Article

Progesterone receptor transactivation of the secretory leukocyte protease inhibitor gene in Ishikawa endometrial epithelial cells involves recruitment of Krüppel-like factor 9/basic transcription element binding protein-1.

Department of Physiology and Biophysics, University of Arkansas for Medical Sciences and Arkansas Children's Nutrition Center, Little Rock, 72202, USA.
Endocrinology (impact factor: 4.46). 05/2006; 147(4):1969-78. DOI:10.1210/en.2005-1419 pp.1969-78
Source: PubMed

ABSTRACT Progesterone receptor (PR), a ligand-inducible transcription factor, mediates the physiological actions of progesterone (P) through two distinct isoforms, PR-A and PR-B, and numerous nuclear coregulators. We previously demonstrated that basic transcription element binding protein-1 (BTEB1), a transcription factor of the Krüppel-like family, is a functional PR-interacting protein, based on the subfertility phenotype and reduced P sensitivity of uterine PR target genes, on BTEB1 null mutation. Here we examined the role of BTEB1 in PR-mediated signaling in endometrial epithelial cells using Ishikawa human endocarcinoma cells and the P-responsive secretory leukocyte protease inhibitor (SLPI) gene. Treatment of Ishikawa cells with P for 24 h increased SLPI and BTEB1 transcript levels without similar effects on PR expression. P induction was abolished by the PR antagonist RU486, whereas knockdown of BTEB1 with short interfering RNA reduced P-responsive BTEB1 but not SLPI expression to basal levels. Forced expression of BTEB1, either by stable or transient transfections of BTEB1 expression constructs in endometrial carcinoma cells, enhanced SLPI promoter activity. Chromatin immunoprecipitation with anti-BTEB1 antibody demonstrated BTEB1 recruitment to the proximal GC-rich containing SLPI promoter region (-97 to -86) in human endometrial carcinoma (Hec1A) cells overexpressing BTEB1. In Ishikawa cells, recruitment of BTEB1 to the proximal, GC-rich region and the distal, progesterone-responsive element-like containing region (-635 to -514) was P dependent and was accompanied by corecruitment of PR and the PR coactivator cAMP-response element binding protein-binding protein. PR-B, rather than PR-A isoform, preferentially associated with BTEB1 in the GC-rich region, whereas both PR isoforms were recruited to the progesterone-responsive element-like site along with BTEB1. Our findings define a novel pathway for BTEB1/PR cross-talk to facilitate P-dependent gene transcription in endometrial epithelial cells.

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Keywords

BTEB1 expression constructs
 
BTEB1 null mutation
 
BTEB1/PR cross-talk
 
findings define
 
functional PR-interacting protein
 
Krüppel-like family
 
ligand-inducible transcription factor
 
novel pathway
 
numerous nuclear coregulators
 
P-dependent gene transcription
 
P-responsive BTEB1
 
physiological actions
 
PR antagonist RU486
 
PR-mediated signaling
 
progesterone-responsive element-like
 
progesterone-responsive element-like site
 
proximal GC-rich
 
SLPI promoter activity
 
SLPI promoter region
 
uterine PR target genes