Cargo receptor-assisted endoplasmic reticulum export of pathogenic α1-antitrypsin polymers
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ABSTRACT:
PROVIDER: PRJNA665693 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR12712407.fastq.gz | Fastqsanger.gz | |||
| SRR12712408.fastq.gz | Fastqsanger.gz | |||
| SRR12712409.fastq.gz | Fastqsanger.gz | |||
| SRR12712410.fastq.gz | Fastqsanger.gz | |||
| SRR12712411.fastq.gz | Fastqsanger.gz |
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Project description:Background: Circulating polymers of alpha1-antitrypsin (α1AT) are chemo-attractant for neutrophils and contribute to inflammation in pulmonary, vascular and adipose tissues. Cellular factors affecting the intracellular itinerary of mutant polymerogenic α1AT remain obscure. Methods: Here, we report on an unbiased genome-wide CRISPR/Cas9 screen for regulators of trafficking of the polymerogenic α1AT-H334D variant. Single guide RNAs targeting genes whose inactivation enhanced accumulation of polymeric α1AT were enriched by iterative construction of CRISPR libraries based on genomic DNA from fixed cells selected for high polymer content by fluorescence-activated cell sorting. This approach bypassed the limitation to conventional enrichment schemes imposed by cell fixation. Results: Our screen identified 121 genes involved in polymer retention at false discovery rate < 0.1. From that set of genes, the pathway ‘cargo loading into COPII-coated vesicles’ was overrepresented with 16 significant genes, including two transmembrane cargo receptors, LMAN1 (ERGIG-53) and SURF4. LMAN1 and SURF4-disrupted cells displayed a secretion defect extended beyond α1AT monomers to polymers, whose low-level secretion was especially dependent on SURF4 and correlated with SURF4-α1AT-H334D physical interaction and with enhanced co-localisation of polymeric α1AT-H334D with the endoplasmic reticulum (ER). Conclusions: These findings suggest that ER cargo receptors co-ordinate intracellular progression of α1AT out of the ER and modulate the accumulation of polymeric α1AT not only by controlling the concentration of precursor monomers but also through a previously-unrecognised role in secretion of the polymers themselves.
2021-06-02 | GSE158574 | GEO
Project description:Circulating polymers of α1-antitrypsin (α1AT) are neutrophil chemo-attractants and contribute to inflammation, yet cellular factors affecting their secretion remain obscure. We report on a genome-wide CRISPR-Cas9 screen for genes affecting trafficking of polymerogenic α1ATH334D. A CRISPR enrichment approach based on recovery of single guide RNA (sgRNA) sequences from phenotypically selected fixed cells reveals that cells with high-polymer content are enriched in sgRNAs targeting genes involved in "cargo loading into COPII-coated vesicles," where "COPII" is coat protein II, including the cargo receptors lectin mannose binding1 (LMAN1) and surfeit protein locus 4 (SURF4). LMAN1- and SURF4-disrupted cells display a secretion defect extending beyond α1AT monomers to polymers. Polymer secretion is especially dependent on SURF4 and correlates with a SURF4-α1ATH334D physical interaction and with their co-localization at the endoplasmic reticulum (ER). These findings indicate that ER cargo receptors co-ordinate progression of α1AT out of the ER and modulate the accumulation of polymeric α1AT not only by controlling the concentration of precursor monomers but also by promoting secretion of polymers.
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Project description:The selective export of proteins and lipids from the endoplasmic reticulum (ER) is mediated by the coat protein complex II (COPII) that assembles onto the ER membrane. In higher eukaryotes, COPII proteins assemble at discrete sites on the membrane known as ER exit sites (ERES). Here, we identify Sec16 as the protein that defines ERES in mammalian cells. Sec16 localizes to ERES independent of Sec23/24 and Sec13/31. Overexpression, and to a lesser extent, small interfering RNA depletion of Sec16, both inhibit ER-to-Golgi transport suggesting that Sec16 is required in stoichiometric amounts. Sar1 activity is required to maintain the localization of Sec16 at discrete locations on the ER membrane, probably through preventing its dissociation. Our data suggest that Sar1-GTP-dependent assembly of Sec16 on the ER membrane forms an organized scaffold defining an ERES.
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Project description:The cellular mechanisms that ensure the selectivity and fidelity of secretory cargo protein transport from the endoplasmic reticulum (ER) to the Golgi are still not well understood. The p24 protein complex acts as a specific cargo receptor for GPI-anchored proteins by facilitating their ER exit through a specialized export pathway in yeast. In parallel, the p24 complex can also exit the ER using the general pathway that exports the rest of secretory proteins with their respective cargo receptors. Here, we show biochemically that the p24 complex associates at the ER with other cargo receptors in a COPII-dependent manner, forming high-molecular weight multireceptor complexes. Furthermore, live cell imaging analysis reveals that the p24 complex is required to retain in the ER secretory cargos when their specific receptors are absent. This requirement does not involve neither the unfolded protein response nor the retrograde transport from the Golgi. Our results suggest that, in addition to its role as a cargo receptor in the specialized GPI-anchored protein pathway, the p24 complex also plays an independent role in secretory cargo selectivity during its exit through the general ER export pathway, preventing the non-selective bulk flow of native secretory cargos. This mechanism would ensure receptor-regulated cargo transport, providing an additional layer of regulation of secretory cargo selectivity during ER export.
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Project description:PIWI-interacting RNAs (piRNAs) guide transposon silencing in animals. The 22-30nt piRNAs are processed in the cytoplasm from long non-coding RNAs. How piRNA precursors, which often lack RNA processing hallmarks of export-competent transcripts, achieve nuclear export is unknown. Here, we uncover the RNA export pathway specific for piRNA precursors in the Drosophila germline. This pathway requires Nxf3-Nxt1, a variant of the hetero-dimeric mRNA export receptor Nxf1-Nxt1. Nxf3 interacts with UAP56, a nuclear RNA helicase essential for mRNA export, and CG13741/Bootlegger, which recruits Nxf3-Nxt1 and UAP56 to heterochromatic piRNA source loci. Upon RNA cargo binding, Nxf3 achieves nuclear export via the exportin Crm1, and accumulates together with Bootlegger in peri-nuclear nuage, suggesting that after export, Nxf3-Bootlegger delivers precursor transcripts to the piRNA processing sites. Our findings indicate that the piRNA pathway bypasses nuclear RNA surveillance systems to achieve export of heterochromatic, unprocessed transcripts to the cytoplasm, a strategy also exploited by retroviruses.
2019-03-28 | GSE126578 | GEO
Project description:The mRNA cargo of B-16V and B-16V-delta-BAG6 cells was sequenced with RNA seq.
2019-11-29 | E-MTAB-7123 | biostudies-arrayexpress
Project description:Erythropoietin (EPO) stimulates erythroid differentiation and maturation. Though the transcriptional regulation of EPO has been well studied, the molecular determinants of EPO secretion remain unknown. Here, we generated a HEK293T reporter cell line that provides a quantifiable and selectable readout of intracellular EPO levels and performed a genome-scale CRISPR screen that identified SURF4 as an important mediator of EPO secretion. Targeting SURF4 with multiple independent single guide RNAs (sgRNAs) resulted in intracellular accumulation and extracellular depletion of EPO. Both of these phenotypes were rescued by expression of SURF4 cDNA. Additionally, we found that disruption of SURF4 resulted in accumulation of EPO in the endoplasmic reticulum (ER) compartment and that SURF4 and EPO physically interact. Furthermore, SURF4 disruption in Hep3B cells also caused a defect in the secretion of endogenous EPO under conditions mimicking hypoxia, ruling out an artifact of heterologous overexpression. This work demonstrates that SURF4 functions as an ER cargo receptor that mediates the efficient secretion of EPO. Our findings also suggest that modulating SURF4 may be an effective treatment for disorders of erythropoiesis that are driven by aberrant EPO levels. Finally, we show that SURF4 overexpression results in increased secretion of EPO, suggesting a new strategy for more efficient production of recombinant EPO.
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Project description:In this study, we sought to thoroughly characterize the liver pathophysiology of a human transgenic mouse model for alpha-1 antitrypsin deficiency (AATD) with a strong manifestation of AATD-mediated liver disease. Male and female transgenic mice for normal variant human alpha-1 antitrypsin (Pi*M) and mutant human alpha-1 antitrypsin (Pi*Z) at 3 and 6 months of age with a C57BL/6J background were subjected to study. The progression of hepatic accumulation of mutant alpha-1 antitrypsin (ZAAT), hepatocyte injury, steatosis, liver inflammation and fibrotic features of this mouse model were monitored by performing an in vivo study.
2023-03-19 | GSE206619 | GEO
Project description:Alpha-1 antitrypsin (A1AT) is a glycoprotein that has been shown to protect tissues from proteolytic damage under various inflammatory conditions. Several studies show that A1AT may be associated with pre-eclampsia. However, the role of A1AT expression in placental physiology is not fully understood. In the present study, we aim to characterize the expression and function of placental A1AT. A1AT knockdown is found to reduce the expression of the serine protease HTRA1 in a trophoblast cell line. In addition, A1AT overexpression (A1AT-OE) increases the expression of HTRA1, IL6, CXCL8, and several markers of endoplasmic reticulum (ER) stress. Treatment with tunicamycin or thapsigargin, which induces ER stress, increases HTRA1 expression. Furthermore, immunohistochemistry reveals that HTRA1 is expressed in trophoblasts and the endometrial decidual cells of human placentas. An invasion assay shows that A1AT and HTRA1 stimulate cell invasion, but treatment with the ER stress inhibitors reduces the expression of HTRA1 and ER stress markers and prevents cell invasion in A1AT-OE trophoblasts. These results suggest that endogenous A1AT regulates inflammatory cytokine expression and HTRA1-induced trophoblast invasion via the induction of ER stress. It is concluded that an imbalance in the functional link between A1AT and ER stress at the maternal-fetal interface might cause abnormal placental development.
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Project description:Whole genome mRNA and microRNA profiling of bronchoalveolar lavage (BAL) and peripheral blood mononuclear cell (PBMC) in Alpha-1 Antitrypsin Deficiency patients with PiZZ or PiMZ alpha-1 antitrypsin genotypes
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