Endothelin-induced cardiac myocyte hypertrophy: role for focal adhesion kinase.
Endothelin-1 (ET) produces neonatal rat ventricular myocyte (NRVM) hypertrophy and activates focal adhesion kinase (FAK) in other cell types. In the present study, we examined whether ET activated FAK in NRVM and whether FAK was necessary and/or sufficient for ET-induced NRVM hypertrophy. Chronic ET-1 stimulation (100 nM, 48 h) increased protein-to-DNA and myosin heavy chain (MHC)-to-DNA ratios and stimulated the assembly of newly synthesized MHC into sarcomeres. ET-1 also induced the assembly of focal adhesions and costameres, as evidenced by increased phosphotyrosine, FAK, and paxillin immunostaining. Acutely, ET treatment rapidly increased tyrosine phosphorylation of FAK and paxillin. FAK was also activated by phorbol 12-myristate 13-acetate (2 microM, 5 min). Pretreatment with chelerythrine (5 microM) or rottlerin (10 microM) completely blocked ET-induced FAK phosphorylation, indicating that protein kinase C activation was upstream of ET-induced FAK activation. In contrast, ET-induced FAK activation was not affected by blocking calcium influx via L-type voltage-gated calcium channels. Adenoviruses (Adv) containing FAK and FAK-related nonkinase (FRNK) were used to specifically define the role of FAK in ET-induced hypertrophy. ET stimulation failed to increase total protein-to-DNA or MHC-to-DNA ratios or to stimulate sarcomeric assembly in myocytes infected with Adv-FRNK. However, Adv-FAK alone did not increase total protein-to-DNA or MHC-to-DNA ratios and failed to increase the number or size of myofibrils as evidenced by double immunofluorescence labeling for MHC and FAK. Thus, although FAK is necessary for ET-induced NRVM hypertrophy, other ET-generated signals are also required to elicit the hypertrophic phenotype.
Eble
D M
DM
Cardiovascular Institute and Departments of Medicine and Physiology, Loyola University Chicago, Maywood, Illinois 60153, USA. deble@luc.edu
Strait
J B
JB
Govindarajan
G
G
Lou
J
J
Byron
K L
KL
Samarel
A M
AM
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D006332:Cardiomegaly / Q000139:chemically induced* / Q000201:enzymology* / Q000473:pathology; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D016232:Endothelins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006321:Heart / Q000187:drug effects*; D009206:Myocardium / Q000737:chemistry / Q000166:cytology / Q000201:enzymology*; D018995:Myosin Heavy Chains / Q000032:analysis; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
D002121:Calcium Channel Blockers; D003598:Cytoskeletal Proteins; D016232:Endothelins; D004791:Enzyme Inhibitors; D051419:Paxillin; D010750:Phosphoproteins; C496063:Pxn protein, rat; D011994:Recombinant Proteins; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D011493:Protein Kinase C; D018995:Myosin Heavy Chains; D013755:Tetradecanoylphorbol Acetate