Publication Date:
2017-09-01
Description:
The mechanism underlying how transcription factors regulate mesenchymal stem cell lineage commitment remains unclear. To determine the role of core-binding factor subunit beta (Cbfβ) in osteoblast lineage commitment, we generated three mouse models by deletingCbfβat different osteoblast lineage stages. We demonstrated that theCbfβf/fPrx1-Cre, Cbfβf/fCol2α1-Cre, andCbfβf/fOsx-Cremice exhibited severe osteoporosis with substantial accumulation of marrow adipocytes resembling aged bone from enhanced adipogenesis, indicating that mesenchymal stem cells and osteoblasts can be programed and reprogramed, respectively, into adipocytes. Consistently,Cbfβ-deficient calvarial cells and bone marrow mesenchymal stem cells displayed strong adipogenic potential, with 5- to ∼70-fold increased adipocyte gene expression, which can be rescued by Cbfβ overexpression. Canonical Wnt signaling was impeded in theCbfβ-deficient cells, with ∼80% decrease of Wnt10b expression. Accordingly, ChIP and luciferase assays demonstrated that Cbfβ/RUNX2 binds toWnt10bpromoter drivingWnt10bexpression. Furthermore, Wnt3a suppressed adipogenesis but did not rescue osteoblastogenesis inCbfβ-deficient cells. Notably, mixing culture ofCbfβ-deficient with normal cells demonstrates that Cbfβ functions not only through WNT paracrine pathway but also through endogenous signaling. Further analysis shows that Cbfβ/RUNX2 inhibitsc/ebpαexpression at transcriptional level. Our results show that, besides its osteogenic role, Cbfβ governs osteoblast−adipocyte lineage commitment both cell nonautonomously through enhancing β-catenin signaling and cell autonomously through suppressing adipogenesis gene expression to maintain osteoblast lineage commitment, indicating Cbfβ may be a therapeutic target for osteoporosis.
Print ISSN:
0027-8424
Electronic ISSN:
1091-6490
Topics:
Biology
,
Medicine
,
Natural Sciences in General
