Department of Endocrinology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, China.
Institute of Cardiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, China.
J Diabetes Res. 2020 Aug 10;2020:7574245. doi: 10.1155/2020/7574245. eCollection 2020.
The proliferation of vascular smooth muscle cells (VSMCs) induced by oxidative injury is one of the main features in diabetes-accelerated atherosclerosis. Geranylgeranyl transferase-I (GGTase-I) is an essential enzyme mediating posttranslational modification, especially the geranylgeranylation of small GTPase, Rac1. Our previous studies found that GGTase-I played an important role in diabetes-accelerated atherosclerosis. However, its exact role is largely unclear. In this study, mouse conditional knockout of VSMC GGTase-I (Pggt1b mice) was generated using the CRISPR/Cas9 system. The mouse model of diabetes-accelerated atherosclerosis was induced by streptozotocin injections and an atherogenic diet. We found that GGTase-I knockout attenuated diabetes-accelerated atherosclerosis in vivo and suppressed high-glucose-induced VSMC proliferation in vitro. Moreover, after a 16-week duration of diabetes, Pggt1b mice exhibited lower -smooth muscle actin (-SMA) and nitrotyrosine level, Rac1 activity, p47phox and NOXO1 expression, and phospho-ERK1/2 and phosphor-JNK content than wild-type mice. Meanwhile, the same changes were found in Pggt1b VSMCs cultured with high glucose (22.2 mM) in vitro. In conclusion, GGTase-I knockout efficiently blocked diabetes-accelerated atherosclerosis, and this protective effect must be related to the inhibition of VSMC proliferation. The potential mechanisms probably involved interfering Rac1 geranylgeranylation, inhibiting the assembly of NADPH oxidase cytosolic regulatory subunits, reducing oxidative injury, and decreasing ERK1/2 and JNK phosphorylation.
氧化损伤诱导的血管平滑肌细胞（VSMCs）增殖是糖尿病加速动脉粥样硬化的主要特征之一。法尼基转移酶-I（GGTase-I）是一种介导翻译后修饰的必需酶，特别是小 GTPase Rac1 的法尼基化。我们之前的研究发现 GGTase-I 在糖尿病加速动脉粥样硬化中起重要作用。然而，其确切作用在很大程度上尚不清楚。在这项研究中，我们使用 CRISPR/Cas9 系统生成了血管平滑肌细胞 GGTase-I 条件性敲除（Pggt1b 小鼠）。糖尿病加速动脉粥样硬化的小鼠模型通过链脲佐菌素注射和致动脉粥样硬化饮食诱导。我们发现 GGTase-I 敲除可减轻体内糖尿病加速的动脉粥样硬化，并抑制体外高葡萄糖诱导的 VSMC 增殖。此外，在糖尿病持续 16 周后，Pggt1b 小鼠表现出较低的 -平滑肌肌动蛋白（-SMA）和硝基酪氨酸水平、Rac1 活性、p47phox 和 NOXO1 表达以及磷酸化 ERK1/2 和磷酸化 JNK 含量，而野生型小鼠。同时，在体外高葡萄糖（22.2 mM）培养的 Pggt1b 血管平滑肌细胞中也发现了相同的变化。总之，GGTase-I 敲除有效地阻止了糖尿病加速的动脉粥样硬化，这种保护作用必须与抑制 VSMC 增殖有关。潜在的机制可能涉及干扰 Rac1 法尼基化、抑制 NADPH 氧化酶胞质调节亚基的组装、减少氧化损伤以及减少 ERK1/2 和 JNK 磷酸化。
