bims-lypmec 2024-12-15 papers

bims-lypmec

Biomed News

on Lysosomal positioning and metabolism in cardiomyocytes

Issue of 2024–12–15
eleven papers selected by
Satoru Kobayashi, New York Institute of Technology

LAMTOR1 regulates dendritic lysosomal positioning in hippocampal neurons through TRPML1 inhibition.
Lysosomal Trafficking and Degradation of Extracellular Proteins via Multivalent Small Molecule Ligand Display on Dextran Scaffolds.
Lysosomal damage due to cholesterol accumulation triggers immunogenic cell death.
USP4 depletion-driven RAB7A ubiquitylation impairs autophagosome-lysosome fusion and aggravates periodontitis.
Protocol for purifying and reconstituting a vacuole membrane transporter Ypq1 into proteoliposomes.
Cardiac dysfunction and altered gene expression in acid ceramidase deficient mice.
Iron in ventricular remodeling and aneurysms post-myocardial infarction.
ORP5 promotes cardiac hypertrophy by regulating the activation of mTORC1 on lysosome.
Inhibition of the upregulated phosphodiesterase 4D isoforms improves SERCA2a function in diabetic cardiomyopathy.
Diabetes and cardiovascular disease in older adults.
Rubicon regulates exosome secretion via the non-autophagic pathway.

Front Cell Neurosci. 2024 ;18 1495546

LAMTOR1 regulates dendritic lysosomal positioning in hippocampal neurons through TRPML1 inhibition.

Jiandong Sun, Weiju Lin, Xiaoning Hao, Michel Baudry, Xiaoning Bi.

  Intracellular lysosomal trafficking and positioning are fundamental cellular processes critical for proper neuronal function. Among the diverse array of proteins involved in regulating lysosomal positioning, the Transient Receptor Potential Mucolipin 1 (TRPML1) and the Ragulator complex have emerged as central players. TRPML1, a lysosomal cation channel, has been implicated in lysosomal biogenesis, endosomal/lysosomal trafficking including in neuronal dendrites, and autophagy. LAMTOR1, a subunit of the Ragulator complex, also participates in the regulation of lysosomal trafficking. Here we report that LAMTOR1 regulates lysosomal positioning in dendrites of hippocampal neurons by interacting with TRPML1. LAMTOR1 knockdown (KD) increased lysosomal accumulation in proximal dendrites of cultured hippocampal neurons, an effect reversed by TRPML1 KD or inhibition. On the other hand, TRPML1 activation with ML-SA1 or prevention of TRPML1 interaction with LAMTOR1 using a TAT-decoy peptide induced dendritic lysosomal accumulation. LAMTOR1 KD-induced proximal dendritic lysosomal accumulation was blocked by the dynein inhibitor, ciliobrevin D, suggesting the involvement of a dynein-mediated transport. These results indicate that LAMTOR1-mediated inhibition of TRPML1 is critical for normal dendritic lysosomal distribution and that release of this inhibition or direct activation of TRPML1 results in abnormal dendritic lysosomal accumulation. The roles of LAMTOR1-TRPML1 interactions in lysosomal trafficking and positioning could have broad implications for understanding cognitive disorders associated with lysosomal pathology and calcium dysregulation.

Keywords:  LAMP2; Ragulator; calcium; dynein; lysosomal trafficking; mTOR

DOI:  https://doi.org/10.3389/fncel.2024.1495546
Biomacromolecules. 2024 Dec 12.

Lysosomal Trafficking and Degradation of Extracellular Proteins via Multivalent Small Molecule Ligand Display on Dextran Scaffolds.

Benoit Louage, Demi Defreyne, Heleen Lauwers, Jamie De Baere, Annemiek Uvyn, Haixia Peng, Yong Chen, Bruno G De Geest.

Targeted protein degradation (TPD) marks a shift in drug development from conventional inhibition to the complete removal of pathological proteins. Traditional TPD technologies target intracellular proteins of interest (POIs) for degradation but are ineffective against extracellular cell surface and soluble proteins, a significant portion of the human proteome. Recent advances involve the formation of ternary complexes between a POI and a cell surface lysosomal trafficking receptor, directing POIs to lysosomes for degradation. We report on DEXtran TRAfficking Chimeras (DEXTRACs) comprising multiple copies of synthetic small molecule ligands for a model POI and the cation-independent mannose-6-phosphate receptor (CI-M6PR) lysosomal trafficking receptor. These ligands are arranged along the dextran backbones. We demonstrate that DEXTRACs leverage multivalency with their efficacy dependent on the dextran chain length and ligand density to form high-avidity ternary complexes. Our in vitro studies confirmed that DEXTRACs traffic the target POI to lysosomes and facilitate its degradation.

DOI: https://doi.org/10.1021/acs.biomac.4c01603
Autophagy. 2024 Dec 11.

Lysosomal damage due to cholesterol accumulation triggers immunogenic cell death.

Karla Alvarez-Valadez, Allan Sauvat, Julien Diharce, Marion Leduc, Gautier Stoll, Lionel Guittat, Flavia Lambertucci, Juliette Paillet, Omar Motino, Lucille Ferret, Alexandra Muller, Sabrina Forveille, Maria Chiara Maiuri, Oliver Kepp, Alexandre G de Brevern, Harald Wodrich, Jonathan G Pol, Guido Kroemer, Mojgan Djavaheri-Mergny.

  Cholesterol serves as a vital lipid that regulates numerous physiological processes. Nonetheless, its role in regulating cell death processes remains incompletely understood. In this study, we investigated the role of cholesterol trafficking in immunogenic cell death. Through cell-based drug screening, we identified two antidepressants, sertraline and indatraline, as potent inducers of the nuclear translocation of TFEB (transcription factor EB). Activation of TFEB was mediated through the autophagy-independent lipidation of MAP1LC3/LC3 (microtubule associated protein 1 light chain 3). Both compounds promoted cholesterol accumulation within lysosomes, resulting in lysosomal membrane permeabilization, disruption of autophagy and cell death that could be reversed by cholesterol depletion. Molecular docking analysis indicated that sertraline and indatraline have the potential to inhibit cholesterol binding to the lysosomal cholesterol transporters, NPC1 (NPC intracellular cholesterol transporter 1) and NPC2. This inhibitory effect might be further enhanced by the upregulation of NPC1 and NPC2 expression by TFEB. Both antidepressants also upregulated PLA2G15 (phospholipase A2 group XV), an enzyme that elevates lysosomal cholesterol. In cancer cells, sertraline and indatraline elicited immunogenic cell death, converting dying cells into prophylactic vaccines that were able to confer protection against tumor growth in mice. In a therapeutic setting, a single dose of each compound was sufficient to significantly reduce the outgrowth of established tumors in a T-cell-dependent manner. These results identify sertraline and indatraline as immunostimulatory agents for cancer treatment. More generally, this research shed light on novel therapeutic avenues harnessing lysosomal cholesterol transport to regulate immunogenic cell death.

Keywords:  Autophagy; NPC intracellular cholesterol transporter 1 and 2; TFEB; cancer; lipid transport; lysosomal membrane permeabilization

DOI:  https://doi.org/10.1080/15548627.2024.2440842
Autophagy. 2024 Dec 11. 1-18

USP4 depletion-driven RAB7A ubiquitylation impairs autophagosome-lysosome fusion and aggravates periodontitis.

Sen Kang, Shuxin Liu, Xian Dong, Haoyu Li, Yuanyi Qian, Anna Dai, Wentao He, Xiaojun Li, Qianming Chen, Huiming Wang, Pei-Hui Ding.

  Periodontitis, a prevalent and chronic inflammatory disease, is intricately linked with macroautophagy/autophagy, which has a dual role in maintaining periodontal homeostasis. Despite its importance, the precise interplay between autophagy and periodontitis pathogenesis remains to be fully elucidated. In this study, our investigation revealed that the ubiquitination of RAB7A, mediated by reduced levels of the deubiquitinating enzyme USP4 (ubiquitin specific peptidase 4), disrupts normal lysosomal trafficking and autophagosome-lysosome fusion, thereby contributing significantly to periodontitis progression. Specifically, through genomic and histological analysis of clinical gingival samples, we observed a decreased RAB7A expression and impaired autophagic activity in periodontitis. This was further substantiated through experimental periodontitis mice, where RAB7A inactivation was shown to directly affect autophagy efficiency and drive periodontitis progression. Next, we explored the function of active RAB7A to promote lysosomal trafficking dynamics and autophagosome-lysosome fusion, which was inhibited by RAB7A ubiquitination in macrophages stimulated by Porphyromonas gingivalis (P. g.), one of the keystone pathogens of periodontitis. Last, by proteomics analysis, we revealed that the ubiquitination of RAB7A was mediated by USP4 and validated that upregulation of USP4 could attenuate periodontitis in vivo. In conclusion, these findings highlight the interaction between USP4 and RAB7A as a promising target for therapeutic intervention in managing periodontal diseases.Abbreviation: 3-MA: 3-methyladenine; Baf A1:bafilomycin A1; BECN1: beclin 1, autophagy related; CEJ-ABC: cementoenamel junctionto alveolar bone crest; IL1B/IL-1β: interleukin 1 beta; KD:knockdown; LPS: lipopolysaccharide; MOI: multiplicity of infection;OE: overexpression; P.g.: Porphyromonasgingivalis; RILP: Rabinteracting lysosomal protein; ScRNA-seq: single-cell RNA sequencing; SQSTM1/p62: sequestosome 1; S.s.: Streptococcus sanguinis; USP4:ubiquitin specific peptidase 4.

Keywords:  Autophagy; GTP-RAB7A; IL1B; porphyromonas gingivalis; ubiquitination

DOI:  https://doi.org/10.1080/15548627.2024.2429371
STAR Protoc. 2024 Dec 10. pii: S2666-1667(24)00648-8. [Epub ahead of print]5(4): 103483

Protocol for purifying and reconstituting a vacuole membrane transporter Ypq1 into proteoliposomes.

Felichi Mae Arines, Aleksander Wielenga, Randy B Stockbridge, Ming Li.

  Studying the biochemical function of membrane transporters is important in understanding the biology of transporter-laden organelles such as lysosomes and vacuoles. We present a protocol for overexpressing, purifying, and reconstituting a vacuole membrane transporter Ypq1 into proteoliposomes and describe steps to measure transport activity using radioactive substrates. The protocols established here can be used to study other vacuolar or lysosomal membrane transporters. For complete details on the use and execution of this protocol, please refer to Arines et al.1.

Keywords:  Cell Membrane; Protein Biochemistry; Protein expression and purification

DOI:  https://doi.org/10.1016/j.xpro.2024.103483
Am J Physiol Heart Circ Physiol. 2024 Dec 12.

Cardiac dysfunction and altered gene expression in acid ceramidase deficient mice.

Annie Kleynerman, Jitka Rybova, William M McKillop, Theresa A Dlugi, Mary L Faber, Maria Fuller, Caitlin C O'Meara, Jeffrey A Medin.

  Farber disease (FD) is an ultra-rare, autosomal-recessive, lysosomal storage disorder attributed to ASAH1 gene mutations. FD is characterized by acid ceramidase (ACDase) deficiency and the accumulation of ceramide in various tissues. Classical FD patients typically manifest symptoms including lipogranulomatosis, respiratory complications, and neurological deficits, often leading to mortality during infancy. Cardiac abnormalities in several FD patients have been described; however, a detailed examination of cardiac pathology in FD has not been conducted. Here we report pronounced cardiac pathophysiology in a new P361R-FD mouse model of ACDase deficiency that we generated. P361R-FD mice displayed smaller hearts, altered cardiomyocyte architecture, disrupted tissue composition, and inclusion-containing macrophages. Echocardiography suggested ventricular atrophy, valve dysfunction, decreased cardiac output, and lowered stroke volumes. Troponin I was significantly elevated in P361R-FD mice. Hearts from P361R-FD mice were found to have increased ceramide, cholesterol, and other lipids. Histopathological analysis of heart tissue from neonatal P361R-FD mice revealed lysosomal disruption as early as postnatal day 1. Lastly, we report cardiac conduction, striated muscle contraction, and sphingolipid homeostasis gene expression differences during cardiac development in P361R-FD mice. In summary, we investigated the heart in a mouse model of ACDase deficiency, demonstrating that ACDase deficiency induced lysosomal dysfunction, sphingolipid and cholesterol imbalances, tissue disruption, and significant inflammation, leading to impaired cardiac function in these animals.

Keywords:  Farber disease; cardiac development; ceramide; lysosomal storage disorder; neonatal

DOI:  https://doi.org/10.1152/ajpheart.00289.2024
Open Med (Wars). 2024 ;19(1): 20241109

Iron in ventricular remodeling and aneurysms post-myocardial infarction.

Zuoyan Wang, Xiang Ding, Jingyu Pan, Xueyan Wang, Jieming Lin, Xinzhu Wang.

   Background: Post-myocardial infarction (MI) complications, including ventricular remodeling (VR) and left ventricular aneurysm (LVA) formation, significantly affect patient prognosis and quality of life. Both iron overload and deficiency play critical roles in these pathological processes.
Objectives: This review aims to explore the mechanisms linking abnormal iron metabolism with post-MI VR and LVA formation and to highlight therapeutic strategies that regulate iron levels to mitigate adverse cardiac remodeling.
Methods: The review analyzes existing clinical and experimental research on the role of iron metabolism in post-MI complications. It focuses on iron overload, oxidative stress, ferroptosis, and the impact of iron deficiency on mitochondrial function, energy metabolism, and cardiomyocyte repair.
Results: Iron overload exacerbates myocardial injury through oxidative stress, ferroptosis, and inflammation, leading to fibrosis and ventricular dilation. In contrast, iron-deficiency impairs mitochondrial function, energy metabolism, and cardiomyocyte repair, further contributing to adverse remodeling outcomes. Therapeutic strategies such as iron chelators, ferroptosis inhibitors, and iron supplementation are potential interventions for mitigating adverse remodeling.
Conclusion: Abnormal iron metabolism, both overload and deficiency, plays a critical role in post-MI complications. Therapeutic strategies targeting iron levels hold promise for reducing adverse cardiac remodeling and improving patient outcomes after MI.

Keywords:  ferroptosis; iron metabolism; left ventricular aneurysm; myocardial infarction; oxidative stress; ventricular remodeling

DOI:  https://doi.org/10.1515/med-2024-1109
J Adv Res. 2024 Dec 10. pii: S2090-1232(24)00591-5. [Epub ahead of print]

ORP5 promotes cardiac hypertrophy by regulating the activation of mTORC1 on lysosome.

Di Zhao, Ran Xu, Yufei Zhou, Jiaying Wu, Xiaoxue Zhang, Hong Lin, Jienan Wang, Zhiwen Ding, Yunzeng Zou.

   INTRODUCTION: Oxysterol binding protein (OSBP)-related protein 5 (ORP5) mainly functions as a lipid transfer protein at membrane contact sites (MCS). ORP5 facilitates cell proliferation through the activation of mTORC1 signaling. While the pro-hypertrophic effects of mTORC1 are well-documented, the specific role of ORP5 in the context of pathological cardiac hypertrophy remains inadequately understood.
METHODS: To investigate the role of ORP5 in pathological cardiac hypertrophy, AAV9-treated mice and neonatal rat ventricular myocytes (NRVMs) were utilized. Cardiac function, morphology, and mTORC1 signaling alterations induced by pro-hypertrophic stimuli were assessed in both myocardium and NRVMs. Additionally, a range of molecular techniques were employed to elucidate the regulatory mechanisms of ORP5 on mTORC1 in hypertrophied hearts.
RESULTS: Increased expression of ORP5 was observed in the hearts of patients with hypertrophic cardiomyopathy (HCM), in mice subjected to transverse aortic constriction (TAC), and in NRVMs treated with angiotensin II (AngII). We found that ORP5 binds to mTOR in cardiomyocytes. Upon exposure to TAC surgery, ORP5-deficient hearts exhibited enhanced cardiac function, reduced cardiomyocyte hypertrophy, and diminished collagen deposition than wild type. Conversely, overexpression of ORP5 significantly aggravated hypertrophic responses in both hearts and NRVMs. Notably, the promotion of cardiac hypertrophy induced by ORP5 overexpression was reversed by rapamycin, an inhibitor of mTORC1. Mechanistically, our study elucidated that the ORD domain of ORP5 interacts with mTORC1, facilitating its translocation to the outer membrane of the lysosome for subsequent activation. This activation triggers the downstream signaling pathways involving S6K1 and 4E-BP1, which initiate protein synthesis, thereby promoting pathological cardiac hypertrophy.
CONCLUSIONS: Our findings provide the inaugural evidence that ORP5 facilitates pathological ventricular hypertrophy through the translocation of mTORC1 to the lysosome for subsequent activation. Consequently, ORP5 has the potential to serve as a diagnostic biomarker or therapeutic target for pathological cardiac hypertrophy in the future.

Keywords:  Heart failure; Lysosome; ORP5; Pathological cardiac hypertrophy; mTORC1

DOI:  https://doi.org/10.1016/j.jare.2024.12.014
Br J Pharmacol. 2024 Dec 11.

Inhibition of the upregulated phosphodiesterase 4D isoforms improves SERCA2a function in diabetic cardiomyopathy.

Zhenduo Zhu, Qiuyun Guan, Bing Xu, Sherif Bahriz, Ao Shen, Toni M West, Yu Zhang, Bingqing Deng, Wei Wei, Yongsheng Han, Qingtong Wang, Yang K Xiang.

   BACKGROUND AND PURPOSE: Sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) is impaired in heart failure. Phosphodiesterases (PDEs) are implicated in the modulation of local cAMP signals and protein kinase A (PKA) activity essential for cardiac function. We characterise PDE isoforms that underlie decreased activities of SERCA2a and reduced cardiac contractile function in diabetic cardiomyopathy.
EXPERIMENTAL APPROACH: Wild type mice were fed with either normal chow or a high-fat diet (HFD). Cardiomyocytes were isolated for excitation-contraction coupling (ECC), fluorescence resonant energy transfer PKA biosensor and proximity ligation assays.
KEY RESULTS: The upregulated PDE4D3 and PDE4D9 isoforms in HFD cardiomyocytes specifically bound to SERCA2a but not ryanodine receptor 2 (RyR2) on the sarcoplasmic reticulum (SR). The increased association of PDE4D isoforms with SERCA2a in HFD cardiomyocytes led to reduced local PKA activities and phosphorylation of phospholamban (PLB) but minimally effected the PKA activities and phosphorylation of RyR2. These changes correlate with slower calcium decay tau in the SR and attenuation of ECC in HFD cardiomyocytes. Selective inhibition of PDE4D3 or PDE4D9 restored PKA activities and phosphorylation of PLB at the SERCA2a complex, recovered calcium decay tau, and increased ECC in HFD cardiomyocytes. Therapies with PDE4 inhibitor roflumilast, PDE4D inhibitor BPN14770 or genetical deletion of PDE4D restored PKA phosphorylation of PLB and cardiac contractile function.
CONCLUSION AND IMPLICATIONS: The current study identifies upregulation of specific PDE4D isoforms that selectively inhibit SERCA2a function in HFD-induced cardiomyopathy, indicating that this remodelling can be targeted to restore cardiac contractility in diabetic cardiomyopathy.

Keywords:  PDE4D; SERCA2a; diabetic cardiomyopathy; excitation contraction coupling; myocytes

DOI:  https://doi.org/10.1111/bph.17411
Ann N Y Acad Sci. 2024 Dec 12.

Diabetes and cardiovascular disease in older adults.

Anika Bilal, Richard Pratley.

  An aging population combined with a rapidly increasing prevalence of diabetes foreshadows a global epidemic of cardiovascular and kidney disease that threatens to halt improvements in life and health-span and will have particularly severe consequences in older adults. The management of diabetes has been transformed with the recent development of newer anti-hyperglycemic agents that have demonstrated superior efficacy. However, the utility of these drugs extends beyond glycemic control to benefits for managing obesity, cardiovascular disease (CVD), chronic kidney disease, and heart failure. Numerous cardiovascular and kidney outcomes trials of these drugs have played an instrumental role in shaping current guidelines for the management of diabetes and CVD. Older adults with diabetes are diverse in terms of their comorbidities, diabetic complications, and cognitive and functional status. Therefore, there is an unmet need for personalized management of diabetes and CVD in this population. In this review, we provide an overview of the epidemiological burden and management of diabetes and CVD in older adults. We then focus on randomized cardiovascular and kidney outcome trials with anti-hyperglycemic agents to propose an evidence-based approach to the management of diabetes in older adults with high risk of cardiovascular and kidney disease.

Keywords:  cardiovascular disease; chronic kidney disease; diabetes; heart failure; newer anti‐hyperglycemic drugs; older adults

DOI:  https://doi.org/10.1111/nyas.15259
Autophagy. 2024 Dec 12. 1-3

Rubicon regulates exosome secretion via the non-autophagic pathway.

Kyosuke Yanagawa, Tamotsu Yoshimori.

  Exosomes are small extracellular vesicles (EVs), which have the diameter of 50-150 nm and originate from intralumenal vesicles in multivesicular endosomes (MVBs). Exosomes secreted from donor cells are delivered to recipient cells for transferring of exosome cargos, such as proteins, lipids and nucleic acids. The cargo transfer by exosomes has a pivotal role in cell-to-cell communication for many cellular processes; however, the detailed mechanism remains largely elusive. In our recent study, we found that RUBCN/rubicon regulates exosome secretion through endosomal recruitment of WIPI2, which promotes ESCRT-dependent MVB formation. We further showed that this pathway is essential for age-dependent increasing of exosomes, which transfer the pro-senescent microRNAs, including Mir26a and Mir486a, and accelerate cellular senescence in the recipient cells. Our findings highlight RUBCN's key role in exosome secretion and its impact on cellular senescence, providing insights into its potential contributions to aging.

Keywords:  Aging; autophagy; exosome; extracellular vesicle; microRNA; senescence

DOI:  https://doi.org/10.1080/15548627.2024.2437653