Recent studies have shown that heterogeneity among adipocytes exists even within a single white adipose tissue depot. Previous studies from our laboratory have identified three functionally distinct subpopulations of adipocytes with different gene expression and metabolic properties. These adipocyte subpopulations differentially contribute to the individual white adipose tissue depots and can be distinguished by their specific expression of three marker genes: Wilms Tumor 1 (Wt1), Transgelin (Tagln), and Myxovirus 1 (Mx1). In this study, we extend these observations by determining the contributions of these adipocyte subpopulations to other adipose tissue depots including the interscapular brown, dermal, and bone marrow adipose tissue depots. Lineage tracing analysis of Wt1-cre and Tagln-cre crossed to a dual-fluorescent reporter mice which mark type 1 and type 2 preadipocytes and adipocytes, respectively, was performed in two to four month old mice and preadipocytes and adipocytes were quantified by FACS analysis and confocal microscopy. In all depots analyzed in this study, little to no type 1 preadipocytes or adipocytes were present in any of these depots. On the other hand, a significant number of type 2 preadipocytes and adipocytes were found in all depots. In dermal tissue, type 2 adipocytes comprised 9±2% of adipocytes and 45±7% of preadipocytes. Type 2 adipocytes significantly contributed to the bone marrow adipose tissue as 51±4% of adipocytes present and 83±3% of preadipocytes were type 2 cells. Lastly, in brown adipose tissue, type 2 cells comprised 15±1% of adipocytes and 10±3% of preadipocytes. Further studies investigating the metabolism and thermogenic properties of these type 2 brown adipocytes is currently being performed, as a more thorough understanding these adipocyte subpopulations may lead to novel, targeted treatments for obesity and diabetes.
N.D. Powell: None. R. Sharma: None. J. Huang: None. K.Y. Lee: None.