Protein kinase C activation after cellular adhesion on fibronectin: partial suppression after inhibition of protein isoprenylation.
The cellular events following interaction between matrix proteins and cells are important requisites for physiological mechanisms as well as the progress of a number of diseases. Cellular adhesion to fibronectin, an important component of the extracellular matrix has been demonstrated to be associated with translocation of protein kinase C (PKC) by an integrin-dependent pathway. For this process G-proteins may play an important role as coupling proteins. Membrane association and activity of G-proteins has been shown to be regulated by isoprenylation. We therefore studied whether fibronectin mediated adhesion resulted in PKC translocation and if isoprenylation of cellular proteins may play a role for this integrin-dependent pathway of PKC activation. Chinese hamster ovary (CHO) cells were pretreated with either the Hydroxy-methylglutaryl(HMG)-CoA reductase inhibitor lovastatin or prenylation inhibitor limonene. For the stimulation by extracellular matrices, CHO cells were plated on tissue culture dishes coated with fibronectin or bovine serum albumin and PKC activity was determined. To investigate direct effects of inhibition of isoprenylation on cytoskeletal organization, phalloidin-stained stress fibers were characterized after adhesion on different matrices. CHO cells seeded on fibronectin displayed over twice the PKC translocation to the particulate fraction in comparison to that measured in cells on albumin. Pretreatment of CHO cells with lovastatin or limonene resulted in partial suppression of PKC activation after cell-seeding on the specific matrix fibronectin. Changed PKC distribution was not due to a disorganization of the actin skeleton. These data show that inhibition of isoprenylation of cellular proteins, possibly small Guanosine triphosphate(GTP)-binding proteins, alters only the integrin-mediated PKC distribution but does not greatly influence constitutive PKC distribution.
Kreuzer
J
J
Innere Medizin III, Universität Heidelberg, Bergheimer Str. 58, Heidelberg D-69115, Germany.
Schmidts
A
A
Marquetant
R
R
Niebauer
J
J
Strasser
R H
RH
D000818:Animals; D016466:CHO Cells; D002417:Cattle; D002448:Cell Adhesion / Q000502:physiology*; D002462:Cell Membrane / Q000201:enzymology; D006224:Cricetinae; D053138:Cyclohexenes; D003600:Cytosol / Q000201:enzymology; D005353:Fibronectins / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000378:metabolism; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D000077222:Limonene; D008148:Lovastatin / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D017368:Protein Prenylation / Q000187:drug effects*; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013729:Terpenes / Q000494:pharmacology*
D053138:Cyclohexenes; D005353:Fibronectins; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D013729:Terpenes; D012710:Serum Albumin, Bovine; D008148:Lovastatin; D000077222:Limonene; D011493:Protein Kinase C; D019204:GTP-Binding Proteins