NR2F2 Pioneers Neonatal Beige Adipogenesis to Protect Against Later-life Obesity

(no more than 30 lines): Over the last 40 years, childhood obesity prevalence has increased ~ten-fold in the US and remains alarmingly high. In the first six months, infants significantly increase their body fat, but accelerated adipose deposition is a strong risk factor for childhood obesity. The composition of breast milk fatty acids plays a crucial role in adipose tissue development. Recent shifts towards higher omega-6 fatty acids (n6-FA) in human breast milk is associated with increased infant adipose deposition. Still, very little is known about the mechanisms through which n6-FA operate leading to formation of obesity-prone adipose. We reported in mice that developmental exposure to excessive n6-FA resulted in adipocytes with characteristics of insulin resistance and an obesity-prone gene expression pattern observed at postnatal day 14 (PND14). Both white and beige adipocytes share a common pool of Adipocyte Stem-like Cells (ASCs) that respond to developmental FA signals. Moreover, we reported pups exposed developmentally to high n6-FA preferentially formed white adipocytes, having less beige adipose tissue. We identified their inguinal ASCs had reduced Nuclear Receptor 2 group F member 2 (NR2F2) protein abundance, a known metabolic regulator, suggesting NR2F2 as an important player in early-life adipgenesis. The NR2F2 low ASCs from the n6-FA exposed pups had suppressed beige regulator gene expression and impaired mitochondrial oxidation. Based on these findings, our overarching hypothesis is that NR2F2 in ASCs is a main driver of beige adipocyte determination and its activation might protect against diet induced obesity. The parent R01 proposal investigates how n6-FA exposure during adipose development impacts ASC fate, including beige adipogenic potential, ASC and adipocyte mitochondrial oxidation, and whether their impaired whole-body can be restored by manipulating the NR2F2 axis in vivo. A mechanistic gap remains in how early life n6-FA pathways might be reversible, giving rise to persistent beige adipocytes that can benefit adult metabolic health. Our approach combines in vitro and in vivo strategies that manipulate NR2F2, in combination with early life exposures n6- and n3-FA, and metabolic rescue using bioactive lipids. Importantly, we generated an ASC-restricted NR2F2 null mouse that is essential for testing NR2F2 as a critical developmental driver of beige adipogenesis. ASC-NR2F2 null pups will be compared to wildtype littermates using metabolic phenotyping, histological and molecular marker analyses, and in vitro ASC differentiation potential and cellular metabolism assays. Altogether, R56 funding will allow preservation, propagation, and utilization of mouse lines needed to generate key data that strengthens the parent R01 application. Collectively, our project has the potential to uncover novel NR2F2-driven mechanisms that can promote beige adipogenesis and metabolic activity to mitigate childhood obesity risk.