Stretch-induced MAP kinase activation in cardiac myocytes: Differential regulation through β1-integrin and focal adhesion kinase

Abstract

Mitogen-activated protein (MAP) kinases have been implicated in hemodynamic load induced heart failure. Both angiotensin II (Ang II) and mechanical stretch activate MAP kinases in cardiac myocytes. In this study, we used a neonatal rat ventricular myocyte (NRVM) model to determine the role of focal-adhesion kinase (FAK) in β 1 integrin mediated MAP kinase activation in response to mechanical stretch in presence and absence of Ang II receptor blockade (ATB). NRVM plated on deformable membranes coated with collagen IV were exposed to 20% equiaxial static-stretch. β 1 integrin signaling was blocked by adenovirus-mediated expression of a dominant-negative form of β 1D integrin (tac-β 1D ). FAK signaling was disrupted by infecting NRVM with adenovirus expressing FAK-related non-kinase (FRNK). Western blot analysis was used to assess the phosphorylation of MAP kinases. In the presence and absence of ATB, mechanical stretch caused maximal phosphorylation of ERK, p38 and JNK at 5 min, which was significantly attenuated in NRVM expressing tac-β 1D . In the presence of ATB, FRNK overexpression significantly increased basal phosphorylation of ERK (40.2 ± 8.6% p<0.05), p38 (39.5 ± 11.7%, P<0.05), JNK (86 ± 29.4%, P<0.05) and stretch-induced p38 (48.1 ± 8.7%, P<0.05) and JNK (85.0 ± 19.4%, P<0.05) phosphorylation. However, in the absence of ATB, FRNK overexpression significantly reduced basal and stretch-induced phosphorylation of only ERK. Examination of FAK activation revealed that β 1 integrin was required for stretch-induced phosphorylation of FAK at Y 397 and Y 925 , but not Y 861 . In summary, mechanical stretch-activated ERK1/2, p38 and JNK through FAK independent and dependent mechanisms. β 1 integrin was required for FAK independent activation of all three MAP kinases, whereas cross-talk between β 1 integrin and Ang II receptors mediated FAK dependent regulation of ERK1/2.

High frequency electrical stimulation reveals a p38-mTOR signaling module correlated with force-time integral

“…This is consistent with the widely recognized role of FAK and other members of the integrin-associated focal adhesion complex as mechanotransducers (Flück et al, 1999;Lal et al, 2007). Phosphorylation of p38 increased in response to HFC-induced mechanical stress (Nader and Esser, 2001;Wretman et al, 2001) or passive mechanical stretch (Aikawa et al, 2002).…”

“…Phosphorylation of p38 increased in response to HFC-induced mechanical stress (Nader and Esser, 2001;Wretman et al, 2001) or passive mechanical stretch (Aikawa et al, 2002). The correlations between FTI, FAK and p38 may represent a single pathway, as a hypertrophic signaling pathway involving integrin-FAK and p38 induced by mechanical stress has been reported (Aikawa et al, 2002;Lal et al, 2007). Activation of p38 may contribute to increased protein synthesis via phosphorylation of TSC2-and MNK-induced phosphorylation of eIF4E and p70S6k on T421/S424 (Cully et al, 2010;Hernández et al, 2011;Wang et al, 1998) and is required for myogenic differentiation via activation of MEF2 and MRF4 (Lluís et al, 2006), both processes required for muscle hypertrophy.…”

Cyclic stretch-induced TGF-β1 and fibronectin expression is mediated by β1-integrin through c-Src- and STAT3-dependent pathways in renal epithelial cells

“…However, the molecular mechanisms by which ␤1-integrin attenuates UUO-induced fibrosis are not well characterized. Although it had been shown that mechanical stretch induced ␤1-integrin protein expression in different tissues and that ␤1-integrin is highly expressed in renal tubular epithelial cells (22,33,66,67,70), the functions of ␤1-integrin in renal epithelial cells during mechanical stretch-induced fibrogenesis has never been reported.…”

“…Although it had been shown that mechanical stretch induced ␤1-integrin protein expression in different tissues and that ␤1-integrin is highly expressed in renal tubular epithelial cells (22,33,66,67,70), the functions of ␤1-integrin in renal epithelial cells during mechanical stretch-induced fibrogenesis has never been reported. To address whether the fibrogenic effect of mechanical stretch is ␤1-integrin dependent, we first examined whether ␤1-integrin was upregulated by cyclic mechanical stretch in HK-2 cells.…”

Focal Adhesion Kinase as a Cellular Mechano-Sensor

“…Phosphorylation, being if cis or trans, is re-quired to open FAK. Also, studies have showed that the auto-phosphorylation of Tyr397 is regulated by external force [33,123,124]. Thus, the opening motion of FAK is considered as the first reaction in our kinetic model.…”