In the bone marrow stroma, skeletal stem cells (SSCs) and their derived stromal cells, osteoblasts and bone marrow adipocytes (BMAs) provide the niche microenvironment to support the self-renewal and differentiation of hematopoietic stem cells (HSCs). However, it’s still largely mysterious how the bone-fat balance is disrupted and whether marrow adiposity contributes to the skewed differentiation of HSCs toward myeloid over lymphoid cells. Here we showed that the O-linked β-N-acetylglucosamine (O-GlcNAc) modification on intracellular proteins determined the adipogenic vs. osteogenic differentiation of SSCs. Conditional deletion of O-GlcNAc transferase (OGT) in Osx1+ cells promoted BMA formation while impaired osteoblast development and bone ossification, which resulted in defective B cell development. To determine the role of BM adipokines in hematopoiesis, we selectively ablated Kit ligand (Kitl) in Osx1+ and Adipoq+ lineages. Both Osx1-Kitl KO and Adipoq-Kitl KO mice lost myeloid progenitors in BM and developed macrocytic anemia. Collectively, our data identified protein O-GlcNAcylation as a novel regulator of SSCs differentiation and demonstrated that BMAs are functionally essential for unperturbed hematopoiesis.
Z. Zhang: None. Z. Huang: None. H. Ruan: None.
National Institutes of Health