NWCRF Institute, School of Biological Sciences, College of Natural Sciences, Bangor University, Bangor LL572UW, UK.
J Cell Sci. 2010 Sep 15;123(Pt 18):3189-200. doi: 10.1242/jcs.072801. Epub 2010 Aug 24.
Extracellular signal-regulated kinase 5 (ERK5) is activated in response to environmental stress and growth factors. Gene ablation of Erk5 in mice is embryonically lethal as a result of disruption of cardiovascular development and vascular integrity. We investigated vascular endothelial growth factor (VEGF)-mediated ERK5 activation in primary human dermal microvascular endothelial cells (HDMECs) undergoing proliferation on a gelatin matrix, and tubular morphogenesis within a collagen gel matrix. VEGF induced sustained ERK5 activation on both matrices. However, manipulation of ERK5 activity by siRNA-mediated gene silencing disrupted tubular morphogenesis without impacting proliferation. Overexpression of constitutively active MEK5 and ERK5 stimulated tubular morphogenesis in the absence of VEGF. Analysis of intracellular signalling revealed that ERK5 regulated AKT phosphorylation. On a collagen gel, ERK5 regulated VEGF-mediated phosphorylation of the pro-apoptotic protein BAD and increased expression of the anti-apoptotic protein BCL2, resulting in decreased caspase-3 activity and apoptosis suppression. Our findings suggest that ERK5 is required for AKT phosphorylation and cell survival and is crucial for endothelial cell differentiation in response to VEGF.
细胞外信号调节激酶 5（ERK5）在应对环境压力和生长因子时被激活。由于心血管发育和血管完整性的破坏，ERK5 基因敲除的小鼠在胚胎期致死。我们研究了在明胶基质上增殖的原代人真皮微血管内皮细胞（HDMEC）和胶原凝胶基质内管状形态发生过程中，血管内皮生长因子（VEGF）介导的 ERK5 激活。VEGF 在两种基质上均诱导持续的 ERK5 激活。然而，通过 siRNA 介导的基因沉默来操纵 ERK5 活性会破坏管状形态发生，而不会影响增殖。组成性激活的 MEK5 和 ERK5 的过表达在没有 VEGF 的情况下刺激管状形态发生。细胞内信号分析表明，ERK5 调节 AKT 磷酸化。在胶原凝胶中，ERK5 调节 VEGF 介导的促凋亡蛋白 BAD 的磷酸化，并增加抗凋亡蛋白 BCL2 的表达，导致 caspase-3 活性降低和凋亡抑制。我们的研究结果表明，ERK5 是 AKT 磷酸化和细胞存活所必需的，并且对于内皮细胞对 VEGF 的反应中的分化至关重要。
