Abstract
Background: Bone is a rigid organ that provides support and physical protection to vital organs of the body. Several bone loss disorders are commonly associated with increased bone marrow adipose tissue. Bone marrow mesenchymal stromal/stem cells (BMSCs) are multipotent progenitors differentiating into osteoblasts, adipocytes, and chondrocytes. CDC20 is a co-activator of APC/C, required for full ubiquitin ligase activity. In our previous study, CDC20 promoted the osteogenic commitment of BMSCs and Cdc20 conditional knockout mice suggested a decline in bone mass. In this study, we investigated the function of CDC20 in the adipogenic differentiation of BMSCs and provided a new clue between adipogenesis and osteogenesis. Methods: Lentivirus containing CDC20 shRNA was used for CDC20 knockdown in hBMSCs. Primary mBMSCs were isolated from Cdc20f/f and Sp7-Cre;Cdc20f/f mice. Adipogenesis was examined by qRT-PCR and western blot analysis of adipogenic regulators, Oil Red O staining and transplantation into nude mice. The CDC20 knockout efficiency was determined through immunochemistry, qRT-PCR and western blot of bone marrow. Accumulation of adiposity was measured through histology and staining of bone sections. Results: CDC20 expression in hBMSCs was significantly decreased during adipogenic differentiation. Knockdown of CDC20 enhanced adipogenic differentiation of hBMSCs in vitro. CDC20-knockdown hBMSCs showed more adipose tissue–like constructs in H&E staining and Oil Red O staining. Sp7-Cre;Cdc20f/f mice presented increased adipocytes in bone marrow compared with control mice. mBMSCs from Sp7-Cre;Cdc20f/f mice exerted upregulated adipogenic differentiation. Conclusions: Our findings showed that knockdown of CDC20 enhanced adipogenesis of h(m)BMSCs in vitro and in vivo. Overall, CDC20 regulated both adipogenesis and osteogenesis of BMSCs, and may lead to the development of new therapeutic target for “fatty bone” and osteoporosis.