Objective To identify the effects of virus specific amino acids in the fusion active domains of paramyxovirus fusion proteins on the specific membrane fusion. Methods Site-directed mutagenesis was used to obtain mutants in the identified fusion active domains of Newcastle disease virus (NDV) fusion protein (F) and human parainfluenza virus (hPIV) fusion protein (F). All the mutant F genes were co-expressed with their homol-ogous or heterogenous hemagglutinin-neuraminidase (HN) genes in eukaryocytes. The fusion functions of mutants were assayed by Giemsa staining and reporter gene method. The expression efficiencies of mutants were assayed by fluorescence-activated cell sorter (FACS). Results In the NDV F mutants, N150D-L152D had 46.31% fusion activity of wide type. The fusion activities of N257D-N258D-Q259E, G271D-N272D and Q279E-Q281E almost disappeared, and they had only 1.25%, 3.14% and 2.23% of fusion activities, respectively, compared with wide type. N296D-N297D had 97.68% fusion activity of wide type. In the hPIV F mutants, D143A-E145A had 32.63% fusion activity of wide type. The fusion activity of E223Q-K224A almost disappeared, and it had only 1.91% fusion activity of wide type. K263A-R265A, D268A-D270A and R475A-R476A had 14.63%, 19.52% and 28.95% of fusion activities respectively compared with wild type. The analysis of FACS indicated that proteins of NDV F N257D-N258D-Q259E, G271D-N272D, Q279E-Q281E and hPIV F E223Q-K224A were not expressed on the cell surface, while proteins of the rest mutants were expressed nearly as the same as the wide types. Con-clusion As to NDV F, the amino acids of N257, N258, Q259, G271, N272, Q279 and Q281 were significant to the specific membrane fusion, and N150 and L152 were also important, but N296 and N297 were not. For hPIV F, the amino acids of E223 and K224 were significant to the specific membrane fusion, and D143, E145, K263, 11265, D268, D270, R475 and R476 were also important.

AIM:To investigate the mechanism of 9-cis-RA inhibiting the growth of lung adenocarcinoma cells, and we detect the expressional changes of cyclinD1 and cdk4 in lung adenocarcinoma cells PG, A_(549), SPC-A_1 before and after being treated with 9-cis-retinoic acid(9-cis-RA). METHODS: RT-PCR was used to analyse the transcriptional changes of cyclinD1 and cdk4 in PG, A_(549) and SPC-A_1. RESULTS:9-cis-RA decreased the transcription of cyclinD1 in PG and A_(549)(P

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. Fat accumulation "sensitizes" the liver to insult and leads to nonalcoholic steatohepatitis (NASH). G protein-coupled receptor 35 (GPR35) is involved in metabolic stresses, but its role in NAFLD is unknown. We report that hepatocyte GPR35 mitigates NASH by regulating hepatic cholesterol homeostasis. Specifically, we found that GPR35 overexpression in hepatocytes protected against high-fat/cholesterol/fructose (HFCF) diet-induced steatohepatitis, whereas loss of GPR35 had the opposite effect. Administration of the GPR35 agonist kynurenic acid (Kyna) suppressed HFCF diet-induced steatohepatitis in mice. Kyna/GPR35 induced expression of StAR-related lipid transfer protein 4 (STARD4) through the ERK1/2 signaling pathway, ultimately resulting in hepatic cholesterol esterification and bile acid synthesis (BAS). The overexpression of STARD4 increased the expression of the BAS rate-limiting enzymes cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and CYP8B1, promoting the conversion of cholesterol to bile acid. The protective effect induced by GPR35 overexpression in hepatocytes disappeared in hepatocyte STARD4-knockdown mice. STARD4 overexpression in hepatocytes reversed the aggravation of HFCF diet-induced steatohepatitis caused by the loss of GPR35 expression in hepatocytes in mice. Our findings indicate that the GPR35-STARD4 axis is a promising therapeutic target for NAFLD.