Sartoretto Juliano L, Jin Benjamin Y, Bauer Michael, Gertler Frank B, Liao Ronglih, Michel Thomas
Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Am J Physiol Heart Circ Physiol. 2009 Nov;297(5):H1697-710. doi: 10.1152/ajpheart.00595.2009. Epub 2009 Sep 4.
Vasodilator-stimulated phosphoprotein (VASP) is a major substrate for cyclic nucleotide-dependent kinases that has been implicated in cardiac pathology, yet many aspects of VASP's molecular regulation in cardiomyocytes are incompletely understood. In these studies, we explored the role of VASP, both in signaling pathways in isolated murine myocytes, as well as in a model of cardiac hypertrophy in VASP(null) mice. We found that the beta-adrenergic agonist isoproterenol promotes the rapid and reversible phosphorylation of VASP at Ser157 and Ser239. Forskolin and the cAMP analog 8-(4-chlorophenylthio)-cAMP promote a similar pattern of VASP phosphorylation at both sites. The effects of isoproterenol are blocked by atenolol and by compound H-89, an inhibitor of the cAMP-dependent protein kinase. By contrast, phosphorylation of VASP only at Ser239 is seen following activation of particulate guanylate cyclase by atrial natriuretic peptide, or following activation of soluble guanylate cyclase by sodium nitroprusside, or following treatment of myocytes with cGMP analog. We found that basal and isoproterenol-induced VASP phosphorylation is entirely unchanged in cardiomyocytes isolated from either endothelial or neuronal nitric oxide synthase knockout mice. In cardiomyocytes isolated from diabetic mice, only basal VASP phosphorylation is increased, whereas, in cells isolated from mice subjected to ascending aortic constriction (AAC), we found a significant increase in basal VASP expression, along with an increase in VASP phosphorylation, compared with cardiac myocytes isolated from sham-operated mice. Moreover, there is further increase in VASP phosphorylation in cells isolated from hypertrophic hearts following isoproterenol treatment. Finally, we found that VASP(null) mice subjected to transverse aortic constriction develop cardiac hypertrophy with a pattern similar to VASP(+/+) mice. Our findings establish differential receptor-modulated regulation of VASP phosphorylation in cardiomyocytes by cyclic nucleotides. Furthermore, these studies demonstrate for the first time that VASP expression is upregulated in hypertrophied heart.
血管舒张刺激磷蛋白（VASP）是环核苷酸依赖性激酶的主要底物，与心脏病理学有关，但VASP在心肌细胞中的分子调节的许多方面尚未完全了解。在这些研究中，我们探讨了VASP在分离的小鼠心肌细胞信号通路以及VASP基因敲除小鼠心脏肥大模型中的作用。我们发现β-肾上腺素能激动剂异丙肾上腺素可促进VASP在Ser157和Ser239处快速且可逆的磷酸化。福斯高林和cAMP类似物8-（4-氯苯硫基）-cAMP在这两个位点促进类似的VASP磷酸化模式。异丙肾上腺素的作用被阿替洛尔和cAMP依赖性蛋白激酶抑制剂化合物H-89阻断。相比之下，心房利钠肽激活颗粒鸟苷酸环化酶后、硝普钠激活可溶性鸟苷酸环化酶后或用cGMP类似物处理心肌细胞后，仅观察到VASP在Ser239处的磷酸化。我们发现，从内皮型或神经元型一氧化氮合酶基因敲除小鼠分离的心肌细胞中，基础和异丙肾上腺素诱导的VASP磷酸化完全没有变化。在从糖尿病小鼠分离的心肌细胞中，仅基础VASP磷酸化增加，而在从接受升主动脉缩窄（AAC）的小鼠分离的细胞中，我们发现与假手术小鼠分离的心肌细胞相比，基础VASP表达显著增加，同时VASP磷酸化增加。此外，异丙肾上腺素处理后从肥厚心脏分离的细胞中VASP磷酸化进一步增加。最后，我们发现接受横向主动脉缩窄的VASP基因敲除小鼠出现心脏肥大，其模式与VASP（+/+）小鼠相似。我们的研究结果确立了环核苷酸对心肌细胞中VASP磷酸化的不同受体调节。此外，这些研究首次证明VASP表达在肥厚心脏中上调。
