title: Coactivator function of positive cofactor 4 (PC4) in Sp1-directed luteinizing hormone receptor (LHR) gene transcription.
abstract: The LHR has an essential role in sexual development and reproductive function, and its transcription is subjected to several modes of regulation. In this study, we investigated PC4 coactivator function in the control of LHR transcription. Knockdown of PC4 by siRNA inhibited the LHR basal promoter activity and trichostatin A (TSA)-induced gene transcriptional activation and expression in MCF-7 cells. While overexpression of PC4 alone had no effect on the LHR gene, it significantly enhanced Sp1- but not Sp3-mediated LHR transcriptional activity. PC4 directly interacts with Sp1 at the LHR promoter, and this interaction is negatively regulated by PC4 phosphorylation. The coactivator domain (22-91 aa) of PC4 and DNA binding domain of Sp1 are essential for PC4/Sp1 interaction. ChIP assay revealed significant occupancy of PC4 at the LHR promoter that increased upon TSA treatment. Disruption of PC4 expression significantly reduced TSA-induced recruitment of TFIIB and RNAP II, at the promoter. PC4 functions are beyond TSA-induced phosphatase release, PI3K-mediated Sp1 phosphorylation, and HDAC1/2/mSin3A co-repressor release indicating its role as linker coactivator of Sp1 and the transcriptional machinery. These findings demonstrated a critical aspect of LHR modulation whereby PC4 acts as a coactivator of Sp1 to contribute to the human of LHR transcription.
authors.affiliation: Molecular Endocrinology Section, Program of Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4510, USA.
authors.forename: Mingjuan
authors.initials: M
authors.lastname: Liao
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jung-Hoon
authors.initials: JH
authors.lastname: Kang
authors.forename: Maria L
authors.initials: ML
authors.lastname: Dufau
mesh_terms: D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000502:physiology; D017434:Protein Structure, Tertiary; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012319:RNA Polymerase II / Q000378:metabolism; D034741:RNA, Small Interfering; D011974:Receptors, LH / Q000235:genetics*; D016329:Sp1 Transcription Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D035581:Transcription Factor TFIIB / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D006877:Hydroxamic Acids; D011500:Protein Synthesis Inhibitors; D034741:RNA, Small Interfering; D011974:Receptors, LH; C509201:SUB1 protein, human; D016329:Sp1 Transcription Factor; D035581:Transcription Factor TFIIB; D014157:Transcription Factors; C012589:trichostatin A; D012319:RNA Polymerase II