[HTML][HTML] Retinoid X receptors orchestrate osteoclast differentiation and postnatal bone remodeling

MP Menéndez-Gutiérrez, T Rőszer… - The Journal of …, 2015 - Am Soc Clin Investig
MP Menéndez-Gutiérrez, T Rőszer, L Fuentes, V Núñez, A Escolano, JM Redondo…
The Journal of Clinical Investigation, 2015Am Soc Clin Investig
Osteoclasts are bone-resorbing cells that are important for maintenance of bone remodeling
and mineral homeostasis. Regulation of osteoclast differentiation and activity is important for
the pathogenesis and treatment of diseases associated with bone loss. Here, we
demonstrate that retinoid X receptors (RXRs) are key elements of the transcriptional
program of differentiating osteoclasts. Loss of RXR function in hematopoietic cells resulted
in formation of giant, nonresorbing osteoclasts and increased bone mass in male mice and …
Osteoclasts are bone-resorbing cells that are important for maintenance of bone remodeling and mineral homeostasis. Regulation of osteoclast differentiation and activity is important for the pathogenesis and treatment of diseases associated with bone loss. Here, we demonstrate that retinoid X receptors (RXRs) are key elements of the transcriptional program of differentiating osteoclasts. Loss of RXR function in hematopoietic cells resulted in formation of giant, nonresorbing osteoclasts and increased bone mass in male mice and protected female mice from bone loss following ovariectomy, which induces osteoporosis in WT females. The increase in bone mass associated with RXR deficiency was due to lack of expression of the RXR-dependent transcription factor v-maf musculoaponeurotic fibrosarcoma oncogene family, protein B (MAFB) in osteoclast progenitors. Evaluation of osteoclast progenitor cells revealed that RXR homodimers directly target and bind to the Mafb promoter, and this interaction is required for proper osteoclast proliferation, differentiation, and activity. Pharmacological activation of RXRs inhibited osteoclast differentiation due to the formation of RXR/liver X receptor (LXR) heterodimers, which induced expression of sterol regulatory element binding protein-1c (SREBP-1c), resulting in indirect MAFB upregulation. Our study reveals that RXR signaling mediates bone homeostasis and suggests that RXRs have potential as targets for the treatment of bone pathologies such as osteoporosis.
The Journal of Clinical Investigation