Sorghum (Sorghum bicolor) Extract-Induced Adipogenesis Is Independent of PPARγ Ser273 Phosphorylation in 3T3-L1 Adipocytes

Previously we showed that the water-soluble fraction of sorghum extract (SE) improves adipogenesis in 3-isobutyl-1-methylxanthine (IBMX)/dexamethasone/insulin (MDI)/thiazolidinedione (TZD)-induced 3T3-L1 preadipocytes but downregulates genes related to peroxisome proliferator-activated receptor gamma (PPAR gamma) and adipogenesis in both MDI-and MDI/TZD-induced 3T3-L1 adipocytes. In this study, we showed that SE treatment altered the accumulation of stained lipids in 3T3-L1 adipocytes induced by MDI/troglitazone (Tro). Immunoblot analyses indicated that SE treatment reduced adipocyte protein 2 (aP2) expression and induced peroxisome proliferator-activated receptor alpha (PPAR alpha) protein expression in the presence of Tro in 3T3-L1 adipocytes. MDI/Tro treatment, but not MDI treatment, of 3T3-L1 cells induced PPAR gamma phosphorylation at Ser273. SE downregulated PPAR gamma expression in MDI-induced 3T3-L1 adipocytes and did not affect its phosphorylation at Ser273 in MDI-and MDI/Tro-induced 3T3-L1 adipocytes. Therefore, SE likely promotes adipogenesis and lipid metabolism in 3T3-L1 preadipocytes by cooperating with Tro independent of PPAR gamma Ser273 phosphorylation.

Automated summary

This study found that the water-soluble fraction of sorghum extract promotes adipogenesis and lipid metabolism in 3T3-L1 adipocytes. It also alters protein expression to affect cellular functions.