ß3-integrin inhibits lipopolysaccharide-induced autophagy in cardiomyocytes via the Akt signaling pathway

HOXA10 DNA Methylation Level in the Endometrium Women with Endometriosis: A Systematic Review

Endometriosis is an inflammatory chronic systemic disease resulting in pelvic pain and infertility. However, despite a high prevalence of endometriosis, disease identification is still insufficient, and a high percentage of misdiagnosing was observed. Hence, a comprehensive study needs to be done to improve our understanding of the pathogenesis of endometriosis. Aberrant hypermethylation of HOXA10 has been reported to play a role in endometriosis. Thus, a comprehensive literature search was conducted to identify the DNA methylation level of HOXA10 among endometriosis patients across populations. The literature search was done using PubMed, Scopus, EBSCOhost, and Science Direct applying (HOXA10 OR "homeobox A10" OR "HOXA-10" OR HOX1) AND ("DNA methylation" OR methylation) AND (endometriosis OR endometrioma) as keywords. From 491 retrieved studies, five original articles investigating the DNA methylation level of HOXA10 from endometrium tissues among endometriosis women were included. All five included studies were classified as high-quality studies. High HOXA10 DNA methylation level was observed in the endometrium tissue of women with endometriosis in all the included studies. The secretory phase was identified as the best sampling time for HOXA10 DNA methylation study in endometriosis, and the most studied DNA methylation site is the promoter region of the HOXA10. However, more studies are needed to expose the HOXA10 mechanism in the pathogenesis of endometriosis.

Swine Acute Diarrhea Syndrome Coronavirus Induces Autophagy to Promote Its Replication via the Akt/mTOR Pathway

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is an enveloped, single-stranded, positive-sense RNA virus belonging to the Coronaviridae family. Increasingly studies have demonstrated that viruses could utilize autophagy to promote their own replication. However, the relationship between SADS-CoV and autophagy remains unknown. Here, we reported that SADS-CoV infection-induced autophagy and pharmacologically increased autophagy were conducive to viral proliferation. Conversely, suppression of autophagy by pharmacological inhibitors or knockdown of autophagy-related protein impeded viral replication. Furthermore, we demonstrated the underlying mechanism by which SADS-CoV triggered autophagy through the inactivation of the Akt/mTOR pathway. Importantly, we identified integrin α3 (ITGA3) as a potential antiviral target upstream of Akt/mTOR and autophagy pathways. Knockdown of ITGA3 enhanced autophagy and consequently increased the replication of SADS-CoV. Collectively, our studies revealed a novel mechanism that SADS-CoV-induced autophagy to facilitate its proliferation via Akt/mTOR pathway and found that ITGA3 was an effective antiviral factor for suppressing viral infection.

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SADS-CoV triggers autophagy pathway to facilitate its proliferation

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Inhibition of autophagy flux impairs SADS-CoV replication

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SADS-CoV negatively regulates Akt/mTOR pathway to induce autophagy

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ITGA3 prevents SADS-CoV production through autophagy inhibition

Quantitative LC-MS/MS uncovers the regulatory role of autophagy in immune thrombocytopenia

BACKGROUND

Immune thrombocytopenia (ITP) is an autoimmune haemorrhagic disease whose pathogenesis is associated with bone marrow megakaryocyte maturation disorder and destruction of the haematopoietic stem cell microenvironment.

METHODS

In this study, we report the qualitative and quantitative profiles of the ITP proteome. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was conducted to elucidate the protein profiles of clinical bone marrow mononuclear cell (BMMC) samples from ITP patients and healthy donors (controls). Gene Ontology (GO) and Kyoto Encyclopaedia Genes and Genome (KEGG) pathway analyses were performed to annotate the differentially expressed proteins. A protein-protein interaction (PPI) network was constructed with the BLAST online database. Target proteins associated with autophagy were quantitatively identified by parallel reaction monitoring (PRM) analysis.

RESULTS

Our approaches showed that the differentially expressed autophagy-related proteins, namely, HSPA8, PARK7, YWHAH, ITGB3 and CSF1R, were changed the most. The protein expression of CSF1R in ITP patients was higher than that in controls, while other autophagy-related proteins were expressed at lower levels in ITP patients than in controls.

CONCLUSION

Bioinformatics analysis indicated that disruption of the autophagy pathway is a potential pathological mechanism of ITP. These results can provide a new direction for exploring the molecular mechanism of ITP.

Cytoplasmic short linear motifs in ACE2 and integrin β3 link SARS-CoV-2 host cell receptors to mediators of endocytosis and autophagy

SARS-CoV-2, the virus that causes COVID-19, enters cells through endocytosis upon binding to the cell surface receptor ACE2 and potentially others, including integrins. Using bioinformatics, Mészáros et al. predicted the presence of short amino acid sequences, called short linear motifs (SLiMs), in the cytoplasmic tails of ACE2 and various integrins that may engage the endocytic and autophagic machinery. Using affinity binding assays, Kliche et al. not only confirmed that many of these predicted SLiMs interacted with target peptides in various components of the endocytosis and autophagy machinery, but also found that these interactions were regulated by the phosphorylation of SLiM-adjacent amino acids. Together, these findings have identified a potential link between autophagy and integrin signaling and could lead to new ways to prevent viral infection.

The spike protein of SARS-CoV-2 binds the angiotensin-converting enzyme 2 (ACE2) on the host cell surface and subsequently enters host cells through receptor-mediated endocytosis. Additional cell receptors may be directly or indirectly involved, including integrins. The cytoplasmic tails of ACE2 and integrins contain several predicted short linear motifs (SLiMs) that may facilitate internalization of the virus as well as its subsequent propagation through processes such as autophagy. Here, we measured the binding affinity of predicted interactions between SLiMs in the cytoplasmic tails of ACE2 and integrin β₃ with proteins that mediate endocytic trafficking and autophagy. We validated that a class I PDZ-binding motif mediated binding of ACE2 to the scaffolding proteins SNX27, NHERF3, and SHANK, and that a binding site for the clathrin adaptor AP2 μ2 in ACE2 overlaps with a phospho-dependent binding site for the SH2 domains of Src family tyrosine kinases. Furthermore, we validated that an LC3-interacting region (LIR) in integrin β₃ bound to the ATG8 domains of the autophagy receptors MAP1LC3 and GABARAP in a manner enhanced by LIR-adjacent phosphorylation. Our results provide molecular links between cell receptors and mediators of endocytosis and autophagy that may facilitate viral entry and propagation.

Integrin β3 promotes cardiomyocyte proliferation and attenuates hypoxia-induced apoptosis via regulating the PTEN/Akt/mTOR and ERK1/2 pathways

Objective: Integrin β3 is one of the main integrin heterodimer receptors on the surface of cardiac myocytes. Our previous studies showed that hypoxia induces apoptosis and increases integrin β3 expression in cardiomyocytes. However, the exact mechanism by which integrin β3 protects against apoptosis remains unclear. Hence, the present investigation aimed to explore the mechanism of integrin β3 in cardiomyocyte proliferation and hypoxia-induced cardiomyocyte apoptosis. Methods: Stable cells and in vivo acute and chronic heart failure rat models were generated to reveal the essential role of integrin β3 in cardiomyocyte proliferation and apoptosis. Western blotting and immunohistochemistry were employed to detect the expression of integrin β3 in the stable cells and rat cardiac tissue. Flow cytometer was used to investigate the role of integrin β3 in hypoxia-induced cardiomyocyte apoptosis. Confocal microscopy was used to detect the localization of integrin β3 and integrin αv in cardiomyocytes. Results: A cobaltous chloride-induced hypoxic microenvironment stimulated cardiomyocyte apoptosis and increased integrin β3 expression in H9C2 cells, AC16 cells, and cardiac tissue from acute and chronic heart failure rats. The overexpression of integrin β3 promoted cardiomyocyte proliferation, whereas silencing integrin β3 expression resulted in decreased cell proliferation in vitro. Furthermore, knocking down integrin β3 expression using shRNA or the integrin β3 inhibitor cilengitide exacerbated cobaltous chloride-induced cardiomyocyte apoptosis, whereas overexpression of integrin β3 weakened cobaltous chloride-induced cardiomyocytes apoptosis. We found that integrin β3 promoted cardiomyocytes proliferation through the regulation of the PTEN/Akt/mTOR and ERK1/2 signaling pathways. In addition, we found that knockdown of integrin αv or integrin β1 weakened the effect of integrin β3 in cardiomyocyte proliferation. Conclusion: Our findings revealed the molecular mechanism of the role of integrin β3 in cardiomyocyte proliferation and hypoxia-induced cardiomyocyte apoptosis, providing new insights into the mechanisms underlying myocardial protection.

Thy-1 depletion and integrin β3 upregulation-mediated PI3K-Akt-mTOR pathway activation inhibits lung fibroblast autophagy in lipopolysaccharide-induced pulmonary fibrosis

Lipopolysaccharide (LPS)-induced autophagy inhibition in lung fibroblasts is closely associated with the activation of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K-Akt-mTOR) pathway. However, the underlying mechanism remains unknown. In this study, we demonstrated that LPS activated the PI3K-Akt-mTOR pathway and inhibited lung fibroblast autophagy by depleting thymocyte differentiation antigen-1 (Thy-1) and upregulating integrin β3 (Itgb3). Challenge of the human lung fibroblast MRC-5 cell line with LPS resulted in significant upregulation of integrin β3, activation of the PI3K-Akt-mTOR pathway and inhibition of autophagy, which could be abolished by integrin β3 silencing by specific shRNA or treatment with the integrin β3 inhibitor cilengitide. Meanwhile, LPS could inhibit Thy-1 expression accompanied with PI3K-Akt-mTOR pathway activation and lung fibroblast autophagy inhibition; these effects could be prevented by Thy-1 overexpression. Meanwhile, Thy-1 downregulation with Thy-1 shRNA could mimic the effects of LPS, inducing the activation of PI3K-Akt-mTOR pathway and inhibiting lung fibroblast autophagy. Furthermore, protein immunoprecipitation analysis demonstrated that LPS reduced the binding of Thy-1 to integrin β3. Thy-1 downregulation, integrin β3 upregulation and autophagy inhibition were also detected in a mouse model of LPS-induced pulmonary fibrosis, which could be prohibited by intratracheal injection of Thy-1 overexpressing adeno-associated virus (AAV) or intraperitoneal injection of the integrin β3 inhibitor cilengitide. In conclusion, this study demonstrated that Thy-1 depletion and integrin β3 upregulation are involved in LPS-induced pulmonary fibrosis, and may serve as potential therapeutic targets for pulmonary fibrosis.

Integrin β3 inhibits hypoxia-induced apoptosis in cardiomyocytes

Hypoxia-induced apoptosis plays an important role in cardiovascular diseases. Integrin β3 is one of the main integrin heterodimer receptors on the surface of cardiac myocytes. However, despite the important role that integrin β3 plays in the cardiovascular disease, its exact role in the hypoxia response remains unclear. Hence, in the present investigation we aimed to study the role of integrin β3 in hypoxia-induced apoptosis in H9C2 cells and primary rat myocardial cells. MTT assay, flow cytometry and TUNEL assay results showed that hypoxia inhibited cardiomyocyte proliferation and induced cardiomyocyte apoptosis. The expression levels of integrin β3 and HIF1α were upregulated in hypoxia-induced cardiomyocytes as revealed by real-time PCR and western blot analysis. Furthermore, knockdown of integrin β3 expression by siRNA increased hypoxia-induced cardiomyocyte apoptosis. In addition, integrin β3 overexpression weakened hypoxia-induced cardiomyocyte apoptosis. The protein expressions of integrin β3 and HIF1α were upregulated in acute myocardial infarction rat cardiac tissues compared with the control rat cardiac tissues. Our data suggest that integrin β3 plays a protective role in cardiomyocytes during hypoxia-induced apoptosis.

Decreased Expression of HOXA10 May Activate the Autophagic Process in Ovarian Endometriosis

Autophagy is a survival process that maintains homeostasis in all eukaryotic cells. Recent studies show an abnormal autophagic activity in endometriosis, but the role of autophagy is controversial. Homeobox A10 (HOXA10) is a transcription factor necessary for embryonic and adult uterine development, and studies indicate that its expression decreases in endometriosis. Homeobox A10 may negatively regulate autophagy in endometriosis. To test this hypothesis, we measured the expression levels of autophagic biomarkers (beclin-1 and LC3-II) and HOXA10 proteins by Western blotting and messenger RNA (mRNA) by quantitative real-time polymerase chain reaction. Furthermore, we evaluated the serum cancer antigen 125 (CA125) levels by immunoassay. Most tested autophagic biomarker proteins and mRNAs were upregulated, whereas HOXA10 protein and mRNA were decreased in ovarian endometriomas compared with eutopic endometria of women with endometriosis and normal endometria. Compared with normal endometrium, only protein expression levels of autophagic biomarkers were increased in the eutopic endometrium of women with endometriosis. Moreover, HOXA10 was found to have a significant negative correlation with autophagy ( P < .01). Serum CA125 was at a high level in endometriosis and increased with elevated revised American Fertility Society staging (I-IV). There was a significant positive correlation between serum CA125 level and LC3-II protein level and/or LC3-II/LC3-I ratio ( P < .01) and a significant negative correlation between serum CA125 level and HOXA10 gene level ( P < .01). In conclusion, our studies support that the deficiency of HOXA10 may induce autophagy in endometriosis, and the relationship among CA125, autophagy, and HOXA10 in endometriosis requires additional research.

Integrin αvβ5 inhibition protects against ischemia-reperfusion-induced lung injury in an autophagy-dependent manner

Integrin αvβ5 mediates pulmonary endothelial barrier function and acute lung injury (LI), but its roles in cell apoptosis and autophagy are unclear. Thus, the aims of this study were to investigate the significance of αvβ5 in ischemia-reperfusion (I/R)-induced apoptosis and LI and to explore the relationship between αvβ5 and autophagy. Human pulmonary microvascular endothelial cells (HPMVECs) were pretreated with an αvβ5-blocking antibody (ALULA) and challenged with oxygen-glucose deprivation/oxygen-glucose restoration, which mimics I/R; then, cellular autophagy and apoptosis were detected, and cell permeability was assessed. In vivo, mice were pretreated with the autophagy inhibitor chloroquine (CLQ), followed by treatment with ALULA. The mice then underwent operative lung I/R. LI was assessed by performing a pathological examination, calculating the wet/dry lung weight ratio and detecting the bronchial alveolar lavage fluid (BALF) protein concentration. αvβ5 inhibition promoted HPMVEC autophagy under I/R in vitro, alleviated cell permeability, decreased the apoptosis ratio, and activated caspase-3 expression. These outcomes were significantly diminished when autophagy was inhibited with a small-interfering RNA construct targeting autophagy-related gene 7 (siATG7). Moreover, ALULA pretreatment alleviated I/R-induced LI (I/R-LI), which manifested as a decreased wet/dry lung weight ratio, an altered BALF protein concentration, and lung edema. Preinhibiting autophagy with CLQ, however, eliminated the protective effects of ALULA on I/R-LI. Therefore, inhibiting αvβ5 effectively ameliorated I/R-induced endothelial cell apoptosis and I/R-LI. This process was dependent on improved autophagy and its inhibitory effects on activated caspase-3.