ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of coronavirus disease 2019 (COVID-19), it binds to angiotensin-converting enzyme 2 (ACE2) to enter into human cells. The expression level of ACE2 potentially determine the susceptibility and severity of COVID-19, it is thus of importance to understand the regulatory mechanism of ACE2 expression. Tripartite motif containing 28 (TRIM28) is known to be involved in multiple processes including antiviral restriction, endogenous retrovirus latency and immune response, it is recently reported to be co-expressed with SARS-CoV-2 receptor in type II pneumocytes; however, the roles of TRIM28 in ACE2 expression and SARS-CoV-2 cell entry remain unclear. This study showed that knockdown of TRIM28 induces ACE2 expression and increases pseudotyped SARS-CoV-2 cell entry of A549 cells and primary pulmonary alveolar epithelial cells (PAEpiCs). In a co-culture model of NK cells and lung epithelial cells, our results demonstrated that NK cells inhibit TRIM28 and promote ACE2 expression in lung epithelial cells, which was partially reversed by depletion of interleukin-2 and blocking of granzyme B in the co-culture medium. Furthermore, TRIM28 knockdown enhanced interferon-{gamma} (IFN-{gamma})-induced ACE2 expression through a mechanism involving upregulating IFN-{gamma} receptor 2 (IFNGR2) in both A549 and PAEpiCs. Importantly, the upregulated ACE2 induced by TRIM28 knockdown and co-culture of NK cells was partially reversed by dexamethasone in A549 cells but not PAEpiCs. Our study identified TRIM28 as a novel regulator of ACE2 expression and SARS-CoV-2 cell entry.
ABSTRACT
Objective To study a nucleic acid extraction method suitable for detecting methicillin‐resistant Staphylococcus aureus (MRSA) by PCR method .Methods Under different incubation conditions ,MRSA was cracked by lysozyme ,lysostaphin or chel‐ex100R resin for obtaining DNA ,then the target gene was detected by using the PCR method .Results DNA was obtained by sim‐ultaneously using lysozyme ,lysostaphin and chelex100R resin solution ,the obtained Ct value was significantly lower than that of the other components of schizolysis solutions when PCR was used to detect mecA gene of obtained DNA .There was no statistically sig‐nificant difference between adopting the 56 ℃ one‐step method and the 37 ℃ and 56 ℃ two‐step method for conducting MRSA schizolysis(P> 0 .05) ,but the steps were simplified .Conclusion Incubating MRSA in solution containing lysozyme ,lysostaphin , chelex100R resin for 30 min at 56 ℃ is the convenient and efficient schizolysis method to extract DNA ,which can be used immedi‐ately for the next step of PCR and lays the foundation for PCR rapid detection of clinical MRSA infection .
