Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Vascular Surgery, Graduate School of Medical Sciences, International University of Health and Welfare, Narita, Japan.
J Vasc Surg. 2018 Aug;68(2):576-586.e1. doi: 10.1016/j.jvs.2017.07.119. Epub 2017 Sep 30.
Budding uninhibited by benzimidazole-related 1 (BubR1), a cell cycle-related protein, is an essential component of the spindle checkpoint that regulates cell division. Mice in which BubR1 expression is reduced to 10% of the normal level display the phenotypic features of progeria. However, the role of BubR1 in vascular diseases and angiogenesis remains unknown. To investigate the influence of BubR1 on angiogenesis, we generated a low-null-BubR1-expressing (BubR1) mouse strain with reduced BubR1 expression as low as 15% of the normal level without any abnormalities in appearance.
To elucidate the role of BubR1 in angiogenesis, we used a hind limb ischemia model induced in BubR1 mice and age-matched wild-type (WT) littermates. To evaluate the pathologic influence of BubR1 on angiogenesis, we measured the blood flow before and after hind limb ischemia surgery, and the expression of typical angiogenic factors in vivo and in vitro.
In WT mice, blood flow in the ischemic left limb gradually recovered to approximately 80%, 14 days after surgery. Conversely, in the BubR1 group, blood flow in the left ischemic limb recovered to at most 30% (14 days after surgery, P < .01; immediately after the operation, and 5 and 9 days after surgery, P < .05). In adductor and calf muscles from BubR1 mice, regenerated muscle bundles, granulation tissue, and inflammatory cell invasion were more evident than in calf muscles from WT mice at 14 days after surgery. All WT mice at 14 days after surgery had complete limb salvage, but loss of limbs was observed in approximately 70% of BubR1 mice (P < .05). The vascular endothelial growth factor protein increase in ischemic hind limb muscles was lower in BubR1 mice compared with WT mice (P < .05), and vascular endothelial growth factor levels in human aortic smooth muscle cells treated with BubR1 knockdown siRNA were lower compared with scramble siRNA under hypoxic conditions (P < .01). HIF1α protein levels in the muscles after hind limb ischemia surgery were also significantly lower in BubR1 mice compared with WT mice (P < .05).
BubR1 insufficiency impairs angiogenesis and results in limb loss in ischemic hind limbs. BubR1 may be a crucial angiogenic factor and might be beneficial for the treatment of limb ischemia.
芽殖不受苯并咪唑相关 1（BubR1）抑制，是一种细胞周期相关蛋白，是调节细胞分裂的纺锤体检验点的一个重要组成部分。BubR1 表达水平降低至正常水平的 10%的小鼠表现出早衰的表型特征。然而，BubR1 在血管疾病和血管生成中的作用仍然未知。为了研究 BubR1 对血管生成的影响，我们构建了一种低表达 BubR1 的（BubR1）小鼠品系，其 BubR1 表达水平低至正常水平的 15%，但外观无任何异常。
为了阐明 BubR1 在血管生成中的作用，我们使用了一种在 BubR1 小鼠和年龄匹配的野生型（WT）同窝仔鼠中诱导的后肢缺血模型。为了评估 BubR1 对血管生成的病理影响，我们测量了后肢缺血手术后前后肢的血流，并在体内和体外测量了典型的血管生成因子的表达。
在 WT 小鼠中，缺血左肢的血流在手术后 14 天逐渐恢复到大约 80%。相反，在 BubR1 组中，左肢缺血的血流最多恢复到 30%（手术后 14 天，P<0.01；手术后即刻，以及 5 天和 9 天，P<0.05）。在手术后 14 天的 BubR1 仔鼠的内收肌和小腿肌肉中，再生的肌束、肉芽组织和炎症细胞浸润比 WT 仔鼠的小腿肌肉更明显。所有 WT 仔鼠在手术后 14 天都完全保留了肢体，但约 70%的 BubR1 仔鼠出现了肢体丢失（P<0.05）。与 WT 仔鼠相比，缺血后肢肌肉中血管内皮生长因子蛋白的增加在 BubR1 仔鼠中较低（P<0.05），并且在缺氧条件下用 BubR1 敲低 siRNA 处理的人主动脉平滑肌细胞中的血管内皮生长因子水平也低于 scramble siRNA（P<0.01）。手术后后肢肌肉中的 HIF1α 蛋白水平在 BubR1 仔鼠中也明显低于 WT 仔鼠（P<0.05）。
BubR1 不足会损害血管生成，并导致缺血后肢的肢体丢失。BubR1 可能是一个关键的血管生成因子，可能对治疗肢体缺血有益。
