Related Experiment Videos
Regulation of Wnt signaling during adipogenesis
Christina N Bennett1, Sarah E Ross, Kenneth A Longo
1Department of Physiology, 7620 Medical Science II, University of Michigan Medical School, 1301 E. Catherine Street, Ann Arbor, MI 48109-0622, USA.
Abstract:
We have identified Wnt10b as a potent inhibitor of adipogenesis that must be suppressed for preadipocytes to differentiate in vitro. Here, we demonstrate that a specific inhibitor of glycogen synthase kinase 3, CHIR 99021, mimics Wnt signaling in preadipocytes. CHIR 99021 stabilizes free cytosolic beta-catenin and inhibits adipogenesis by blocking induction of CCAAT/enhancer-binding protein alpha and peroxisome proliferator-activated receptor gamma. Preadipocyte differentiation is inhibited when 3T3-L1 cells are exposed to CHIR 99021 for any 24 h period during the first 3 days of adipogenesis. Consistent with this time frame of inhibition, expression of Wnt10b mRNA is suppressed upon induction of differentiation, with a 50% decline by 6 h and complete inhibition by 36 h. Of the agents used to induce differentiation, exposure of 3T3-L1 cells to methyl-isobutylxanthine or cAMP is sufficient to suppress expression of Wnt10b mRNA. Inhibition of adipogenesis by Wnt10b is likely mediated by Wnt receptors, Frizzled 1, 2, and/or 5, and co-receptors low density lipoprotein receptor-related proteins 5 and 6. These receptors, like Wnt10b, are highly expressed in preadipocytes and stromal vascular cells. Finally, we demonstrate that disruption of extracellular Wnt signaling by expression of secreted Frizzled related proteins causes spontaneous adipocyte conversion.
Insights
Wnt10b inhibits adipocyte differentiation. Suppressing Wnt signaling, using glycogen synthase kinase 3 inhibitor CHIR 99021, blocks preadipocyte differentiation by stabilizing beta-catenin and inhibiting key adipogenic factors.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Wnt10b is identified as a potent inhibitor of adipogenesis.
- Preadipocyte differentiation requires suppression of Wnt signaling.
- Wnt signaling pathways play crucial roles in cell differentiation processes.
Purpose of the Study:
- To investigate the role of Wnt10b in adipogenesis.
- To determine how Wnt signaling affects preadipocyte differentiation.
- To identify molecular mechanisms underlying Wnt-mediated inhibition of adipogenesis.
Main Methods:
- Using CHIR 99021, a specific inhibitor of glycogen synthase kinase 3, to mimic Wnt signaling.
- Treating 3T3-L1 cells with CHIR 99021 during differentiation.
- Analyzing the expression of Wnt10b mRNA and key adipogenic factors (CCAAT/enhancer-binding protein alpha, peroxisome proliferator-activated receptor gamma).
- Investigating the involvement of Wnt receptors (Frizzled 1, 2, 5) and co-receptors (low density lipoprotein receptor-related proteins 5, 6).
Main Results:
- CHIR 99021 treatment inhibits adipogenesis by stabilizing beta-catenin and blocking the induction of CCAAT/enhancer-binding protein alpha and peroxisome proliferator-activated receptor gamma.
- Preadipocyte differentiation is inhibited by CHIR 99021 exposure during the initial days of adipogenesis.
- Wnt10b mRNA expression is suppressed upon induction of differentiation, with significant decline observed early.
- Disruption of extracellular Wnt signaling using secreted Frizzled related proteins leads to spontaneous adipocyte conversion.
Conclusions:
- Wnt10b acts as a critical inhibitor of adipogenesis.
- Wnt signaling, mimicked by CHIR 99021, prevents adipocyte differentiation by interfering with key transcription factors.
- Wnt receptors and co-receptors are likely involved in mediating Wnt10b's inhibitory effects.
- Modulating Wnt signaling offers a potential strategy to control adipogenesis.