Differential Regulation of POC5 by ERα in Human Normal and Scoliotic Cells

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional spinal deformity. The incidence of AIS in females is 8.4 times higher than in males. Several hypotheses on the role of estrogen have been postulated for the progression of AIS. Recently, Centriolar protein gene POC5 (<i>POC5</i>) was identified as a causative gene of AIS. POC5 is a centriolar protein that is important for cell cycle progression and centriole elongation. However, the hormonal regulation of POC5 remains to be determined. Here, we identify <i>POC5</i> as an estrogen-responsive gene under the regulation of estrogen receptor ERα in normal osteoblasts (NOBs) and other ERα-positive cells. Using promoter activity, gene, and protein expression assays, we found that the <i>POC5</i> gene was upregulated by the treatment of osteoblasts with estradiol (E2) through direct genomic signaling. We observed different effects of E2 in NOBs and mutant <i>POC5</i>^A429V AIS osteoblasts. Using promoter assays, we identified an estrogen response element (ERE) in the proximal promoter of <i>POC5</i>, which conferred estrogen responsiveness through ERα. The recruitment of ERα to the ERE of the <i>POC5</i> promoter was also potentiated by estrogen. Collectively, these findings suggest that estrogen is an etiological factor in scoliosis through the deregulation of POC5.