Nagata D, Suzuki E, Nishimatsu H, Yoshizumi M, Mano T, Walsh K, Sata M, Kakoki M, Goto A, Omata M, Hirata Y
Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Circ Res. 2000 Oct 13;87(8):699-704. doi: 10.1161/01.res.87.8.699.
The GATA-6 transcription factor is reported to be expressed in vascular myocytes. Because glomerular mesangial cells (GMCs) and vascular myocytes have similar properties, we examined whether GATA-6 was expressed in cultured GMCs and whether overexpression of GATA-6 induced cell cycle arrest in GMCs, using a recombinant adenovirus that expresses GATA-6 (Ad GATA-6). GATA-6 expression in GMCs was downregulated when quiescent GMCs were stimulated by serum to reenter the cell cycle. [(3)H]thymidine uptake was inhibited in GMCs infected with Ad GATA-6 in a dose- and time-dependent manner. The expression of cyclin A protein was decreased and that of the cyclin-dependent kinase inhibitor p21(cip1) was increased in GMCs infected with Ad GATA-6. Although the expression of p21(cip1) transcripts did not change remarkably, p21(cip1) protein was stabilized in GMCs infected with Ad GATA-6, suggesting a post-transcriptional regulation of p21(cip1) expression. Northern blot analysis showed that expression of the cyclin A transcript was decreased in Ad GATA-6-infected cells, whereas this decrease of cyclin A was not observed in GMCs derived from p21(cip1) null mice. Our results demonstrate that GATA-6 is endogenously expressed in GMCs and that overexpression of GATA-6 can induce cell cycle arrest. Our results also show that GATA-6-induced cell cycle arrest is associated with inhibition of cyclin A expression and p21(cip1) upregulation. Finally, our results indicate that the GATA-6-induced suppression of cyclin A expression depends on the presence of p21(cip1).
据报道，GATA-6转录因子在血管肌细胞中表达。由于肾小球系膜细胞（GMCs）和血管肌细胞具有相似的特性，我们使用表达GATA-6的重组腺病毒（Ad GATA-6），研究了GATA-6是否在培养的GMCs中表达，以及GATA-6的过表达是否会诱导GMCs细胞周期停滞。当静止的GMCs受到血清刺激重新进入细胞周期时，GATA-6在GMCs中的表达下调。感染Ad GATA-6的GMCs中，[³H]胸苷摄取以剂量和时间依赖性方式受到抑制。感染Ad GATA-6的GMCs中，细胞周期蛋白A蛋白的表达降低，而细胞周期蛋白依赖性激酶抑制剂p21（cip1）的表达增加。尽管p21（cip1）转录本的表达没有明显变化，但感染Ad GATA-6的GMCs中p21（cip1）蛋白稳定，提示p21（cip1）表达存在转录后调控。Northern印迹分析显示，Ad GATA-6感染的细胞中细胞周期蛋白A转录本的表达降低，而在源自p21（cip1）基因敲除小鼠的GMCs中未观察到细胞周期蛋白A的这种降低。我们的结果表明，GATA-6在GMCs中内源性表达，GATA-6的过表达可诱导细胞周期停滞。我们的结果还表明，GATA-6诱导的细胞周期停滞与细胞周期蛋白A表达的抑制和p21（cip1）上调有关。最后，我们的结果表明，GATA-6诱导的细胞周期蛋白A表达抑制依赖于p21（cip1）的存在。
