Trigonelline induces autophagy to protect mesangial cells in response to high glucose via activating the miR-5189-5p-AMPK pathway.

BACKGROUND: Diabetic nephropathy (DN) is a primary cause of end-stage renal disease. Increasing evidence indicates that microRNAs (miRNAs) are involved in DN pathogenesis. Trigonelline (TRL) has been shown to lower blood sugar and cholesterol levels, promote nerve regeneration, and exert anti-cancer and sedative properties. METHOD: The effect of TRL on human mesangial cell (HMC) growth was assessed using the MTT assay. Differentially expressed miRNAs were validated using real-time quantitative polymerase chain reaction (real-time PCR). Bioinformatics, cell transfection, and Western blot analyses were utilized to confirm the binding of miR-5189-5p to HIF1AN. The effects of miR-5189-5 expression on cell proliferation were also assessed. Western blot analysis was used to determine the activation of multiple signaling molecules including phosphorylated-(p)-AMPK, SIRT1, LC3B, p62, and Beclin-1 in the autophagy pathway. RESULTS: TRL improved proliferation, increased the expression of miR-5189-5p, reduced HIF1AN, and restored the inhibition of autophagy in HMCs induced by high glucose. MiR-5189-5p mimics inhibited HIF1AN expression, and the miR-5189-5p inhibitor increased HIF1AN expression. MiR-5189-5p mimics significantly improved the proliferation of HMCs induced by high glucose, reduced the relative protein expression of p-AMPK, SIRT1, LC3B, and Beclin-1, and significantly increased the relative protein expression of p62. CONCLUSION: We showed that TRL up-regulated miR-5189-5p expression, activated the AMPK pathway, and activated autophagy in HMCs. Our study demonstrates that TRL could be a new treatment strategy to protect mesangial cells in response to high glucose.

Role of tissue transglutaminase in the pathogenesis of diabetic cardiomyopathy and the intervention effect of rutin.

The aim of this study was to investigate the role of tissue transglutaminase (tTG) in the pathogenesis of diabetic cardiomyopathy (DCM) and the intervention effect of rutin. DCM was induced in rats by the injection of streptozotocin (STZ; 25 mg/kg). After a preliminary examination, the rats were randomly divided into four groups: Control (n=8), STZ-induced DCM (n=8), STZ + positive drug (captopril; n=6) and STZ + rutin (n=8) groups. The DCM model was evaluated using blood sugar values, serum enzyme levels, hematoxylin and eosin staining and Masson's staining, ex vivo. The protein and mRNA expression of tTG was assessed with immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The rat model of DCM was successfully established by STZ administration, and the expression levels of tTG were significantly increased in the DCM model. Following the injection of captopril or rutin, the blood sugar values, collagen content and expression levels of tTG were gradually reduced and serum enzyme levels were increased, as compared with those in the STZ-induced DCM group. In conclusion, tTG plays an important role in STZ-induced DCM. In addition, rutin may inhibit the expression of tTG and regulate myocardial injury in STZ-induced DCM.

[Expression and implication of angiotensin II type 1 receptor in myocardial fibrosis of rats].

OBJECTIVE: To investigate the expression and pathobiological implications of angiotensin II type 1 receptor (AT1R) in development of myocardial fibrosis of rats. METHODS: Rat myocardial necrosis model was established using isoproterenol injection (15 mg/kg). Rat serum aspartate transaminase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) and creatine kinase isoenzymes (CK-MB) were detected by MD-100 automatic biochemical analyzer. Masson staining was used to evaluate the morphological changes. The expression of AT1R protein was determined by immunohistochemistry and its mRNA expression was analyzed by RT-PCR. The expression of collage type I and III was determined by immunohistochemistry. RESULTS: Serum LDH, CK and CK-MB reached their peaks at 4 h (chi2 = 16.90, P < 0.05), and AST achieved its peak in 6 h (chi2 = 16.90, P < 0.05). AT1R mRNA expression was increased 2 - 12 h after isoproterenol injection, but no statistical significance (P > 0.05) was observed comparing with the control. However, a significant AT1R mRNA increase was present at 24 h and decreased gradually after 48 h, and back to the control level after 3 weeks. Protein expression of AT1R increased proportionally with the severity of the fibrosis. CONCLUSIONS: AT1R mRNA and protein expressions increase significantly during myocardial ischemia, and is closely correlated with the fibrosis. These findings indicate that AT1R may play an important role in the pathogenesis of myocardial fibrosis.

[Ameliorative effect of ginseng glycopeptide on cross-linking of rat tail tendon collagen].

OBJECTIVE: To investigate the ameliorative effect of ginseng glycopeptide on cross-linking of rat tail tendon collagen. METHOD: ELISA was used to determine the inhibitory effect of ginseng glycopeptide on cross-linking of rat tail tendon collagen in vitro. After ginseng glycopeptide was intraperitoneally administrated to streptozotocin-induced diabetic rats for 12 weeks, the acid solubility, limited pepsin degradation properties and solubility in SDS-2-mercaptoethanol of the rat tail tendon collagen were determined, and the effect of ginseng glycopeptide on the tail tendon collagen cross-linking was evaluated. RESULT: Ginseng glycopeptide inhibited significantly the cross-linking of rat tail tendon collagen in vitro. The solubility of the tail tendon collagen (in acid, pepsin and SDS-2-mercaptoethanol) was markedly decreased in diabetic rats and ginseng glycopeptide-treated diabetic rats had significantly an increase in the collagen solubility in the above-mentioned solutions, suggesting that ginseng glycopeptide decreased severity of the collagen cross-linking. CONCLUSION: Ginsengglycopeptide exhibits an significantly ameliorative effect on cross-linking of rat tail tendon collagen.