A Role for Focal Adhesion Kinase in Phenylephrine-induced Hypertrophy of Rat Ventricular Cardiomyocytes

Abstract

A variety of agonists including phenylephrine (PE) induce hypertrophy in neonatal ventricular cardiomyocytes. Here we report that signals provided by extracellular matrix proteins (ECM) augment the PE-induced hypertrophic response of cardiomyocytes and provide evidence that ECM-dependent signaling is mediated in part by the protein tyrosine kinase, focal adhesion kinase (FAK). Addition of PE to cultured neonatal cardiomyocytes stimulated sarcomeric organization, increased cell size, and induced atrial natriuretic factor in cardiomyocytes plated on the ECM protein laminin or fibronectin. In contrast, cardiomyocytes plated on the non-adhesive substrate gelatin exhibited a reduced capacity to undergo these PE-stimulated hypertrophic changes. In cardiomyocytes cultured on ECM, PE stimulated a rapid increase in tyrosine phosphorylation of focal adhesion proteins including FAK, paxillin, and p130 Crk-associated substrate and subsequent formation of peripheral focal complexes. Inhibition of the PEinduced hypertrophic response by genistein and herbimycin-A indicated a requirement for protein tyrosine kinases in PE signaling. To determine whether activation of FAK is required for PE-induced hypertrophy, a dominant-interfering mutant form of FAK, termed FRNK (FAK-related non-kinase), was ectopically expressed in cardiomyocytes using a replication-defective adenovirus expression system. FRNK expression attenuated PE-stimulated hypertrophy as assessed by cell size, sarcomeric organization, and induction of atrial natriuretic factor. These data indicate that the signal transduction pathways leading to cardiomyocyte hypertrophy are strongly influenced by and/or dependent upon an integrin-mediated signaling process requiring FAK.Cardiomyocyte hypertrophy, characterized by increased volume and myofibrillar protein content, is important for the normal developmental growth of the heart. However, in the fully developed adult heart, pressure or volume overload, myocardial infarction, or hormonal imbalance can lead to chronic pathological hypertrophy characterized by induction of immediate early genes, re-activation of an embryonic gene program, and reorganization of myocyte cytoskeletal architecture (1).The ability of integrins, extracellular matrix receptors, to regulate cytoskeletal architecture has been well characterized, and integrin signaling has clearly been implicated in hormone and growth factor-induced alterations in gene transcription in variety of cell types (2). Integrins are a family of heterodimeric transmembrane receptors (composed of ␣ and ␤ subunits) containing extracellular ligand binding domains that show binding specificity for extracellular matrix (ECM) 1 components and a short cytoplasmic domain that serves to couple integrins with the actin cytoskeleton (3). Several studies have shown that cardiac hypertrophy is accompanied by alterations in ECM components and cardiac integrin expression (4 -6). Specifically, enhanced expression of collagen III, fibronectin, osteopontin, and ␤ 1 , ␣ 3 , and ␣ 5 integrin subu...

Role of the integrin-linked kinase/PINCH1/alpha-parvin complex in cardiac myocyte hypertrophy

“…5,28 This effect is partially explained by PE-induced rapid tyrosine phosphorylation of costamere complex proteins, including focal adhesion kinase (FAK), paxillin and p130 Crk-associated substrate, 28 an effect dependent on intact integrin and FAK functions. Our data demonstrate that PE also synergizes with FN in inducing increased costamere localization of ILK and PIPcomplex proteins, suggesting that these proteins play a role in hypertrophic signaling.…”

“…24 Interestingly, ILK and IPAP1 complex assembly are required for cytoskeletal association of paxillin in epithelial cells 14 and a significant increase in ILK mRNA has been observed in a pressure-overload mouse model of cardiac hypertrophy. 25 Studies from our laboratory 26 and others 27,28 have demonstrated that FN induces cardiac myocyte hypertrophy in neonatal rat ventricular myocytes (NRVM). Moreover, FN-induced hypertrophy depended on intact integrin signaling, as evidenced by inhibition with anti-b1-integrin antibody, [26][27][28] and potentiated hypertrophy induced by the alphaadrenergic agonist PE.…”

“…25 Studies from our laboratory 26 and others 27,28 have demonstrated that FN induces cardiac myocyte hypertrophy in neonatal rat ventricular myocytes (NRVM). Moreover, FN-induced hypertrophy depended on intact integrin signaling, as evidenced by inhibition with anti-b1-integrin antibody, [26][27][28] and potentiated hypertrophy induced by the alphaadrenergic agonist PE. 29 In this study, we examine the hypothesis that FN and PE stimulation regulate the expression and localization of ILK, PARVA and PINCH1 proteins in cardiac myocytes where they may play a role in promoting cellular survival and transducing extracellular signals leading to hypertrophy.…”

Adenoviruses increase endothelial cell proliferation, migration, and tube formation: Partial reversal by the focal adhesion kinase inhibitor, FRNK

“…Adenovirus-green fluorescent protein (Ad-GFP) and Adenovirus Green fluorescent protein-FRNK fusion protein (Ad-GFP-FRNK), which were produced as previously described (Taylor et al 2000), were a gift from Joan Taylor (University of North Carolina-Chapel Hill). A control adenovirus lacking an insert (Ad-Empty) was generated by us as previously described (Kornberg, 2005).…”

ADAM23 in Cardiomyocyte Inhibits Cardiac Hypertrophy by Targeting FAK‐AKT Signaling

“…In the integrin initiating signaling pathway, clustering of integrins leads to the recruitment of FAK to the newly formed focal adhesion which results in auto‐phosphorylation and concomitant activation of FAK 30, 32. A recent study supported a role for integrin‐mediated signaling through FAK in the development of cardiac hypertrophy 33. Furthermore, Aikawa and his colleagues demonstrated that the activation of integrin‐FAK might be necessary for stretch‐induced hypertrophic responses 34.…”