title: Platelet-derived growth factor reorganizes the actin cytoskeleton through 3-phosphoinositide-dependent and 3-phosphoinositide-independent mechanisms in human mesangial cells.
abstract: BACKGROUND
  Platelet-derived growth factor (PDGF) is a potent activator of mesangial cell proliferation and migration. Although phosphoinositide 3-kinase (PI3K) enzymes are important downstream targets of the PDGF receptor, the contribution made by their 3-phosphoinositide products in the reorganization of actin cytoskeleton and focal adhesions has been questioned.
  
  
  RESULTS
  Pharmacological inhibition of the PI3K activity blocks PDGF-induced migration of human primary mesangial cells using an in vitro scrape wound healing assay. Acute (<10 min) inhibition of the PI3K activity did not alter the effect of PDGF on either stress fibre dissolution or reorganization of focal adhesions. However, at later times (>30 min), PDGF-stimulated responses were inhibited. In contrast, PDGF-stimulated membrane ruffling remained insensitive to PI3K inhibitors throughout. Inhibition of protein kinase C and Erk also attenuated PDGF-stimulated mesangial cell migration; however, neither signaling pathway was responsible for the initial effects on filamentous actin and focal adhesions.
  
  
  CONCLUSIONS
  We propose that following PDGF stimulation of mesangial cells, reorganization of the actin cytoskeleton occurs in a biphasic manner. The mechanism responsible for mesangial cell migration that occurs immediately following PDGF stimulation may serve to 'prime' for the subsequent 3-phosphoinositide-, protein-kinase-C-, and Erk-dependent migration.
authors.affiliation: Renal Section, Imperial College London, UK.
authors.forename: Lisa
authors.initials: L
authors.lastname: Harper
authors.forename: Yasuyo
authors.initials: Y
authors.lastname: Kashiwagi
authors.forename: Charles D
authors.initials: CD
authors.lastname: Pusey
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Hendry
authors.forename: Jan
authors.initials: J
authors.lastname: Domin
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D000199:Actins / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D050527:Mesangial Cells / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism