Aim To compare the cytotoxicity of geni-poside (GS)and its metabolite genipin (GP)on hu-man hepatocelluar HepG2 cells and explore the sub-stance and mechanism of hepatotoxicity induced by Fructus Gardeniae.Methods The cytotoxic effect of GS and GP was analyzed by MTT method;the antioxi-dant enzyme activities of manganese superoxide dis-mutase (Mn-SOD),catalase (CAT)and levels of glu-tathione (GSH)were detected by respective kits;the change of intracellular reactive oxygen species (ROS ) was measured by 2′,7′-dichlorofluorescin diacetate (DCFH-DA)staining method;multiparameter cytotox-icity analysis (cell loss,nuclear size and morphologi-cal changes,DNA content,cell membrane permeabili-ty,mitochondrial membrane potential changes,cyto-chrome C release ) were measured simultaneously by high content screening (HCS)assays.Results No cytotoxicity was found in GS (20~1 000 μmol·L-1 ) groups (P>0.05 ),but GP was found to exert obvi-ous cytotoxic effect,and 50μmol·L-1 GP could obvi-ously inhibit HepG2 cell proliferation (P<0.05 ),and the IC50 value was (450.00 ±26.15)μmol·L-1;GS showed no obvious effects on Mn-SOD, CAT, GSH ,ROS (P >0. 0 5 ),GP could significantly decrease the activity of Mn-SOD,CAT and the level of GSH,and obviously increase the content of ROS (P<0.05 or P <0.01 );treatment with 50,500,1 000μmol·L-1 GP resulted in loss of mitochondrial mem-brane potential,cytochrome C release and increased cell permeability (P<0.05 or P<0.01),500,1 000μmol· L-1 GP could also show abvious nuclear con-densation,increased total nuclear intensity and cell loss (P<0.0 1 ).Opposed with GP,GS had no signif-icant effect on the cytotoxic parameters (P>0.05 ). Conclusion GP is the direct substance of hepatotox-icity induced by Fructus Gardeniae,and the mecha-nism might be associated with oxidative stress,mito-chondria injury and apoptosis.

BACKGROUND:Piezo1,a mechanosensitive protein,is tightly connected to osteogenic differentiation,and it has been demonstrated that TAZ has a role in regulating osteogenic differentiation.It is unclear whether TAZ participates in the regulation of osteogenic differentiation of human bone marrow mesenchymal stem cells by Piezo1,so it is crucial to investigate its unique mechanism to prevent osteonecrosis of the femoral head. OBJECTIVE:To elucidate what function Piezo1 plays in osteogenic differentiation and TAZ expression in human bone marrow mesenchymal stem cells. METHODS:The siRNA targeting Piezo1 was constructed and transfected into 293T cells.The silencing efficiency was detected by RT-qPCR.The selected Piezo1-Home-2337 was packaged according to the silencing efficiency,and its optimal multiplicity of infection value was assayed by immunofluorescence staining.The packaged Piezo1 silencing recombinant lentivirus was transfected into human bone marrow mesenchymal stem cells,and its silencing effect was detected by RT-qPCR and western blot assay.Alizarin red staining,alkaline phosphatase activity analysis,immunofluorescence staining,RT-qPCR and western blot assay were utilized to analyze the effect of silencing Piezo1 on the osteogenic differentiation of human bone marrow mesenchymal stem cells. RESULTS AND CONCLUSION:(1)The mRNA and protein levels of Piezo1 in human bone marrow mesenchymal stem cells transfected by si-Piezo1 were decreased significantly,with a statistically significant difference compared with normal and negative control groups.(2)The alkaline phosphatase activity in the si-Piezo1 group was much lower and the calcium deposition in the si-Piezo1 group was significantly reduced compared with the negative control group.(3)The mRNA levels of osteogenesis-related genes including Runt-related transcription factor 2(Runx2),osteopontin(OPN),distal-less homeobox 5(DLX5),osteocalcin,β-catenin and Tafazzin(TAZ)in the si-Piezo1 group were significantly decreased compared with the negative control group.Afterward,the expression levels of TAZ and β-catenin protein in the si-Piezo1 group were down-regulated significantly compared with the negative control group,whereas the expression levels of p-TAZ and p-β-catenin protein in the si-Piezo1 group had the opposite condition.(4)The results of immunofluorescence staining showed that the expression of TAZ and β-catenin in human bone marrow mesenchymal stem cells in the si-Piezo1 group was less compared with the negative control group.(5)These findings indicate that Piezo1 can promote the osteogenic differentiation of human bone marrow mesenchymal stem cells.The osteogenic ability of human bone marrow mesenchymal stem cells is significantly reduced after silencing Piezo1,and the expression of TAZ is also reduced.