Abstract: FR-PO267
SMYD3 Regulates Cyst Growth and Ciliogenesis in Autosomal Dominant Polycystic Kidney Disease
Session Information
- Genetic Diseases of the Kidneys: Cystic - II
November 04, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1101 Genetic Diseases of the Kidneys: Cystic
Authors
- Agborbesong, Ewud, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Zhou, Xia, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Li, Xiaoyan, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Li, Xiaogang, Mayo Clinic Minnesota, Rochester, Minnesota, United States
Background
Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder that results in renal cyst formation with the eventual loss of renal function. In addition, ADPKD is associated with abnormal primary cilia function. Yet the regulation of cystogenesis and ciliogenesis in ADPKD are not fully known. Deregulation of epigenetic modulators has emerged as a common etiological factor in ADPKD. How epigenetic modifiers regulate cystogenesis and ciliogenesis remains unclear. We investigated the role of the histone methyltransferase, SMYD3, on cyst growth and ciliogenesis in ADPKD.
Methods
To investigate the role and mechanism of SMYD3 on cyst growth and ciliogenesis in ADPKD, we generated double conditional knockout Pkd1fl/fl:Smyd3fl/fl:Ksp-Cre mice. To further define the mechanisms, we knocked down Smyd3 with shRNA and siRNA, and performed immunostaining, western blot, qRT-PCR and chromatin immunoprecipitation analysis in renal epithelial cells and tissues.
Results
Smyd3 was upregulated in Pkd1 mutant mouse and human ADPKD kidneys, and its knockout reduced cyst growth as seen by decreased cystic index, KW/BW ratios, BUN levels, and cyst lining epithelial cell proliferation in Pkd1 mutant mice. This decreased cyst growth correlated with shortening of cilia in Pkd1 mutant kidney tissues. We found that Smyd3 is located at the centrosome and its depletion disrupted centrosome integrity and decreased recruitment of basal body components such as Cep164 and Ttbk2. We further found that Smyd3 interacted with Ttbk2 and α-tubulin, and via methylation of α-tubulin regulated microtubule stability which contributed to ciliogenesis. Also, Smyd3 regulated the transcription of ciliary genes by binding to their promoters, and regulated the activation of PKD associated signaling pathways including Erk, Stat3, NF-κB and β-catenin. In addition, Smyd3 played a crucial role in the activation of the hedgehog signaling pathway in renal epithelial cells.
Conclusion
Smyd3 is a novel basal body constituent that regulates centriole assembly and ciliogenesis through its interactions with novel binding partners and transcriptional regulation of ciliary genes. The activation of Smyd3 mediated cilia dependent hedgehog and PKD signaling pathways associated with cell proliferation promotes cystogenesis, providing a novel link between cyst growth and cilia formation and function in ADPKD.
Funding
- NIDDK Support