Naringenin Targeting The Let-7a / TGFBR1 Signaling Pathway To Delay Diabetic Nephropathy

PART Ⅰ NARINGENIN AMELIORATES KIDNEY INJURYIN DIABETIC NEPHROPATHY RATSObjective To explore the protectory effects of naringenin(NAR) on kidney of diabetic nephropathy rats.Methods DN rats were formed by a combination method of high-sugar-high-fat diet and low dose streptozotocin. Experimental rats were randomly assigned into DN group and NAR group. After rats were treated with naringenin for 6 weeks, the 24h-urinary protein(24h-UP), Ccr and kidney index(KI) were detected. Glomerular pathological changes and glomerular area(GA) were observed by HE-straning. The expressions of Col4 and FN m RNA were detected by Real-time PCR, and protein levels of Col4 and FN were detected by western blot and immunofluorescence.Results Compared with CON group, the 24h-UP, KI and GA were increased, Ccr was declined in DN group, the m RNA and protein expressions of Col4 and FN were increased. Naringenin attenuated the renal lesion, inhibited the expressions of Col4 and FN in DN.Conclusion Naringenin ameliorated renal function, had marked protectory effects on kidneys in diabetic nephropathy, possibly through reduced the deposition of ECM proteins.PART Ⅱ EFFECT OF NARINGENIN ON THE MOUSE GLOMERULAR MESANGIAL CELL IN HIGH GLUCOSE CONDITIONObjective To investigate the effect of naringenin on the proliferation of glomerular mesangial cells in high glucose condition.Methods Mesangial cells in high glucose condition were exposed to different concentration of naringenin and the cell proliferation rates were detected by MTT assay. Cell cycle was determined by flow cytometry. The expressions of Col4 and FN protein levels were detected by western blot and immunofluorescence.Results Naringenin inhibited mesangial cell proliferation at a dose and time-dependent manner by blocked the G2 phase. Moreover, naringenin inhibited the productions of Col4 and FN.Conclusion Naringenin has an obvious inhibitory effect on the proliferation of mesangial cell in high glucose condition and naringenin inhibited the production of extracellular matrix protein.PART Ⅲ NARINGENIN AMELIORATED KIDNEY INJURY THROUGH LET-7A/TGFBR1 SIGNALING IN DIABETIC NEPHROPATHYObjective To detect the specific role of naringenin in ameliorating diabetic kidney injury and to explore the relationship between let-7a/TGFBR1 and NAR in diabetic nephropathy.Methods Let-7a expression was detected in DN rats and MMCs. Bioinformatics methods were used for let-7a target prediction and analysis. Dual luciferase reporter assay system and western blot were used for let-7a target verification. The expressions of Col4、FN、TGF-β1、TGFBR1、smad7、t-smad2 and p-smad2 were detected by western blot.Results Let-7a was down-expressed in both DN rats and MMCs, and NAR increased let-7a expression. Let-7a negatively regulated the expression of TGFBR1. TGF-β1/smad signaling was activation in DN rats and MMCs, NAR inhibited the acrivation of TGF-β1/smad signaling. Interestingly, NAR inhibited TGF-β1/smads signaling activation by up-regulating let-7a. Surprisingly, NAR affected the expressions of Col4 and FN through up-regulating let-7a and suppressing TGFBR1.Conclusion TGFBR1 was a target for let-7a. NAR ameliorated kidney injury by regulating let-7a/TGFBR1 signaling.