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论文类型：期刊论文

发表时间：2012-05-01

发表刊物：BIOLOGY OF THE CELL

收录刊物：SCIE、PubMed、Scopus

卷号：104

期号：5

页面范围：287-296

ISSN号：0248-4900

关键字：AIB1; PIAS; SUMO; SUMO ligase; Transcriptional activity

摘要：Background information. Amplified in breast cancer 1 (AIB1) is a transcriptional coactivator of nuclear receptors and other transcription factors. It is required for animal growth and reproductive development, and has also been implicated in breast carcinogenesis. Although AIB1 is known to be covalently modified by SUMO-1, which serves to regulate its stability and transcriptional activity, the exact SUMO E3 ligase involved in its sumoylation has not been determined. In order to resolve this question, we investigated the interaction between AIB1 and different members of PIAS proteins (all are SUMO E3 ligases) through immunoprecipiation.
   Results. Among the five different PIAS proteins, only PIAS1 co-immunoprecipitated with AIB1 in extract prepared from breast cancer cells (MCF-7). Over-expression of PIAS1 together with AIB1 in MCF-7 cells led to increased sumoylation of AIB1, resulting in repression of its transcriptional activity. In contrast, the PIAS1 mutant (C350S) lacking E3 ligase activity appeared to have no effect on the sumoylation of AIB1. Through sumoylation of AIB1, PIAS1 also promoted the stability of AIB1 and attenuated its interaction with estrogen receptor alpha (ER alpha), resulting in repression of the transactivation activity of ER alpha. In addition, MCF-7 cells co-transfected with wild-type PIAS1 and AIB1 showed about 40% reduction in cell growth, while cells co-transfected with wild-type PIAS1 and mutant AIB1 resistant to sumoylation showed about 34% increase in cell growth compared to cells transformed with wild-type AIB1 only.
   Conclusions. Taken together, these results suggested that PIAS1 may play a crucial role in the regulation of AIB1 transcriptional activity through sumoylation.