Ting Chen, Cassandra Thakurdin, Michela Ranieri, Mary Meynardie, Daniel S Levin, Janaye Stephens, Alison Chafitz, Joy Chen, Mia S Donald-Paladino, Jaylen M Powell, Ze-Yan Zhang, Wei Chen, Magdalena Ploszaj, Han Han, Shengqing Gu, Tinghu Zhang, Baoli Hu, Benjamin A Nacev, Medard Ernest Kaiza, Alice H Berger, Xuerui Wang, Jing Li, Xuejiao Sun, Yang Liu, Xiaoyang Zhang, Tullia C Bruno, Nathanael S Gray, Behnam Nabet, Kwok-Kin Wong, Hua Zhang.

  KRAS is the most frequently mutated oncogene in lung adenocarcinoma, with G12C and G12V being the most predominant forms. Recent breakthroughs in KRASG12C inhibitors have transformed the clinical management of patients with G12C mutation and advanced our understanding of its function. However, little is known about the targeted disruption of KRASG12V, partly due to a lack of specific inhibitors. Here, we leverage the degradation tag (dTAG) system to develop a KRASG12V transgenic mouse model. We explore the therapeutic potential of KRASG12V degradation and characterize its impact on the tumor microenvironment (TME). Our study reveals that degrading KRASG12V abolishes lung and pancreatic tumors in mice and causes a robust inhibition of KRAS-regulated cancer intrinsic signaling. Importantly, targeted degradation of KRASG12V reprograms the TME towards a stimulatory milieu and drives antitumor immunity, elicited mainly by effector and cytotoxic CD8+ T cells. Our work provides important insights into the impact of degrading KRASG12V on both tumor progression and immune response, highlighting degraders as a powerful strategy for targeting KRAS mutant cancers.

Keywords:  Immunology; Lung cancer; Oncology

DOI:  https://doi.org/10.1172/JCI174249
Methods Protoc. 2024 Dec 11. pii: 99. [Epub ahead of print]7(6):

Liver Cancer Neuroscience: Regulating Liver Tumors via Selective Hepatic Vagotomy.

Kylynda C Bauer, Shadin Ghabra, Chi Ma, Lee Chedester, Tim F Greten.

  Both the prevalence and mortality of liver cancers continue to rise. Early surgical interventions, including liver transplantation or resection, remain the only curative treatment. Nerves in the periphery influence tumor growth within visceral organs. Emerging cancer neuroscience efforts linked parasympathetic vagus nerves with tumor pathology, underscoring the value of vagal nerve denervation methods within cancer mouse models. Here, we describe a selective hepatic vagotomy that largely maintains non-liver parasympathetic innervation in mice. To address vagal interactions in hepatic tumor pathology, we provide an adapted methodology utilizing an established liver metastatic model. We anticipate that this methodology will expand the burgeoning field of cancer neuroscience, enabling the study of the neuroimmune, neurometabolic, and/or nerve-microbiota interactions shaping liver cancer progression and treatment.

Keywords:  A20; hepatic vagotomy; liver cancer; metastases; parasympathetic nervous system; vagus

DOI:  https://doi.org/10.3390/mps7060099
Cell Death Discov. 2024 Dec 21. 10(1): 510

Limiting serine availability during tumor progression promotes muscle wasting in cancer cachexia.

Erica Pranzini, Livio Muccillo, Ilaria Nesi, Alice Santi, Caterina Mancini, Giulia Lori, Massimo Genovese, Tiziano Lottini, Giuseppina Comito, Anna Caselli, Annarosa Arcangeli, Lina Sabatino, Vittorio Colantuoni, Maria Letizia Taddei, Paolo Cirri, Paolo Paoli.

Cancer cachexia is a multifactorial syndrome characterized by a progressive loss of body weight occurring in about 80% of cancer patients, frequently representing the leading cause of death. Dietary intervention is emerging as a promising therapeutic strategy to counteract cancer-induced wasting. Serine is the second most-consumed amino acid (AA) by cancer cells and has emerged to be strictly necessary to preserve skeletal muscle structure and functionality. Here, we demonstrate that decreased serine availability during tumor progression promotes myotubes diameter reduction in vitro and induces muscle wasting in in vivo mice models. By investigating the metabolic crosstalk between colorectal cancer cells and muscle cells, we found that incubating myotubes with conditioned media from tumor cells relying on exogenous serine consumption triggers pronounced myotubes diameter reduction. Accordingly, culturing myotubes in a serine-free medium induces fibers width reduction and suppresses the activation of the AKT-mTORC1 pathway with consequent impairment in protein synthesis, increased protein degradation, and enhanced expression of the muscle atrophy-related genes Atrogin1 and MuRF1. In addition, serine-starved conditions affect myoblast differentiation and mitochondrial oxidative metabolism, finally inducing oxidative stress in myotubes. Consistently, serine dietary deprivation strongly strengthens cancer-associated weight loss and muscle atrophy in mice models. These findings uncover serine consumption by tumor cells as a previously undisclosed driver in cancer cachexia, opening new routes for possible therapeutic approaches.

DOI: https://doi.org/10.1038/s41420-024-02271-1
Semin Cancer Biol. 2024 Dec 25. pii: S1044-579X(24)00097-X. [Epub ahead of print]

Organoids, tissue slices and organotypic cultures: advancing our understanding of pancreatic ductal adenocarcinoma through in vitro and ex vivo models.

Secil Ak Aksoy, Julie Earl, Jelena Grahovac, Didem Karakas, Giulia Lencioni, Sıla Sığırlı, Maarten F Bijlsma.

  Pancreatic ductal adenocarcinoma (PDAC) has one of the worst prognoses of all common solid cancers. For the large majority of PDAC patients, only systemic therapies with very limited efficacy are indicated. In addition, immunotherapies have not brought the advances seen in other cancer types. Several key characteristics of PDAC contribute to poor treatment outcomes, and in this review, we will discuss how these characteristics are best captured in currently available ex vivo or in vitro model systems. For instance, PDAC is hallmarked by a highly desmoplastic and immune-suppressed tumor microenvironment that impacts disease progression and therapy resistance. Also, large differences in tumor biology exist between and within tumors, complicating treatment decisions. Furthermore, PDAC has a very high propensity for locally invasive and metastatic growth. The use of animal models is often not desirable or feasible and several in vitro and ex vivo model systems have been developed, such as organotypic cocultures and tissue slices, among others. However, the absence of a full host organism impacts the ability of these models to accurately capture the characteristics that contribute to poor outcomes in PDAC. We will discuss the caveats and advantages of these model systems in the context of PDAC's key characteristics and provide recommendations on model choice and the possibilities for optimization. These considerations should be of use to researchers aiming to study PDAC in the in vitro setting.

Keywords:  experimental models; metastasis; organoids; pancreatic cancer; therapy resistance

DOI:  https://doi.org/10.1016/j.semcancer.2024.12.003
Elife. 2024 Dec 23. pii: RP86194. [Epub ahead of print]12

Impairment of lipid homeostasis causes lysosomal accumulation of endogenous protein aggregates through ESCRT disruption.

John Yong, Jacqueline E Villalta, Ngoc Vu, Matthew A Kukurugya, Niclas Olsson, Magdalena Preciado López, Julia R Lazzari-Dean, Kayley Hake, Fiona E McAllister, Bryson D Bennett, Calvin H Jan.

  Protein aggregation increases during aging and is a pathological hallmark of many age-related diseases. Protein homeostasis (proteostasis) depends on a core network of factors directly influencing protein production, folding, trafficking, and degradation. Cellular proteostasis also depends on the overall composition of the proteome and numerous environmental variables. Modulating this cellular proteostasis state can influence the stability of multiple endogenous proteins, yet the factors contributing to this state remain incompletely characterized. Here, we performed genome-wide CRISPRi screens to elucidate the modulators of proteostasis state in mammalian cells, using a fluorescent dye to monitor endogenous protein aggregation. These screens identified known components of the proteostasis network and uncovered a novel link between protein and lipid homeostasis. Increasing lipid uptake and/or disrupting lipid metabolism promotes the accumulation of sphingomyelins and cholesterol esters and drives the formation of detergent-insoluble protein aggregates at the lysosome. Proteome profiling of lysosomes revealed ESCRT accumulation, suggesting disruption of ESCRT disassembly, lysosomal membrane repair, and microautophagy. Lipid dysregulation leads to lysosomal membrane permeabilization but does not otherwise impact fundamental aspects of lysosomal and proteasomal functions. Together, these results demonstrate that lipid dysregulation disrupts ESCRT function and impairs proteostasis.

Keywords:  CRISPR; ESCRT; aggregation; cell biology; human; lipid dysregulation; lysosome; proteostasis

DOI:  https://doi.org/10.7554/eLife.86194
Aging Cell. 2024 Dec 27. e14462

Effects of Aging on Glucose and Lipid Metabolism in Mice.

Evan C Lien, Ngoc Vu, Anna M Westermark, Laura V Danai, Allison N Lau, Yetiş Gültekin, Matthew A Kukurugya, Bryson D Bennett, Matthew G Vander Heiden.

  Aging is accompanied by multiple molecular changes that contribute to aging associated pathologies, such as accumulation of cellular damage and mitochondrial dysfunction. Tissue metabolism can also change with age, in part, because mitochondria are central to cellular metabolism. Moreover, the cofactor NAD+, which is reported to decline across multiple tissues during aging, plays a central role in metabolic pathways such as glycolysis, the tricarboxylic acid cycle, and the oxidative synthesis of nucleotides, amino acids, and lipids. To further characterize how tissue metabolism changes with age, we intravenously infused [U-13C]-glucose into young and old C57BL/6J, WSB/EiJ, and diversity outbred mice to trace glucose fate into downstream metabolites within plasma, liver, gastrocnemius muscle, and brain tissues. We found that glucose incorporation into central carbon and amino acid metabolism was robust during healthy aging across these different strains of mice. We also observed that levels of NAD+, NADH, and the NAD+/NADH ratio were unchanged in these tissues with healthy aging. However, aging tissues, particularly brain, exhibited evidence of upregulated fatty acid and sphingolipid metabolism reactions that regenerate NAD+ from NADH. These data suggest that NAD+-generating lipid metabolism reactions may help to maintain the NAD+/NADH ratio during healthy aging.

Keywords:  NAD; aging; metabolic rate; mice

DOI:  https://doi.org/10.1111/acel.14462
Mol Cancer Ther. 2024 Dec 23.

Pan-KRAS inhibitors BI-2493 and BI-2865 display potent anti-tumor activity in tumors with KRAS wild-type allele amplification.

Antonio Tedeschi, Fiorella Schischlik, Francesca Rocchetti, Johannes Popow, Florian Ebner, Daniel Gerlach, Antonia Geyer, Valeria Santoro, Andrew S Boghossian, Matthew G Rees, Melissa M Ronan, Jennifer A Roth, Jesse Lipp, Matthias Samwer, Michael Gmachl, Norbert Kraut, Mark Pearson, Dorothea Rudolph.

KRASG12C selective inhibitors, such as sotorasib and adagrasib, have raised hopes of targeting other KRAS mutant alleles in cancer patients. We report that KRAS wild-type amplified tumor models are sensitive to treatment with the small molecule KRAS inhibitors BI-2493 and BI-2865. These pan-KRAS inhibitors directly target the "OFF" state of KRAS and result in potent anti-tumor activity in pre-clinical models of cancers driven by KRAS mutant proteins. Here, we used the high-throughput cellular viability PRISM assay to assess the anti-proliferative activity of BI-2493 in a 900+ cancer cell line panel, expanding on our previous work. KRAS wild-type amplified cancer cell lines, with a copy number >7, were identified as the most sensitive, across cell lines with any KRAS alterations, to our pan-KRAS inhibitors. Importantly, our data suggest that a KRAS "OFF" inhibitor is better suited to treat KRAS wild-type amplified tumors than a KRAS "ON" inhibitor. KRAS wild-type amplification is common in patients with gastroesophageal cancers where it has been shown to act as a unique cancer driver with little overlap to other actionable mutations. The pan-KRAS inhibitors BI-2493 and BI-2865 show potent anti-tumor activity in vitro and in vivo in KRAS wild-type amplified cell lines from this and other tumor types. In conclusion, this is the first study to demonstrate that direct pharmacological inhibition of KRAS shows anti-tumor activity in preclinical models of cancer with KRAS wild-type amplification, suggesting a novel therapeutic concept for patients with cancers bearing this KRAS alteration.

DOI: https://doi.org/10.1158/1535-7163.MCT-24-0386
bioRxiv. 2024 Dec 12. pii: 2024.09.23.614468. [Epub ahead of print]

Caveolin-1 regulates context-dependent signaling and survival in Ewing Sarcoma.

Dagan Segal, Xiaoyu Wang, Hanieh Mazloom-Farisbaf, Divya Rajendran, Erin Butler, Bingying Chen, Bo-Jui Chang, Khushi Ahuja, Averi Perny, Kushal Bhatt, Dana Kim Reed, Diego H Castrillon, Jeon Lee, Elise Jeffery, Lei Wang, Khai Nguyen, Noelle S Williams, Stephen X Skapek, Satwik Rajaram, Reto Fiolka, Khuloud Jaqaman, Gary Hon, James F Amatruda, Gaudenz Danuser.

Cellular plasticity is a hallmark function of cancer, but many of the underlying mechanisms are not well understood. In this study, we identify Caveolin-1, a scaffolding protein that organizes plasma membrane domains, as a context-dependent regulator of survival signaling in Ewing sarcoma (EwS). Single cell analyses reveal a distinct subpopulation of EwS cells, which highly express the surface marker CD99 as well as Caveolin-1. CD99 High cells exhibit distinct morphology, gene expression, and enhanced survival capabilities compared to CD99 Low cells. Mechanistically, we show that elevated Caveolin-1 expression in CD99 High cells orchestrates PI3K/AKT survival signaling by modulating the spatial organization of PI3K activity at the cell surface. Notably, CD99 itself is not directly involved in this pathway, making it a useful independent marker for identifying these subpopulations. We propose a model where the CD99 High state establishes a Cav-1-driven signaling network to support cell survival that is distinct from the AKT-independent survival mechanisms of CD99 Low cells. This work reveals a dynamic state transition in EwS cells and highlights Caveolin-1 as a key driver of context-specific survival signaling.

DOI: https://doi.org/10.1101/2024.09.23.614468
Trends Neurosci. 2024 Dec 26. pii: S0166-2236(24)00242-X. [Epub ahead of print]

Peripheral, central, and chemotherapy-induced neuropathic changes in pancreatic cancer.

Luju Jiang, Shuqi Cai, Zheqi Weng, Shan Zhang, Shu-Heng Jiang.

  In pancreatic cancer, significant alterations occur in the local nervous system, including axonogenesis, neural remodeling, perineural invasion, and perineural neuritis. Pancreatic cancer can impact the central nervous system (CNS) through cancer cell-intrinsic factors or systemic factors, particularly in the context of cancer cachexia. These peripheral and central neuropathic changes exert substantial influence on cancer initiation and progression. Moreover, chemotherapy-induced neuropathy is common in pancreatic cancer, causing peripheral nerve damage and cognitive dysfunction. Targeting the crosstalk between pancreatic cancer and the nervous system, either peripherally or centrally, holds promise in cancer treatment, pain relief, and improved quality of life. Here, we summarize recent findings on the molecular mechanisms behind these neuropathic changes in pancreatic cancer and discuss potential intervention strategies.

Keywords:  brain–cancer interactions; cancer neuroscience; cognitive impairment; nerve dependence; neural invasion; tumor innervation

DOI:  https://doi.org/10.1016/j.tins.2024.11.008
Biophys J. 2024 Dec 20. pii: S0006-3495(24)04101-8. [Epub ahead of print]

Diet therapy abates mutant APC and KRas effects by reshaping plasma membrane cholesterol nanodomains.

Eunjoo Kim, Alfredo Erazo-Oliveras, Mónica Munoz-Vega, Natividad R Fuentes, Michael L Salinas, Miranda J George, Roger S Zoh, Martha E Hensel, Bhimanagouda S Patil, Ivan Ivanov, Nancy D Turner, Robert S Chapkin.

Cholesterol-enriched plasma membrane domains are known to serve as signaling platforms in a diverse array of cellular processes. However, the link between cholesterol homeostasis and mutant APC-KRas-associated colorectal tumorigenesis remains to be established. Thus, we investigated the impact of Apc-Kras on (i) colonocyte plasma membrane cholesterol homeostasis, order, and receptor nanoclustering, (ii) colonocyte cell proliferation, and (iii) whether these effects are modulated by select membrane active dietaries (MADs). We observed that oncogenic APC-KRas increased membrane order by perturbing cholesterol homeostasis when cell proliferation is upregulated, in part by altering the expression of genes associated with cholesterol influx, export and de novo synthesis in mouse colorectal cancer (CRC) models and CRC patients. Additionally, oncogene-induced loss of cholesterol homeostasis altered Fzd7, LRP6 and KRas cluster structure/organization. Notably, we show that the combination of chemo-protective MADs, i.e., n-3 PUFAs and curcumin, reduced colonic membrane free cholesterol, order, receptor cluster size, cell proliferation and the number of dysplastic foci in mutant APC-KRas models. This work highlights the dynamic shaping of plasma membrane organization during colon tumorigenesis and the utility of membrane-targeted cancer therapy.

DOI: https://doi.org/10.1016/j.bpj.2024.12.020
FEBS Lett. 2024 Dec 23.

Membrane structure-responsive lipid scramblase activity of the TMEM63/OSCA family.

Yugo Miyata, Megumi Nishimura, Aya Nagata, Xu Jing, Cheryl S Sultan, Risa Kuribayashi, Katsuya Takahashi, Yongchan Lee, Tomohiro Nishizawa, Katsumori Segawa.

  Phospholipids are asymmetrically distributed in the plasma membrane (PM), and scramblases disrupt this asymmetry by shuffling phospholipids. We recently identified mouse Tmem63b as a membrane structure-responsive scramblase. Tmem63b belongs to the TMEM63/OSCA family of ion channels; however, the conservation of the scramblase activity within this family remains unclear. We expressed human TMEM63 paralogs, TMEM63B orthologs, and plant OSCA1.1 in Tmem63b-deficient mouse pro-B cells and found that vertebrate TMEM63B orthologs exhibit scramblase activity at the PM. Previously, ten pathogenic human TMEM63B variants were identified, some of which exhibited constitutive scramblase activity. Upon expressing all variants, we found that nine variants displayed constitutive scramblase activity. These results suggest that membrane structure-responsive scramblase activity at the PM is conserved among vertebrate TMEM63B orthologs.

Keywords:  ion channel; mechanotransduction; neurodegeneration; phospholipid; plasma membrane; scramblase

DOI:  https://doi.org/10.1002/1873-3468.15084
J Biochem. 2024 Dec 27. pii: mvae091. [Epub ahead of print]

Targeting senescent cells for the treatment of age-associated diseases.

Masayoshi Suda, Tamar Tchkonia, James L Kirkland, Tohru Minamino.

  Cellular senescence, which entails cellular dysfunction and inflammatory factor release-the senescence-associated secretory phenotype (SASP)-is a key contributor to multiple disorders, diseases, and the geriatric syndromes. Targeting senescent cells using senolytics has emerged as a promising therapeutic strategy for these conditions. Among senolytics, the combination of dasatinib and quercetin (D + Q) was the earliest and one of the most successful so far. D + Q delays, prevents, alleviates, or treats multiple senescence-associated diseases and disorders with improvements in healthspan across various preclinical models. While early senolytic therapies have demonstrated promise, ongoing research is crucial to refine them and address such challenges as off-target effects. Recent advances in senolytics include new drugs and therapies that target senescent cells more effectively. The identification of senescence-associated antigens-cell surface molecules on senescent cells-pointed to another promising means for developing novel therapies and identifying biomarkers of senescent cell abundance.

Keywords:  Cell surface proteins; Cellular senescence; Immunotherapy; Seno-antigens; Senolytics

DOI:  https://doi.org/10.1093/jb/mvae091
Eur J Cancer. 2024 Dec 21. pii: S0959-8049(24)01804-5. [Epub ahead of print]216 115197

Extensive molecular profiling of KRAS wild-type as compared to KRAS mutated pancreatic ductal adenocarcinoma on 318 patients.

Jeanne Lena, Mélissa Alamé, Antoine Italiano, Isabelle Soubeyran, Laura Blouin, Emmanuel Khalifa, Sophie Cousin, Simon Pernot, Lola-Jade Palmieri.

   PURPOSE: Molecular profiling is increasingly implemented to guide treatment of advanced pancreatic ductal adenocarcinoma (PDAC), especially when for clinical trials enrollment. This study aimed to describe actionable alterations detected in KRAS mutated (KRASm) versus KRAS wild-type (KRASwt) PDAC, the latter group being considered enriched in molecular alterations.
METHODS: This prospective monocentric study included patients with locally advanced or metastatic PDAC who underwent next-generation sequencing (NGS) on liquid biopsy and/or tissue samples between 2015 and 2023, as part of the BIP academic study (NCT02534649). Actionable alterations were classified using the ESCAT (ESMO Scale for Clinical Actionability of molecular Targets).
RESULTS: A total of 378 patients with a PDAC underwent NGS: 73 on tissue samples, 162 on liquid biopsies, and 143 on both tissue and liquid. Liquid biopsies had a 59.3 % performance (181 informative samples out of 305). Among 318 informative NGS samples, 273 (86 %) were KRASm, and 45 (14 %) were KRASwt. Median overall survival (OS) was 19.35 in KRASwt patients and 16.89 months for KRASm patients (HR 0.67, 95 %CI (0.49-0.90), p = 0.02). ESCAT alterations were found in 15.7 % of total population, with 31.1 % in KRASwt tumors and 13.2 % in KRASm tumors. BRCA1/2 mutations were identified in 7.5 % of the population, and one NTRK fusion was found in a KRASwt PDAC. The molecular tumor board considered 71 patients (22.3 %) eligible for early-phase trials, with 14 treated with matched therapy.
CONCLUSION: Although actionable mutations were more frequent in KRASwt tumors, 13.2 % of KRASm PDAC harbored ESCAT alterations, emphasizing the importance of molecular profiling regardless of KRAS status.

Keywords:  ESCAT; Liquid biopsy; Molecular profiling; Pancreatic ductal adenocarcinoma; Precision medicine

DOI:  https://doi.org/10.1016/j.ejca.2024.115197
FEBS Open Bio. 2024 Dec 23.

Cost-effective and simple flow cytometry quantification of receptor-mediated autophagy using fluorescent tagging.

Mija Marinković, Ana Rožić, Denis Polančec, Ivana Novak.

  Mitophagy, a selective clearance of damaged or superfluous mitochondria via autophagy machinery and lysosomal degradation, is an evolutionarily conserved process essential for various physiological functions, including cellular differentiation and immune responses. Defects in mitophagy are implicated in numerous human diseases, such as neurodegenerative disorders, cancer, and metabolic conditions. Despite significant advancements in mitophagy research over recent decades, novel and robust methodologies are necessary to elucidate its molecular mechanisms comprehensively. In this study, we present a detailed protocol for quantitatively assessing mitophagy through flow cytometry using a mitochondria-targeted fluorescent mitophagy receptor, GFP-BNIP3L/NIX. This method offers a rapid alternative to conventional microscopy or immunoblotting techniques for analyzing mitophagy activity. Additionally, this approach can theoretically be adapted to utilize any fluorescent-tagged selective autophagy receptor, enabling the direct and rapid analysis of various types of receptor-mediated selective autophagy.

Keywords:  BNIP3L/NIX; flow cytometry; fluorescent tagging; receptor‐mediated mitophagy

DOI:  https://doi.org/10.1002/2211-5463.13958
Mol Cell. 2024 Dec 10. pii: S1097-2765(24)00950-X. [Epub ahead of print]

RNA sensing induced by chromosome missegregation augments anti-tumor immunity.

Nobunari Sasaki, Mizuki Homme, Takahiko Murayama, Tatsuya Osaki, Toshiyuki Tenma, Tadaichi An, Yujiro Takegami, Tetsuo Tani, Patrick C Gedeon, Yoshihisa Kobayashi, Israel Cañadas, David A Barbie, Ryoji Yao, Shunsuke Kitajima.

  Viral mimicry driven by endogenous double-stranded RNA (dsRNA) stimulates innate and adaptive immune responses. However, the mechanisms that regulate dsRNA-forming transcripts during cancer therapy remain unclear. Here, we demonstrate that dsRNA is significantly accumulated in cancer cells following pharmacologic induction of micronuclei, stimulating mitochondrial antiviral signaling (MAVS)-mediated dsRNA sensing in conjunction with the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway. Activation of cytosolic dsRNA sensing cooperates with double-stranded DNA (dsDNA) sensing to upregulate immune cell migration and antigen-presenting machinery. Tracing of dsRNA-sequences reveals that dsRNA-forming transcripts are predominantly generated from non-exonic regions, particularly in locations proximal to genes exhibiting high chromatin accessibility. Activation of this pathway by pulsed monopolar spindle 1 (MPS1) inhibitor treatment, which potently induces micronuclei formation, upregulates cytoplasmic dsRNA sensing and thus promotes anti-tumor immunity mediated by cytotoxic lymphocyte activation in vivo. Collectively, our findings uncover a mechanism in which dsRNA sensing cooperates with dsDNA sensing to boost immune responses, offering an approach to enhance the efficacy of cancer therapies targeting genomic instability.

Keywords:  MAVS; Mps1; STING; cGAS; chromosome missegregation; dsRNA; micronuclei; tumor immunity; type I interferon

DOI:  https://doi.org/10.1016/j.molcel.2024.11.025
bioRxiv. 2024 Dec 11. pii: 2024.12.02.626454. [Epub ahead of print]

Heat-Induced Phosphatidylserine Changes Drive HSPA1A's Plasma Membrane Localization.

Jensen Low, Rachel Altman, Allen Badolian, Azalea Blythe Cuaresma, Carolina Briseño, Uri Keshet, Oliver Fiehn, Robert V Stahelin, Nikolas Nikolaidis.

  Heat shock protein A1A (HSPA1A) is a molecular chaperone crucial in cell survival. In addition to its cytosolic functions, HSPA1A translocates to heat-shocked and cancer cells' plasma membrane (PM). In cancer, PM-localized HSPA1A (mHSPA1A) is associated with increased tumor aggressiveness and therapeutic resistance, suggesting that preventing its membrane localization could have therapeutic value. This translocation depends on HSPA1A's interaction with PM phospholipids, including phosphatidylserine (PS). Although PS binding regulates HSPA1A's membrane localization, the exact trigger for this movement remains unclear. Given that lipid modifications are a cancer hallmark, we hypothesized that PS is a crucial lipid driving HSPA1A translocation and that heat-induced changes in PS levels trigger HSPA1A's PM localization in response to heat stress. We tested this hypothesis using pharmacological inhibition and RNA interference (RNAi) targeting PS synthesis, combined with confocal microscopy, lipidomics, and western blotting. Lipidomic analysis and PS-specific biosensors confirmed a heat shock-induced PS increase, peaking immediately post-stress. Inhibition of PS synthesis with fendiline and RNAi significantly reduced HSPA1A's PM localization, while depletion of cholesterol or fatty acids had minimal effects, confirming specificity for PS. Further experiments showed that PS saturation and elongation changes did not significantly impact HSPA1A's PM localization, indicating that the total PS increase, rather than specific PS species, is the critical factor. These findings reshape current models of HSPA1A trafficking, demonstrating that PS is a crucial regulator of HSPA1A's membrane translocation during the heat shock response. This work offers new insights into lipid-regulated protein trafficking and highlights the importance of PS in controlling cellular responses to stress.

Keywords:  HSPA1A localization; Lipidomics; Phosphatidylserine; Plasma membrane; Stress response

DOI:  https://doi.org/10.1101/2024.12.02.626454
bioRxiv. 2024 Dec 14. pii: 2024.12.06.627264. [Epub ahead of print]

Deciphering Colorectal Cancer-Hepatocyte Interactions: A Multiomic Platform for Interrogation of Metabolic Crosstalk in the Liver-Tumor Microenvironment.

Alisa B Nelson, Lyndsay E Reese, Elizabeth Rono, Eric D Queathem, Yinjie Qiu, Braedan M McCluskey, Alexandra Crampton, Eric Conniff, Katherine Cummins, Ella Boytim, Senali Dansou, Justin Hwang, Sandra Safo, Patrycja Puchalska, David K Wood, Kathryn L Schwertfeger, Peter A Crawford.

Metabolic reprogramming is a hallmark of cancer, enabling tumor cells to adapt to and exploit their microenvironment for sustained growth. The liver is a common site of metastasis, but the interactions between tumor cells and hepatocytes remain poorly understood. In the context of liver metastasis, these interactions play a crucial role in promoting tumor survival and progression. This study leverages multiomics coverage of the microenvironment via liquid chromatography and high-resolution, high-mass accuracy mass spectrometry-based untargeted metabolomics, 13 C-stable isotope tracing, and RNA sequencing to uncover the metabolic impact of co-localized primary hepatocytes and a colon adenocarcinoma cell line, SW480, using a 2D co-culture model. Metabolic profiling revealed disrupted Warburg metabolism with an 80% decrease in glucose consumption and 94% decrease in lactate production by hepatocyte-SW480 co-cultures relative to SW480 control cultures. Decreased glucose consumption was coupled with alterations in glutamine and ketone body metabolism, suggesting a possible fuel switch upon co-culturing. Further, integrated multiomic analysis indicates that disruptions in metabolic pathways, including nucleoside biosynthesis, amino acids, and TCA cycle, correlate with altered SW480 transcriptional profiles and highlight the importance of redox homeostasis in tumor adaptation. Finally, these findings were replicated in 3-dimensional microtissue organoids. Taken together, these studies support a bioinformatic approach to study metabolic crosstalk and discovery of potential therapeutic targets in preclinical models of the tumor microenvironment.

DOI: https://doi.org/10.1101/2024.12.06.627264
Soft Matter. 2024 Dec 24.

Influence of the glycocalyx on the size and mechanical properties of plasma membrane-derived vesicles.

Purvil Jani, Marshall J Colville, Sangwoo Park, Youlim Ha, Matthew J Paszek, Nicholas L Abbott.

Recent studies have reported that the overexpression of MUC1 glycoproteins on cell surfaces changes the morphology of cell plasma membranes and increases the blebbing of vesicles from them, supporting the hypothesis that entropic forces exerted by MUC1 change the spontaneous curvature of cell membranes. However, how MUC1 is incorporated into and influences the size and biophysical properties of plasma-membrane-blebbed vesicles is not understood. Here we report single-vesicle-level characterization of giant plasma membrane vesicles (GPMVs) derived from cells overexpressing MUC1, revealing a 40× variation in MUC1 density between GPMVs from a single preparation and a strong correlation between GPMV size and MUC1 density. By dispersing GPMVs in aqueous liquid crystals (LCs), we show that the elasticity of the LC can be used to strain individual GPMVs into spindle-like shapes, consistent with the straining of fluid-like membranes. To quantify the influence of MUC1 on membrane mechanical properties, we analyze the shapes of strained GPMVs within a theoretical framework that integrates the effects of MUC1 density and GPMV size on strain. We measure the spontaneous curvature of GPMV membranes to be 2-10 μm-1 and weakly influenced by the 40× variation in MUC1 density, a conclusion we validate by performing independent experiments in which MUC1 is enzymatically removed from GPMVs. Overall, our study advances the understanding of heterogeneity in size and MUC1 density in GPMVs, and establishes single-vesicle-level methods for characterization of mechanical properties within a heterogeneous population of GPMVs. Furthermore, our measurements highlight differences between membrane properties of GPMVs and their parent cells.

DOI: https://doi.org/10.1039/d4sm01317d
Nat Chem Biol. 2025 Jan;21(1): 18-19

The many paths ascending to ferroptosis.

Marcus Conrad, Adam Wahida.

DOI: https://doi.org/10.1038/s41589-024-01794-z
Nat Commun. 2024 Dec 23. 15(1): 10719

Preventing excessive autophagy protects from the pathology of mtDNA mutations in Drosophila melanogaster.

Najla El Fissi, Florian A Rosenberger, Kai Chang, Alissa Wilhalm, Tom Barton-Owen, Fynn M Hansen, Zoe Golder, David Alsina, Anna Wedell, Matthias Mann, Patrick F Chinnery, Christoph Freyer, Anna Wredenberg.

Aberration of mitochondrial function is a shared feature of many human pathologies, characterised by changes in metabolic flux, cellular energetics, morphology, composition, and dynamics of the mitochondrial network. While some of these changes serve as compensatory mechanisms to maintain cellular homeostasis, their chronic activation can permanently affect cellular metabolism and signalling, ultimately impairing cell function. Here, we use a Drosophila melanogaster model expressing a proofreading-deficient mtDNA polymerase (POLγexo-) in a genetic screen to find genes that mitigate the harmful accumulation of mtDNA mutations. We identify critical pathways associated with nutrient sensing, insulin signalling, mitochondrial protein import, and autophagy that can rescue the lethal phenotype of the POLγexo- flies. Rescued flies, hemizygous for dilp1, atg2, tim14 or melted, normalise their autophagic flux and proteasome function and adapt their metabolism. Mutation frequencies remain high with the exception of melted-rescued flies, suggesting that melted may act early in development. Treating POLγexo- larvae with the autophagy activator rapamycin aggravates their lethal phenotype, highlighting that excessive autophagy can significantly contribute to the pathophysiology of mitochondrial diseases. Moreover, we show that the nucleation process of autophagy is a critical target for intervention.

DOI: https://doi.org/10.1038/s41467-024-55559-2
Neuron. 2024 Dec 19. pii: S0896-6273(24)00875-4. [Epub ahead of print]

A neurodegenerative cellular stress response linked to dark microglia and toxic lipid secretion.

Anna Flury, Leen Aljayousi, Hye-Jin Park, Mohammadparsa Khakpour, Jack Mechler, Siaresh Aziz, Jackson D McGrath, Pragney Deme, Colby Sandberg, Fernando González Ibáñez, Olivia Braniff, Thi Ngo, Simira Smith, Matthew Velez, Denice Moran Ramirez, Dvir Avnon-Klein, John W Murray, Jia Liu, Martin Parent, Susana Mingote, Norman J Haughey, Sebastian Werneburg, Marie-Ève Tremblay, Pinar Ayata.

  The brain's primary immune cells, microglia, are a leading causal cell type in Alzheimer's disease (AD). Yet, the mechanisms by which microglia can drive neurodegeneration remain unresolved. Here, we discover that a conserved stress signaling pathway, the integrated stress response (ISR), characterizes a microglia subset with neurodegenerative outcomes. Autonomous activation of ISR in microglia is sufficient to induce early features of the ultrastructurally distinct "dark microglia" linked to pathological synapse loss. In AD models, microglial ISR activation exacerbates neurodegenerative pathologies and synapse loss while its inhibition ameliorates them. Mechanistically, we present evidence that ISR activation promotes the secretion of toxic lipids by microglia, impairing neuron homeostasis and survival in vitro. Accordingly, pharmacological inhibition of ISR or lipid synthesis mitigates synapse loss in AD models. Our results demonstrate that microglial ISR activation represents a neurodegenerative phenotype, which may be sustained, at least in part, by the secretion of toxic lipids.

Keywords:  Alzheimer’s disease; ISR; dark microglia; integrated stress response; lipid secretion; lipotoxicity; microglia; neurodegeneration; neurotoxic microglia; non-cell-autonomous stress

DOI:  https://doi.org/10.1016/j.neuron.2024.11.018
Dev Cell. 2024 Dec 17. pii: S1534-5807(24)00721-4. [Epub ahead of print]

Global versus local matrix remodeling drives rotational versus invasive collective migration of epithelial cells.

Sural K Ranamukhaarachchi, Alyssa Walker, Man-Ho Tang, William D Leineweber, Sophia Lam, Wouter-Jan Rappel, Stephanie I Fraley.

  The coordinated movement of cell collectives is essential for normal epithelial tissue development, maintenance, and cancer progression. Here, we report on a minimal 3D extracellular matrix (ECM) system wherein both invasive collective migration (ICM) and rotational collective migration (RCM) arise spontaneously from individually seeded epithelial cells of mammary and hepatic origin, regardless of whether they express adherens junctions, and lead to ductal-like and acinar-like structures, respectively. Quantitative microscopy and cellular Potts modeling reveal that initial differences in cell protrusion dynamics and matrix-remodeling localization generate RCM and ICM behavior in confining 3D ECM. Matrix-remodeling activity by matrix metalloproteinases (MMPs) is localized to the base of protrusions in cells that initiate ICM, whereas RCM does not require MMPs and is associated with ITGβ1-mediated remodeling localized globally around the cell body. Further analysis in vitro and in vivo supports the concept that distinct matrix-remodeling strategies encode collective migration behaviors and tissue structure.

Keywords:  ITGβ1; MT1-MMP; adherens junctions; adhesion; collective migration; invasive migration; matrix metalloproteinase; matrix remodeling; rotational migration

DOI:  https://doi.org/10.1016/j.devcel.2024.11.021
J Nanobiotechnology. 2024 Dec 24. 22(1): 795

Reprogramming tumor-associated macrophages with lipid nanosystems reduces PDAC tumor burden and liver metastasis.

Adrián Palencia-Campos, Laura Ruiz-Cañas, Marcelina Abal-Sanisidro, Juan Carlos López-Gil, Sandra Batres-Ramos, Sofia Mendes Saraiva, Balbino Yagüe, Diego Navarro, Sonia Alcalá, Juan A Rubiolo, Nadège Bidan, Laura Sánchez, Simona Mura, Patrick C Hermann, María de la Fuente, Bruno Sainz.

   BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) requires innovative therapeutic strategies to counteract its progression and metastatic potential. Since the majority of patients are diagnosed with advanced metastatic disease, treatment strategies targeting not only the primary tumor but also metastatic lesions are needed. Tumor-Associated Macrophages (TAMs) have emerged as central players, significantly influencing PDAC progression and metastasis. Our objective was to validate an innovative therapeutic strategy involving the reprogramming of TAMs using lipid nanosystems to prevent the formation of a pro-metastatic microenvironment in the liver.
RESULTS: In vitro results demonstrate that M2-polarized macrophages lose their M2-phenotype following treatment with lipid nanoemulsions composed of vitamin E and sphingomyelin (VitE:SM), transitioning to an M0/M1 state. Specifically, VitE:SM nanoemulsion treatment decreased the expression of macrophage M2 markers such as Arg1 and Egr2, while M1 markers such as Cd86, Il-1b and Il-12b increased. Additionally, the TGF-βR1 inhibitor Galunisertib (LY2157299) was loaded into VitE:SM nanoemulsions and delivered to C57BL/6 mice orthotopically injected with KPC PDAC tumor cells. Treated mice showed diminished primary tumor growth and reduced TAM infiltration in the liver. Moreover, we observed a decrease in liver metastasis with the nanoemulsion treatment in an intrasplenic model of PDAC liver metastasis. Finally, we validated the translatability of our VitE:SM nanosystem therapy in a human cell-based 3D co-culture model in vivo, underscoring the pivotal role of macrophages in the nanosystem's therapeutic effect in the context of human PDAC metastasis.
CONCLUSIONS: The demonstrated effectiveness and safety of our nanosystem therapy highlights a promising therapeutic approach for PDAC, showcasing its potential in reprogramming TAMs and mitigating the occurrence of liver metastasis.

Keywords:  Galunisertib; Lipid nanoemulsions; Liver metastasis; Pancreatic ductal adenocarcinoma; Reprogramming; Tumor microenvironment; Tumor-associated macrophages

DOI:  https://doi.org/10.1186/s12951-024-03010-5
Biochimie. 2024 Dec 18. pii: S0300-9084(24)00301-8. [Epub ahead of print]

50 years since the concept of homeoviscous adaptation.

Dmitry A Los, Anna V Leusenko.

  This mini review focuses on the phenomenon of homeoviscous adaptation (HVA). The concept, which dominated for decades, had a significant impact on membrane and lipid research. It includes the functional characterization of biological membranes and their domains, the role of lipids and fatty acids in cell metabolic control, and the characterization of fatty acid desaturases and their roles in membrane properties modulation. This hypothesis led to the discovery of a feed-back manner of desaturase expression and membrane-associated temperature sensors in bacteria.

Keywords:  Cold stress; Fatty acid desaturases; Fatty acids; Heat stress; Homeoviscous adaptation; Lipids; Membrane compressibility; Membrane fluidity; Membrane viscosity; Membranes

DOI:  https://doi.org/10.1016/j.biochi.2024.12.008
Autophagy. 2024 Dec 26.

Identification of the mammalian VPS4A as a selective lipophagy receptor.

Dimitra Dialynaki, Daniel J Klionsky.

  Lipophagy is a selective type of autophagy where lipid droplets are targeted to the lysosome/vacuole for degradation. Even though lipophagy has been reported in various species, many questions remain unaddressed. How are the lipid droplets sequestered to the lysosome? What is the lipophagy receptor(s)? How is this receptor(s) regulated at a posttranslational level? A new collaborative study among several universities conducted on mouse and human hepatocytes sheds light on these questions, deciphering the lipophagy mechanism in the liver. In a recent paper, Das and colleagues identified VPS4A (vacuolar protein sorting 4 homolog A) as a selective receptor, providing new insights into the mechanistic pathway of lipophagy in mammals and its inverse association with steatotic liver diseases.

Keywords:  Autophagy; LD homeostasis; VPS4A; lipophagy; lipophagy receptor

DOI:  https://doi.org/10.1080/15548627.2024.2441535
Angew Chem Int Ed Engl. 2024 Dec 23. e202419529

Controlled Lipid Domain Positioning and Polarization in Confined Minimal Cell Models.

Koyomi Nakazawa, Antoine Lévrier, Sergii Rudiuk, Ayako Yamada, Mathieu Morel, Damien Baigl.

  Giant unilamellar vesicles (GUVs) are widely used minimal cell models where essential biological features can be reproduced, isolated and studied. Although precise spatio-temporal distribution of membrane domains is a process of crucial importance in living cells, it is still highly challenging to generate anisotropic GUVs with domains at user-defined positions. Here we describe a novel and robust method to control the spatial position of lipid domains of liquid-ordered (Lo) / liquid-disordered (Ld) phase in giant unilamellar vesicles (GUVs). Our strategy consists in confining Lo/Ld phase-separated GUVs in microfluidic channels to define free curved regions where the minority-phase domains localize and coalesce by decreasing the line energy through domain fusion. We show that this process is governed by the respective fraction of the two phases, and not by the chemical nature of the lipids involved. The spatial position and number of domains are controlled by the design of the confining microchannel and could result in polarized GUVs with a controllable number of poles. The developed method is versatile and user-friendly, while allowing to perform multiple single-vesicle experiments in parallel.

Keywords:  Giant Unilamellar Vesicle; Lipid domain; Microfluidics; Polarization; Synthetic Cell

DOI:  https://doi.org/10.1002/anie.202419529
Nat Chem Biol. 2025 Jan;21(1): 6-15

Thoughts for the future.

Lona M Alkhalaf, Cheryl Arrowsmith, Emily P Balskus, Giovanna Bergamini, Rashna Bhandari, Christopher J Chang, Peng Chen, Xing Chen, Alessio Ciulli, Julia A Cricco, Benjamin G Davis, Martina Delbianco, Natalia Dudareva, Erin Dueber, Fleur Ferguson, Priscila Oliveira de Giuseppe, Itaru Hamachi, Ming Chen Hammond, Stavroula K Hatzios, Won Do Heo, Jon Paul Janet, Siddhesh S Kamat, Stefan Knapp, Yamuna Krishnan, Kathrin Lang, Luca Laraia, Reuben B Leveson-Gower, Xiang David Li, David R Liu, Mo-Fang Liu, Nir London, Nilkamal Mahanta, Cristina Mayor-Ruiz, Tom Muir, Mário Tyago Murakami, Hyun-Woo Rhee, Matt Robers, Alex Satz, Brenda A Schulman, Ben Shen, Brian Shoichet, Erick Strauss, Tsutomu Suzuki, Pratyush Tiwary, Herbert Waldmann, Thomas R Ward, Amy Weeks, Eranthie Weerapana, Georg Winter.

DOI: https://doi.org/10.1038/s41589-024-01802-2
J Biophotonics. 2024 Dec 23. e202400496

A Miniaturized In Vivo Fluorescence Microscopy Method for Monitoring Circulating Tumor Cells in Freely Moving Animals.

Bingchen Yu, Yuxi Zhu, Fan Zhang, Da Sun, Rui Xu, Chenzheng Wang, Kai Pang.

  Metastasis is the leading cause of death in tumor patients, with circulating tumor cells (CTCs) serving as key biomarkers for tumor progression, metastasis, and recurrence. CTC quantity is closely linked to tumor dynamics, which are influenced by biological rhythms. Studying CTC distribution under various physiological conditions provides insights into metastasis mechanisms. However, due to the low abundance of CTCs, detection accuracy is limited, especially with small blood samples, making continuous data collection challenging. To address this, we developed a dual-channel miniaturized in vivo fluorescence microscopy system for real-time monitoring of CTCs in experimental animals. This system, which can be fixed to the head or back, enables dynamic, quantitative analysis of CTCs in the circulatory system. It offers a valuable tool for investigating tumor metastasis rhythms, drug evaluation, and prognostic assessment in freely moving animals, advancing research in metastasis mechanisms and cancer treatment.

Keywords:  biological rhythms; circulating tumor cells; deep learning; freely moving animals; miniaturized in vivo fluorescence microscopy

DOI:  https://doi.org/10.1002/jbio.202400496
Nat Aging. 2024 Dec 27.

Generation of a selective senolytic platform using a micelle-encapsulated Sudan Black B conjugated analog.

Sophia Magkouta, Dimitris Veroutis, Angelos Papaspyropoulos, Maria Georgiou, Nikolaos Lougiakis, Natassa Pippa, Sophia Havaki, Anastasia Palaiologou, Dimitris-Foivos Thanos, Konstantinos Kambas, Nefeli Lagopati, Nikos Boukos, Nicole Pouli, Panagiotis Marakos, Athanassios Kotsinas, Dimitris Thanos, Konstantinos Evangelou, Fotios Sampaziotis, Constantin Tamvakopoulos, Stergios Pispas, Russell Petty, Nicholas Kotopoulos, Vassilis G Gorgoulis.

The emerging field of senolytics is centered on eliminating senescent cells to block their contribution to the progression of age-related diseases, including cancer, and to facilitate healthy aging. Enhancing the selectivity of senolytic treatments toward senescent cells stands to reduce the adverse effects associated with existing senolytic interventions. Taking advantage of lipofuscin accumulation in senescent cells, we describe here the development of a highly efficient senolytic platform consisting of a lipofuscin-binding domain scaffold, which can be conjugated with a senolytic drug via an ester bond. As a proof of concept, we present the generation of GL392, a senolytic compound that carries a dasatinib senolytic moiety. Encapsulation of the GL392 compound in a micelle nanocarrier (termed mGL392) allows for both in vitro and in vivo (in mice) selective elimination of senescent cells via targeted release of the senolytic agent with minimal systemic toxicity. Our findings suggest that this platform could be used to enhance targeting of senotherapeutics toward senescent cells.

DOI: https://doi.org/10.1038/s43587-024-00747-4
Cell. 2024 Dec 17. pii: S0092-8674(24)01347-3. [Epub ahead of print]

Inflammation switches the chemoattractant requirements for naive lymphocyte entry into lymph nodes.

Kevin Y Chen, Marco De Giovanni, Ying Xu, Jinping An, Nikhita Kirthivasan, Erick Lu, Kan Jiang, Stephen Brooks, Serena Ranucci, Jiuling Yang, Shuto Kanameishi, Kenji Kabashima, Kevin Brulois, Michael Bscheider, Eugene C Butcher, Jason G Cyster.

  Sustained lymphocyte migration from blood into lymph nodes (LNs) is important for immune responses. The CC-chemokine receptor-7 (CCR7) ligand CCL21 is required for LN entry but is downregulated during inflammation, and it has been unclear how recruitment is maintained. Here, we show that the oxysterol biosynthetic enzyme cholesterol-25-hydroxylase (Ch25h) is upregulated in LN high endothelial venules during viral infection. Lymphocytes become dependent on oxysterols, generated through a transcellular endothelial-fibroblast metabolic pathway, and the receptor EBI2 for inflamed LN entry. Additionally, Langerhans cells are an oxysterol source. Ch25h is also expressed in inflamed peripheral endothelium, and EBI2 mediates B cell recruitment in a tumor model. Finally, we demonstrate that LN CCL19 is critical in lymphocyte recruitment during inflammation. Thus, our work explains how naive precursor trafficking is sustained in responding LNs, identifies a role for oxysterols in cell recruitment into inflamed tissues, and establishes a logic for the CCR7 two-ligand system.

Keywords:  CCL19; CCL21; GPR183; cholesterol metabolites; high endothelial venules; lymph nodes; lymphocyte trafficking; stromal cells; tumors; viral infection

DOI:  https://doi.org/10.1016/j.cell.2024.11.031