Tamamori-Adachi Mimi, Takagi Hiromitsu, Hashimoto Kimio, Goto Kazumichi, Hidaka Toshinori, Koshimizu Uichi, Yamada Kazuhiko, Goto Ikuko, Maejima Yasuhiro, Isobe Mitsuaki, Nakayama Keiichi I, Inomata Norio, Kitajima Shigetaka
Department of Biochemical Genetics, Medical Research Institute and Laboratory for Gene Structure and Regulation, School of Biomedical Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
Cardiovasc Res. 2008 Nov 1;80(2):181-90. doi: 10.1093/cvr/cvn183. Epub 2008 Jul 2.
Cyclins and other cell-cycle regulators have been used in several studies to regenerate cardiomyocytes in ischaemic heart failure. However, proliferation of cardiomyocytes induced by nuclear-targeted cyclin D1 (D1NLS) stops after one or two rounds of cell cycles due in part to accumulation of p27Kip1, an inhibitor of cyclin-dependent kinase (CDK). Thus, expression of S-phase kinase-associated protein 2 (Skp2), a negative regulator of p27Kip1, significantly enhances the effect of D1NLS and CDK4 on cardiomyocyte proliferation in vitro. Here, we examined whether Skp2 can also improve cardiomyocyte regeneration and post-ischaemic cardiac performance in vivo.
Wistar rats underwent ischaemia/reperfusion injury by ligation of the coronary artery followed by injection of adenovirus vectors for D1NLS and CDK4 with or without Skp2. Enhanced proliferation of cardiomyocytes in the presence of Skp2 was demonstrated by increased expression of Ki67, a marker of proliferating cells (1.95% vs. 4.00%), and mitotic phosphorylated histone H3 (0.24% vs. 0.58%). Compared with rats that received only D1NLS and CDK4, expression of Skp2 improved left ventricular function as measured by the maximum and minimum rates of change in left ventricular pressure, the left ventricle end-diastolic pressure, left ventricle end-diastolic volume index, and the lung/body weight ratio.
Expression of Skp2 enhanced the effect of D1NLS and CDK4 on the proliferation of cardiomyocytes and further contributed to improved post-ischaemic cardiac function. Skp2 might be a versatile tool to improve the effect of cyclins on post-ischaemic regeneration of cardiomyocytes in vivo.
在多项研究中，细胞周期蛋白及其他细胞周期调节因子已被用于在缺血性心力衰竭中再生心肌细胞。然而，核靶向细胞周期蛋白D1（D1NLS）诱导的心肌细胞增殖在一到两轮细胞周期后就会停止，部分原因是细胞周期蛋白依赖性激酶（CDK）的抑制剂p27Kip1的积累。因此，p27Kip1的负调节因子S期激酶相关蛋白2（Skp2）的表达显著增强了D1NLS和CDK4在体外对心肌细胞增殖的作用。在此，我们研究了Skp2是否也能在体内改善心肌细胞再生和缺血后心脏功能。
Wistar大鼠通过结扎冠状动脉进行缺血/再灌注损伤，随后注射携带或不携带Skp2的D1NLS和CDK4腺病毒载体。增殖细胞标志物Ki67表达增加（1.95%对4.00%）以及有丝分裂磷酸化组蛋白H3表达增加（0.24%对0.58%）证明了在Skp2存在的情况下心肌细胞增殖增强。与仅接受D1NLS和CDK4的大鼠相比，Skp2的表达改善了左心室功能，这通过左心室压力的最大和最小变化率、左心室舒张末期压力、左心室舒张末期容积指数以及肺/体重比来衡量。
Skp2的表达增强了D1NLS和CDK4对心肌细胞增殖 的作用，并进一步有助于改善缺血后心脏功能。Skp2可能是一种通用工具，可提高细胞周期蛋白对体内缺血后心肌细胞再生的作用。
