Abstract 11722: S-nitrosylation Regulates the Balance of Adipogenesis and Osteogenesis in Mesenchymal Stem Cells
Introduction: Circulating bone marrow-derived mesenchymal stem cells (BMMSCs) are attracted to the arterial wall where they can undergo adipogenic or osteogenic differentiation to form ectopic aggregates of fat and bone in atherosclerosis. We assessed the role of nitric oxide (NO), an inhibitor of lipid formation and vascular calcification, in BMMSC differentiation. We hypothesized that S-nitrosylation mediated-NO signaling controls the balance between adipogenic and osteogenic differentiation of BMMSCs.
Methods: BMMSCs were isolated from wild type mice (WT) and mice deficient in S-nitrosoglutathione reductase (GSNOR-/-), a denitrosylase that governs levels of protein S-nitrosylation. Cells were cultured in either adipogenic or osteogenic differentiation media followed by functional and gene expression assays.
Results: BMMSCs derived from GSNOR-/- mice had reduced fat droplet formation and expression of the adipogenic markers PPARγ (1329±415.3-fold increase in WT vs. 158±65.61-fold in GSNOR-/-, P<0.05) and FABP4 (11.06±3.29-fold in WT vs. 4.06±0.62-fold in GSNOR-/-, P<0.05). Conversely, GSNOR-/- MSCs exhibited enhanced osteogenic differentiation as indicated by greater calcium deposition and higher expression of the osteogenic marker Osteopontin (1.48±0.17-fold in WT vs. 16.18±5.26-fold in GSNOR-/-, P<0.05). Interestingly, GSNOR-/- cells had higher baseline expression of Osteopontin, Osteocalcin and Runx2. Treatment of GSNOR-/- MSCs with L-NAME, a nitric oxide synthase (NOS) inhibitor, decreased osteogenic differentiation without affecting adipogenic differentiation. Baseline level of S-nitrosylated PPARγ, a master regulator of adipogenesis and osteogenesis, was increased in GSNOR-/- MSCs.
Conclusion: Denitrosylation via GSNOR regulates the balance between adipogenic and osteogenic differentiation of BMMSCs by affecting the transcriptional and post-translational modification of PPARγ.
- © 2012 by American Heart Association, Inc.