AP-1 regulates cyclin D1 and c-MYC transcription in an AKT-dependent manner in response to mTOR inhibition: role of AIP4/Itch-mediated JUNB degradation

AP-1以AKT依赖的方式调节细胞周期蛋白D1和c-MYC转录以响应mTOR抑制:AIP4/Itch介导的JUNB降解的作用

阅读:2
作者:Raffi Vartanian, Janine Masri, Jheralyn Martin, Cheri Cloninger, Brent Holmes, Nicholas Artinian, Alex Funk, Teresa Ruegg, Joseph Gera

Abstract

One mechanism by which AKT kinase-dependent hypersensitivity to mammalian target of rapamycin (mTOR) inhibitors is controlled is by the differential expression of cyclin D1 and c-MYC. Regulation of posttranscriptional processes has been demonstrated to be crucial in governing expression of these determinants in response to rapamycin. Our previous data suggested that cyclin D1 and c-MYC expression might additionally be coordinately regulated in an AKT-dependent manner at the level of transcription. Under conditions of relatively quiescent AKT activity, treatment of cells with rapamycin resulted in upregulation of cyclin D1 and c-MYC nascent transcription, whereas in cells containing active AKT, exposure repressed transcription. Promoter analysis identified AKT-dependent rapamycin responsive elements containing AP-1 transactivation sites. Phosphorylated c-JUN binding to these promoters correlated with activation of transcription whereas JUNB occupancy was associated with promoter repression. Forced overexpression of JunB or a conditionally active JunB-ER allele repressed cyclin D1 and c-MYC promoter activity in quiescent AKT-containing cells following rapamycin exposure. AIP4/Itch-dependent JUNB protein degradation was found to be markedly reduced in active AKT-containing cells compared with cells harboring quiescent AKT. Moreover, silencing AIP4/Itch expression or inhibiting JNK mediated AIP4 activity abrogated the rapamycin-induced effects on cyclin D1 and c-MYC promoter activities. Our findings support a role for the AKT-dependent regulation of AIP4/Itch activity in mediating the differential cyclin D1 and c-MYC transcriptional responses to rapamycin.

特别声明

1、本文转载旨在传播信息,不代表本网站观点,亦不对其内容的真实性承担责任。

2、其他媒体、网站或个人若从本网站转载使用,必须保留本网站注明的“来源”,并自行承担包括版权在内的相关法律责任。

3、如作者不希望本文被转载,或需洽谈转载稿费等事宜,请及时与本网站联系。

4、此外,如需投稿,也可通过邮箱info@biocloudy.com与我们取得联系。