TMEM41B is an endoplasmic reticulum Ca2+ release channel maintaining naive T cell quiescence and responsiveness
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ABSTRACT:
PROVIDER: PRJNA1203242 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR31840478_1.fastq.gz | Fastqsanger.gz | |||
| SRR31840478_2.fastq.gz | Fastqsanger.gz | |||
| SRR31840479_1.fastq.gz | Fastqsanger.gz | |||
| SRR31840479_2.fastq.gz | Fastqsanger.gz |
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Project description:In mammalian cells, endoplasmic reticulum (ER) passively releases Ca2+ under steady state, but channels involved remain elusive. Here, we report that TMEM41B, an ER-resident membrane protein critical for autophagy, lipid metabolism, and viral infection, functions as an ER Ca2+ release channel. Biochemically, purified recombinant TMEM41B forms a concentration-dependent Ca2+ channel in single-channel electrophysiology assays. Cellularly, TMEM41B deficiency causes ER Ca2+ overload, while overexpression of TMEM41B depletes ER Ca2+. Immunologically, ER Ca2+ overload leads to upregulation of IL-2 and IL-7 receptors in naive T cells, which in turn increases basal signaling of JAK-STAT, AKT-mTOR, and MAPK pathways. This dysregulation drives TMEM41B-deficient naive T cells into a metabolically activated yet immunologically naive state. ER Ca2+ overload also downregulates CD5, lowering the activation threshold of TMEM41B-deficient T cells and leading to heightened T cell responses during infections. In summary, we identify TMEM41B as a concentration-dependent ER Ca2+ release channel, revealing an unexpected role of ER Ca2+ in naive T cell quiescence and responsiveness.
2025-03-01 | GSE285373 | GEO
Project description:The endoplasmic reticulum (ER) contains various enzymes that metabolize fatty acids (FAs). How FA metabolic enzymes cooperate with other ER functions, such as calcium (Ca2+) accumulation and its regulated release to the cytosol, is elusive. Trans-2-enoyl-CoA reductase (TER) is a FA reductase present in the ER membrane, and catalyzes the last step of FA elongation cycle and sphingosine degradation pathway. Here we show that TER directly binds to an ER Ca2+ pump, sarco(endo)plasmic reticulum Ca2+-ATPase 2b (SERCA2b), and regulates its activity. Thapsigargin, a specific SERCA inhibitor, inhibits this binding. TER binds to SERCA2b through its conserved C-terminal region. TER overexpression suppresses SERCA2b ATPase activity in microsomal membranes. Depletion of TER increases the ER Ca2+ storage and accelerates SERCA2b-dependent Ca2+ uptake to the ER after ligand-induced Ca2+ release. These results demonstrate that TER is a negative regulator of SERCA2b, implying the direct linkage of FA metabolism and Ca2+ accumulation in the ER.
2021-01-13 | PXD020792 | Pride
Project description:To investigate whether ER stress underpins the secretion of mis-glycosylated glycoproteins by trophoblast, we treated trophoblast-like BeWo cells with the ER stress inducer thapsigargin (Tg), an inhibitor specific for sarco/endoplasmic reticulum Ca2+-ATPase.
2022-12-04 | E-MTAB-10943 | biostudies-arrayexpress
Project description:Autophagy maintains cellular homeostasis by targeting damaged organelles, pathogens or misfolded protein aggregates for lysosomal degradation. The autophagic process is initiated by the formation of autophagosomes, which can selectively enclose cargo via autophagy cargo receptors. A machinery of well-characterized autophagy-related proteins orchestrate the biogenesis of autophagosomes, however, the origin of the required membranes is incompletely understood. Here, we applied sensitized pooled CRISPR screens and identified the uncharacterized transmembrane protein TMEM41B as a novel regulator of autophagy. In the absence of TMEM41B, autophagosome biogenesis is stalled, LC3 accumulates at WIPI2- and DFCP1-positive isolation membranes, and lysosomal flux of autophagy cargo receptors and intracellular bacteria is impaired. In addition to defective autophagy, we found that TMEM41B knockout cells display significantly enlarged lipid droplets and reduced mobilization and β-oxidation of fatty acids. TMEM41B localizes to the endoplasmic reticulum (ER) and interacts with SIGMAR1, a chaperone which regulates calcium and lipid transfer at ER contact sites with mitochondria and lipid droplets. Taken together, we propose that TMEM41B is a novel regulator of autophagosome biogenesis and ER lipid mobilization.
2018-08-20 | PXD010207 | Pride
Project description:Flaviviruses pose a constant threat to human health. These RNA viruses are transmitted by the bite of infected mosquitoes and ticks and regularly cause outbreaks. To identify host factors required for flavivirus infection we performed full-genome loss of function CRISPR-Cas9 screens. Based on these results we focused our efforts on characterizing the roles that TMEM41B and VMP1 play in the virus replication cycle. Our mechanistic studies on TMEM41B revealed that all members of the Flaviviridae family that we tested require TMEM41B. We tested 12 additional virus families and found that SARS-CoV-2 of the Coronaviridae also required TMEM41B for infection. Remarkably, single nucleotide polymorphisms (SNPs) present at nearly twenty percent in East Asian populations reduce flavivirus infection. Based on our mechanistic studies we propose that TMEM41B is recruited to flavivirus RNA replication complexes to facilitate membrane curvature, which creates a protected environment for viral genome replication.
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Project description:In eukaryotic cells, the spatial regulation of protein expression is frequently conferred through the coupling of mRNA localization and the local control of translation. mRNA localization to the endoplasmic reticulum (ER) is a prominent example of such regulation and serves a ubiquitous role in segregating the synthesis of secretory and integral membrane proteins to the ER. Recent genomic and biochemical studies have now expanded this view to suggest a role for the ER in global protein synthesis. We have utilized cell fractionation and ribosome profiling to obtain a genomic survey of the subcellular organization of mRNA translation and report that ribosomal loading of mRNAs, a proxy for mRNA translation, is biased to the ER. Notably, ER-associated mRNAs encoding both cytosolic and topogenic signal-encoding proteins display similar ribosome loading densities, suggesting that ER-associated ribosomes serve a global role in mRNA translation. We propose that the partitioning of mRNAs and their translation between the cytosol and ER compartments may represent a novel mechanism for the post-transcriptional regulation of gene expression. HEK293 cells were fractionated between the cytosol and endoplasmic reticulum. Within each fraction, ribosome footprints were generated and sequenced. In parallel, total mRNA was sequenced.
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Project description:Dolutegravir (DTG) - based antiretroviral therapy is the contemporary first-line therapy to treat HIV infection. Despite its efficacy, mounting evidence has suggested a higher risk of neuropsychiatric adverse effect (NPAE) associated with DTG use with a limited understanding of the underlying mechanisms. Our laboratory has previously reported a toxic effect of DTG but not bictegravir (BTG) in disrupting the blood-brain barrier (BBB) integrity. The current study aimed to investigate the underlying mechanism of DTG toxicity. Primary cultures of mouse brain microvascular endothelial cells were treated with DTG and BTG at therapeutic relevant concentrations. RNA-sequencing, qPCR, western blot analysis and cell stress assays (Ca2+ flux, H2DCFDA, TMRE, MTT) were applied to assess the results. The Gene Ontology (GO) analysis revealed an enriched transcriptome signature of endoplasmic reticulum (ER) stress following DTG treatment. We demonstrated that therapeutic concentrations of DTG but not BTG activated the ER stress sensor proteins (PERK, IRE1, p-IRE1) and downstream ER stress markers (eIF2α, p-eIF2α, Hspa5, Atf4, Ddit3, Ppp1r15a, Xbp1, spliced-Xbp1). In addition, DTG treatment resulted in a transient Ca2+ flux, an aberrant mitochondrial membrane potential, and a significant increase in reactive oxygen species in treated cells. Furthermore, we found that prior treatment of ER sensor inhibitors significantly mitigated the DTG-induced downregulation of tight junction proteins (Zo-1, Ocln, Cldn5) and elevation of pro-inflammatory cytokines and chemokines (Il6, Il23a, Il12b, Cxcl1, Cxcl2). The current study provides valuable insights into DTG-mediated cellular toxicity mechanisms, which may serve as a potential explanation of DTG-associated NPAEs in the clinic.
2025-02-02 | GSE285595 | GEO
Project description:In this study, Bax inhibitor-1 (BI-1) overexpression reduces the ER pool of Ca(2+) released by thapsigargin. Cells overexpressing BI-1 also showed lower intracellular Ca(2+) release induced by the Ca(2+) ionophore ionomycin as well as agonists of ryanodine receptors and inositol trisphosphate receptors. In contrast, cells expressing carboxyl-terminal deleted BI-1 (CDelta-BI-1 cells) displayed normal intracellular Ca(2+) mobilization. Basal Ca(2+) release rates from the ER were higher in BI-1-overexpressing cells than in control or CDelta-BI-1 cells. We determined that the carboxyl-terminal cytosolic region of BI-1 contains a lysine-rich motif (EKDKKKEKK) resembling the pH-sensing domains of ion channels. Acidic conditions triggered more extensive Ca(2+) release from ER microsomes from BI-1-overexpressing cells and BI-1-reconstituted liposomes. Acidic conditions also induced BI-1 protein oligomerization. Interestingly subjecting BI-1-overexpressing cells to acidic conditions induced more Bax recruitment to mitochondria, more cytochrome c release from mitochondria, and more cell death. These findings suggest that BI-1 increases Ca(2+) leak rates from the ER through a mechanism that is dependent on pH and on the carboxyl-terminal cytosolic region of the BI-1 protein. The findings also reveal a cell death-promoting phenotype for BI-1 that is manifested under low pH conditions.
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