Contact (Thousand Oaks (Ventura County, Calif.))最新文献

{"title":"Remodelling of Cellular Protein Homeostasis by Enhanced ER-Mitochondrial Tethering.","authors":"Elisa Tonelli, Justyna Malecka, Elettra Barberis, Camilla Romano, Emanuela Pessolano, Maria Talmon, Armando A Genazzani, Claudio Casali, Marco Biggiogera, Marcello Manfredi, Laura Tapella, Dmitry Lim, Giulia Dematteis","doi":"10.1177/25152564251329704","DOIUrl":"10.1177/25152564251329704","url":null,"abstract":"<p><p>Alterations of endoplasmic reticulum (ER)-mitochondrial interaction have been associated with different pathological conditions, including neurodegenerative diseases, characterized by dysregulation of protein homeostasis. However, little is known about how enhanced ER-mitochondrial tethering affects cellular proteostatic machinery. Here, we transiently overexpressed synthetic ER-mitochondrial linkers (EMLs), stabilizing the ER-mitochondrial distance at ≤5 nm (denominated as 5 nm-EML) and ∼10 nm (10 nm-EML), in HeLa cells. No alterations were found in cell growth, although metabolic activity and total ATP were significantly reduced. In EML-expressing cells, global protein synthesis was significantly reduced, accompanied by a reduction of total PERK and eIF2α protein levels, but increased p-eIF2α. Unfolded protein response (UPR) markers ATF4 and ATF6 were upregulated, suggesting that enhanced ER-mitochondrial tethering deranges protein synthesis and induces a low-grade ER stress/UPR. To further investigate ER-mitochondrial tethering-induced protein dyshomeostasis, we performed shotgun mass spectrometry proteomics followed by bioinformatic analysis. Analysis of highly changed proteins and the most significantly overrepresented gene ontology (GO) terms revealed that ≤5 nm tethering preferentially affected the expression of proteins involved in RNA processing and splicing and proteasomal protein degradation, while ∼10 nm tethering preferentially affected protein translation. Both EMLs affected expression of proteins involved in mitochondrial bioenergetics and metabolism, defense against oxidative stress, ER protein homeostasis, signaling and secretion. Finally, lipidomic analysis suggests that 5 nm-EML and 10 nm-EML differentially affect lipid homeostasis. Altogether, our results suggest that enhanced ER-mitochondrial tethering leads to a profound remodeling of cellular protein homeostasis, which may play a key role in pathogenesis of Alzheimer's and other neurodegenerative diseases.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"8 ","pages":"25152564251329704"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11963730/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143775189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative Analysis of SPLICS and MCS-DETECT for Detecting Mitochondria-ER Contact Sites (MERCs).","authors":"Jieyi Zheng, Ben Cardoen, Milene Ortiz-Silva, Ghassan Hamarneh, Ivan R Nabi","doi":"10.1177/25152564251313721","DOIUrl":"10.1177/25152564251313721","url":null,"abstract":"<p><p>Detection of mitochondria-ER contacts (MERCs) from diffraction limited confocal images commonly uses fluorescence colocalization analysis of mitochondria and endoplasmic reticulum (ER) as well as split fluorescent probes, such as the split-GFP-based contact site sensor (SPLICS). However, inter-organelle distances (∼10-60 nm) for MERCs are lower than the 200-250 nm diffraction limited resolution obtained by standard confocal microscopy. Super-resolution microscopy of 3D volume analysis provides a two-fold resolution improvement (∼120 nm XY; 250 nm Z), which remains unable to resolve MERCs. MCS-DETECT, a membrane contact site (MCS) detection algorithm faithfully detects elongated ribosome-studded riboMERCs when applied to 3D STED super-resolution image volumes. Here, we expressed the SPLICS_L reporter in HeLa cells co-transfected with the ER reporter RFP-KDEL and label fixed cells with antibodies to RFP and the mitochondrial protein TOM20. MCS-DETECT analysis of 3D STED volumes was compared to contacts determined by co-occurrence colocalization analysis of mitochondria and ER or the SPLICS_L probe. Percent mitochondria coverage by MCS-DETECT derived contacts was significantly smaller than those obtained for colocalization analysis or SPLICS_L, and more closely matched contact site metrics obtained by 3D electron microscopy. Further, STED analysis localized a subset of the SPLICS_L label to mitochondria with some SPLICS_L puncta observed to be completely enveloped by mitochondria in 3D views. These data suggest that MCS-DETECT reports on a limited set of MERCs that more closely corresponds to those observed by EM.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"8 ","pages":"25152564251313721"},"PeriodicalIF":0.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11923443/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143672165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitochondria-Lysosome Contact Sites: Emerging Players in Cellular Homeostasis and Disease.","authors":"Francesca Rizzollo, Patrizia Agostinis","doi":"10.1177/25152564251329250","DOIUrl":"10.1177/25152564251329250","url":null,"abstract":"<p><p>Mitochondria and lysosomes regulate a multitude of biological processes that are essential for the maintenance of nutrient and metabolic homeostasis and overall cell viability. Recent evidence reveals that these pivotal organelles, similarly to others previously studied, communicate through specialized membrane contact sites (MCSs), hereafter referred to as mitochondria-lysosome contacts (or MLCs), which promote their dynamic interaction without involving membrane fusion. Signal integration through MLCs is implicated in key processes, including mitochondrial fission and dynamics, and the exchange of calcium, cholesterol, and amino acids. Impairments in the formation and function of MLCs are increasingly associated with age-related diseases, specifically neurodegenerative disorders and lysosomal storage diseases. However, MLCs may play roles in other pathological contexts where lysosomes and mitochondria are crucial. In this review, we introduce the methodologies used to study MLCs and discuss known molecular players and key factors involved in their regulation in mammalian cells. We also argue other potential regulatory mechanisms depending on the acidic lysosomal pH and their impact on MLC's function. Finally, we explore the emerging implications of dysfunctional mitochondria-lysosome interactions in disease, highlighting their potential as therapeutic targets in cancer.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"8 ","pages":"25152564251329250"},"PeriodicalIF":0.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11920999/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143665795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial on Special Collection in <i>Contact</i>: Lipid Transfer Proteins: From Molecular Mechanisms to Functional Validation.","authors":"Bruno Mesmin","doi":"10.1177/25152564251322628","DOIUrl":"10.1177/25152564251322628","url":null,"abstract":"","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"8 ","pages":"25152564251322628"},"PeriodicalIF":0.0,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11843700/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143485345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitochondrial-ER Contact Sites and Tethers Influence the Biosynthesis and Function of Coenzyme Q.","authors":"Noelle Alexa Novales, Hadar Meyer, Yeynit Asraf, Maya Schuldiner, Catherine F Clarke","doi":"10.1177/25152564251316350","DOIUrl":"10.1177/25152564251316350","url":null,"abstract":"<p><p>Coenzyme Q (CoQ) is an essential redox-active lipid that plays a major role in the electron transport chain, driving mitochondrial ATP synthesis. In <i>Saccharomyces cerevisiae</i> (yeast), CoQ biosynthesis occurs exclusively in the mitochondrial matrix via a large protein-lipid complex, the CoQ synthome, comprised of CoQ itself, late-stage CoQ-intermediates, and the polypeptides Coq3-Coq9 and Coq11. Coq11 is suggested to act as a negative modulator of CoQ synthome assembly and CoQ synthesis, as its deletion enhances Coq polypeptide content, produces an enlarged CoQ synthome, and restores respiration in mutants lacking the CoQ chaperone polypeptide, Coq10. The CoQ synthome resides in specific niches within the inner mitochondrial membrane, termed CoQ domains, that are often located adjacent to the endoplasmic reticulum-mitochondria encounter structure (ERMES). Loss of ERMES destabilizes the CoQ synthome and renders CoQ biosynthesis less efficient. Here we show that deletion of <i>COQ11</i> suppresses the respiratory deficient phenotype of select <i>ERMES</i> mutants, results in repair and reorganization of the CoQ synthome, and enhances mitochondrial CoQ domains. Given that ER-mitochondrial contact sites coordinate CoQ biosynthesis, we used a Split-MAM (Mitochondrial Associated Membrane) artificial tether consisting of an ER-mitochondrial contact site reporter, to evaluate the effects of artificial membrane tethers on CoQ biosynthesis in both wild-type and <i>ERMES</i> mutant yeast strains. Overall, this work identifies the deletion of <i>COQ11</i> as a novel suppressor of phenotypes associated with <i>ERMES</i> deletion mutants and indicates that ER-mitochondria tethers influence CoQ content and turnover, highlighting the role of membrane contact sites in regulating mitochondrial respiratory homeostasis.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"8 ","pages":"25152564251316350"},"PeriodicalIF":0.0,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11792030/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143191653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Remodeling of ER Membrane Contact Sites During Cell Division.","authors":"Fang Yu, Khaled Machaca","doi":"10.1177/25152564241309207","DOIUrl":"https://doi.org/10.1177/25152564241309207","url":null,"abstract":"<p><p>Membrane contact sites (MCS) provide specialized conduits for inter-organelle communications to maintain cellular homeostasis. Most organelles are interconnected, which supports their coordination and function. M-phase (mitosis or meiosis) is associated with dramatic cellular remodeling to support cell division, including the equal distribution of organelles to the two daughter cells. However, the fate of MCS in M-phase is poorly understood. Here we review recent advances arguing for differential remodeling of endoplasmic reticulum (ER) MCS with the plasma membrane (PM, ERPMCS) and the mitochondria (MERCS) during cell division.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"8 ","pages":"25152564241309207"},"PeriodicalIF":0.0,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11775993/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143070547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitochondria-Associated Endoplasmic Reticulum Membranes in Microglia: One Contact Site to Rule Them all.","authors":"Elisa Navarro, Jorge Montesinos","doi":"10.1177/25152564241312807","DOIUrl":"https://doi.org/10.1177/25152564241312807","url":null,"abstract":"<p><p>Microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in maintaining tissue homeostasis by monitoring and responding to environmental changes through processes such as phagocytosis, cytokine production or synapse remodeling. Their dynamic nature and diverse functions are supported by the regulation of multiple metabolic pathways, enabling microglia to efficiently adapt to fluctuating signals. A key aspect of this regulation occurs at mitochondria-associated ER membranes (MAM), specialized contact sites between the ER and mitochondria. These structures facilitate the exchange of calcium, lipids, and metabolites and serve as metabolic and signaling hubs. This review synthesizes current research on how MAM influence microglial physiology, with an emphasis on their role in immunometabolism, offering new insights into the integration of metabolic and immune functions in the CNS and its impact in the context of neurodegeneration.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"8 ","pages":"25152564241312807"},"PeriodicalIF":0.0,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11775980/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143070481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Arv1; a \"Mover and Shaker\" of Subcellular Lipids.","authors":"J Jose Corbalan, Karla K Frietze, Joseph Nickels, Stephen L Sturley","doi":"10.1177/25152564251314601","DOIUrl":"10.1177/25152564251314601","url":null,"abstract":"<p><p>The composition of eukaryotic membranes reflects a varied but precise amalgam of lipids. The genetic underpinning of how such diversity is achieved or maintained is surprisingly obscure, despite its clear metabolic and pathophysiological impact. The Arv1 protein is represented in all eukaryotes and was initially identified in the model eukaryote <i>Sacccharomyces cerevisiae</i> as a candidate transporter of lipids from the endoplasmic reticulum. Human Arv1 has been shown to directly bind cholesterol and fatty acid affinity probes. Murine <i>in vivo</i> studies point to a role for ARV1 in regulating obesity, glucose tolerance, insulin sensitivity and brain function. Multiple human ARV1 variants have been associated with epileptic encephalopathy, cerebellar ataxia, and severe intellectual deficits. We hypothesize that Arv1 acts as an energy independent, lipid scramblase at the endoplasmic reticulum thereby modulating membrane lipid asymmetry and thus the trafficking of sterols and the substituents of glycosyl-phosphatidylinositol and sphingolipid biosynthesis.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"8 ","pages":"25152564251314601"},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11748065/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Channels, Transporters, and Receptors at Membrane Contact Sites.","authors":"Maria Casas, Eamonn James Dickson","doi":"10.1177/25152564241305593","DOIUrl":"10.1177/25152564241305593","url":null,"abstract":"<p><p>Membrane contact sites (MCSs) are specialized regions where two or more organelle membranes come into close apposition, typically separated by only 10-30 nm, while remaining distinct and unfused. These sites play crucial roles in cellular homeostasis, signaling, and metabolism. This review focuses on ion channels, transporters, and receptors localized to MCSs, with particular emphasis on those associated with the plasma membrane and endoplasmic reticulum (ER). We discuss the molecular composition and functional significance of these proteins in shaping both organelle and cellular functions, highlighting their importance in excitable cells and their influence on intracellular calcium signaling. Key MCSs examined include ER-plasma membrane, ER-mitochondria, and ER-lysosome contacts. This review addresses our current knowledge of the ion channels found within these contacts, the dynamic regulation of MCSs, their importance in various physiological processes, and their potential implications in pathological conditions.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"7 ","pages":"25152564241305593"},"PeriodicalIF":0.0,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11686659/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142916811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Vacuole Lipid Droplet Contact Site vCLIP.","authors":"Duy Trong Vien Diep, Maria Bohnert","doi":"10.1177/25152564241308722","DOIUrl":"10.1177/25152564241308722","url":null,"abstract":"<p><p>Lipid droplets frequently form contact sites with the membrane of the vacuole, the lysosome-like organelle in yeast. These vacuole lipid droplet (vCLIP) contact sites respond strongly to metabolic cues: while only a subset of lipid droplets is bound to the vacuole when nutrients are abundant, other metabolic states induce stronger contact site formation. Physical lipid droplet-vacuole binding is related to the process of lipophagy, a lipid droplet-specific form of microautophagy. The molecular basis for the formation and function of vCLIP contact sites remained enigmatic for a long time. This knowledge gap was filled when it was found that vCLIP is formed by the structurally related lipid droplet tether proteins Ldo16 and Ldo45, and the vacuolar surface protein Vac8. Ldo45 additionally recruits the phosphatidylinositol transfer protein Pdr16 to vCLIP. Here, we review the literature on the lipid droplet-vacuole contact site in light of the progress in our understanding of its molecular basis and discuss future directions for the field.</p>","PeriodicalId":101304,"journal":{"name":"Contact (Thousand Oaks (Ventura County, Calif.))","volume":"7 ","pages":"25152564241308722"},"PeriodicalIF":0.0,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11664512/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142884000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}