Probes for INS

Mutations in polycystin-1 which is encoded by the PKD1 gene are the main causes for the development of autosomal dominant polycystic kidney disease. However, only little is known about the physiological function of polycystin-1 and even less about the regulation of its expression. Here, we show that expression of PKD1 is induced by hypoxia and compounds that stabilize the hypoxia-inducible transcription factor (HIF) 1α in primary human tubular epithelial cells. Knockdown of HIF subunits confirms HIF-1α-dependent regulation of polycystin-1 expression. Furthermore, HIF ChIP-seq reveals that HIF interacts with a regulatory DNA element within the PKD1 gene in renal tubule-derived cells. HIF-dependent expression of polycystin-1 can also be demonstrated in vivo in kidneys of mice treated with substances that stabilize HIF. Polycystin-1 and HIF-1α have been shown to promote epithelial branching during kidney development. In line with these findings, we show that expression of polycystin-1 within mouse embryonic ureteric bud branches is regulated by HIF. Our finding links expression of one of the main regulators of accurate renal development with the hypoxia signalling pathway and provides additional insight into the pathophysiology of polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) causes renal cysts and leads to end-stage-renal-disease in midlife due mainly to PKD1 gene mutations. Virtually no studies have explored gene therapeutic strategies for long-term effective treatment of PKD. Toward this aim, the severely cystic Pkd1 null mouse model was targeted by series of transgene transfer using genomic Pkd1 under its regulatory elements (Pkd1wt), kidney-targeted Pkd1 gene (SBPkd1) or Pkd1Minigene. The introduced Pkd1 wt gene constructs with ∼8-fold overexpression display similar endogenous cellular profile, full complementation of Pkd1-/- phenotype and establish the referral Pkd1 genomic length for proper regulation. SBPkd1 transgene transfers expressing 0.6- or 7-fold Pkd1 endogenous levels are sufficient to correct glomerular and proximal tubular cysts as well as markedly postpone cysts in other tubular segments, showing that the small SB elements appreciably overlap with Pkd1 promoter/5’UTR regulation. Renal targeted Pkd1Minigene at high-copy conveys similar expression level to endogenous Pkd1 gene with widespread and homogeneous weak Pkd1 cellular signal, partially rescuing all cystic tubular segments. These transgene transfers determine that Pkd1 intragenic sequences not only regulate expression levels but also spatiotemporal pattern. Importantly, our study demonstrates that Pkd1 re-expression from hybrid therapeutic constructs can ameliorate, with considerably extended lifespan, or eliminate PKD.