RIPK4 in Osteolineage cells regulate bone and bone marrow homeostasis via MFN2

Human RIPK4 mutation leads to Bartsocas-Papas syndrome (BPS), characterized by severe craniofacial, skin and limb abnormalities. However, how RIPK4 regulates skeletal system development remains largely elusive. Herein, using global RIPK4 ablation mice model, we demonstrated that RIPK4 deficiency caused musculoskeletal disorders including severe osteoporosis, kyphosis, sarcopenia and induced myeloid-biased hematopoiesis and subsequently altered peripheral immune responses. Further detailed investigation confirmed that osteolineage RIPK4, not epidermal RIPK4, regulated the osteogenesis and bone marrow myelopoiesis via MFN2. These findings deciphered the essential role of RIPK4 in maintaining skeletal homeostasis and unveiled an unappreciated mechanism of RIPK4-MFN2 axis in regulating osteogenesis and bone marrow myelopoiesis. RNA sequencing was performed on cortical bones from UbcCre/ERT2 Ripk4fl/fl and Ripk4fl/fl mice mice.Selected osteogenesis related gene ontology (GO) analysis was performed.