FLASH interacts with p160 coactivator subtypes and differentially suppresses transcriptional activity of steroid hormone receptors.
We previously reported that tumor necrosis factor alpha receptor- and Fas-associated FLASH interacts with one of the p160 nuclear receptor coactivators, glucocorticoid receptor-interacting protein (GRIP) 1, at its nuclear receptor-binding (NRB) domain, and that inhibits the transcriptional activity of the glucocorticoid receptor (GR) by interfering with association of GR and GRIP1. Here, we further examined the specificity of FLASH suppressive effect and the physical/functional interactions between this protein and two other p160 family subtypes. The suppressive effect of FLASH on GR transactivation was observed in several cell lines and on the chromatin-integrated mouse mammary tumor virus (MMTV) promoter. FLASH strongly interacted with the NRB domain of the thyroid hormone receptor activator molecule (TRAM) 1, a member of the steroid hormone receptor coactivator (SRC) 3/nuclear receptor coactivator (N-CoA) 3 subtypes, as well as with SRC2/N-CoA2 p160 coactivator GRIP1, while its interaction with SRC1a, one of the SRC1/N-CoA1 proteins, was faint in yeast two-hybrid assays. Accordingly, FLASH strongly suppressed TRAM1- and GRIP1-induced enhancement of GR-stimulated transactivation of the MMTV promoter in HCT116 cells, while it did not affect SRC1a-induced potentiation of transcription. Furthermore, FLASH suppressed androgen- and progesterone receptor-induced transcriptional activity, but did not influence estrogen receptor-induced transactivation, possibly due to their preferential use of p160 coactivators in HCT116 and HeLa cells. Thus, FLASH differentially suppresses steroid hormone receptor-induced transcriptional activity by interfering with their association with SRC2/N-CoA2 and SRC3/N-CoA3 but not with SRC1/N-CoA1.
Kino
Tomoshige
T
Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development, Building 10, Clinical Research Center, Room 1-3140 , 10 Center Drive, MSC 1109, Bethesda, MD 20892-1109, USA. kinot@mail.nih.gov
Ichijo
Takamasa
T
Chrousos
George P
GP
D000818:Animals; D051017:Apoptosis Regulatory Proteins; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002522:Chlorocebus aethiops; D006801:Humans; D051958:Nuclear Receptor Coactivator 2; D011485:Protein Binding; D011987:Receptors, Steroid / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000145:classification* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics
D051017:Apoptosis Regulatory Proteins; C485604:CASP8AP2 protein, human; D002135:Calcium-Binding Proteins; C498001:NCOA2 protein, human; D051958:Nuclear Receptor Coactivator 2; D011987:Receptors, Steroid; D014157:Transcription Factors