Endothelin-1 inhibits PPAR gamma expression and slows pre-adipocyte differentiation into mature adipocytes

Endothelin-1(ET-1) is increased in obesity and plays a significant role in the development of multiple obesity related conditions including insulin resistance; however, the mechanisms are poorly understood. Our lab recently reported that targeted deletion of the ET B receptor, specifically in adipocytes, improved insulin sensitivity and mitigated dyslipidemia in obese mice fed a high-fat diet for 10 weeks. These improvements were associated with increased adiponectin levels and enhanced expression of peroxisome proliferator-activated receptor gamma (PPARg), suggesting that ET-1 inhibits PPARg via ET B receptors. Given that PPARg is essential to adipocyte differentiation and adipogenesis, we hypothesized that ET-1 inhibits adipogenesis by blocking differentiation of preadipocytes into mature adipocytes. To test this hypothesis, primary preadipocytes were isolated from visceral adipose of 4-week old floxed control and adipocyte specific ET B receptor knockout (adET B KO) mice. Preadipocytes were cultured and differentiated by exposure to a well-described cocktail of adipogenic hormones. After exposure to differentiation cocktail for two days, cells were allowed to mature to full adipocytes, then treated with vehicle or ET-1 (100nM) for 24 hours. Consistent with published data, treatment of mature adipocytes with ET-1 reduced PPARg mRNA levels (408±83.23 vs. 241.3± 53.53 copies/50 ng RNA) in matured preadipocytes from floxed control mice. Interestingly, baseline mRNA expression of PPARg and adiponectin levels in differentiated preadipocytes from adETBKO mice, were significantly higher 3-fold and 6-fold respectively [ (1584 ± 110.2 vs 408 ± 83.23 copies/50 ng RNA), (7.56 ± 1.021 vs1.35 ± 0.16 copies/50 ng RNA), suggesting greater differentiation efficiency, and treatment with ET-1 had no significant effect on PPARg or adiponectin. Quantification of oil red O staining demonstrated a significant increase in lipid laden adipocytes in adET B KO cells with lipid accumulation present in approximately 2.3-fold more cells compared to controls suggestive of enhanced adipogenic differentiation. Our results suggest that ET-1 inhibits differentiation of visceral preadipocytes into mature lipid storing adipocytes and are consistent with previous findings that ET-1/ETB activation reduces adiponectin by inhibiting PPARg. R01DK124327 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.