Tripartite motif-containing protein 31 confers protection against nonalcoholic steatohepatitis by deactivating mitogen-activated protein kinase kinase kinase 7.

BACKGROUND AIMS: As a global health threat, NASH has been confirmed to be a chronic progressive liver disease that is strongly associated with obesity. However, no approved drugs or efficient therapeutic strategies are valid, mainly because its complicated pathological processes is underestimated. APPROACH RESULTS: We identified the RING-type E3 ubiquitin transferase-tripartite motif-containing protein 31 (TRIM31), a member of the E3 ubiquitin ligases family, as an efficient endogenous inhibitor of transforming growth factor-beta-activated kinase 1 (mitogen-activated protein kinase kinase kinase 7; MAP3K7), and we further confirmed that TRIM31 is an MAP3K7-interacting protein and promotes MAP3K7 degradation by enhancing ubiquitination of K48 linkage in hepatocytes. Hepatocyte-specific Trim31 deletion blocks hepatic metabolism homeostasis, concomitant with glucose metabolic syndrome, lipid accumulation, up-regulated inflammation, and dramatically facilitates NASH progression. Inversely, transgenic overexpression, lentivirus, or adeno-associated virus-mediated Trim31 gene therapy restrain NASH in three dietary mice models. Mechanistically, in response to metabolic insults, TRIM31 interacts with MAP3K7 and conjugates K48-linked ubiquitination chains to promote MAP3K7 degradation, thus blocking MAP3K7 abundance and its downstream signaling cascade activation in hepatocytes. CONCLUSIONS: TRIM31 may serve as a promising therapeutic target for NASH treatment and associated metabolic disorders.

[Anti-tumor effect of Huaier extract supernatant on human gastric cancer HGC-27 and MGC-803 cells].

The purpose of this study was to investigate the effect of Huaier extract supernatant(HES) on the proliferation, apoptosis, autophagy, and migration of human gastric cancer HGC-27 and MGC-803 cells and its molecular mechanisms. The main components in HES were preliminarily analyzed by high-performance liquid chromatography-mass spectrometry(HPLC-MS). Methyl thiazolyl tetrazolium(MTT) assay, colony formation assay, and 5-ethynyl-2'-deoxyuridine(EdU) staining assay were used to explore the effect of HES on the proliferation of human gastric cancer HGC-27 and MGC-803 cells. Hoechst staining and flow cytometry assay were used to determine the effect of HES on apoptosis of human gastric cancer HGC-27 and MGC-803 cells. Acridine orange staining and cell scratch assay were used to determine the effect of HES on autophagy and migration of human gastric cancer HGC-27 and MGC-803 cells, respectively. Western blot was used to investigate the regulatory effect of HES on the expression levels of proteins related to apoptosis, epithelial-mesenchymal transition(EMT), and signaling pathways in human gastric cancer HGC-27 and MGC-803 cells. The results showed that HES mainly contained some components with high polarities. HES significantly reduced the cell viability of human gastric cancer cells in a dose-and time-dependent manner. The IC_(50 )values after 48 h of HES treatment in human gastric cancer HGC-27 and MGC-803 cells were 7.56 and 10.77 g·L~(-1), respectively. Meanwhile, HES inhibited the colony-forming ability and short-term proliferation of human gastric cancer cells. The apoptosis rates of HGC-27 and MGC-803 cells treated with 8 g·L~(-1) HES for 72 h were 62.13%±8.92% and 54.50%±3.26%, respectively. HES also promoted autophagy in human gastric cancer cells and impaired their migration ability in vitro. Moreover, HES up-regulated the cleavage of the apoptosis marker poly ADP-ribose polymerase(PARP) and the protein expression level of the epithelial cell marker E-cadherin, and down-regulated the protein levels of phosphorylated-mammalian target of rapamycin(p-mTOR), phosphorylated-S6(p-S6), and phosphorylated-extracellular signal-regulated kinase(p-ERK) in human gastric cancer cells. Therefore, HES is one of the effective anti-tumor components of Huaier, which inhibits the proliferation and migration of human gastric cancer cells, and induces apoptosis and autophagy. Moreover, the mTOR signal and ERK signal may be involved in the anti-gastric cancer effect of HES. This study provides novel references for the in-depth research and clinical application of Huaier. It is also of great significance to promote the scientific development and utilization of Huaier.