Premium
Cholera toxin treatment of vascular smooth muscle cells decreases smooth muscle α‐actin content and abolishes the platelet‐derived growth factor‐BB‐stimulated DNA synthesis
Author(s) -
Sachinidis Agapios,
Seul Claudia,
GouniBerthold Ioanna,
Seewald Stefan,
Ko Yon,
Vetter Hans,
Fingerle Jürgen,
Hoppe Jürgen
Publication year - 2000
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0703480
Subject(s) - platelet derived growth factor receptor , tyrosine phosphorylation , biology , vascular smooth muscle , platelet derived growth factor , actin , paxillin , microbiology and biotechnology , phosphorylation , second messenger system , cholera toxin , dna synthesis , growth factor , signal transduction , endocrinology , focal adhesion , biochemistry , receptor , dna , smooth muscle
The second messenger cyclic AMP regulates diverse biological processes such as cell morphology and cell growth. We examined the role of the second messenger cyclic AMP on rat aortic vascular smooth muscle cell (VSMC) morphology and the intracellular transduction pathway mediated by platelet‐derived growth factor β‐receptor (PDGF‐Rβ). The effect of PDGF‐BB on VSMCs growth was assessed by [ 3 H]‐thymidine incorporation. Tyrosine phosphorylation of PDGF‐Rβ, PLC‐γ1, ERK1 and ERK2, p125 FAK and paxillin as well as Sm α‐actin was examined by the chemiluminescence Western blotting method. Actin mRNA level was quantitated by Northern blotting. Visualization of Sm α‐actin filaments, paxillin and PDGF‐Rβ was performed by immunfluorescence microscopy. Cholera toxin (CTX; 10 n M ) treatment lead to a large and sustained increase in the cyclic AMP concentration after 2 h which correlated with change of VSMC morphology including complete disruption of the Sm α‐actin filament array and loss of focal adhesions. Treatment of VSMCs with CTX did not influence tyrosine phosphorylation of p125 FAK and paxillin but decreased the content of a Sm α‐actin protein. Maximal decrease of 70% was observed after 24 h of treatment. CTX also caused a 90% decrease of the actin mRNA level. CTX treatment completely abolished PDGF‐BB stimulated DNA‐synthesis although PDGF‐Rβ level and subcellular distribution and translocation was not altered. Furthermore CTX attenuated the PDGF‐BB‐induced tyrosine phosphorylation of the PDGF‐Rβ, PI 3′‐K, PLC‐γ1 and ERK1/2 indicating an action of cyclic AMP on PDGF‐β receptor. We conclude that although cyclic AMP attenuates the PDGF‐Rβ mediated intracellular transduction pathway, an intact actin filament may be required for the PDGF‐BB‐induced DNA synthesis in VSMCs.British Journal of Pharmacology (2000) 130 , 1561–1570; doi: 10.1038/sj.bjp.0703480