Menashi Emmanuel B, Loftus Joseph C
Department of Biochemistry and Molecular Biology, Mayo Clinic Arizona, Scottsdale, 85259, USA.
Cell Tissue Res. 2009 Aug;337(2):243-55. doi: 10.1007/s00441-009-0807-9. Epub 2009 May 12.
The related cytoplasmic non-receptor tyrosine kinases Pyk2 (proline-rich tyrosine kinase 2) and FAK (focal adhesion kinase) have been implicated in phenylephrine-induced G-protein-coupled receptor-mediated signaling mechanisms leading to cardiomyocyte hypertrophy. We report that, in phenylephrine-stimulated neonatal rat ventricular myocytes (NRVM), Pyk2 augments expression of the hypertrophic marker atrial natriuretic factor (ANF) but reduces cytoskeletal organization and cell spreading. In contrast, FAK attenuates ANF production but does not alter cytoskeletal organization and cell spreading. Pyk2 and FAK exhibit differential localization in both unstimulated and phenylephrine-stimulated myocytes. Pyk2 catalytic activity is required for Pyk2 to augment ANF secretion but is not necessary to reduce cell spreading. Pyk2 autophosphorylation is required but not sufficient for Pyk2 to augment ANF secretion. Expression of the Pyk2 FERM domain as an autonomous fragment inhibits phenylephrine-mediated ANF secretion and reduces cell spreading. In addition, expression of the Pyk2 FERM domain inhibits the ability of Pyk2 to augment ANF secretion; this is correlated with reduced Pyk2 autophosphorylation. These data indicate that Pyk2 and FAK have different roles and occupy different positions in signaling pathways leading to the development of cardiomyocyte hypertrophy.
相关的胞质非受体酪氨酸激酶Pyk2（富含脯氨酸的酪氨酸激酶2）和FAK（粘着斑激酶）与去氧肾上腺素诱导的G蛋白偶联受体介导的信号传导机制有关，该机制可导致心肌细胞肥大。我们报道，在去氧肾上腺素刺激的新生大鼠心室肌细胞（NRVM）中，Pyk2增强了肥厚标志物心钠素（ANF）的表达，但减少了细胞骨架组织和细胞铺展。相比之下，FAK减弱了ANF的产生，但不改变细胞骨架组织和细胞铺展。Pyk2和FAK在未刺激和去氧肾上腺素刺激的心肌细胞中均表现出不同的定位。Pyk2催化活性是Pyk2增强ANF分泌所必需的，但不是减少细胞铺展所必需的。Pyk2自身磷酸化是Pyk2增强ANF分泌所必需的，但并不充分。作为自主片段的Pyk2 FERM结构域的表达抑制了去氧肾上腺素介导的ANF分泌并减少了细胞铺展。此外，Pyk2 FERM结构域的表达抑制了Pyk2增强ANF分泌的能力；这与Pyk2自身磷酸化减少相关。这些数据表明，Pyk2和FAK在导致心肌细胞肥大发展的信号通路中具有不同的作用并占据不同的位置。
