ATP6V1H encodes subunit H of vacuolar ATPase (V-ATPase) and may regulate osteoclastic function. The deficiency of ATP6V1H caused bone loss in human, mouse and zebrafish. In this report, we identified the mechanisms by which ATP6V1H regulates proliferation and differentiation of bone marrow stromal cells (BMSCs). We found that ATP6V1H was expressed in BMSCs, and Atp6v1h(+/-) BMSCs exhibited the lower proliferation rate, cell cycle arrest and reduced osteogenic differentiation capacity, as well as the increased adipogenic potentials. Histologic analysis confirmed less bone formation and more fatty degeneration in Atp6v1h(+/-) mice in the different age groups. Q-PCR analysis revealed that loss of ATP6V1H function downregulated the mRNA level of TGF-beta 1 receptor, and its binding molecule, subunit beta of adaptor protein complex 2 (AP-2), suggesting ATP6V1H regulates the proliferation and differentiation of BMSCs by interacting with TGF-beta receptor I and AP-2 complex. (C) 2018 Elsevier Inc. All rights reserved.