Related Experiment Video
Updated: Apr 26, 2026
Isolation and Differentiation of Stromal Vascular Cells to Beige/Brite Cells
Published on: March 28, 2013
Retinaldehyde dehydrogenase 1 deficiency inhibits PPARγ-mediated bone loss and marrow adiposity
Shriram Nallamshetty1, Phuong T Le2, Hong Wang1
1Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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.
Insights
Retinaldehyde dehydrogenase 1 (Aldh1a1) and retinaldehyde (Rald) regulate bone health by modulating PPARγ-RXR activity. Aldh1a1 deficiency protects against bone loss, revealing new therapeutic targets for osteoporosis.
Area of Science:
- Bone biology
- Nuclear receptor signaling
- Retinoid metabolism
Background:
- Peroxisome proliferator-activated receptor gamma (PPARγ) is crucial for bone homeostasis and is targeted by anti-diabetic drugs.
- PPARγ activation by thiazolidinediones leads to bone loss and increased marrow adiposity.
- Understanding PPARγ regulation is vital for treating low bone mineral density disorders.
Purpose of the Study:
- To identify novel regulators of PPARγ-retinoid X receptor (RXR) complex activity in the skeleton.
- To investigate the role of retinaldehyde dehydrogenase 1 (Aldh1a1) and its substrate retinaldehyde (Rald) in bone remodeling.
Main Methods:
- Utilized Aldh1a1-deficient (Aldh1a1(-/-)) and wild-type (WT) mice.
- Administered thiazolidinedione rosiglitazone and high-fat diet to induce bone changes.
- Performed in vitro studies on osteoblastogenesis, adipogenesis, and osteoclastogenesis using mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs).
Main Results:
- Aldh1a1(-/-) mice were protected from bone loss and marrow adiposity induced by rosiglitazone or high-fat diet.
- Accumulated Rald in Aldh1a1(-/-) mice inhibited rosiglitazone-induced suppression of osteoblastogenesis.
- Rald inhibited adipogenesis in MSCs and osteoclastogenesis in HSCs in vitro.
Conclusions:
- Aldh1a1 and Rald are novel determinants of PPARγ-RXR signaling in the bone marrow niche.
- Retinoid metabolism via Aldh1a1 influences bone remodeling by modulating PPARγ-RXR activity.
- Targeting Rald and retinoid metabolism may offer new therapeutic strategies for bone disorders.
