Abstract: SA-PO470
SMYD3: A Novel Regulator of Cystogenesis and Ciliogenesis 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
- Agborbesong, Ewud, University of Kansas Medical Center, Kansas City, Kansas, United States
- Zhou, Xia, University of Kansas Medical Center, Kansas City, Kansas, United States
- Li, Xiaogang, Mayo Clinic, Rochester, Minnesota, United States
Background
Deregulation of lysine methylation signaling has emerged as a common aetiological factor in disease pathogenesis, such as cancers. We found that the lysine methyltransferase, SMYD3, is upregulated in ADPKD, a genetic and “ciliopathy” disease characterized by renal cyst formation and ciliogenesis defects. However, if and how SMYD3 regulates cyst formation and its relationship to ciliogenesis remains elusive.
Methods
We investigate the role of Smyd3 on renal cystogenesis by knockout of Smyd3 in Pkd1 conditional knockout mouse kidneys, and investigate if Smyd3 regulates ciliogenesis in mIMCD3 and RCTE cells with and without knockdown of Smyd3 and in primary renal cells isolated from Smyd3 fl/fl:Ksp-Cre mouse kidneys. We determine the effect of Smyd3 on the localization of proteins on the basal body and ciliary axoneme by immunofluorescence.
Results
We found that knockout of Smyd3 delayed cyst growth as seen by decreased cystic index, kidney weight (KW)/body weight (BW) ratios, blood urea nitrogen (BUN) levels, and cyst lining epithelial cell proliferation in Pkd1 mutant mice (all p < 0.05). We further found that knockout of Smyd3 decreased the activity of STAT3 and β-Catenin. In addition, we found that Smyd3 interacted with CDK2, a direct regulator of the cell cycle, and knockout of Smyd3 decreased the phosphorylation of CDK2 in Pkd1 mutant mouse kidneys. We further found that Smyd3 is localized on the centrosome and basal body and silencing or knockout of Smyd3 inhibits primary cilia assembly in renal cells. Smyd3 is co-localized with centriolar distal appendage proteins, Cep164, C2CD3 and Ofd1, and interacts with Ofd1, Ift88 and TTBK2 proteins, known to play an essential role in ciliogenesis. Depletion of Smyd3 increased the recruitment of Ift140, but decreased the recruitment of Rab8a and Cep164 to the ciliary axoneme. Last, knockdown of Smyd3 regulated the expression of key distal appendage and trafficking related proteins at the transcript and protein levels.
Conclusion
Smyd3 regulates cystic renal epithelial cell proliferation via STAT3, β-catenin and Cdk2 signaling to promote cystogenesis, and regulates ciliogenesis by acting as a gate protein, controlling the trafficking of proteins in and out of the cilia. The interactions between Smyd3 and its novel binding partners provide novel mechanisms of Smyd3 in regulating cystogenesis and ciliogenesis in ADPKD.
Funding
- NIDDK Support