The Alcohol Extract of Coreopsis tinctoria Nutt Ameliorates Diabetes and Diabetic Nephropathy in db/db Mice through miR-192/miR-200b and PTEN/AKT and ZEB2/ECM Pathways

The study aims to investigate the effects of the alcohol extract of Coreopsis tinctoria Nutt (AC) on diabetic nephropathy (DN) mice. A total of 30 db/db (DN) mice were divided into 3 groups, which were treated with AC (300 mg/kg/day), metformin (180 mg/kg/day), or saline by gavage for 10 weeks. Ten db/m mice treated with saline were used as normal control (NC group). Body weight (BW) and fasting blood glucose (FBG), HbA1c, 24 h urinary albumin excretion (UAE), and renal pathological fibrosis were analyzed. Expression of miR-192, miR-200b, and proteins in the PTEN/PI3K/AKT pathway was analyzed by qPCR or western blot. The DN mice had significantly higher BW, FBG, and 24 h UAE, as well as more severe pathological fibrosis when compared with NC. Treatment of AC could decrease BW, FBG, and 24 h UAE and alleviated kidney damage. Compared with the NC group, expressions of miR-192 and miR-200b were increased, whereas their target proteins (ZEB2 and PTEN) were reduced in the kidneys of DN mice, which further modulated the expression of their downstream proteins PI3K p85α, P-AKT, P-smad3, and COL4 α1; these proteins were increased in the kidneys of DN mice. In contrast, AC treatment reversed the expression changes of these proteins. These findings demonstrate that AC may protect the kidneys of DN mice by decreasing miR-192 and miR-200b, which could further regulate their target gene expression and modulate the activity of the PTEN/PI3K/AKT pathway to reduce the degree of renal fibrosis.