Pneumocytes are distinguished by highly elevated expression of the ER stress biomarker GRP78, a co-receptor for SARS-CoV-2, in COVID-19 autopsies

AbstractRecent studies from Slc4a11 KO mice have identified mitochondrial dysfunction as a major contributor toward oxidative stress and cell death in Congenital Hereditary Endothelial Dystrophy. Here we asked if this stress activated autophagy in the Slc4a11 KO cell line and in KO mouse endothelial tissue. Early indicators of autophagy, phospho-mTOR and LC3-II indicated activation, however P62 was elevated suggesting an impairment of autophagy flux. The activity and the number of lysosomes, the organelle responsible for the final degradation of autophagy substrates, were found to be reduced in the KO. In addition, the expression of the master regulator of lysosomal function and biogenesis, TFEB, was significantly reduced in the KO corneal endothelia. Also, we observed increased Unfolded Protein Response, as well as elevated expression of ER stress markers, BIP and CHOP. To test if lysosomal and ER stress stems from elevated mitochondrial ROS, we treated Slc4a11 KO corneal endothelial cells with the mitochondrial ROS quencher, MitoQ. MitoQ restored lysosomal enzymes as well as TFEB, reduced ER stress, and increased autophagy flux. MitoQ injections of Slc4a11 KO mice decreased corneal edema, the major phenotype associated with CHED. We conclude that mitochondrial ROS causes ER stress and lysosomal dysfunction with impairment of autophagy in Slc4a11 KO corneal endothelium. Our study is the first to identify the presence as well as cause of lysosomal dysfunction and ER stress in an animal model of CHED, and to characterize inter-organelle relationship in a corneal cell type.

Download Full-text

Expression profiles of endoplasmic reticulum stress-related molecules in demyelinating lesions and multiple sclerosis

Multiple Sclerosis Journal ◽

10.1177/1352458511399114 ◽

2011 ◽

Vol 17 (7) ◽

pp. 808-818 ◽

Cited By ~ 43

Author(s):

Paula Cunnea ◽

Aoife Ní Mháille ◽

Stephen McQuaid ◽

Michael Farrell ◽

Jill McMahon ◽

...

Keyword(s):

Multiple Sclerosis ◽

Endoplasmic Reticulum ◽

White Matter ◽

Er Stress ◽

Real Time Pcr ◽

Post Mortem ◽

Stress Genes ◽

Biopsy Specimens ◽

Elevated Expression ◽

Demyelinating Lesions

Background: Increasing evidence associates the endoplasmic reticulum (ER) stress signalling pathway as a potential treatment target in multiple sclerosis (MS). Objective: To establish the expression profile of markers of ER stress both in demyelinating biopsy specimens and microdissected lesions in human post-mortem MS tissue. Methods: Immunohistochemical detection of C/EBP homologous protein (CHOP), immunoglobulin heavy chain binding protein (BiP), and hypoxia marker antigen D-110 in biopsies from three patients with MS primary or secondary progressive, three patients with clinically isolated syndrome, and one patient with lesional epilepsy was carried out. Laser capture microdissection of normal, perilesion and lesion tissue from post-mortem MS tissue and non-diseased control tissue was performed, followed by real-time PCR to detect ER stress genes. Results: In biopsy specimens, increased expression of the ER and hypoxic stress molecules in a range of cell types in most of the actively demyelinating lesions and perilesions was detected. Real-time PCR analysis demonstrated statistically significant elevated expression of the ER stress genes in normal-appearing white matter relative to control white matter. Moreover, significantly increased expression of CHOP was detected in the perilesion of active plaques ( p < 0.01). Conclusions: Our results, showing detection of elevated expression of ER stress molecules in lesional tissue, offer compelling evidence for further investigation of the ER stress signalling pathway as a potential therapeutic target for the treatment of MS.

Download Full-text

FoxO suppresses endoplasmic reticulum stress to inhibit growth of Tsc1-deficient tissues under nutrient restriction

eLife ◽

10.7554/elife.53159 ◽

2020 ◽

Vol 9 ◽

Author(s):

Avantika Gupta ◽

Hugo Stocker

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Target Genes ◽

Degradation Pathway ◽

Nutrient Restriction ◽

Loss Of Function ◽

Er Stress Response ◽

Stress Markers ◽

Stress Response Pathway ◽

Elevated Expression

The transcription factor FoxO has been shown to block proliferation and progression in mTORC1-driven tumorigenesis but the picture of the relevant FoxO target genes remains incomplete. Here, we employed RNA-seq profiling on single clones isolated using laser capture microdissection from Drosophila larval eye imaginal discs to identify FoxO targets that restrict the proliferation of Tsc1-deficient cells under nutrient restriction (NR). Transcriptomics analysis revealed downregulation of endoplasmic reticulum-associated protein degradation pathway components upon foxo knockdown. Induction of ER stress pharmacologically or by suppression of other ER stress response pathway components led to an enhanced overgrowth of Tsc1 knockdown tissue. Increase of ER stress in Tsc1 loss-of-function cells upon foxo knockdown was also confirmed by elevated expression levels of known ER stress markers. These results highlight the role of FoxO in limiting ER stress to regulate Tsc1 mutant overgrowth.

Download Full-text

Human CPA1 mutation causes digestive enzyme misfolding and chronic pancreatitis in mice

Gut ◽

10.1136/gutjnl-2018-315994 ◽

2018 ◽

Vol 68 (2) ◽

pp. 301-312 ◽

Cited By ~ 21

Author(s):

Eszter Hegyi ◽

Miklós Sahin-Tóth

Keyword(s):

Chronic Pancreatitis ◽

Er Stress ◽

Digestive Enzyme ◽

Pancreatic Disease ◽

Mutant Mice ◽

Inflammatory Disorder ◽

Loss Of Function ◽

Stress Markers ◽

Elevated Expression

ObjectiveChronic pancreatitis is a progressive, relapsing inflammatory disorder of the pancreas, which often develops in the background of genetic susceptibility. Recently, loss-of-function mutations in CPA1, which encodes the digestive enzyme carboxypeptidase A1, were described in sporadic early onset cases and in hereditary pancreatitis. Mutation-induced misfolding of CPA1 and associated endoplasmic reticulum (ER) stress was suggested as potential disease mechanism; however, in vivo evidence has been lacking. The objective of the present study was to create a mouse model that recapitulates features of CPA1-associated chronic pancreatitis.DesignWe knocked-in the most frequently occurring p.N256K human CPA1 mutation to the mouse Cpa1 locus. Mutant mice were characterised with respect to pancreas pathology and ER stress and compared with C57BL/6N and CPA1 null control mice.ResultsIn the CPA1 N256K mutant mice, we observed hallmarks of chronic pancreatitis that included progressive acinar cell atrophy, inflammatory cell infiltration, fibrosis and acinar-ductal metaplasia. In contrast, similarly to the C57BL/6N mice, the CPA1 null control strain exhibited no signs of pancreatic disease. Mutation p.N256K induced misfolding of mouse CPA1 and resulted in elevated expression of ER stress markers Hspa5 (BiP) and Ddit3 (CHOP) both in cell culture and mutant mice.ConclusionThe results offer categorical evidence that CPA1 mutations elicit enzyme misfolding and cause chronic pancreatitis via an ER stress-related mechanism.

Download Full-text

Uncoupling Lipid Metabolism from Inflammation through Fatty Acid Binding Protein-Dependent Expression of UCP2

Molecular and Cellular Biology ◽

10.1128/mcb.01122-14 ◽

2015 ◽

Vol 35 (6) ◽

pp. 1055-1065 ◽

Cited By ~ 51

Author(s):

Hongliang Xu ◽

Ann V. Hertzel ◽

Kaylee A. Steen ◽

Qigui Wang ◽

Jill Suttles ◽

...

Keyword(s):

Fatty Acid ◽

Er Stress ◽

Fatty Acid Binding Protein ◽

Binding Protein ◽

Uncoupling Protein ◽

Mitochondrial Protein ◽

Fatty Acid Binding ◽

Acid Binding Protein ◽

Ucp2 Expression ◽

Elevated Expression

Chronic inflammation in obese adipose tissue is linked to endoplasmic reticulum (ER) stress and systemic insulin resistance. Targeted deletion of the murine fatty acid binding protein (FABP4/aP2) uncouples obesity from inflammation although the mechanism underlying this finding has remained enigmatic. Here, we show that inhibition or deletion of FABP4/aP2 in macrophages results in increased intracellular free fatty acids (FFAs) and elevated expression of uncoupling protein 2 (UCP2) without concomitant increases in UCP1 or UCP3. Silencing of UCP2 mRNA in FABP4/aP2-deficient macrophages negated the protective effect of FABP loss and increased ER stress in response to palmitate or lipopolysaccharide (LPS). Pharmacologic inhibition of FABP4/aP2 with the FABP inhibitor HTS01037 also upregulated UCP2 and reduced expression of BiP, CHOP, and XBP-1s. Expression of native FABP4/aP2 (but not the non-fatty acid binding mutant R126Q) into FABP4/aP2 null cells reduced UCP2 expression, suggesting that the FABP-FFA equilibrium controls UCP2 expression. FABP4/aP2-deficient macrophages are resistant to LPS-induced mitochondrial dysfunction and exhibit decreased mitochondrial protein carbonylation and UCP2-dependent reduction in intracellular reactive oxygen species. These data demonstrate that FABP4/aP2 directly regulates intracellular FFA levels and indirectly controls macrophage inflammation and ER stress by regulating the expression of UCP2.

Download Full-text

1823-P: Bromocriptine (BC) Normalizes Elevated Expression of Liver Genes Involved in Fatty Acid Oxidation, Lipogenesis, Inflammation, and Endoplasmic Reticulum (ER) Stress and Glucose Intolerance of High-Fat/Sucrose Diet-Fed Rats

Diabetes ◽

10.2337/db20-1823-p ◽

2020 ◽

Vol 69 (Supplement 1) ◽

pp. 1823-P

Author(s):

YAHONG ZHANG ◽

MICHAEL EZROKHI ◽

NICHOLAS COMINOS ◽

ANTHONY H. CINCOTTA

Keyword(s):

Endoplasmic Reticulum ◽

Fatty Acid ◽

Er Stress ◽

Fatty Acid Oxidation ◽

Glucose Intolerance ◽

Acid Oxidation ◽

High Fat ◽

Sucrose Diet ◽

Elevated Expression

Download Full-text

Interaction between PSMD10 and GRP78 accelerates endoplasmic reticulum stress-mediated hepatic apoptosis induced by homocysteine

Gut Pathogens ◽

10.1186/s13099-021-00455-z ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Kun Xiao ◽

Shengchao Ma ◽

Long Xu ◽

Ning Ding ◽

Hui Zhang ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Liver Injury ◽

Er Stress ◽

Luciferase Reporter ◽

Expression Levels ◽

Elevated Expression ◽

Associated Proteins ◽

Underlying Mechanisms ◽

Induced Apoptosis ◽

Related Proteins

Abstract Background The liver plays an important role in production and metabolism of homocysteine (Hcy), which has been reported to be involved in liver injury. In our previous work, we confirm that Hcy can induce liver injury by activating endoplasmic reticulum (ER) stress. However, the underlying mechanisms remain largely unknown. Results In present study, we established the Hcy-induced liver injury model by feeding cbs+/− mice with high methionine diet, and found that a considerable mass of disordered arrangement of hepatocytes and enlarged space between hepatocytes were frequently occurred in the liver of cbs+/− mice, accompanied with elevated expression levels of apoptosis-related proteins. In addition, Hcy could activate ER stress both in cbs+/− mice and hepatocytes. Mechanistically, Hcy promoted the expression levels of proteasome 26S subunit non-ATPase 10 (PSMD10) in hepatocytes; and the expression of ER stress indicators and apoptosis-associated proteins were significantly suppressed when PSMD10 was silenced in hepatocytes under Hcy treatment. Moreover, bioinformatics analysis and luciferase reporter assay demonstrated that PSMD10 was a target gene of miR-212-5p. Consistently, miR-212-5p overexpression could inhibit ER stress-mediated apoptosis of hepatocytes under Hcy treatment. With the help of co-immunoprecipitation assay, we identified that the interaction between PSMD10 and GRP78 accelerated ER stress-mediated hepatic apoptosis induced by Hcy. Conclusions Our findings indicate that miR-212-5p directly targets PSMD10 and subsequently activates ER stress to promote Hcy-induced apoptosis of hepatocytes. We propose that endogenous PSMD10 physically interacts with GRP78 to regulate ER stress. Our study may provide the therapeutic target for the liver injury induced by Hcy.

Download Full-text