Albanese C, D'Amico M, Reutens A T, Fu M, Watanabe G, Lee R J, Kitsis R N, Henglein B, Avantaggiati M, Somasundaram K, Thimmapaya B, Pestell R G
Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
J Biol Chem. 1999 Nov 26;274(48):34186-95. doi: 10.1074/jbc.274.48.34186.
The adenovirus E1A protein interferes with regulators of apoptosis and growth by physically interacting with cell cycle regulatory proteins including the retinoblastoma tumor suppressor protein and the coactivator proteins p300/CBP (where CBP is the CREB-binding protein). The p300/CBP proteins occupy a pivotal role in regulating mitogenic signaling and apoptosis. The mechanisms by which cell cycle control genes are directly regulated by p300 remain to be determined. The cyclin D1 gene, which is overexpressed in many different tumor types, encodes a regulatory subunit of a holoenzyme that phosphorylates and inactivates PRB. In the present study E1A12S inhibited the cyclin D1 promoter via the amino-terminal p300/CBP binding domain in human choriocarcinoma JEG-3 cells. p300 induced cyclin D1 protein abundance, and p300, but not CBP, induced the cyclin D1 promoter. cyclin D1 or p300 overexpression inhibited apoptosis in JEG-3 cells. The CH3 region of p300, which was required for induction of cyclin D1, was also required for the inhibition of apoptosis. p300 activated the cyclin D1 promoter through an activator protein-1 (AP-1) site at -954 and was identified within a DNA-bound complex with c-Jun at the AP-1 site. Apoptosis rates of embryonic fibroblasts derived from mice homozygously deleted of the cyclin D1 gene (cyclin D1(-/-)) were increased compared with wild type control on several distinct matrices. p300 inhibited apoptosis in cyclin D1(+/+) fibroblasts but increased apoptosis in cyclin D1(-/-) cells. The anti-apoptotic function of cyclin D1, demonstrated by sub-G(1) analysis and annexin V staining, may contribute to its cellular transforming and cooperative oncogenic properties.
腺病毒E1A蛋白通过与包括视网膜母细胞瘤肿瘤抑制蛋白和共激活蛋白p300/CBP（其中CBP是CREB结合蛋白）在内的细胞周期调节蛋白进行物理相互作用，干扰细胞凋亡和生长的调节因子。p300/CBP蛋白在调节有丝分裂信号传导和细胞凋亡中起关键作用。p300直接调节细胞周期控制基因的机制仍有待确定。细胞周期蛋白D1基因在许多不同肿瘤类型中过表达，编码一种全酶的调节亚基，该亚基使PRB磷酸化并使其失活。在本研究中，E1A12S通过人绒毛膜癌JEG-3细胞中的氨基末端p300/CBP结合域抑制细胞周期蛋白D1启动子。p300诱导细胞周期蛋白D1蛋白丰度增加，且p300而非CBP诱导细胞周期蛋白D1启动子。细胞周期蛋白D1或p300过表达抑制JEG-3细胞凋亡。诱导细胞周期蛋白D1所需的p300的CH3区域也是抑制细胞凋亡所必需的。p300通过位于-954的激活蛋白-1（AP-1）位点激活细胞周期蛋白D1启动子，并在AP-1位点与c-Jun形成的DNA结合复合物中被鉴定出来。与野生型对照相比，在几种不同基质上，来自细胞周期蛋白D1基因纯合缺失小鼠（细胞周期蛋白D1(-/-)）的胚胎成纤维细胞的凋亡率增加。p300抑制细胞周期蛋白D1(+/+)成纤维细胞的凋亡，但增加细胞周期蛋白D1(-/-)细胞的凋亡。通过亚G(1)分析和膜联蛋白V染色证明的细胞周期蛋白D1的抗凋亡功能，可能有助于其细胞转化和协同致癌特性。
