NRF2 function in osteocytes is required for bone homeostasis and drives osteocytic gene expression.
Redox Biol 2020;
40:101845. [PMID:
33373776 PMCID:
PMC7773566 DOI:
10.1016/j.redox.2020.101845]
[Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 12/21/2020] [Indexed: 12/17/2022] Open
Abstract
Osteocytes, the most abundant bone cell type, are derived from osteoblasts through a process in which they are embedded in an osteoid. We previously showed that nutrient restriction promotes the osteocyte transcriptional program and is associated with increased mitochondrial biogenesis. Here, we show that increased mitochondrial biogenesis increase reactive oxygen species (ROS) levels and consequently, NRF2 activity during osteocytogenesis. NRF2 activity promotes osteocyte-specific expression of Dmp1, Mepe, and Sost in IDG-SW3 cells, primary osteocytes, and osteoblasts, and in murine models with Nfe2l2 deficiency in osteocytes or osteoblasts. Moreover, ablation of Nfe2l2 in osteocytes or osteoblasts generates osteopenia and increases osteoclast numbers with marked sexual dimorphism. Finally, treatment with dimethyl fumarate prevented the deleterious effects of ovariectomy in trabecular bone masses of mice and restored osteocytic gene expression. Altogether, we uncovered the role of NRF2 activity in osteocytes during the regulation of osteocyte gene expression and maintenance of bone homeostasis.
ROS levels and NRF2 activity are increased during osteocytogenesis.
NRF2 drives osteocyte specification and activate the transcription of osteocyte-specific genes.
NRF2 in osteocytes has a fundamental role in bone homeostasis and its deletion induces osteopenia.
Activation of NRF2 with dimethyl fumarate prevents osteopenia induced by ovariectomy.
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