From the Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, OH (J.D.B., U.M.C., M.S.W., E.G.T., R.B., P.E.D.); and Department of Aerospace and Mechanical Engineering, University of Notre Dame, IN (J.D.B.).
Arterioscler Thromb Vasc Biol. 2014 May;34(5):1020-31. doi: 10.1161/ATVBAHA.114.303403. Epub 2014 Feb 27.
Angiogenesis is the formation of new blood vessels through endothelial cell sprouting. This process requires the mitogen-activated protein kinases, signaling molecules that are negatively regulated by the mitogen-activated protein kinase phosphatase-1 (MKP-1). The purpose of this study was to evaluate the role of MKP-1 in neovascularization in vivo and identify associated mechanisms in endothelial cells.
We used murine hindlimb ischemia as a model system to evaluate the role of MKP-1 in angiogenic growth, remodeling, and arteriogenesis in vivo. Genomic deletion of MKP-1 blunted angiogenesis in the distal hindlimb and microvascular arteriogenesis in the proximal hindlimb. In vitro, endothelial MKP-1 depletion/deletion abrogated vascular endothelial growth factor-induced migration and tube formation, and reduced proliferation. These observations establish MKP-1 as a positive mediator of angiogenesis and contrast with the canonical function of MKP-1 as a mitogen-activated protein kinase phosphatase, implying an alternative mechanism for MKP-1-mediated angiogenesis. Cloning and sequencing of MKP-1-bound chromatin identified localization of MKP-1 to exonic DNA of the angiogenic chemokine fractalkine, and MKP-1 depletion reduced histone H3 serine 10 dephosphorylation on this DNA locus and blocked fractalkine expression. In vivo, MKP-1 deletion abrogated ischemia-induced fractalkine expression and macrophage and T-lymphocyte infiltration in distal hindlimbs, whereas fractalkine delivery to ischemic hindlimbs rescued the effect of MKP-1 deletion on neovascular hindlimb recovery.
MKP-1 promoted angiogenic and arteriogenic neovascular growth, potentially through dephosphorylation of histone H3 serine 10 on coding-region DNA to control transcription of angiogenic genes, such as fractalkine. These observations reveal a novel function for MKP-1 and identify MKP-1 as a potential therapeutic target.
血管生成是通过内皮细胞出芽形成新血管的过程。这个过程需要丝裂原活化蛋白激酶（MAPK），MAPK 是一种信号分子，可被丝裂原活化蛋白激酶磷酸酶-1（MKP-1）负调控。本研究旨在评估 MKP-1 在体内新生血管形成中的作用，并确定内皮细胞中相关的机制。
我们使用小鼠后肢缺血模型系统来评估 MKP-1 在体内血管生成、重塑和动脉生成中的作用。MKP-1 的基因缺失削弱了后肢远端的血管生成和后肢近端的微血管动脉生成。在体外，内皮细胞中 MKP-1 的缺失或耗竭阻断了血管内皮生长因子诱导的迁移和管腔形成，并减少了增殖。这些观察结果确立了 MKP-1 是血管生成的正调节剂，与 MKP-1 作为丝裂原活化蛋白激酶磷酸酶的典型功能形成对比，暗示了 MKP-1 介导血管生成的另一种机制。克隆和测序与 MKP-1 结合的染色质，鉴定出 MKP-1 定位于促血管生成趋化因子 fractalkine 的外显子 DNA 上，MKP-1 的耗竭减少了该 DNA 位点上组蛋白 H3 丝氨酸 10 的去磷酸化，并阻断了 fractalkine 的表达。在体内，MKP-1 的缺失阻断了缺血诱导的 fractalkine 表达和后肢远端的巨噬细胞和 T 淋巴细胞浸润，而 fractalkine 递送至缺血后肢挽救了 MKP-1 缺失对新生后肢恢复的影响。
MKP-1 促进了血管生成和动脉生成的新生血管生长，可能是通过磷酸化组蛋白 H3 丝氨酸 10 上的编码区 DNA 来控制 fractalkine 等促血管生成基因的转录。这些观察结果揭示了 MKP-1 的一个新功能，并确定了 MKP-1 作为一个潜在的治疗靶点。
