Plekhg5 regulates the unconventional secretion of Sod1 by presynaptic secretory autophagy
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ABSTRACT:
PROVIDER: PRJNA1122581 | ENA |
REPOSITORIES: ENA
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Project description:Increasing evidence suggests an essential function for autophagy in unconventional protein secretion (UPS). However, despite its relevance for the secretion of aggregate-prone proteins, the mechanisms of secretory autophagy in neurons have remained elusive. Here we show that the lower motoneuron disease-associated protein Plekhg5 drives the UPS of Sod1. Mechanistically, Sod1 is sequestered into the intermembrane space of autophagosomes which fuse with secretory lysosomal-related organelles (LROs). Deletion of Plekhg5 in mice disrupts the secretion of these LROs causing Sod1 accumulation at swollen presynaptic sites. A reduced secretion of toxic ALS-linked SOD1G93A following deletion of Plekhg5 in SOD1G93A mice accelerated disease onset while prolonging survival due to an attenuated microglia activation. Using human isogenic iPSC-derived motoneurons we show an impaired secretion of ALS-linked SOD1D90A, which coincided with a reduced PLEKHG5 expression. Our findings highlight an unexpected pathophysiological mechanism that converges two motoneuron disease-associated proteins into a common pathway.
2024-08-28 | GSE269588 | GEO
Project description:In cells, several cargoes are delivered to the cell surface or the extracellular space via unconventional secretion routes. GRASP55 is a Golgi protein that regulates unconventional secretion of distinct proteins and controls the assembly and membrane stacking of Golgi cisternae. Recent work suggested that the role of GRASP55 in unconventional secretion may involve its relocalization to other organelles. However, the stimuli that drive GRASP55-dependent unconventional secretion, the signaling events that regulate GRASP55 function, the subcellular locations where GRASP55 acts, and the cargoes that follow this route for secretion remain unclear. Here, we show that mTORC1 directly phosphorylates GRASP55 at multiple sites to maintain its Golgi localization. Cellular stresses or drugs that inhibit mTORC1 cause GRASP55 dephosphorylation and relocalization to autophagosomal / MVB structures. Using secretome and surfactome analyses in GRASP55-null cells, we identify for the first time numerous -previously unknown- cargoes that rely on this unconventional secretory pathway.
2021-09-09 | PXD020331 | Pride
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:Investigation of conventional and unconventional protein secretion using galectin-3
| PRJNA663090 | ENA
Project description:Signal-sequence-lacking superoxide dismutase 1 (SOD1) is secreted upon nutrient starvation, but the physiological relevance of this secretion is unclear. We now report that secreted SOD1 is functionally active. In addition, a secretome analysis has revealed number of other secreted cytoplasmic antioxidant enzymes, including both thioredoxins, (Trx1 and Trx2), and the peroxiredoxin Ahp1. Our data reveal that starvation triggers increased mitochondrial activity, leading to increased production of reactive oxygen species (ROS). Inhibiting mitochondrial activity or ROS, inhibited secretion of the antioxidants. We suggest elevated ROS that evade cytoplasmic antioxidants, can permeate across the plasma membrane to the extracellular space. Cells secrete antioxidants to prevent ROS-mediated damage to the extracellular space. These findings thus provide an understanding of why cells secrete signal sequence lacking proteins like SOD1 and the larger family of antioxidants.
2019-05-14 | PXD010849 | Pride
Project description:Intracellular degradation of proteins and organelles by the autophagy-lysosome system is essential for cellular quality control and energy homeostasis. Besides degradation, endolysosomal organelles can fuse with the plasma membrane and contribute to unconventional secretion. Here, we identify a function for mammalian SKP1 in endolysosomes that is independent of its established role as an essential component of the family of SCF/CRL1 ubiquitin ligases. We found that, under nutrient poor conditions, SKP1 is phosphorylated on Thr131, allowing its interaction with V1 subunits of the vacuolar ATPase (V-ATPase). This event, in turn, promotes V-ATPase assembly to acidify late endosomes and enhance endolysosomal degradation. Under nutrient rich conditions, SUMOylation of phosphorylated SKP1 allows its binding to and dephosphorylation by the PPM1B phosphatase. Dephosphorylated SKP1 interacts with SEC22B, recently shown to participate in unconventional secretion, to promote secretion of the content of less acidified hybrid endosomal/autophagic compartments. The differences in abundance of specific proteins between ECVs of SKP1WT and SKP1T131A cells motivated us to determine possible changes in extracellular vesicles (ECV) content depending on SKP1 phosphorylation. To this effect, we performed MS analysis and comparative proteomics of ECVs from SKP1WT and SKP1T131A cells (Fig. 5I, Table S7). We found a higher number of proteins displaying increased abundance (greater than 0.321 log2 fold change) in SKP1T131A cells (127 proteins) compared to SKP1WT cells (16 proteins). The mass spectrometric raw files for this analysis are included here.
Collectively, our study implicates SKP1 phosphorylation as a switch between autophagy and unconventional secretion in a manner dependent on cellular nutrient status.
Corresponding authors:
ana-maria.cuervo@einsteinmed.edu and michele.pagano@nyulangone.org
2023-07-06 | MSV000092361 | MassIVE
Project description:Nutrient deprivation triggers the release of signal-sequence-lacking antioxidant superoxide dismutase 1 (SOD1). We now report that secreted SOD1 is functionally active and accompanied by export of other antioxidant enzymes such as thioredoxins, (Trx1 and Trx2) and peroxiredoxin Ahp1. Our data reveal that starvation increases mitochondrial activity, which generates higher, but non-toxic, levels of reactive oxygen species (ROS). Inhibiting mitochondrial activity or ROS prevents antioxidants secretion. We suggest that in response to ROS production that can permeate the plasma membrane, the cells respond by secreting antioxidants to prevent ROS-mediated damage in the extracellular space. These findings provide an understanding of why cells secrete signal sequence lacking antioxidant enzymes in response to starvation.
2020-03-26 | PXD016815 | Pride
Project description:Living cell surface proteome - Tracing putative trafficking of the glycolytic enzyme enolase via SNARE-driven unconventional secretion
2012-07-20 | PRD000729 | Pride
Project description:An appreciation of the functional properties of the cytoplasmic fatty acid binding protein 4 (FABP4) has advanced with the recent demonstration that an extracellular form secreted by adipocytes regulates a wide range of physiological functions. Little, however, is known about the mechanisms that mediate the unconventional secretion of FABP4. Here, we demonstrate that FABP4 secretion is mediated by a membrane-bounded compartment, independent of the conventional endoplasmic reticulum-Golgi secretory pathway. We show that FABP4 secretion is also independent of GRASP proteins, autophagy, and multivesicular bodies but involves enclosure within endosomes and secretory lysosomes. We highlight the physiological significance of this pathway with the demonstration that an increase in plasma levels of FABP4 is inhibited by chloroquine treatment of mice. These findings chart the pathway of FABP4 secretion and provide a potential therapeutic means to control metabolic disorders associated with its dysregulated secretion.
| S-EPMC5800802 | biostudies-literature
Project description:Abstract: Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretory cells, such as those of the pancreas, salivary and mammary glands. Here, we report that the CrebA/Creb3-like family of bZip transcription factors functions to upregulate expression of both the general protein machinery required in all cells for secretion and of cell-type specific secreted proteins. Drosophila CrebA directly binds the enhancers of secretory pathway genes and is both necessary and sufficient to activate expression of every secretory pathway component gene examined thus far. Microarray profiling reveals that CrebA also upregulates expression of genes encoding cell type specific secreted components. Finally, we find that the human CrebA orthologues, Creb3L1 and Creb3L2, have the ability to upregulate the secretory pathway in non-secretory cell types. This SuperSeries is composed of the following subset Series: GSE23334: Active Creb3L1 can upregulate secretory pathway genes in HeLa cells GSE23346: CrebA is a major and direct regulator of secretory pathway gene expression Refer to individual Series
2010-10-18 | E-GEOD-23349 | biostudies-arrayexpress