bims-nenemi 2022-11-27 papers

bims-nenemi

Biomed News

on Neuroinflammation, neurodegeneration and mitochondria

Issue of 2022–11–27
eightteen papers selected by
Marco Tigano, Thomas Jefferson University

Double-Stranded RNA Induces Mortality in an MDA5-Mediated Type I Interferonopathy Model.
Characterization of Mitochondrial Alterations in Aicardi-Goutières Patients Mutated in RNASEH2A and RNASEH2B Genes.
SRSF6 balances mitochondrial-driven innate immune outcomes through alternative splicing of BAX.
Mito-SiPE is a sequence-independent and PCR-free mtDNA enrichment method for accurate ultra-deep mitochondrial sequencing.
Collateral deletion of the mitochondrial AAA+ ATPase ATAD1 sensitizes cancer cells to proteasome dysfunction.
Autophagy promotes cell survival by maintaining NAD levels.
Mitophagy bridges DNA sensing with metabolic adaption to expand lung cancer stem-like cells.
Compact zinc finger base editors that edit mitochondrial or nuclear DNA in vitro and in vivo.
Changes in Mitochondrial Size and Morphology in the RPE and Photoreceptors of the Developing and Ageing Zebrafish.
RIP140-Mediated NF-κB Inflammatory Pathway Promotes Metabolic Dysregulation in Retinal Pigment Epithelium Cells.
Mitochondrial topoisomerase 1 inhibition induces topological DNA damage and T cell dysfunction in patients with chronic viral infection.
BNIP3-dependent mitophagy safeguards ESC genomic integrity via preventing oxidative stress-induced DNA damage and protecting homologous recombination.
Exploring the pathogenesis of age-related macular degeneration: A review of the interplay between retinal pigment epithelium dysfunction and the innate immune system.
Inflammatory Milieu Induces Mitochondrial Alterations and Neuronal Activations in Hypothalamic POMC Neurons in a Time-Dependent Manner.
Sirt3 mitigates LPS-induced mitochondrial damage in renal tubular epithelial cells by deacetylating YME1L1.
Radiation therapy induces immunosenescence mediated by p90RSK.
Differential integrated stress response and asparagine production drive symbiosis and therapy resistance of pancreatic adenocarcinoma cells.
Mitochondrial permeability transition pore-dependent necrosis.

J Immunol. 2022 Dec 01. 209(11): 2093-2103

Double-Stranded RNA Induces Mortality in an MDA5-Mediated Type I Interferonopathy Model.

Francine Lianne Emralino, Saya Satoh, Nobuhiro Sakai, Masamichi Takami, Fumihiko Takeuchi, Nan Yan, Frank Rutsch, Takashi Fujita, Hiroki Kato.

Gain-of-function mutations in the viral dsRNA sensor melanoma differentiation-associated protein 5 (MDA5) lead to autoimmune IFNopathies, including Singleton-Merten syndrome (SMS) and Aicardi-Goutières syndrome. However, much remains unclear regarding the mechanism of disease progression and how external factors such as infection or immune stimulation with vaccination can affect the immune response. With this aim, we generated mice with human MDA5 bearing the SMS-associated mutation R822Q (hM-R822Q). hM-R822Q transgenic (Tg) mice developed SMS-like heart fibrosis, aortic valve enlargement, and aortic calcification with a systemic IFN-stimulated gene signature resulting in the activation of the adaptive immune response. Although administration of the viral dsRNA mimic polyinosinic-polycytidylic acid [poly(I:C)] did not have remarkable effects on the cardiac phenotype, dramatic inflammation was observed in the intestines where IFN production was most elevated. Poly(I:C)-injected hM-R822Q Tg mice also developed lethal hypercytokinemia marked by massive IL-6 levels in the serum. Interrupting the IFN signaling through mitochondrial antiviral signaling protein or IFN-α/β receptor alleviated hM-R822Q-induced inflammation. Furthermore, inhibition of JAK signaling with tofacitinib reduced cytokine production and ameliorated mucosal damage, enabling the survival of poly(I:C)-injected hM-R822Q Tg mice. These findings demonstrate that the MDA5 R822Q mutant introduces a critical risk factor for uncontrollable inflammation on viral infection or vaccination.

DOI: https://doi.org/10.4049/jimmunol.2200367
Int J Mol Sci. 2022 Nov 21. pii: 14482. [Epub ahead of print]23(22):

Characterization of Mitochondrial Alterations in Aicardi-Goutières Patients Mutated in RNASEH2A and RNASEH2B Genes.

Francesca Dragoni, Jessica Garau, Daisy Sproviero, Simona Orcesi, Costanza Varesio, Silvia De Siervi, Stella Gagliardi, Cristina Cereda, Orietta Pansarasa.

  Aicardi-Goutières syndrome (AGS) is a rare encephalopathy characterized by neurological and immunological features. Mitochondrial dysfunctions may lead to mitochondrial DNA (mtDNA) release and consequent immune system activation. We investigated the role of mitochondria and mtDNA in AGS pathogenesis by studying patients mutated in RNASEH2B and RNASEH2A genes. Lymphoblastoid cell lines (LCLs) from RNASEH2A- and RNASEH2B-mutated patients and healthy control were used. Transmission Electron Microscopy (TEM) and flow cytometry were used to assess morphological alterations, reactive oxygen species (ROS) production and mitochondrial membrane potential variations. Seahorse Analyzer was used to investigate metabolic alterations, and mtDNA oxidation and VDAC1 oligomerization were assessed by immunofluorescence. Western blot and RT-qPCR were used to quantify mtTFA protein and mtDNA release. Morphological alterations of mitochondria were observed in both mutated LCLs, and loss of physiological membrane potential was mainly identified in RNASEH2A LCLs. ROS production and 8-oxoGuanine levels were increased in RNASEH2B LCLs. Additionally, the VDAC1 signal was increased, suggesting a mitochondrial pore formation possibly determining mtDNA release. Indeed, higher cytoplasmic mtDNA levels were found in RNASEH2B LCLs. Metabolic alterations confirmed mitochondrial damage in both LCLs. Data highlighted mitochondrial alterations in AGS patients' LCLs suggesting a pivotal role in AGS pathogenesis.

Keywords:  Aicardi–Goutières syndrome; IFN-α; ROS; autoimmune diseases; inflammation; mitochondrial disorder; mitochondrial stress; mtDNA

DOI:  https://doi.org/10.3390/ijms232214482
Elife. 2022 Nov 21. pii: e82244. [Epub ahead of print]11

SRSF6 balances mitochondrial-driven innate immune outcomes through alternative splicing of BAX.

Allison R Wagner, Chi G Weindel, Kelsi O West, Haley M Scott, Robert O Watson, Kristin L Patrick.

  To mount a protective response to infection while preventing hyperinflammation, gene expression in innate immune cells must be tightly regulated. Despite the importance of pre-mRNA splicing in shaping the proteome, its role in balancing immune outcomes remains understudied. Transcriptomic analysis of murine macrophage cell lines identified Serine/Arginine Rich Splicing factor 6 (SRSF6) as a gatekeeper of mitochondrial homeostasis. SRSF6-dependent orchestration of mitochondrial health is directed in large part by alternative splicing of the pro-apoptosis pore-forming protein BAX. Loss of SRSF6 promotes accumulation of BAX-k, a variant that sensitizes macrophages to undergo cell death and triggers upregulation of interferon stimulated genes through cGAS sensing of cytosolic mitochondrial DNA. Upon pathogen sensing, macrophages regulate SRSF6 expression to control the liberation of immunogenic mtDNA and adjust the threshold for entry into programmed cell death. This work defines BAX alternative splicing by SRSF6 as a critical node not only in mitochondrial homeostasis, but also in the macrophage's response to pathogens.

Keywords:  chromosomes; gene expression; immunology; inflammation; mouse

DOI:  https://doi.org/10.7554/eLife.82244
Commun Biol. 2022 Nov 19. 5(1): 1269

Mito-SiPE is a sequence-independent and PCR-free mtDNA enrichment method for accurate ultra-deep mitochondrial sequencing.

Darren J Walsh, David J Bernard, Faith Pangilinan, Madison Esposito, Denise Harold, Anne Parle-McDermott, Lawrence C Brody.

The analysis of somatic variation in the mitochondrial genome requires deep sequencing of mitochondrial DNA. This is ordinarily achieved by selective enrichment methods, such as PCR amplification or probe hybridization. These methods can introduce bias and are prone to contamination by nuclear-mitochondrial sequences (NUMTs), elements that can introduce artefacts into heteroplasmy analysis. We isolated intact mitochondria using differential centrifugation and alkaline lysis and subjected purified mitochondrial DNA to a sequence-independent and PCR-free method to obtain ultra-deep (>80,000X) sequencing coverage of the mitochondrial genome. This methodology avoids false-heteroplasmy calls that occur when long-range PCR amplification is used for mitochondrial DNA enrichment. Previously published methods employing mitochondrial DNA purification did not measure mitochondrial DNA enrichment or utilise high coverage short-read sequencing. Here, we describe a protocol that yields mitochondrial DNA and have quantified the increased level of mitochondrial DNA post-enrichment in 7 different mouse tissues. This method will enable researchers to identify changes in low frequency heteroplasmy without introducing PCR biases or NUMT contamination that are incorrectly identified as heteroplasmy when long-range PCR is used.

DOI: https://doi.org/10.1038/s42003-022-04182-2
Elife. 2022 Nov 21. pii: e82860. [Epub ahead of print]11

Collateral deletion of the mitochondrial AAA+ ATPase ATAD1 sensitizes cancer cells to proteasome dysfunction.

Jacob M Winter, Heidi L Fresenius, Corey N Cunningham, Peng Wei, Heather R Keys, Jordan A Berg, Alex J Bott, Tarun Yadav, Jeremy A Ryan, Deepika Sirohi, Sheryl R Tripp, Paige Barta, Neeraj Agarwal, Anthony Letai, David M Sabatini, Matthew L Wohlever, Jared Rutter.

  The tumor suppressor gene PTEN is the second most commonly deleted gene in cancer. Such deletions often include portions of the chromosome 10q23 locus beyond the bounds of PTEN itself, which frequently disrupts adjacent genes. Coincidental loss of PTEN-adjacent genes might impose vulnerabilities that could either affect patient outcome basally or be exploited therapeutically. Here we describe how the loss of ATAD1, which is adjacent to and frequently co-deleted with PTEN, predisposes cancer cells to apoptosis triggered by proteasome dysfunction and correlates with improved survival in cancer patients. ATAD1 directly and specifically extracts the pro-apoptotic protein BIM from mitochondria to inactivate it. Cultured cells and mouse xenografts lacking ATAD1 are hypersensitive to clinically used proteasome inhibitors, which activate BIM and trigger apoptosis. This work furthers our understanding of mitochondrial protein homeostasis and could lead to new therapeutic options for the hundreds of thousands of cancer patients who have tumors with chromosome 10q23 deletion.

Keywords:  biochemistry; cancer biology; chemical biology; human; mouse

DOI:  https://doi.org/10.7554/eLife.82860
Dev Cell. 2022 Nov 21. pii: S1534-5807(22)00760-2. [Epub ahead of print]57(22): 2584-2598.e11

Autophagy promotes cell survival by maintaining NAD levels.

Tetsushi Kataura, Lucia Sedlackova, Elsje G Otten, Ruchika Kumari, David Shapira, Filippo Scialo, Rhoda Stefanatos, Kei-Ichi Ishikawa, George Kelly, Elena Seranova, Congxin Sun, Dorothea Maetzel, Niall Kenneth, Sergey Trushin, Tong Zhang, Eugenia Trushina, Charles C Bascom, Ryan Tasseff, Robert J Isfort, John E Oblong, Satomi Miwa, Michael Lazarou, Rudolf Jaenisch, Masaya Imoto, Shinji Saiki, Manolis Papamichos-Chronakis, Ravi Manjithaya, Oliver D K Maddocks, Alberto Sanz, Sovan Sarkar, Viktor I Korolchuk.

  Autophagy is an essential catabolic process that promotes the clearance of surplus or damaged intracellular components. Loss of autophagy in age-related human pathologies contributes to tissue degeneration through a poorly understood mechanism. Here, we identify an evolutionarily conserved role of autophagy from yeast to humans in the preservation of nicotinamide adenine dinucleotide (NAD) levels, which are critical for cell survival. In respiring mouse fibroblasts with autophagy deficiency, loss of mitochondrial quality control was found to trigger hyperactivation of stress responses mediated by NADases of PARP and Sirtuin families. Uncontrolled depletion of the NAD(H) pool by these enzymes ultimately contributed to mitochondrial membrane depolarization and cell death. Pharmacological and genetic interventions targeting several key elements of this cascade improved the survival of autophagy-deficient yeast, mouse fibroblasts, and human neurons. Our study provides a mechanistic link between autophagy and NAD metabolism and identifies targets for interventions in human diseases associated with autophagic, lysosomal, and mitochondrial dysfunction.

Keywords:  DNA damage; NAD; PARP; Sirtuins; ageing; autophagy; metabolism; mitochondria; mitophagy

DOI:  https://doi.org/10.1016/j.devcel.2022.10.008
EMBO Rep. 2022 Nov 23. e54006

Mitophagy bridges DNA sensing with metabolic adaption to expand lung cancer stem-like cells.

Zhen Liu, Shan Shan, Zixin Yuan, Fengying Wu, Ming Zheng, Ying Wang, Jun Gui, Wei Xu, Chunhong Wang, Tao Ren, Zhenke Wen.

  While previous studies have identified cancer stem-like cells (CSCs) as a crucial driver for chemoresistance and tumor recurrence, the underlying mechanisms for populating the CSC pool remain unclear. Here, we identify hypermitophagy as a feature of human lung CSCs, promoting metabolic adaption via the Notch1-AMPK axis to drive CSC expansion. Specifically, mitophagy is highly active in CSCs, resulting in increased mitochondrial DNA (mtDNA) content in the lysosome. Lysosomal mtDNA acts as an endogenous ligand for Toll-like receptor 9 (TLR9) that promotes Notch1 activity. Notch1 interacts with AMPK to drive lysosomal AMPK activation by inducing metabolic stress and LKB1 phosphorylation. This TLR9-Notch1-AMPK axis supports mitochondrial metabolism to fuel CSC expansion. In patient-derived xenograft chimeras, targeting mitophagy and TLR9-dependent Notch1-AMPK pathway restricts tumor growth and CSC expansion. Taken together, mitochondrial hemostasis is interlinked with innate immune sensing and Notch1-AMPK activity to increase the CSC pool of human lung cancer.

Keywords:  AMPK; Notch1; TLR9; cancer stem-like cell; mitophagy

DOI:  https://doi.org/10.15252/embr.202154006
Nat Commun. 2022 Nov 23. 13(1): 7204

Compact zinc finger base editors that edit mitochondrial or nuclear DNA in vitro and in vivo.

Julian C W Willis, Pedro Silva-Pinheiro, Lily Widdup, Michal Minczuk, David R Liu.

DddA-derived cytosine base editors (DdCBEs) use programmable DNA-binding TALE repeat arrays, rather than CRISPR proteins, a split double-stranded DNA cytidine deaminase (DddA), and a uracil glycosylase inhibitor to mediate C•G-to-T•A editing in nuclear and organelle DNA. Here we report the development of zinc finger DdCBEs (ZF-DdCBEs) and the improvement of their editing performance through engineering their architectures, defining improved ZF scaffolds, and installing DddA activity-enhancing mutations. We engineer variants with improved DNA specificity by integrating four strategies to reduce off-target editing. We use optimized ZF-DdCBEs to install or correct disease-associated mutations in mitochondria and in the nucleus. Leveraging their small size, we use a single AAV9 to deliver into heart, liver, and skeletal muscle in post-natal mice ZF-DdCBEs that efficiently install disease-associated mutations. While off-target editing of ZF-DdCBEs is likely too high for therapeutic applications, these findings demonstrate a compact, all-protein base editing research tool for precise editing of organelle or nuclear DNA without double-strand DNA breaks.

DOI: https://doi.org/10.1038/s41467-022-34784-7
Cells. 2022 Nov 09. pii: 3542. [Epub ahead of print]11(22):

Changes in Mitochondrial Size and Morphology in the RPE and Photoreceptors of the Developing and Ageing Zebrafish.

Thomas Burgoyne, Maria Toms, Chris Way, Dhani Tracey-White, Clare E Futter, Mariya Moosajee.

  Mitochondria are essential adenosine triphosphate (ATP)-generating cellular organelles. In the retina, they are highly numerous in the photoreceptors and retinal pigment epithelium (RPE) due to their high energetic requirements. Fission and fusion of the mitochondria within these cells allow them to adapt to changing demands over the lifespan of the organism. Using transmission electron microscopy, we examined the mitochondrial ultrastructure of zebrafish photoreceptors and RPE from 5 days post fertilisation (dpf) through to late adulthood (3 years). Notably, mitochondria in the youngest animals were large and irregular shaped with a loose cristae architecture, but by 8 dpf they had reduced in size and expanded in number with more defined cristae. Investigation of temporal gene expression of several mitochondrial-related markers indicated fission as the dominant mechanism contributing to the changes observed over time. This is likely to be due to continued mitochondrial stress resulting from the oxidative environment of the retina and prolonged light exposure. We have characterised retinal mitochondrial ageing in a key vertebrate model organism, that provides a basis for future studies of retinal diseases that are linked to mitochondrial dysfunction.

Keywords:  ageing; mitochondria; retina; zebrafish

DOI:  https://doi.org/10.3390/cells11223542
Curr Issues Mol Biol. 2022 Nov 21. 44(11): 5788-5801

RIP140-Mediated NF-κB Inflammatory Pathway Promotes Metabolic Dysregulation in Retinal Pigment Epithelium Cells.

Zeli Guo, Yuli Shen, Jianwen Zhong, Zhuoyun Li, Qi Guo, Xiangchao Yao, Yandong Wang, Wenyu Wu.

  Metabolic dysregulation of the retinal pigment epithelium (RPE) has been implicated in age-related macular degeneration (AMD). However, the molecular regulation of RPE metabolism remains unclear. RIP140 is known to affect oxidative metabolism and mitochondrial biogenesis by negatively controlling mitochondrial pathways regulated by PPAR-γ co-activator-1 α(PGC-1α). This study aims to disclose the effect of RIP140 on the RPE metabolic program in vitro and in vivo. RIP140 protein levels were assayed by Western blotting. Gene expression was tested using quantitative real-time PCR (qRT-PCR), ATP production, and glycogen concentration assays, and the release of inflammatory factors was analyzed by commercial kits. Mice photoreceptor function was measured by electroretinography (ERG). In ARPE-19 cells, RIP140 overexpression changed the expression of the key metabolic genes and lipid processing genes, inhibited mitochondrial ATP production, and enhanced glycogenesis. Moreover, RIP140 overexpression promoted the translocation of NF-κB and increased the expression and production of IL-1β, IL-6, and TNF-α in ARPE-19 cells. Importantly, we also observed the overexpression of RIP140 through adenovirus delivery in rat retinal cells, which significantly decreased the amplitude of the a-wave and b-wave measured by ERG assay. Therapeutic strategies that modulate the activity of RIP140 could have clinical utility for the treatment of AMD in terms of preventing RPE degeneration.

Keywords:  NF-κB; RIP140; age-related macular degeneration; inflammation; metabolism

DOI:  https://doi.org/10.3390/cimb44110393
Front Cell Infect Microbiol. 2022 ;12 1026293

Mitochondrial topoisomerase 1 inhibition induces topological DNA damage and T cell dysfunction in patients with chronic viral infection.

Xindi Dang, Dechao Cao, Juan Zhao, Madison Schank, Sushant Khanal, Lam Ngoc Thao Nguyen, Xiao Y Wu, Yi Zhang, Jinyu Zhang, Yong Jiang, Shunbin Ning, Ling Wang, Mohamed El Gazzar, Jonathan P Moorman, Zhi Q Yao.

  T cells are crucial for controlling viral infections; however, the mechanisms that dampen their responses during viral infections remain incompletely understood. Here, we studied the role and mechanisms of mitochondrial topoisomerase 1 (Top1mt) inhibition in mitochondrial dysfunction and T cell dysregulation using CD4 T cells from patients infected with HCV or HIV and compared it with CD4 T cells from healthy individuals following treatment with Top1 inhibitor - camptothecin (CPT). We found that Top1mt protein levels and enzymatic activity are significantly decreased, along with Top1 cleavage complex (Top1cc) formation, in mitochondria of CD4 T cells from HCV- and HIV-infected patients. Notably, treatment of healthy CD4 T cells with CPT caused similar changes, including inhibition of Top1mt, accumulation of Top1cc in mitochondria, increase in PARP1 cleavage, and decrease in mtDNA copy numbers. These molecular changes resulted in mitochondrial dysfunction, T cell dysregulation, and programmed cell death through multiple signaling pathways, recapitulating the phenotype we detected in CD4 T cells from HCV- and HIV-infected patients. Moreover, treatment of CD4 T cells from HCV or HIV patients with CPT further increased cellular and mitochondrial reactive oxygen species (ROS) production and cell apoptosis, demonstrating a critical role for Top1 in preventing mtDNA damage and cell death. These results provide new insights into the molecular mechanisms underlying immune dysregulation during viral infection and indicate that Top1 inhibition during chronic HCV or HIV infection can induce mtDNA damage and T cell dysfunction. Thus, reconstituting Top1mt protein may restore the mtDNA topology and T cell functions in humans with chronic viral infection.

Keywords:  HCV; HIV; T cell dysregulation; mitochondrial dysfunction; topoisomerase I

DOI:  https://doi.org/10.3389/fcimb.2022.1026293
Cell Death Dis. 2022 Nov 19. 13(11): 976

BNIP3-dependent mitophagy safeguards ESC genomic integrity via preventing oxidative stress-induced DNA damage and protecting homologous recombination.

Qian Zhao, Kun Liu, Lin Zhang, Zheng Li, Liang Wang, Jiani Cao, Youqing Xu, Aihua Zheng, Quan Chen, Tongbiao Zhao.

Embryonic stem cells (ESCs) have a significantly lower mutation load compared to somatic cells, but the mechanisms that guard genomic integrity in ESCs remain largely unknown. Here we show that BNIP3-dependent mitophagy protects genomic integrity in mouse ESCs. Deletion of Bnip3 increases cellular reactive oxygen species (ROS) and decreases ATP generation. Increased ROS in Bnip3-/- ESCs compromised self-renewal and were partially rescued by either NAC treatment or p53 depletion. The decreased cellular ATP in Bnip3-/- ESCs induced AMPK activation and deteriorated homologous recombination, leading to elevated mutation load during long-term propagation. Whereas activation of AMPK in X-ray-treated Bnip3+/+ ESCs dramatically ascended mutation rates, inactivation of AMPK in Bnip3-/- ESCs under X-ray stress remarkably decreased the mutation load. In addition, enhancement of BNIP3-dependent mitophagy during reprogramming markedly decreased mutation accumulation in established iPSCs. In conclusion, we demonstrated a novel pathway in which BNIP3-dependent mitophagy safeguards ESC genomic stability, and that could potentially be targeted to improve pluripotent stem cell genomic integrity for regenerative medicine.

DOI: https://doi.org/10.1038/s41419-022-05413-4
Front Neurosci. 2022 ;16 1009599

Exploring the pathogenesis of age-related macular degeneration: A review of the interplay between retinal pigment epithelium dysfunction and the innate immune system.

Josephine H C Wong, Jessica Y W Ma, Andrew I Jobling, Alice Brandli, Ursula Greferath, Erica L Fletcher, Kirstan A Vessey.

  Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss in the older population. Classical hallmarks of early and intermediate AMD are accumulation of drusen, a waste deposit formed under the retina, and pigmentary abnormalities in the retinal pigment epithelium (RPE). When the disease progresses into late AMD, vision is affected due to death of the RPE and the light-sensitive photoreceptors. The RPE is essential to the health of the retina as it forms the outer blood retinal barrier, which establishes ocular immune regulation, and provides support for the photoreceptors. Due to its unique anatomical position, the RPE can communicate with the retinal environment and the systemic immune environment. In AMD, RPE dysfunction and the accumulation of drusen drive the infiltration of retinal and systemic innate immune cells into the outer retina. While recruited endogenous or systemic mononuclear phagocytes (MPs) contribute to the removal of noxious debris, the accumulation of MPs can also result in chronic inflammation and contribute to AMD progression. In addition, direct communication and indirect molecular signaling between MPs and the RPE may promote RPE cell death, choroidal neovascularization and fibrotic scarring that occur in late AMD. In this review, we explore how the RPE and innate immune cells maintain retinal homeostasis, and detail how RPE dysfunction and aberrant immune cell recruitment contribute to AMD pathogenesis. Evidence from AMD patients will be discussed in conjunction with data from preclinical models, to shed light on future therapeutic targets for the treatment of AMD.

Keywords:  age related macular degeneration (AMD); dendritic cell; inflammation; macrophage; microglia; mononuclear phagocyte (MP); para-inflammation; retinal pigment epithelium (RPE)

DOI:  https://doi.org/10.3389/fnins.2022.1009599
Mol Neurobiol. 2022 Nov 23.

Inflammatory Milieu Induces Mitochondrial Alterations and Neuronal Activations in Hypothalamic POMC Neurons in a Time-Dependent Manner.

Yi-Chun Liao, Yeou San Lim, Pei-Wen Chu, Shau-Kwaun Chen.

  Inflammation has been associated with numerous neurological disorders. Inflammatory environments trigger a series of cellular and physiological alterations in the brain. However, how inflammatory milieu affects neuronal physiology and how neuronal alterations progress in the inflammatory environments are not fully understood. In this study, we examined the effects of pro-inflammatory milieu on mitochondrial functions and neuronal activities in the hypothalamic POMC neurons. Treating mHypoA-POMC/GFP1 with the conditioned medium collected from LPS activated macrophage were employed to mimic the inflammatory milieu during hypothalamic inflammation. After a 24-h treatment, intracellular ROS/RNS levels were elevated, and the antioxidant enzymes were reduced. Mitochondrial respiration and mitochondrial functions, including basal respiratory rate, spared respiration capacity, and maximal respiration, were all significantly compromised by inflammatory milieu. Moreover, pro-inflammatory cytokines altered mitochondrial dynamics in a time-dependent manner, resulting in the elongation of mitochondria in POMC neurons after a 24-h treatment. Additionally, the increase of C-Fos and Pomc genes expression indicated that the neurons were activated upon the stimulation of inflammatory environment. This neuronal activation of were confirmed on the LPS-challenged mice. Collectively, a short-term to midterm exposure to inflammatory milieu stimulated metabolic switch and neuronal activation, whereas chronic exposure triggered the elevation of oxidative stress, the decrease of the mitochondrial respiration, and the alterations of mitochondrial dynamics.

Keywords:  Hypothalamic POMC neurons; Inflammation; Mitochondrial dynamics; Mitochondrial functions; Pro-inflammatory cytokines

DOI:  https://doi.org/10.1007/s12035-022-03128-3
Cell Prolif. 2022 Nov 26. e13362

Sirt3 mitigates LPS-induced mitochondrial damage in renal tubular epithelial cells by deacetylating YME1L1.

Yonghong Jian, Yifei Yang, Lingli Cheng, Xueyan Yang, Hongyan Liu, Wei Li, Yuhan Wan, Dingping Yang.

Acute kidney injury (AKI) is often secondary to sepsis. Increasing evidence suggests that mitochondrial dysfunction contributes to the pathological process of AKI. In this study, we aimed to examine the regulatory roles of Sirt3 in Lipopolysaccharide (LPS)-induced mitochondrial damage in renal tubular epithelial cells (TECs). Sirt3 knockout mice were intraperitoneally injected with LPS, and cultured TECs were stimulated with LPS to evaluate the effects of Sirt3 on mitochondrial structure and function in TECs. Electron microscopy was used to assess mitochondrial morphology. Immunofluorescence staining was performed to detect protein expression and examine mitochondrial morphology. Western blotting was used to quantify protein expression. We observed that LPS increased apoptosis, induced disturbances in mitochondrial function and dynamics, and downregulated Sirt3 expression in a sepsis-induced AKI mouse model and human proximal tubular (HK-2) cells in vitro. Sirt3 deficiency further exacerbated LPS-induced renal pathological damage, apoptosis and disturbances in mitochondrial function and dynamics. On the contrary, Sirt3 overexpression in HK-2 cells alleviated these lesions. Functional studies revealed that Sirt3 overexpression alleviated LPS-induced mitochondrial damage and apoptosis in TECs by promoting OPA1-mediated mitochondrial fusion through the deacetylation of i-AAA protease (YME1L1), an upstream regulatory molecule of OPA1. Our study has identified Sirt3 as a vital factor that protects against LPS-induced mitochondrial damage and apoptosis in TECs via the YME1L1-OPA1 signaling pathway.

DOI: https://doi.org/10.1111/cpr.13362
Front Cardiovasc Med. 2022 ;9 988713

Radiation therapy induces immunosenescence mediated by p90RSK.

Masaki Imanishi, Haizi Cheng, Sivareddy Kotla, Anita Deswal, Nhat-Tu Le, Eduardo Chini, Kyung Ae Ko, Venkata S K Samanthapudi, Ling-Ling Lee, Joerg Herrmann, Xiaolei Xu, Cielito Reyes-Gibby, Sai-Ching J Yeung, Keri L Schadler, Syed Wamique Yusuf, Zhongxing Liao, Roza Nurieva, El-Ad David Amir, Jared K Burks, Nicolas L Palaskas, John P Cooke, Steven H Lin, Michihiro Kobayashi, Momoko Yoshimoto, Jun-Ichi Abe.

  Radiation therapy (RT) to the chest increases the patients' risk of cardiovascular disease (CVD). A complete understanding of the mechanisms by which RT induces CVD could lead to specific preventive, therapeutic approaches. It is becoming evident that both genotoxic chemotherapy agents and radiation induce mitochondrial dysfunction and cellular senescence. Notably, one of the common phenotypes observed in cancer survivors is accelerated senescence, and immunosenescence is closely related to both cancer risk and CVD development. Therefore, suppression of immunosenescence can be an ideal target to prevent cancer treatment-induced CVD. However, the mechanism(s) by which cancer treatments induce immunosenescence are incompletely characterized. We isolated peripheral blood mononuclear cells (PBMCs) before and 3 months after RT from 16 thoracic cancer patients. We characterized human immune cell lineages and markers of senescence, DNA damage response (DDR), efferocytosis, and determinants of clonal hematopoiesis of indeterminant potential (CHIP), using mass cytometry (CyTOF). We found that the frequency of the B cell subtype was decreased after RT. Unsupervised clustering of the CyTOF data identified 138 functional subsets of PBMCs. Compared with baseline, RT increased TBX21 (T-bet) expression in the largest B cell subset of Ki67-/DNMT3a+naïve B cells, and T-bet expression was correlated with phosphorylation of p90RSK expression. CD38 expression was also increased in naïve B cells (CD27-) and CD8+ effector memory CD45RA T cells (TEMRA). In vitro, we found the critical role of p90RSK activation in upregulating (1) CD38+/T-bet+ memory and naïve B, and myeloid cells, (2) senescence-associated β-gal staining, and (3) mitochondrial reactive oxygen species (ROS) after ionizing radiation (IR). These data suggest the crucial role of p90RSK activation in immunosenescence. The critical role of p90RSK activation in immune cells and T-bet induction in upregulating atherosclerosis formation has been reported. Furthermore, T-bet directly binds to the CD38 promoter region and upregulates CD38 expression. Since both T-bet and CD38 play a significant role in the process of immunosenescence, our data provide a cellular and molecular mechanism that links RT-induced p90RSK activation and the immunosenescence with T-bet and CD38 induction observed in thoracic cancer patients treated by RT and suggests that targeting the p90RSK/T-bet/CD38 pathway could play a role in preventing the radiation-associated CVD and improving cancer prognosis by inhibiting immunosenescence.

Keywords:  CD38; T-bet; immunosenescence; p90RSK; radiotherapy

DOI:  https://doi.org/10.3389/fcvm.2022.988713
Nat Cancer. 2022 Nov 21.

Differential integrated stress response and asparagine production drive symbiosis and therapy resistance of pancreatic adenocarcinoma cells.

Christopher J Halbrook, Galloway Thurston, Seth Boyer, Cecily Anaraki, Jennifer A Jiménez, Amy McCarthy, Nina G Steele, Samuel A Kerk, Hanna S Hong, Lin Lin, Fiona V Law, Catherine Felton, Lorenzo Scipioni, Peter Sajjakulnukit, Anthony Andren, Alica K Beutel, Rima Singh, Barbara S Nelson, Fran Van Den Bergh, Abigail S Krall, Peter J Mullen, Li Zhang, Sandeep Batra, Jennifer P Morton, Ben Z Stanger, Heather R Christofk, Michelle A Digman, Daniel A Beard, Andrea Viale, Ji Zhang, Howard C Crawford, Marina Pasca di Magliano, Claus Jorgensen, Costas A Lyssiotis.

The pancreatic tumor microenvironment drives deregulated nutrient availability. Accordingly, pancreatic cancer cells require metabolic adaptations to survive and proliferate. Pancreatic cancer subtypes have been characterized by transcriptional and functional differences, with subtypes reported to exist within the same tumor. However, it remains unclear if this diversity extends to metabolic programming. Here, using metabolomic profiling and functional interrogation of metabolic dependencies, we identify two distinct metabolic subclasses among neoplastic populations within individual human and mouse tumors. Furthermore, these populations are poised for metabolic cross-talk, and in examining this, we find an unexpected role for asparagine supporting proliferation during limited respiration. Constitutive GCN2 activation permits ATF4 signaling in one subtype, driving excess asparagine production. Asparagine release provides resistance during impaired respiration, enabling symbiosis. Functionally, availability of exogenous asparagine during limited respiration indirectly supports maintenance of aspartate pools, a rate-limiting biosynthetic precursor. Conversely, depletion of extracellular asparagine with PEG-asparaginase sensitizes tumors to mitochondrial targeting with phenformin.

DOI: https://doi.org/10.1038/s43018-022-00463-1
J Mol Cell Cardiol. 2022 Nov 18. pii: S0022-2828(22)00563-6. [Epub ahead of print]

Mitochondrial permeability transition pore-dependent necrosis.

Dexter J Robichaux, Mikako Harata, Elizabeth Murphy, Jason Karch.

  Mitochondrial permeability transition pore (mPTP)-dependent necrotic cell death is a form of necrotic cell death that is driven by mitochondrial dysfunction by the opening of the mPTP and is triggered by increases in matrix levels of Ca2+ and reactive oxygen species. This form of cell death has been implicated in ischemic injuries of the heart and brain as well as numerous degenerative diseases in the brain and skeletal muscle. This review focuses on the molecular triggers and regulators of mPTP-dependent necrosis in the context of myocardial ischemia reperfusion injury. Research over the past 50 years has led to the identity of regulators and putative pore-forming components of the mPTP. Finally, downstream consequences of activation of the mPTP as well as ongoing questions and areas of research are discussed. These questions pose a particular interest as targeting the mPTP could potentially represent an efficacious therapeutic strategy to reduce infarct size following an ischemic event.

Keywords:  ANT; ATP synthase; BAK; BAX; Calcium; CypD; Ischemia reperfusion; MPTP; Mitochondria; Mitochondrial dysfunction; Necrosis; Permeability transition; ROS

DOI:  https://doi.org/10.1016/j.yjmcc.2022.11.003