1a.Objectives (from AD-416):
Objective 1: No longer applies.
Objective 2: No longer applies
Objective 3: Gain knowledge regarding the impact of nutrition on the Hedgehog signaling pathway.
1b.Approach (from AD-416):
Children's Nutrition Research Center scientists will further investigate mutant animal models with adipose tissue-specific inactivation of Hedgehog pathway components.
For objective 3, we determined the effect of different dietary treatments on the expression levels of the Hedgehog (Hh) pathway components in adipose tissue. Our results indicated that the expression of the Hh pathway components, specifically the downstream target genes, is significantly lower in mice fed a high fat diet than in mice fed a normal diet. To determine the role of the Hh pathway in the regulation of adipose tissue formation during development and postnatal life (objectives 4-5), we have established mouse models with high Hh pathway activity in both brown and white adipose tissues and started to analyze adipose tissue defects in these mice. In addition, we have characterized the embryonic brown preadipocyte cell line that we generated in the previous year by using standard adipogenic induction reagents. We found that this new cell line responds robustly to adipogenic induction as determined by the accumulation of lipid droplets and the expression of pro-adipogenic genes after induction.
Hedgehog (Hh) signaling inhibits brown fat formation. Brown fat may have potential therapeutic benefits for preventing weight gain due to its function of burning calories to generate heat. Brown fat is formed during development under the control of a signaling network that is not yet well understood. By activating the Hh signaling pathway in developing brown fat tissue, Children's Nutrition Research Center researchers in Houston, Texas, discovered that high level of Hh signaling inhibits brown fat formation. Our studies, therefore, demonstrate a novel role for Hh signaling in the regulation of the brown fat cells.