The Role Of Krüppel-like Factor15(KLF15) In Angiotensin Ⅱ-Induced Renal Fibrosis And Its Mechanism

Objective: The possible role and mechanism of transcription regulator Krüppel-like factor15(KLF15) in the development and progression of renal fibrosis induced by Ang Ⅱ.Methods:(1) In vivo study: Mice subscutaneously implanted with minipumps wererandomized into control group, Ang Ⅱ group, Ang Ⅱ+losartan group, kidney weight/bodyweight, systolic blood pressure, urinary MA/Cr，functional and morphological renalchanges were measured, and the renal fibrosis levels and KLF15were detected byReal-Time PCR, Western Blot and IMF methods respectively.(2) In vitro study:Stimulated with Ang Ⅱ and (or) losartan and (or) infected with Ad-GFP-KLF15, theexpression of KLF15in NRK49F was detected by Real-Time PCR and Western Blot.Meanwhile, gene expressions of TGF-β1、CTGF、Fibronectin、Type I Collagen、Type ⅡICollagen、Type IV Collagen were also detected by Real-Time PCR. The protein of CTGF、Fibronectin、TGF-β1were measured by Western Blot.(3) Mechanism study: CoIP andChIP assay were performed to investigate the relationship among coactivator P/CAF,transcription regulator KLF15, and CTGF promoter.Results:(1) In vivo study: Compared to the control group, the murine model of AngⅡ-induced renal fibrosis demonstrates decrease in renal KLF15expression at4thweek andevident renal fibrosis at6thweek. Administered with losartan in drinking water, theexpression of KLF15in kidney was restored with less renal fibrosis alterations.(2) In vitrostudy: We showed that, Ang Ⅱ stimulation in NRK-49F exhibited significant decreases inKLF15mRNA and protein in2and4hours, followed by a marked increase in profibroticfactors genenrations and ECM secretion, and prevented by AT1receptor blocker losartan.Adenoviral overexpression of KLF15inhibited CTGF production in NRK-49F induced byAng Ⅱ.(3) Mechanism study: Transcription regulator KLF15, directly binded tocoactivator P/CAF, repressed its recruitment to CTGF promoter.Conclusions: Ang Ⅱ could downregulate KLF15via AT1receptor. The mechanism ofKLF15regulating the renal fibrosis induced by Ang Ⅱ, is likely due to that, transcriptionregulator KLF15represses P/CAF recruitment to CTGF promoter, followed by inhibitionof CTGF, with less secretion of ECM.