GATA4 Directly Regulates Expression and Osteoblast Differentiation.

GATA4 is a zinc-finger transcription factor that is a pioneer factor in various tissues and regulates tissue-specific gene regulation. In vivo deletion of using Cre-recombinase under the control of the 2.3 kb promoter showed significantly reduced values for trabecular bone properties by microCT analysis of femur and tibia of 14-week-old male and female mice, suggesting GATA4 is necessary for maintaining normal adult bone phenotype. Quantitative PCR analysis revealed higher expression of in trabecular bone compared with cortical bone, suggesting a role for GATA4 in maintaining normal trabecular bone mass. In vivo and in vitro, reduction of correlates with reduced gene expression, along with reduced osteoblast mineralization. To determine if is a direct target of GATA4, chromatin immunoprecipitation (ChIP) was performed, and it demonstrated that GATA4 is recruited to the two promoters and an enhancer region. Furthermore, when is knocked down, the chromatin at the region is not open, as detected by DNase assays and ChIP with antibodies to the open chromatin marks H3K4me2 (histone 3 lysine 4 dimethylation) and H3K27ac (histone 3 lysine 27 acetylation) and the closed chromatin mark H3K27me2 (histone 3 lysine 27 trimethylation). Together, the data suggest that GATA4 binds near the promoter and enhancer and helps maintain open chromatin to regulate expression leading to bone mineralization.