A Pyrrole-Imidazole Polyamide Targeting Human USF1 Binding Suppresses High Glucose-Induced TGF-β1 and Osteopontin Expression in Human Renal Mesangial Cells.

Transforming growth factor-β1 (TGF-β1) is a key profibrotic mediator in diabetic kidney disease. Upstream stimulatory factor 1 (USF1) enhances TGF-β1 transcription through an E-box/glucose-response element in the TGF-β1 promoter under high-glucose conditions. We designed a sequence-specific pyrrole-imidazole (PI) polyamide targeting the human USF1-binding site in the TGF-β1 promoter and evaluated its activity in human renal mesangial cells (HRMCs). A target PI polyamide and a mismatch PI polyamide were synthesized. DNA binding and inhibition of the USF1-DNA interaction were assessed by gel mobility shift assays. HRMCs were exposed to high glucose with or without PI polyamides, and TGF-β1 and osteopontin expression were quantified by real-time PCR and Western blotting. The target PI polyamide bound the intended promoter sequence and reduced recombinant USF1 binding in vitro. In high-glucose-exposed HRMCs, the target PI polyamide suppressed TGF-β1 mRNA and protein expression, whereas the mismatch PI polyamide did not suppress TGF-β1 expression. The target PI polyamide also reduced osteopontin mRNA expression. These findings provide proof-of-concept that PI polyamide-mediated targeting of the human USF1-TGF-β1 axis can attenuate high-glucose-associated profibrotic responses in HRMCs.