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Kidney Week

Abstract: TH-PO668

HDAC6 Controls Polycystin-2 Expression in Pkd1-Null Cells

Session Information

Category: Genetic Diseases of the Kidney

  • 1001 Genetic Diseases of the Kidney: Cystic

Authors

  • Yao, Qin None, University of Maryland School of Medicine, Baltimore, Maryland, United States
  • Outeda, Patricia, University of Maryland School of Medicine, Baltimore, Maryland, United States
  • Qian, Feng, University of Maryland School of Medicine, Baltimore, Maryland, United States
  • Cebotaru, Liudmila, Johns Hopkins University, Baltimore, Maryland, United States
  • Watnick, Terry J., University of Maryland School of Medicine, Baltimore, Maryland, United States
  • Cebotaru, Valeriu, University of Maryland School of Medicine, Baltimore, Maryland, United States
Background

ADPKD is a hereditary disorder that affects 1:1000 to 1:500 people and is characterized by fluid-filled cysts that arise from renal tubules. ADPKD results from mutations in either the PKD1 or PKD2 gene, which encode the gene products polycystin 1 (PC1) and polycystin 2 (PC2), respectively. Although PC1 and PC2 have been studied intensively, information on how they function is still emerging. It has been previously shown that PC2 is degraded via proteasome in MDCK cells. We have shown that overexpression of PC1 accelerates PC2 degradation via the autophagy in MDCK cells. It is unknown how PC2 is degraded in Pkd1-null cells. Here we proposed to determine degradation pattern of PC2 and whether HDAC6 alters PC2 expression in Pkd1-null cells.

Methods

To determine PC2 degradation pattern we have treated Pkd1-null and control cells with cycloheximide to block translation and then inhibited autophagy with bafilomycin and proteasome with MG132, and examined PC2 expression. Next, we inhibited HDAC6 activity with TSA and examined PC2 expression.

Results

Inhibition of proteasome with MG132 prevented degradation of PC2 in control cells, suggesting that PC2 is degraded via proteasome when PC1 is expressed. Inhibition of autophagy with bafilomycin prevented degradation of PC2 in Pkd1-null cells, suggesting that PC2 is degraded via autophagy when PC1 is absent. In immunoprecipitation assay PC2 had higher affinity for p97/VCP, a proteasome substrate, in control cells than in Pkd1-null cells, indicating that PC2 is degraded via proteasome when PC1 is expressed, but not in Pkd1-null cells. Inhibition of HDAC6 activity with TSA decreased PC2 expression in both Pkd1-null and control cells suggesting that HDAC6 regulates PC2 expression.

Conclusion

PC2 is mainly degraded via autophagy in Pkd1-null cells and via proteasome in control cells. HDAC6 regulates PC2 expression in both Pkd1-null and control cells. Further studies will have to determine whether HDAC6 controls PC2 trafficking in Pkd1-null cells.

Funding

  • NIDDK Support