Fig. 6.

Soluble α-Klotho (s-KL) inactivated the Wnt–β-catenin pathway by upregulating secreted frizzled-related protein 1 (SFRP1). Human renal interstitial fibroblasts (hRIFs) were cultured alone in normal medium (NM) or osteogenic medium (OM) or were cocultured with recombinant KL (r-KL) in OM for 7 days (n = 3), and A qRT-PCR was performed to determine the relative mRNA expression levels of DKK1, SFRP1, SFRP4, and SOST, and B–C WB was performed to determine their relative protein expression levels. D–F HRIFs were retransfected with siRNAs targeting SFRP1 and induced with OM for 7 days (n = 3), and WB was used to determine the relative protein levels of SFRP1, SFRP4, p-β-catenin, β-catenin and osteogenic markers (OCN, MSX2, Runx2). G–I HRIFs were retransfected with siRNAs targeting SFRP4 and induced with OM for 7 days (n = 3), and WB was used to determine the relative protein levels of SFRP4, SFRP1, p-β-catenin, β-catenin and osteogenic markers. (J–L) HRIFs were cotransfected with siRNAs targeting SFRP1 and cocultured with r-KL under osteogenic conditions for 7 days (n = 3), and WB was used to determine the relative protein levels of p-β-catenin, β-catenin and osteogenic markers