Genome-wide CRISPR screening identifies new regulators of glycoprotein secretion
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE133692 | GEO | 2019/07/21
REPOSITORIES: GEO
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Project description:Protein secretion is an essential process in cell biology. The conventional secretion pathway is well known, and involves proteins with a signal sequence being directed into the endoplasmic reticulum. Once in the lumen of the endoplasmic reticulum, proteins are trafficked through the Golgi and remain separate from the cytosol throughout their journey to the outside of the cell. More recently, proteins without a signal sequence have been found outside the cell. These proteins are secreted unconventionally, and avoid the ER-Golgi route. For both pathways, some aspects remain unclear, particularly surrounding the regulation of protein secretion. Galectin-3, an unconventionally secreted protein, was used here to investigate both conventional and unconventional protein secretion. The unconventional protein secretion of galectin-3 is poorly understood. To address this, genetic manipulation of galectin-3 was used to gain insights into the mechanism of galectin-3 secretion. It was found that galectin-3 does not require unfolding or binding to cell surface glycoproteins to be secreted. Galectin-3 was also used to assess protein secretion using a genome-wide CRISPR screen. As galectin‑3 binds to cell surface glycoproteins, galectin-3 on the cell surface was used to assess secretion of these glycoproteins. Hits were validated by a glycoprotein secretion assay. Using this pipeline, 93 hits were identified as involved in protein secretion, of which 51 were novel hits not previously associated with protein secretion. Many of the hits identified also resulted in a phenotype of altered Golgi morphology, and five of these were investigated further. Two novel hits that localised to the Golgi were identified, TMEM220 and GPR161. GPR161 likely mediates its effect on Golgi morphology by its interaction with golgin A5. This thesis presents new insights into both conventional and unconventional protein secretion. Insights into the mechanism for galaectin-3 secretion were revealed. A novel Golgi-localised regulator of secretion, GRP161, was identified, with a mechanism for action suggested. Importantly, the list of 51 novel genes identified will serve as a useful resource for other researchers investigating protein secretion.
2020-09-13 | GSE157864 | GEO
Project description:Genome-wide CRISPR screening identifies new regulators of glycoprotein secretion
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Project description:The cumulative role of cellular organelle’s in shaping the life and function of a cell has been long acknowledged. While each organelle plays a specific role in the growth and development of T cells, numerous studies have thus far focused on targeting mitochondria, endoplasmic reticulum, or lysosome related pathways to improve anti-tumor T cell immune response. Here we highlight the tumor microenvironment (TME) mediated disruption of Golgi architecture and function, termed Golgi stress, contributes to altered redox signaling and affects cell survival. Importantly, the decreased expression if GM130, a marker of Golgi stress and indicating the disruption of Golgi architecture, was reverted upon treatment with hydrogen sulphide (H2S) donor GYY4137, or over expressing cystathionine β-synthase (Cbs), an enzyme involved in biosynthesis of endogenous H2S. Activation and expansion of tumor reactive TCR or chimeric antigen receptor bearing T cells expanded with exogenous H2S promoted stemness, antioxidant capacity and exhibited an increase effector cytokine secretion that correlated to increased protein translation. In in vivo models of melanoma and lymphoma, anti-tumor T cells conditioned ex vivo with exogenous H2S or overexpressing Cbs demonstrated superior tumor control upon ACT. Further, sorting anti- tumor T cells based on Golgi structure and abundance resulted in identification of a Golgihi subset of T cells with a unique metabolic signature, superior fitness, and enhanced anti-tumor capacity. These data suggest that H2S can be used an immunomodulatory agent to enhance the efficacy of ACT, and that the structure and function of the Golgi apparatus is an important feature of T cells that determines their anti-tumor capacity.
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Project description:STING transmits signals downstream of the cytosolic DNA sensor cGAS, leading to transcriptional up-regulation of cytokines. However, components of the STING signaling pathway, such as IRF3 and IFNAR1, are not essential for autoinflammatory disease in STING gain-of-function (SAVI) mice. Recent discoveries revealed that STING also functions as a proton channel that deacidifies the Golgi. Since pH impacts Golgi enzyme activity, protein maturation, and trafficking, we hypothesized that STING proton channel activity influences multiple Golgi functions. Here, we show that STING-mediated proton efflux non-transcriptionally regulates Golgi trafficking of protein cargos. This process requires the Golgi-associated protein ArfGAP2, a cell type-specific dual regulator of STING-mediated proton efflux and signaling. Deletion of ArfGAP2 in hematopoietic and endothelial cells markedly reduces STING-mediated cytokine and chemokine secretion, immune cell activation, and autoinflammatory pathology in SAVI mice. Thus, ArfGAP2 facilitates STING-mediated signaling and cytokine release in hematopoietic cells, significantly contributing to autoinflammatory disease pathogenesis.
2024-12-31 | GSE283416 | GEO
Project description:STING transmits signals downstream of the cytosolic DNA sensor cGAS, leading to transcriptional up-regulation of cytokines. However, components of the STING signaling pathway, such as IRF3 and IFNAR1, are not essential for autoinflammatory disease in STING gain-of-function (SAVI) mice. Recent discoveries revealed that STING also functions as a proton channel that deacidifies the Golgi. Since pH impacts Golgi enzyme activity, protein maturation, and trafficking, we hypothesized that STING proton channel activity influences multiple Golgi functions. Here, we show that STING-mediated proton efflux non-transcriptionally regulates Golgi trafficking of protein cargos. This process requires the Golgi-associated protein ArfGAP2, a cell type-specific dual regulator of STING-mediated proton efflux and signaling. Deletion of ArfGAP2 in hematopoietic and endothelial cells markedly reduces STING-mediated cytokine and chemokine secretion, immune cell activation, and autoinflammatory pathology in SAVI mice. Thus, ArfGAP2 facilitates STING-mediated signaling and cytokine release in hematopoietic cells, significantly contributing to autoinflammatory disease pathogenesis.
2024-12-31 | GSE283415 | GEO
Project description:Drug-induced hepatotoxicity is a leading cause of attrition of candidate drugs in drug development. Therefore new screening methods are necessary which predict these hazards more accurate and earlier in the drug development process. Of all in vitro hepatotoxicity models, primary human hepatocytes are considered as 'the gold standard'. However, the use of these hepatocytes is hindered by their scarcity and major inter-individual variation. These limitations may be overcome with use of primary mouse hepatocytes. Within this context changes in protein expressions in primary mouse hepatocytes, after exposure to cyclosporin A were studied using differential gel electrophoresis. Thereafter, the mRNA expression levels of these deregulated proteins from cyclosporin A-treated cells were analyzed. Cyclosporin A induced ER stress and altered the ER-Golgi transport, which may alter vesicle mediated transport and protein secretion. Moreover are the differentially expressed proteins observed upon challenge by cyclosporin A, associated with cholestatic mechanisms. For each biological experiment, one hybridization was conducted and one sample per array. In total, 6 arrays were used for 2 different conditions (Csa or control at 48 hours).
2013-04-01 | E-GEOD-33742 | biostudies-arrayexpress
Project description:Male germ cells are sensitive to heat stress and testes must be maintained outside the body for optimal fertility. However, no germ cell intrinsic mechanism that protects from heat has been reported. Here, we identify the germ cell specific Golgi glycoprotein MGAT4D as a protector of male germ cells from heat stress. Mgat4d is highly expressed in spermatocytes and spermatids. Unexpectedly, when the Mgat4d gene was inactivated globally or conditionally in spermatogonia, or mis-expressed in spermatogonia, spermatocytes or spermatids, neither spermatogenesis nor fertility were affected. On the other hand, when males were subjected to mild heat stress of the testis (43 °C for 25 min), germ cells with inactivated Mgat4d were markedly more sensitive to the effects of heat stress, and transgenic mice expressing Mgat4d were partially protected from heat stress. Bioinformatics analyses of microarray data from heat stressed versus control germ cells showed that germ cells lacking Mgat4d generally mounted a similar heat shock response to control germ cells, but could not maintain that response. Several pathways activated by heat stress in wild type were induced to a lesser extent in Mgat4d[−/−] heat-stressed germ cells (NFκB response, TNF and TGFβ signaling, Hif1α and Myc genes). Thus, the Golgi glycoprotein MGAT4D is a novel, intrinsic protector of male germ cells from heat stress.
2020-02-24 | GSE137307 | GEO
Project description:Abstract Von Willebrand factor (VWF) is a multimeric hemostatic protein primarily synthesized in endothelial cells (ECs). VWF is stored in endothelial storage organelles, the Weibel-Palade bodies (WPBs), whose biogenesis strongly depends on VWF anterograde trafficking and Golgi architecture. Elongated WPB morphology is correlated to longer VWF strings with better adhesive properties. We previously identified the SNARE SEC22B, which is involved in anterograde ER-to-Golgi transport, as a novel regulator of WPB elongation. To elucidate novel determinants of WPB morphology we explored endothelial SEC22B interaction partners in a mass spectrometry-based approach, identifying the Golgi SNARE Syntaxin 5 (STX5). We established STX5 knockdown in ECs using shRNA-dependent silencing and analyzed WPB and Golgi morphology, using confocal and electron microscopy. STX5-depleted ECs exhibited extensive Golgi fragmentation and decreased WPB length, which was associated with reduced intracellular VWF levels, and impaired stimulated VWF secretion. However, the secretion incompetent organelles in shSTX5 cells maintained WPB markers such as Angiopoietin 2, P-selectin, Rab27A, and CD63. Taken together, our study has identified SNARE protein STX5 as a novel regulator of WPB biogenesis
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Project description:The Golgi is a membrane-bound organelle that is essential for protein and lipid biosynthesis. It represents a central trafficking hub that sorts proteins and lipids to various destinations or for secretion from the cell. The Golgi has emerged as a docking platform for cellular signaling pathways including LRRK2 kinase whose deregulation leads to Parkinson disease. Golgi dysfunction is associated with a broad spectrum of diseases including cancer, neurodegeneration, and cardiovascular diseases. To allow the study of the Golgi at high resolution, we report a rapid Golgi immunoprecipitation technique (Golgi-IP) to isolate intact Golgi mini-stacks for subsequent analysis of their content. By fusing the Golgi-resident protein TMEM115 to three tandem HA epitopes (GolgiTAG), we purified the Golgi using Golgi-IP with minimal contamination from other compartments. We then established an analysis pipeline using liquid chromatography coupled with mass spectrometry to characterize the human Golgi proteome, metabolome, and lipidome. Subcellular proteomics confirmed known Golgi proteins and identified proteins not previously associated with the Golgi. Metabolite profiling established the human Golgi metabolome and revealed the enrichment of uridine-diphosphate (UDP) sugars and their derivatives, which is consistent with their roles in protein and lipid glycosylation. Furthermore, targeted metabolomics validated SLC35A2 as the subcellular transporter for UDP-hexose. Finally, lipidomics analysis showed that phospholipids including phosphatidylcholine, phosphatidylinositol, and phosphatidylserine are the most abundant Golgi lipids and that glycosphingolipids are enriched in this compartment. Altogether, our work establishes a comprehensive molecular map of the human Golgi and provides a powerful method to study the Golgi with high precision in health and disease.
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Project description:Drug-induced hepatotoxicity is a leading cause of attrition of candidate drugs in drug development. Therefore new screening methods are necessary which predict these hazards more accurate and earlier in the drug development process. Of all in vitro hepatotoxicity models, primary human hepatocytes are considered as 'the gold standard'. However, the use of these hepatocytes is hindered by their scarcity and major inter-individual variation. These limitations may be overcome with use of primary mouse hepatocytes. Within this context changes in protein expressions in primary mouse hepatocytes, after exposure to cyclosporin A were studied using differential gel electrophoresis. Thereafter, the mRNA expression levels of these deregulated proteins from cyclosporin A-treated cells were analyzed. Cyclosporin A induced ER stress and altered the ER-Golgi transport, which may alter vesicle mediated transport and protein secretion. Moreover are the differentially expressed proteins observed upon challenge by cyclosporin A, associated with cholestatic mechanisms.
2013-04-01 | GSE33742 | GEO