E2F2 expression induces proliferation of terminally differentiated cardiomyocytes in vivo
E2F2 expression induces proliferation of terminally differentiated cardiomyocytes in vivo
复制标题
DOI：
10.1093/cvr/cvn194
复制
发表时间：
2008-11-01
影响因子：
10.8
通讯作者：
Braun, Thomas
中科院分区：
文献类型：
--
作者：
Ebelt, Henning;Zhang, Ying;Braun, Thomas
在先前的实验中，我们已经证明了转录因子E2 F2和E2 F4的表达足以诱导来自新生大鼠和小鼠的分离的原代心肌细胞的增殖。现在，我们想分析是否E2 F2或E2 F4也能够促进细胞周期的进展，成年心肌细胞在体内，这不同于心肌细胞从新生啮齿动物缺乏进行细胞proliferation.Methods和结果E2 F2或E2 F4的能力，在不同的发育阶段的小鼠心脏中表达的腺病毒载体。在组织学切片上分析关于增殖、肥大和凋亡的影响，并通过实时PCR（聚合酶链反应）和蛋白质印迹法进行细胞周期调控基因的定量评估。我们发现E2 F2和E2 F4都可以刺激心肌细胞的肥大细胞生长。然而，仅定向表达E2 F2而不定向表达E2 F4足以诱导心肌细胞增殖。E2 F2在体内的表达并没有增加心肌细胞凋亡的百分比，但下调了促凋亡基因caspase-6和apaf-1的表达。细胞周期调控机制的进一步分析表明，E2 F2的表达引起了强烈的诱导细胞周期蛋白A和E，而细胞周期蛋白依赖性激酶抑制剂（CKIs），如p21的表达不受影响。结论我们得出结论，有限的诱导心肌细胞增殖可以实现由E2 F2介导的刺激细胞周期蛋白A和E的表达没有减少CKIs。
Aims In previous experiments we have demonstrated that expression of the transcription factors E2F2 and E2F4 is sufficient to induce proliferation of isolated primary cardiomyocytes from newborn rats and mice. We now wanted to analyse whether E2F2 or E2F4 are also able to promote cell cycle progression of adult cardiomyocytes in vivo, which unlike cardiomyocytes from newborn rodents lack the ability to undergo cell proliferation.Methods and results E2F2 or E2F4 was expressed in hearts of mice at different developmental stages using adenoviral vectors. Effects regarding proliferation, hypertrophy, and apoptosis were analysed on histological sections, and quantitative assessment of cell cycle regulatory genes was performed by real-time PCR (polymerase chain reaction) and western blot. We found that both E2F2 and E2F4 can stimulate hypertrophic cell growth of cardiomyocytes. However, only directed expression of E2F2 but not of E2F4 was sufficient to induce proliferation of cardiomyocytes. Expression of E2F2 in vivo did not increase the percentage of apoptotic cardiomyocytes but down-regulated the expression of the pro-apoptotic genes caspase-6 and apaf-1. Further analysis of the cell cycle regulatory machinery revealed that expression of E2F2 caused a strong induction of cyclin A and E while the expression of cyclin-dependent kinase inhibitors (CKIs) such as p21 was not affected.Conclusion We conclude that a limited induction of cardiomyocyte cell proliferation can be achieved by E2F2-mediated stimulation of cyclin A and E expression without a reduction of CKIs.