Regulation of protein phosphatase inhibitor-1 by cyclin-dependent kinase 5

Chan Nguyen, Akinori Nishi, Janice W. Kansy, Joseph Fernandez, Kanehiro Hayashi, Frank Gillardon, Hugh C. Hemmings, Angus C. Nairn, James A. Bibb

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

Inhibitor-1, the first identified endogenous inhibitor of protein phosphatase 1 (PP-1), was previously reported to be a substrate for cyclin-dependent kinase 5 (Cdk5) at Ser67. Further investigation has revealed the presence of an additional Cdk5 site identified by mass spectrometry and confirmed by site-directed mutagenesis as Ser6. Basal levels of phospho-Ser6 inhibitor-1, as detected by a phosphorylation state-specific antibody against the site, existed in specific regions of the brain and varied with age. In the striatum, basal in vivo phosphorylation and dephosphorylation of Ser6 were mediated by Cdk5, PP-2A, and PP-1, respectively. Additionally, calcineurin contributed to dephosphorylation under conditions of high Ca2+. In biochemical assays the function of Cdk5-dependent phosphorylation of inhibitor-1 at Ser6 and Ser 67 was demonstrated to be an intramolecular impairment of the ability of inhibitor-1 to be dephosphorylated at Thr35; this effect was recapitulated in two systems in vivo. Dephosphorylation of inhibitor-1 at Thr35 is equivalent to inactivation of the protein, as inhibitor-1 only serves as an inhibitor of PP-1 when phosphorylated by cAMP-dependent kinase (PKA) at Thr35. Thus, inhibitor-1 serves as a critical junction between kinase- and phosphatase-signaling pathways, linking PP-1 to not only PKA and calcineurin but also Cdk5.

Original languageEnglish (US)
Pages (from-to)16511-16520
Number of pages10
JournalJournal of Biological Chemistry
Volume282
Issue number22
DOIs
StatePublished - Jun 1 2007

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Nguyen, C., Nishi, A., Kansy, J. W., Fernandez, J., Hayashi, K., Gillardon, F., Hemmings, H. C., Nairn, A. C., & Bibb, J. A. (2007). Regulation of protein phosphatase inhibitor-1 by cyclin-dependent kinase 5. Journal of Biological Chemistry, 282(22), 16511-16520. https://doi.org/10.1074/jbc.M701046200