Protein phosphatase 1 dephosphorylates profilin-1 at Ser-137

PLoS One. 2012;7(3):e32802. doi: 10.1371/journal.pone.0032802. Epub 2012 Mar 30.


Profilin-1 (PFN1) plays an important role in the control of actin dynamics, and could represent an important therapeutic target in several diseases. We previously identified PFN1 as a huntingtin aggregation inhibitor, and others have implicated it as a tumor-suppressor. Rho-associated kinase (ROCK) directly phosphorylates PFN1 at Ser-137 to prevent its binding to polyproline sequences. This negatively regulates its anti-aggregation activity. However, the phosphatase that dephosphorylates PFN1 at Ser-137, and thus activates it, is unknown. Using a phospho-specific antibody against Ser-137 of PFN1, we characterized PFN1 dephosphorylation in cultured cells based on immunocytochemistry and a quantitative plate reader-based assay. Both okadaic acid and endothall increased pS137-PFN1 levels at concentrations more consistent with their known IC(50)s for protein phosphatase 1 (PP1) than protein phosphatase 2A (PP2A). Knockdown of the catalytic subunit of PP1 (PP1Cα), but not PP2A (PP2ACα), increased pS137-PFN1 levels. PP1Cα binds PFN1 in cultured cells, and this interaction was increased by a phosphomimetic mutation of PFN1 at Ser-137 (S137D). Together, these data define PP1 as the principal phosphatase for Ser-137 of PFN1, and provide mechanistic insights into PFN1 regulation by phosphorylation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Dicarboxylic Acids / pharmacology
  • Dose-Response Relationship, Drug
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Immunohistochemistry
  • Mice
  • NIH 3T3 Cells
  • Okadaic Acid / pharmacology
  • Phosphorylation / drug effects
  • Profilins / genetics
  • Profilins / metabolism*
  • Protein Binding
  • Protein Phosphatase 1 / antagonists & inhibitors
  • Protein Phosphatase 1 / genetics
  • Protein Phosphatase 1 / metabolism*
  • Protein Phosphatase 2 / antagonists & inhibitors
  • Protein Phosphatase 2 / genetics
  • Protein Phosphatase 2 / metabolism*
  • RNA Interference
  • Serine / genetics
  • Serine / metabolism*


  • Dicarboxylic Acids
  • PFN1 protein, human
  • Profilins
  • endothall
  • Okadaic Acid
  • Serine
  • Protein Phosphatase 1
  • Protein Phosphatase 2