OS 25-03 OVEREXPRESSION OF HETEROGENEOUS NUCLEAR RIBONUCLEOPROTEIN F PREVENTS SYSTEMIC HYPERTENSION AND KIDNEY INJURY AND NORMALIZES RENAL RENIN-ANGIOTENSIN SYSTEM GENES EXPRESSION IN TYPE 2 DIABETIC DB/DB TRANSGENIC MICE.

OBJECTIVE: We aimed to investigate whether overexpression of heterogeneous nuclear ribonucleoprotein F (HnRNP F, a transcription factor) in renal proximal tubular cells (RPTCs) prevents systemic hypertension and kidney injury in type 2 diabetic db/db transgenic (Tg) mice and study its underlying mechanism (s) of action.

DESIGN AND METHOD: Db/db hnRNP F-Tg mice (BKS strain) were generated by cross-breeding of db/m + mice with Tg mice specifically overexpressing HnRNP F in their RPTCs using kidney-specific androgen-regulated protein promoter (KAP2). Adult (10-20 weeks of age) male wild type (WT), db/db and db/db HnRNP F- Tg mice were studied. Kidneys were processed for immunohistochemistry. Blood glucose (BG), systolic blood pressure (SBP) and urinary albumin/creatinine ratio (ACR) were monitored bi-weekly. Immunostaining, Western blotting and real-time qPCR were employed to assess angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin-converting enzyme-2 (ACE-2), angiotensin 1-7 receptor (MasR), transforming growth factor-beta 1 (TGF-β1), Bax and active caspase-3 (Csp-3) protein expression and their mRNA levels in RPTCs, respectively. Rat immortalizaed RPTCs stably transfected with hnRNP F cDNA were studied in vitro.

RESULTS: Db/db mice exhibited increased BG, SBP and ACR as compared to WT mice. Db/db hnRNP F-Tg mice specifically overexpressing HnRNP F in their RPTCs attenuated these abnormalities except BG. AGT, ACE, TGF-β1, Bax and active Csp-3 protein and their respective mRNA expression in RPTCs were significantly increased whereas ACE2 and MasR 2 protein and mRNA were decreased in db/db mice compared to WT. These changes were normalized in db/db HnRNP F-Tg mice except ACE. In vitro, overexpression of HnRNP F inhibited AGT, TGF-β1, Bax and active Csp-3 protein and mRNA expression, whereas it increased ACE-2 and MasR expression in rat RPTCs.

CONCLUSIONS: Our data suggest that intrarenal HnRNP F overexpression attenuates SBP, tubule-interstitial fibrosis and tubular apoptosis, predominantly through decreasing AGT and TGF-β1 expression and increasing ACE-2 and MasR expression.