Glucocorticoid receptor regulates osteoblast differentiation in association with Map7d2 and Erk2 signaling

The glucocorticoid receptor (GR) is an important regulator of skeletal homeostasis; however, the molecular mechanisms through which it regulates osteogenic differentiation remain incompletely understood. Here, we investigated the role of GR using two complementary primary murine osteogenic cell models, bone marrow stromal cells (BMSCs) and bone-derived primary osteoblasts, together with comparative transcriptomic analyses. GR depletion significantly impaired osteogenic differentiation in both cell preparations, as demonstrated by reduced alkaline phosphatase (Alp) activity and altered expression of osteogenic markers. RNA sequencing (RNA-seq) revealed extensive transcriptional changes following GR knockdown, with 3,530 differentially expressed genes (DEGs) in BMSCs and 4,657 in primary osteoblasts. Despite substantial differences in gene expression profiles of the two osteogenic cell models, pathway enrichment analyses revealed common biological processes, including MAPK signaling and cell migration. Comparative transcriptomic analysis further identified only 17 genes that were consistently regulated in the same direction in both cell preparations, among which Map7d2 emerged as a previously unrecognized GR-responsive candidate. Combined depletion of GR and Map7d2 partially restored cellular Alp activity and the expression of selected osteogenic markers compared with GR depletion alone. Western blot analysis further showed restoration of Erk2 phosphorylation and Alp protein expression following combined GR and Map7d2 depletion, demonstrating an association between the partial rescue of selected osteogenic readouts and restoration of Erk2 signaling. Together, these findings identify Map7d2 as a previously unrecognized GR-responsive candidate associated with Erk2 signaling and osteogenic differentiation. Our study reveals common molecular responses to GR depletion across two primary murine osteogenic cell models and provides new insights into the transcriptional and signaling networks underlying GR-regulated osteogenic differentiation.