Regulation Of Osteoblast Mineralization by GATA4 And Estrogen Regulate Bone Mineralization

Osteoporosis is a disease associated with gradual thinning and weakening of bones and occurs more frequently in women after menopause.  During menopause, there is a sharp decrease in estrogen levels and bone mineral density decreases.  Osteoblasts are the cells responsible for the synthesis and mineralization of bone during its formation and remodeling.  There is evidence that estrogen increases bone formation but the mechanisms are unknown.  The objective of our research is to investigate the regulatory effects of 17β-estradiol (E2) on bone mineralization in the presence and absence of the transcription factor GATA4.  To gain further understanding of how E2 and GATA4 regulate mineralization, we performed gene expression assays by obtaining RNA from primary osteoblasts that were collected from mice calvaria and mice bone marrow.  The pre-osteoblastic cell line MC3T3 was also used.  All three types of cells were infected with adenovirus or lentivirus that contained shGATA4 and our control was pLKO-GFP.  To identify that E2 has the potential to increase bone mineralization, qt-PCR analysis was used to define gene expression differences between E2 and EtOH treated cells.  The analysis of mineral accumulation was determined by alizarin red staining which was quantitated after extraction.  The results for the experiments show that by silencing GATA4 bone mineralization decreases.  The results from the experiments that were performed will provide further understanding of the role of estrogen in bone biology that will lead to the development of improved therapies for the prevention and treatment of osteoporosis.