7004 Systems genetics analysis to identify candidate genes for fat distribution in BXD mice

Abstract Disclosure: N. Kim: None. D. Ryu: None. C. Oh: None. Obesity is defined as the accumulation of excess fat in the body. Although obesity is the main cause of metabolic disorders, not all obese people have metabolic disorders. Among many factors identified, the ratio of visceral (vWAT) to subcutaneous white adipose tissue (sWAT), representing body fat distribution, has been elucidated to be closely associated with metabolic health. Body fat distribution has been proposed as a possible explanation for this discrepancy. To investigate the regulation of body fat distribution, we performed a genetic analysis using the phenotype data and male subcutaneous fat microarray data from the BXD mouse genetic reference population. Our analysis identified H2-Ke6 (Hsd17b8), encoding hydroxysteroid 17-beta dehydrogenase, as a candidate target for adipose tissue plasticity. To further explore its role, we employed multiple approaches to reveal the effect of Hsd17b8 inhibition. First, lipid accumulation was attenuated in 3T3-L1 preadipocytes where Hsd17b8 was inhibited by CRISPER/Cas9 as well as lasalocid. Furthermore, we confirmed that the expression of adipogenesis-related transcription factor as well as mature adipocyte marker was decreased in terminally differentiated 3T3-L1. Specifically, CCAAT/enchancer binding protein α (Cebpa), peroxisome proliferator-activated receptor γ (Pparg), adiponectin (Adipoq), and fatty acid binding protein 4 (Fabp4) were transcriptionally downregulated. Consistently, in C. elegans, we used RNA interference (RNAi) to inhibit the expression of the Hsd17b8 ortholog, dhs-25, and observed a reduction in lipid accumulation. All these data suggest that the reduction in lipid accumulation in differentiated 3T3-L1 cells by the inhibition of Hsd17b8 is attributed to the suppression of early differentiation during the adipogenesis process. On top of that, to determine whether Hsd17b8 indeed influences body fat distribution in vitro, we utilized IngWAT Mouse Immortalized Preadipocyte Cell Line derived from subcutaneous white adipose tissue (sWAT) of a wild-type mouse. In contrast to the previous findings, we observed an increase in lipid accumulation of IngWAT when Hsd17b8 was inhibited. Surprisingly, the elevation of lipid accumulation in sWAT, as seen in gynoid obesity, has been revealed to be indicative of robust metabolic health compared to android obesity. Collectively, these data suggest that Hsd17b8 may represent a novel therapeutic target for the treatment of obesity. Our study provides valuable insights into the mechanisms underlying metabolic health in obesity and highlights the potential of Hsd17b8 as a therapeutic target for modulating adipose tissue plasticity. Presentation: 6/3/2024