Noggin depletion in adipocytes promotes obesity in mice

Objective Obesity has increased to pandemic levels and enhanced understanding of adipose regulation is required for new treatment strategies. Although bone morphogenetic proteins (BMPs) influence adipogenesis, the effect of BMP antagonists such as Noggin is largely unknown. The aim of the study was to define the role of Noggin, an extracellular BMP inhibitor, in adipogenesis. Methods We generated adipose-derived progenitor cells and a mouse model with adipocyte-specific Noggin deletion using the AdiponectinCre transgenic mouse, and determined the adipose phenotype of Noggin-deficiency. Results Our studies showed that Noggin is expressed in progenitor cells but declines in adipocytes, possibly allowing for lipid accumulation. Correspondingly, adipocyte-specific Noggin deletion in vivo promoted age-related obesity in both genders with no change in food intake. Although the loss of Noggin caused white adipose tissue hypertrophy, and whitening and impaired function in brown adipose tissue in both genders, there were clear gender differences with the females being most affected. The females had suppressed expression of brown adipose markers and thermogenic genes including peroxisome proliferator activated receptor gamma coactivator 1 alpha (PGC1alpha) and uncoupling protein 1 (UCP1) as well as genes associated with adipogenesis and lipid metabolism. The males, on the other hand, had early changes in a few BAT markers and thermogenic genes, but the main changes were in the genes associated with adipogenesis and lipid metabolism. Further characterization revealed that both genders had reductions in VO2, VCO2, and RER, whereas females also had reduced heat production. Noggin was also reduced in diet-induced obesity in inbred mice consistent with the obesity phenotype of the Noggin-deficient mice. Conclusions BMP signaling regulates female and male adipogenesis through different metabolic pathways. Modulation of adipose tissue metabolism by select BMP antagonists may be a strategy for long-term regulation of age-related weight gain and obesity.
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Highlights • Expression of Noggin is lower in adipocytes than in adipose progenitor cells, allowing for lipid accumulation. • Noggin deletion in mice promotes age-related obesity in both genders without change in food intake. • Loss of Noggin causes hypertrophy of white adipose tissue, and whitening and impaired function in brown adipose tissue. • Both genders have reductions in VO2, VCO2 and RER, whereas females also have reduced heat production. • Select BMP antagonists may be essential for long-term regulation of age-related weight gain and obesity.
Although, bone morphogenetic proteins (BMPs) influence fat development, the role of their inhibitors is largely unknown. This study shows that reduction of Noggin causes obesity related to age but not food intake, suggesting that select BMP antagonists may regulate age-related weight gain and obesity.