Effect of miR-21 on albuminuria in db/db mouse with early stage of diabetic nephropathy / 中华内分泌代谢杂志

ABSTRACT

Objective To explore the effect of miR-21 on 24 h urine albumin excretion (UAE), glomeruli morphology, and its molecular mechanism in db/db mouse with early stage of diabetic nephropathy. Methods Twenty-four 5-week-old male mice were randomized into 4 groups control group (untreated db/m mice, n=6),miR-21-treated db/db group (n=6), control empty plasmid treated db/db group (n =6), and untreated db/db group (n = 6). Mice were injected intraperitoneally using a hydrodynamics-based procedure with plasmids (30 mg · kg-1 · d-1 of miR-21 or 30 mg· kg-1 · d-1 of control plasmid) until albuminuria was detected in the untreated db/db mice. The glomeruli were observed under the light microscope, and measured by the software in the computer. The expression of miR-21 was tested by real-time RT-PCR, the expression of PTEN, p-Akt (Ser 473),and phosphatidylinositol-3-kinase (PI3K) p85α protein levels were examined by western blot and immunohistochemistry. Results Male db/db mice of 9-week-old with hyperglycemia and significant elevation of urinary albumin excretion showed features similar to the early stage of diabetic nephropathy. Real-time RT-PCR showed that miR-21 was increased in the miR-21-treated group. By measurement of glomeruli acreage, the glomeruli were smaller in miR-21-treated group than in the control empty plasmid treated and untreated groups (all P<0.01). By Western blot and immunohistochemistry, PTEN were reduced in the miR-21-treated group, whereas PI3K p85α and phospho-Akt (Ser 473 ) were increased in miR-21-treated group (all P < 0.01). Conclusions miR-21 ameliorates glomerular hypertrophy in db/db mice with diabetic nephropathy, and it may be a novel protecting factor of diabetic nephropathy.