Innate immune sensing of self-derived double-stranded RNA by RIG-I-MAVS-TNF-α regulates the survival and senescence fate of SARS-2-S syncytia

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains an important health threat. Syncytial formation by infected cells mediated by the SARS-CoV-2 spike protein (SARS-2-S) is a hallmark of COVID-19-associated pathology. Although SARS-CoV-2 infection evokes cellular senescence, as in other viruses, the direct link between SARS-2-S-induced syncytia with senescence in the absence of viral infection and their senescence fate determinants remain unknown. Here, we show that syncytia formed by cells expressing exogenously delivered SARS-2-S exhibited a senescence-like phenotype in vitro and that SARS-2-S mRNA induced senescence phenotype in vivo. Extracellular vesicles (EVs) containing SARS-2-S also induced senescent syncytium formation independent of the de novo synthesis of SARS-2-S. Mechanistically, we show that the accumulation of endogenous dsRNA, partially that whose formation is induced by activation of the unfolded protein response (UPR), in SARS-2-S syncytia triggers RIG-I-MAVS signalling to drive the TNF--dependent survival and senescence fate of SARS-2-S syncytia. Our findings suggest that the fusogenic ability of SARS-2-S might contribute to the side effects of particular COVID-19 vaccines or perhaps long COVID-19 syndrome and provide insight into how these effects can be prevented.

GP73 is a glucogenic hormone regulating SARS-CoV-2-induced hyperglycemia

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection induces new-onset diabetes and severe metabolic complications of pre-existing diabetes. The pathogenic mechanism underlying this is incompletely understood. Here, we provided evidence linking circulating GP73 with the exaggerated gluconeogenesis triggered by SARS-CoV-2 infection. We found that SARS-CoV-2 infection or glucotoxic condition increased the cellular secretion of GP73. Secreted GP73 trafficked to the liver and kidney to stimulate gluconeogenesis through cAMP/PKA pathway. By using global phosphoproteomics, we found a drastic remodeling of PKA kinase hub exerted by GP73. Notably, COVID-19 patients showed pathologically elevated plasma GP73, and neutralization of the secreted GP73 inhibited enhanced PKA signaling and glucose production associated with SARS-CoV-2 infection. GP73 blockade also reduced gluconeogenesis and lowered hyperglycemia in type 2 (T2D) diabetic mice. Therefore, our findings provide novel insight into the roles of GP73 as a key glucogenic hormone and mechanistic clues underlying the development of SARS-CoV-induced glucose abnormalities.

SARS-CoV-2 manipulates the SR-B1-mediated HDL uptake pathway for its entry

The recently emerged pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly, leading to a global COVID-19 pandemic. Binding of the viral spike protein (SARS-2-S) to cell surface receptor angiotensin-converting enzyme 2 (ACE2) mediates host cell infection. In the present study, we demonstrate that in addition to ACE2, the S1 subunit of SARS-2-S binds to HDL and that SARS-CoV-2 hijacks the SR-B1-mediated HDL uptake pathway to facilitate its entry. SR-B1 facilitates SARS-CoV-2 entry into permissive cells by augmenting virus attachment. MAb (monoclonal antibody)-mediated blocking of SARS-2-S-HDL binding and SR-B1 antagonists strongly inhibit HDL-enhanced SARS-CoV-2 infection. Notably, SR-B1 is co-expressed with ACE2 in human pulmonary and extrapulmonary tissues. These findings revealed a novel mechanism for SARS-CoV-2 entry and could provide a new target to treat SARS-CoV-2 infection.

Cholesterol Metabolism--Impact for SARS-CoV-2 Infection Prognosis, Entry, and Antiviral Therapies

In this study, we specifically addressed the connection between the SARS-CoV-2 virus with host cholesterol metabolism. Plasma lipid profile was measured in 861 COVID-19 patients classified as mild (n=215), moderate (n=364), severe (n=217) or critical (n=65) and 1108 age- and sex-matched healthy individuals. We showed that the levels of both TG and HDL-C were significantly lower in patients with severe disease than in patients with moderate or mild disease. After successful treatment, cholesterol metabolism was reestablished in patients with SARS-CoV-2 infection. The serum concentrations of TC and HDL-C can be used as indicators of disease severity and prognosis in COVID-19 patients.

BPOZ inhibits proliferation of breast cancer cell lines / 军事医学

Objective To investigate the effect of BTB/POZ ( broad complex, tramtrack and bric a brac/poxviruses and zinc finger) on proliferation of breast cancer cell lines.Methods The eukaryotic expression plasmid pCMV-HA-BPOZ was constructed by cloning from cDNA of human genome.Western blotting was used to detect the expression of pCMV-HA-BPOZ.Cells growth assay was used to detect the effect of BPOZ on proliferation and colony formation assay was used to detect the effect of BPOZ on cell growth ability.Results Western blotting showed that HA-BPOZ was efficiently expressed in cells.Moreover, the growth ability and proliferation of cells were significantly inhibited in BPOZ overexpressed cells compared with the control cells (both P <0.05).Conclusionp CMV-HA-BPOZ plasmid is constructed.BPOZ can restrain breast cancer cell lines MCF7 and ZR-75-1 cells from proliferating and growing.The results of our study can con-tribute to the study of functions of BPOZ in breast cancer.

Molecular mechanism of Golgi protein 73 in inflammation / 军事医学

Objective To study the effect of Golgi protein 73(GP73) on inflammation, and to reveal the effect of GP73 on tumorigenesis and metastasis.Methods The transcriptional activity of NF-κB and the expression of IL-1β, IL-6 and TNF-αwith GP73 overexpression or knockdown were detected to illuminate the role of GP73 in inflammation.According to the TCGA database, the correlation between the transcriptional activity of GP73 and the expression of NF-κB, IL-1β, IL-6 and TNF-αwas analyzed to determine the role of GP73 in tumor inflammation.Results Correlative analysis showed that there was a positive correlation between the expression of GP73 with NF-κB, IL-1β, IL-6 and TNF-α.The transcriptional activity of NF-κB was upregulated by GP73 overexpression, but downregulated by GP73 knockdown.The expression of IL-1β, IL-6 and TNF-αwas upregulated by GP73 overexpression.Ammonium pyrrolidinedithiocarbamate ( PDTC ) was in-volved in inflammation reaction induced by GP73.Conclusion GP73 is possibly involved in inflammation and promotes tu-morigenesis and metastasis.

Construction of H22 GP73 knockout gene stable strain using CRISPR/Cas9 gene editing system and identification of functions / 军事医学

Objective To knock out the GP73 gene in H22 cells originating in mice using CRISPR/Cas9 gene editing system and construct H22 GP73 gene knockout stable strain for identification of its functions .Methods Two pairs of sgRNAs that could specifically identify the upstream and downstream of GP 73 gene first promoter were designed before a recombinant eukaryotic expressional plasmid was constructed using pX 459 .After enzyme digestion and sequencing , two pairs of recombinant plasmids were co-transfected into H22 cells before puromycin was used to screen positive cells and monoclonal cells which stably knocked out GP 73 gene were developed .The knockout effect was measured by Western blotting.Cell Titer 96? AQueous One Solution Assay was used to detect the effect on cell reproductive capacity when the GP73 was knocked out .The transferability was detected through wound healing test .Results The result of Western blotting suggested that GP73 protein was undetected in the construction of H22 GP73 knockout gene stable strain after transfection.The transfer and reproduction slowed down .Conclusion H22 GP73 gene knockout stable strain can be successfully built using CRISPR/Cas9 gene editing system ,thus facilitating studies on the function of GP 73 in hepatocarcinogenesis .