Peroxisome proliferator-activated receptor γ inhibits expression of minichromosome maintenance proteins in vascular smooth muscle cells
Peroxisome proliferator-activated receptor γ inhibits expression of minichromosome maintenance proteins in vascular smooth muscle cells
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DOI：
10.1210/me.2002-0410
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发表时间：
2003-06-01
影响因子：
--
通讯作者：
Law, RE
中科院分区：
文献类型：
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作者：
Bruemmer, D;Yin, F;Law, RE
使用只由细胞周期基因组成的cDNA阵列，我们发现一种新的非噻唑烷二酮部分过氧化物酶体增殖物激活受体γ（PPARgamma）激动剂（nTZDpa）抑制血管平滑肌细胞中微小染色体维持（MCM）蛋白6和7的表达。MCM蛋白是DNA复制的起始和延伸阶段所必需的，并由转录因子E2F调节。丝裂原诱导的MCM6和MCM7 mRNA表达被nTZDpa有效抑制，并在较小程度上被完全PPARgamma激动剂罗格列酮抑制。通过nTZDpa和罗格列酮抑制MCM6和MCM7的表达，可增强其抑制视网膜母细胞瘤蛋白磷酸化和细胞增殖的作用。瞬时转染实验表明，nTZDpa抑制有丝分裂原诱导的MCM6和MCM7启动子活性，涉及转录机制。腺病毒介导的E2F过表达逆转了nTZDpa对MCM6和MCM7表达的抑制作用。此外，由多个E2F元件驱动的荧光素酶报告质粒的活性被nTZDpa抑制，表明它们被nTZDpa下调涉及E2F依赖性机制。过表达显性阴性PPARgamma或加入PPARgamma拮抗剂GW 9662，阻断了nTZDpa对MCM7转录的抑制。腺病毒介导的组成型活性PPARgamma的过表达以与nTZDpa类似的方式抑制MCM7表达。这些发现提供了强有力的证据，PPARgamma的激活减弱了MCM7的转录，并支持这种核受体在调节血管平滑肌细胞增殖中的重要作用。
Using a cDNA array consisting only of cell cycle genes, we found that a novel nonthiazolidinedione partial peroxisome proliferator-activated receptor gamma (PPARgamma) agonist (nTZDpa) inhibited expression of minichromosome maintenance (MCM) proteins 6 and 7 in vascular smooth muscle cells. MCM proteins are required for the initiation and elongation stages of DNA replication and are regulated by the transcription factor E2F. Mitogen-induced MCM6 and MCM7 mRNA expression was potently inhibited by nTZDpa and to a lesser degree by the full PPARgamma agonist, rosiglitazone. Inhibition of MCM6 and MCM7 expression by nTZDpa and rosiglitazone paralleled their effect to inhibit phosphorylation of the retinoblastoma protein and cell proliferation. Transient transfection experiments revealed that the nTZDpa inhibited mitogen-induced MCM6 and MCM7 promoter activity, implicating a transcriptional mechanism. Adenoviral-mediated E2F overexpression reversed the suppressive effect of nTZDpa on MCM6 and MCM7 expression. Furthermore, activity of a luciferase reporter plasmid driven by multiple E2F elements was inhibited by nTZDpa, indicating that their down-regulation by nTZDpa involves an E2F-dependent mechanism. Overexpression of dominant-negative PPARgamma or addition of a PPARgamma antagonist, GW 9662, blocked nTZDpa inhibition of MCM7 transcription. Adenovirus-mediated overexpression of constitutively active PPARgamma inhibited MCM7 expression in a similar manner as the nTZDpa. These findings provide strong evidence that activation of PPARgamma attenuates MCM7 transcription and support the important role of this nuclear receptor in regulating vascular smooth muscle cell proliferation.