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.