Abstract: SA-PO465
RNA Helicase p68 Inhibits Pkd1 Transcription and Promotes Cyst Growth in ADPKD
Session Information
- Cystic Kidney Diseases: Basic/Translational
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1001 Genetic Diseases of the Kidneys: Cystic
Authors
- Zhang, Lu, Mayo Clinic, Rochester, Minnesota, United States
- Li, Xiaoyan, Mayo Clinic, Rochester, Minnesota, United States
- Zhou, Xia, University of Kansas Medical Center, Kansas City, Kansas, United States
- Calvet, James P., University of Kansas Medical Center, Kansas City, Kansas, United States
- Li, Xiaogang, Mayo Clinic, Rochester, Minnesota, United States
Background
Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations of PKD1 and PKD2, resulting in progressive deterioration of kidney function due to the formation of thousands of cysts. Expression of PKD1 is high in the fetal kidney, which is essential for kidney development, and then is reduced after nephron formation has completed. However, the transcriptional regulation of PKD1 remains elusive. In this study, we investigate the roles and underlying mechanisms of p68, a DEAD box RNA helicase, in regulating Pkd1 gene expression.
Methods
To understand the role of p68 in ADPKD, we examined the expression of p68 and its regulation in Pkd1 mutant renal epithelial cells and ADPKD patient kidneys by qRT-PCR, Western blot and immunostaining/immunohistochemistry, and investigated how p68 regulates cystic cell proliferation, oxidative stress and renal fibrosis. To investigate if and how p68 regulates the transcriptional and post-transcriptional processing of the Pkd1 gene, we performed co-IP and ChIP assays in renal epithelial cells with and without knockdown of p68.
Results
We found that p68 was upregulated in Pkd1 mutant renal epithelial cells compared to that in Pkd1 wild type control cells as examined by Western blot and qRT-PCR analysis. The level of p68 was also increased in cyst lining epithelial cells in kidneys from Pkd1 mutant mice and ADPKD patients. Knockdown of p68 increased Pkd1 gene transcription, whereas upregulation of p68 decreased Pkd1 transcription, which involved 1) interaction of p68 with p53 and Drosha to form a ternary complex on the promoter of the Pkd1 gene, and 2) increased p68 mediated microRNA 182 (miR182). Inhibition of miR182 increased Pkd1 mRNA and protein levels. In addition, we found that oxidative stress decreased Pkd1 expression in a p68-dependent manner. We further found that p68 regulated cystic epithelial cell proliferation via the activation of ERK, mTOR and Rb signaling, and regulated renal fibrosis via TGFβ1 signaling.
Conclusion
This is the first study to show that one of the RNA helicases, p68, inhibits the transcription of the Pkd1 gene and promotes cystic renal cell proliferation and the expression of fibrotic markers in these cells. Oxidative stress promotes renal cyst progression via p68 mediated Pkd1 downregulation. Targeting p68 with its inhibitor may be a potent therapeutic strategy for ADPKD treatment.
Funding
- NIDDK Support