PUBLICATION

Protein Kinase C ε Stabilizes β-Catenin and Regulates Its Subcellular Localization in Podocytes

Authors
Duong, M., Yu, X., Teng, B., Schroder, P., Haller, H., Eschenburg, S., Schiffer, M.
ID
ZDB-PUB-170526-11
Date
2017
Source
The Journal of biological chemistry   292(29): 12100-12110 (Journal)
Registered Authors
Keywords
Wnt pathway, beta-catenin (B-catenin ), cadherin, cytoskeleton, glycogen synthase kinase 3 (GSK-3), kidney, podocytes, protein kinase C (PKC)
MeSH Terms
  • Active Transport, Cell Nucleus/drug effects
  • Amino Acid Substitution
  • Animals
  • Biological Assay
  • Carcinogens/toxicity
  • Cell Line, Transformed
  • Gene Expression Regulation/drug effects
  • Glycogen Synthase Kinase 3 beta/metabolism
  • HEK293 Cells
  • Humans
  • Mice, Knockout
  • Mutagenesis, Site-Directed
  • Mutation
  • Phosphorylation/drug effects
  • Podocytes/cytology
  • Podocytes/drug effects
  • Podocytes/metabolism*
  • Protein Kinase C-epsilon/antagonists & inhibitors
  • Protein Kinase C-epsilon/genetics
  • Protein Kinase C-epsilon/metabolism*
  • Protein Processing, Post-Translational*/drug effects
  • Protein Stability/drug effects
  • Recombinant Proteins/chemistry
  • Recombinant Proteins/metabolism
  • Tetradecanoylphorbol Acetate/analogs & derivatives
  • Tetradecanoylphorbol Acetate/toxicity
  • Tissue Culture Techniques
  • beta Catenin/antagonists & inhibitors
  • beta Catenin/chemistry
  • beta Catenin/genetics
  • beta Catenin/metabolism*
PubMed
28539358 Full text @ J. Biol. Chem.
Abstract
Kidney disease has been linked to dysregulated signaling via protein kinase C (PKC) in kidney cells such as podocytes. PKCα is a conventional isoform of PKC and a well-known binding partner of β-catenin, which promotes its degradation. β-Catenin is the main effector of the canonical Wnt pathway and is critical in cell adhesion. However, whether other PKC isoforms interact with β-catenin has not been studied systematically. Here we demonstrate that PKCε-deficient mice, which develop proteinuria and glomerulosclerosis, display a lower β-catenin expression compared to PKC wildtype mice, consistent with an altered phenotype of podocytes in culture. Remarkably, β-catenin showed a reversed subcellular localization pattern: while β-catenin exhibited a perinuclear pattern in undifferentiated wild-type cells, it predominantly localized to the nucleus in PKCε-knockout cells. Phorbol 12-myristate 13-acetate stimulation of both cell types revealed that PKCε positively regulates β-catenin expression and stabilization in a glycogen synthase kinase-3β independent manner. Further, β-catenin overexpression in PKCε-deficient podocytes could restore the wildtype phenotype, similar to the rescue with a PKCε construct. This effect was mediated by upregulation of P-cadherin and the β-catenin downstream target fascin1. Zebrafish studies indicated three PKCε-specific phosphorylation sites in β-catenin that are required for full β-catenin function. Co-immunoprecipitation and pulldown assays confirmed PKCε and β-catenin as binding partners and revealed that ablation of the three PKCε phosphorylation sites weakens their interaction. In summary, we identified a novel pathway for regulation of β-catenin levels and define PKCε as an important β-catenin interaction partner and signaling opponent of other PKC isoforms in podocytes.
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