The transcription factor Bach1 impairs angiogenesis after ischemic injury by suppressing Wnt/β-catenin signaling; however, the specific domains responsible for the anti-angiogenic effects of Bach1 remain unclear. This study determined the role of the BTB domain of Bach1 in ischemic angiogenesis. Bach1 is highly expressed in circulating endothelial cells from acute myocardial infarction patients and is the early induction gene after ischemia. Mice were treated with adenoviruses coding for GFP (AdGFP), Bach1 (AdBach1), or a Bach1 mutant lacking the BTB domain (AdBach1-ΔBTB) after surgically induced hind-limb ischemia. Measures of blood-flow recovery, capillary density, and the expression of vascular endothelial growth factor (VEGF) and heme oxygenase-1 (HO-1) were significantly lower and ROS levels were higher in the AdBach1 group, but not in AdBach1-ΔBTB animals. Furthermore, transfection with AdBach1, but not AdBach1-ΔBTB, in human endothelial cells was associated with significant declines in 1) capillary density and hemoglobin content in the Matrigel-plug assay, 2) proliferation, migration, tube formation, and VEGF and HO-1 expression in endothelial cells. Bach1 binds directly with TCF4, and this interaction is mediated by residues 81-89 of the Bach1 BTB domain and the N-terminal domain of TCF4. Bach1, but not Bach1-ΔBTB, also co-precipitated with histone deacetylase 1 (HDAC1), while the full-length HDAC1 proteins, but not HDAC1 mutants lacking the protein-interaction domain, co-precipitated with Bach1. Collectively, these results demonstrate that the anti-angiogenic activity of Bach1 is crucially dependent on molecular interactions that are mediated by the protein's BTB domain, and this domain could be a drug target for angiogenic therapy.

中文翻译：

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Bach1诱导的血管生成抑制作用取决于BTB结构域。

转录因子Bach1通过抑制Wnt /β-catenin信号传导来抑制缺血性损伤后的血管生成。但是，尚不清楚负责Bach1抗血管生成作用的特定域。这项研究确定了Bach1的BTB结构域在缺血性血管生成中的作用。Bach1在急性心肌梗死患者的循环内皮细胞中高表达，并且是缺血后的早期诱导基因。在小鼠手术后肢缺血后，用编码GFP（AdGFP），Bach1（AdBach1）或缺少BTB结构域的Bach1突变体（AdBach1-ΔBTB）的腺病毒治疗小鼠。AdBach1组的血流恢复，毛细血管密度以及血管内皮生长因子（VEGF）和血红素加氧酶-1（HO-1）的表达均显着降低，而ROS水平较高，但不适用于AdBach1-ΔBTB动物。此外，在人内皮细胞中转染AdBach1，而不转染AdBach1-ΔBTB与1）基质胶塞测定中的毛细血管密度和血红蛋白含量显着下降，2）增殖，迁移，管形成以及VEGF和HO- 1在内皮细胞中表达。Bach1直接与TCF4结合，并且此相互作用是由Bach1 BTB结构域的残基81-89和TCF4的N端结构域介导的。Bach1，但不是Bach1-ΔBTB，也与组蛋白脱乙酰基酶1（HDAC1）共沉淀，而全长HDAC1蛋白，但没有缺少蛋白相互作用域的HDAC1突变体，与Bach1共沉淀。总的来说，这些结果表明，Bach1的抗血管生成活性至关重要地依赖于蛋白质介导的分子相互作用。