Crystal structure of SARS-CoV-2 papain-like protease

The pandemic of coronavirus disease 2019 (COVID-19) is changing the world like never before. This crisis is unlikely contained in the absence of effective therapeutics or vaccine. The papain-like protease (PLpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays essential roles in virus replication and immune evasion, presenting a charming drug target. Given the PLpro proteases of SARS-CoV-2 and SARS-CoV share significant homology, inhibitor developed for SARS-CoV PLpro is a promising starting point of therapeutic development. In this study, we sought to provide structural frameworks for PLpro inhibitor design. We determined the unliganded structure of SARS-CoV-2 PLpro mutant C111S, which shares many structural features of SARS-CoV PLpro. This crystal form has unique packing, high solvent content and reasonable resolution 2.5 Å, hence provides a good possibility for fragment-based screening using crystallographic approach. We characterized the protease activity of PLpro in cleaving synthetic peptide harboring nsp2/nsp3 juncture. We demonstrate that a potent SARS-CoV PLpro inhibitor GRL0617 is highly effective in inhibiting protease activity of SARS-CoV-2 with the IC

Inhibitory effect of 5-FU and cisplatinmediated by miR-449b on the migration of HCC cells / 基础医学与临床

Objective To investigate the impact of 5-fluorouracil (5-FU) and cisplatin on miR-449b expression in human hepatocellular carcinoma (HCC) and elucidate the molecular mechanism of 5-FU and cisplatin inhibiting the migration of HCC cells.Methods Real-time qPCR analysis was conducted to determine the expression of miR-449b in 50 HCC tissues.RT-PCR assay was performed to detect the expression of miR-449b in HCC cells with 5-FU and cisplatin treatment.The migration of HCC cells with the overexpression of miR-449b was determined by wound-healing assay;Rescue assay was employed to investigate the correlation between 5-FU & cisplatin, miR-449b and the migration capacity of HCC cells;The putative targets of miR-449b were predicted and validated using target prediction programs and immunoblots.Results The expression of miR-449b decreased in HCC tissues (P<0.0001).miR-449b expression increased in HCC cells upon the treatment of 5-FU and cisplatin (P<0.001).The overexpression of miR-449b inhibited the migration of HCC cells (P<0.001).Rescue assay revealed that inhibition of miR-449b to prevent 5-FU and cisplatin induction resulted in suppressed migration in SMMC7721 cells(P<0.05).Catenin-δ was a functional target of miR-449b.Conclusions 5-FU and cisplatin inhibit the migration of HCC cells at least partly via inducing the expression of miR-449b.