Protein kinase A-mediated 14-3-3 association impedes human Dapper1 to promote dishevelled degradation

J Biol Chem. 2011 Apr 29;286(17):14870-80. doi: 10.1074/jbc.M110.211607. Epub 2011 Jan 24.

Abstract

Wnt signaling regulates embryo development and tissue homeostasis, and its deregulation leads to an array of diseases, including cancer. Dapper1 has been shown to be a key negative regulator of Wnt signaling. However, its function and regulation remain poorly understood. In this study, we report that 14-3-3β interacts with human Dapper1 (hDpr1). The interaction is dependent on protein kinase A (PKA)-mediated phosphorylation of hDpr1 at Ser-237 and Ser-827. 14-3-3β binding attenuates the ability of hDpr1 to promote Dishevelled (Dvl) degradation, thus enhancing Wnt signaling. We further provide evidence that PKA-mediated Dpr1 phosphorylation may contribute to growth and tumor formation of colon cancer Caco2 cells. Finally, we show that cyclooxygenase-2 expression and PKA activation are positively correlated with Dvl protein levels in colon cancer samples. Together, our findings establish a novel layer of regulation of Wnt signaling by PKA via the 14-3-3-Dpr1-Dvl axis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins / metabolism*
  • Adaptor Proteins, Signal Transducing / antagonists & inhibitors*
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Cell Line, Tumor
  • Cell Proliferation
  • Colonic Neoplasms / pathology
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Dishevelled Proteins
  • Humans
  • Nuclear Proteins / antagonists & inhibitors*
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Protein Binding / physiology
  • Wnt Proteins / metabolism

Substances

  • 14-3-3 Proteins
  • Adaptor Proteins, Signal Transducing
  • DACT1 protein, human
  • Dishevelled Proteins
  • Nuclear Proteins
  • Phosphoproteins
  • Wnt Proteins
  • Cyclic AMP-Dependent Protein Kinases