Silencing of p21-activated kinase attenuates vimentin phosphorylation on Ser-56 and reorientation of the vimentin network during stimulation of smooth muscle cells by 5-hydroxytryptamine

Biochem J. 2005 Jun 15;388(Pt 3):773-83. doi: 10.1042/BJ20050065.

Abstract

Vimentin intermediate filaments undergo spatial reorganization in endothelial cells and fibroblasts in response to stimulation with platelet-derived growth factor and epidermal growth factor. In the present study, the vimentin network exhibited a curved filamentous structure in unstimulated smooth muscle cells. Vimentin filaments became straight and were arranged along the long axis of cells upon stimulation with 5-hydroxytryptamine (5-HT; serotonin). Stimulation of smooth muscle cells with 5-HT also induced phosphorylation of vimentin on Ser-56. Treatment of cells with small interfering RNA selectively down-regulated the expression of PAK1 (p21-activated kinase 1) without affecting the content of smooth muscle alpha-actin. The silencing of PAK1 inhibited the site-specific phosphorylation and spatial rearrangement of the vimentin network in response to stimulation with 5-HT. Neither the disruption of stress fibres by cytochalasin D nor the inhibition of protein tyrosine phosphorylation affects the spatial reorganization of vimentin intermediate filaments in response to stimulation with 5-HT. In addition, stimulation of smooth muscle cells with 5-HT increased the ratio of soluble to insoluble vimentin. PAK1 silencing attenuated increases in the ratio of soluble to insoluble vimentin upon stimulation with 5-HT. These results suggest that the PAK-mediated site-specific phosphorylation of vimentin may play a role in regulating the reorganization of vimentin intermediate filaments during stimulation of smooth muscle cells with 5-HT.

Publication types

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

MeSH terms

  • Actin Cytoskeleton / chemistry
  • Actin Cytoskeleton / metabolism
  • Animals
  • Cells, Cultured
  • Dogs
  • Down-Regulation
  • Gene Expression Regulation, Enzymologic
  • Intermediate Filaments / chemistry
  • Intermediate Filaments / drug effects*
  • Intermediate Filaments / metabolism
  • Muscle, Smooth / cytology
  • Muscle, Smooth / drug effects*
  • Muscle, Smooth / metabolism
  • Phosphorylation / drug effects
  • Phosphoserine / metabolism*
  • Protein-Serine-Threonine Kinases / biosynthesis
  • Protein-Serine-Threonine Kinases / deficiency*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA Interference
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Serotonin / pharmacology*
  • Solubility
  • Trachea
  • Vimentin / chemistry
  • Vimentin / metabolism*
  • p21-Activated Kinases

Substances

  • RNA, Small Interfering
  • Vimentin
  • Phosphoserine
  • Serotonin
  • Protein-Serine-Threonine Kinases
  • p21-Activated Kinases