Berberine Interferes With the Abnormal Glomerular Mesangial Cell C Ycle Re-Distribution to Alleviate Diabetic Nephropathy via PI3K/AKT/AS160/GLUT4 Signaling Pathway

Abstract

Background: Berberine plays a critical role of the glomerular mesangial cells (GMCs) abnormal proliferation during diabetic nephropathy (DN). This study aims to explore the intervention effect of BBR on DN mice and investigate the potential mechanism targeting abnormal GMCs proliferation. Methods: Streptozotocin-induced mice were used to determine the effect of BBR on the renal injury. In vitro, GMCs are cultured in high glucose (30 mmol/L). EdU and MTT assay are used for screening the optimum BBR concentration and intervention time. Flow cytometry is applied to analyze the cell cycle re-distribution. Western blot and RT-qPCR are devoted to studying the relative expression of molecules in PI3K/AKT/AS160/GLUT4 signaling pathway. Additionally, 2-NBDG assay is selected for measuring the glucose uptake of GMCs. Results: HE and PAS staining revealed that the notable mesangial matrix expansion, glomerular hypertrophy and glycogen deposition in diabetic kidney can be alleviated after BBR treatment. Moreover, BBR significantly reduced the positive expression of GLUT4 in tubulointerstitium and glomerular region. EdU shows that high glucose induces the abnormal proliferation of GMCs, which becomes more apparently as time goes on (20h→28h). Meantime, BBR (60 and 90 μmol/L) can not only increase the proportion of G1 phase, but also reduce the proportion of S phase. After 24 h, the same sort of phenomenon has cropped up in BBR (30 μmol/L) group. BBR (60 μmol/L)) significantly degraded the levels of PI3K-p85, p-AKT, p-AS160, and the membrane-GLUT4, while indistinguishable changes of their total protein expressions. Additionally, BBR prominently reduced the glucose uptake and retard the cell cycle of GMCs to stay at G1 phase. Conclusions: The rearrangement effect of BBR on cell cycle is related with PI3K/AKT signaling pathway and GLUT4 trafficking. The key findings of our study collectively indicate that the treatment of GMCs proliferation can be a novel therapeutic strategy in DN.