RSPO2 synergizes with BMP2 to enhance wnt-dependent osteoblast differentiation

Canonical Wnt signaling plays a critical role in osteoblast differentiation and bone formation and is enhanced by R-spondin (RSPO) proteins. Bone morphogenetic protein-2 (BMP2) is a clinically used osteogenic factor whose regenerative efficacy is limited by dose-dependent adverse effects. We recently identified RSPO2 as a contextual enhancer of BMP2-induced bone formation, but the transcriptional mechanisms underlying this synergy remain incompletely understood. To define the molecular basis of BMP2–RSPO2 cooperation, we performed RNA sequencing (RNA-seq) analysis of MC3T3-E1 osteoblast precursor cells treated with vehicle control, RSPO2, BMP2, or BMP2+RSPO2 for 5 days under osteogenic conditions. Transcriptomic analysis revealed distinct and overlapping gene expression programs regulated by BMP2 and RSPO2, with co-treatment inducing a unique transcriptional signature enriched for genes associated with osteoblast differentiation, Wnt signaling, and cytoskeletal regulation. These data provide mechanistic insight into how RSPO2 potentiates BMP2-induced osteogenesis and support a role for RSPO2 as a therapeutic co-factor to enhance BMP2-mediated bone regeneration.