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Bone. 2014 Oct;67:281-91. doi: 10.1016/j.bone.2014.07.005. Epub 2014 Jul 24.

Retinaldehyde dehydrogenase 1 deficiency inhibits PPARγ-mediated bone loss and marrow adiposity.

Author information

1
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
2
Center for Clinical & Translational Research, Maine Medical Center Research Institute, Scarborough, ME, USA.
3
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: jplutzky@rics.bwh.harvard.edu.

Abstract

PPARγ, a ligand-activated nuclear receptor, regulates fundamental aspects of bone homeostasis and skeletal remodeling. PPARγ-activating anti-diabetic thiazolidinediones in clinical use promote marrow adiposity, bone loss, and skeletal fractures. As such, delineating novel regulatory pathways that modulate the action of PPARγ, and its obligate heterodimeric partner RXR, may have important implications for our understanding and treatment of disorders of low bone mineral density. We present data here establishing retinaldehyde dehydrogenase 1 (Aldh1a1) and its substrate retinaldehyde (Rald) as novel determinants of PPARγ-RXR actions in the skeleton. When compared to wild type (WT) controls, retinaldehyde dehydrogenase-deficient (Aldh1a1(-/-)) mice were protected against bone loss and marrow adiposity induced by either the thiazolidinedione rosiglitazone or a high fat diet, both of which potently activate the PPARγ-RXR complex. Consistent with these results, Rald, which accumulates in vivo in Aldh1a1(-/-) mice, protects against rosiglitazone-mediated inhibition of osteoblastogenesis in vitro. In addition, Rald potently inhibits in vitro adipogenesis and osteoclastogenesis in WT mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) respectively. Primary Aldh1a1(-/-) HSCs also demonstrate impaired osteoclastogenesis in vitro compared to WT controls. Collectively, these findings identify Rald and retinoid metabolism through Aldh1a1 as important novel modulators of PPARγ-RXR transactivation in the marrow niche.

KEYWORDS:

PPAR gamma; Retinaldehyde; Retinaldehyde dehydrogenase 1; Retinoid

PMID:
25064526
PMCID:
PMC4209126
DOI:
10.1016/j.bone.2014.07.005
[Indexed for MEDLINE]
Free PMC Article

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