|LU, HSIN-YI - Mississippi State University|
|ZHANG, LI - Mississippi State University|
|PORRES, JESUS - University De Granada|
|CHENG, WEN-HSING - Mississippi State University|
Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2018
Publication Date: 8/1/2018
Citation: Lu, H., Zeng, H., Zhang, L., Porres, J.M., Cheng, W. 2018. Fecal fermentation products of common bean-derived fiber inhibit C/EBP alpha and PPAR gamma expression and lipid accumulation but stimulate PPAR delta and UCP2 expression in the adipogenesis of 3T3-L1 cells. Journal of Nutritional Biochemistry. 60:9-15. https://doi.org/10.1016/j.jnutbio.2018.06.004.
Interpretive Summary: Dietary fiber intake decreases the risk for type 2 diabetes mellitus, obesity, cardiovascular disease, colon cancer, and improves immunity by modulating the gut bacterial composition. Beans are among the best choices for fiber-rich foods. Clinical and animal studies have suggested efficacy of common bean (Phaseolus vulgaris) consumption for preventing obesity. The fermentation of bean-derived dietary fiber by gut bacteria is proposed to modulate obesity; however, the molecular mechanism remains to be determined. In this study, we established a fecal fermentation model to study the biological activity of bean fiber-derived fermentation products. We demonstrate that bean fiber-fermentation products inhibited lipid accumulation and fat cell/tissue formation at the cellular level. Moreover, bean fiber-fermentation products inhibited key fat accumulation genes while activating energy expenditure genes. The information will be useful for scientists and health-care professionals who are interested in the benefits of bean consumption, dietary fiber intake and obesity prevention.
Technical Abstract: Background: Clinical and animal studies have suggested efficacies of common bean (Phaseolus vulgaris) consumption on weight loss. Fermentation of common bean-derived dietary fiber by gut microbiota is proposed to modulate obesity; however, the mechanism by which the adipogenesis is inhibited is unclear. Objective: This study was conducted to investigate whether and how fecal fermentation of dietary fiber from non-digestible common bean impacts adipogenesis in a cell model. Method: Dietary fiber was generated by in vitro digestion of cooked, lyophilized common bean flour, followed by anaerobic fermentation with the use of fresh feces from healthy mice without antibiotics treatment. The murine 3T3-L1 preadipocytes were induced to differentiate and treated with the fermentation products, followed by assessment of cell viability, lipid accumulation, and protein and mRNA levels of key transcriptional factors and activators during the 8-day time course. Data were analyzed by 2-factor (bean x time) or 1-factor ANOVA. Results: Treatment of the fecal fermentation products inhibited adipocyte differentiation and lipid accumulation in a dose- and time-dependent manner. The fermentation products downregulated (P < 0.05) protein levels of two key transcription factors for adipogenesis, CCAAT/enhancer binding protein a and peroxisome proliferator-activated receptor gamma by 79-92% and 78-90 %, respectively, and their downstream target fatty acid binding protein 4 by 49-86% and 63-98% at protein and mRNA levels, respectively, during the time course. In contrast, the fermentation products upregulated (P < 0.05) levels of two proteins promoting energy expenditure, peroxisome proliferator-activated receptor delta (41-58%) at days 2-4 and mitochondrial uncoupling protein 2 (1.1-1.2 fold), at days 4-8. Conclusion: Fecal fermentation of dietary fiber derived from in vitro digestion of common bean temporally inhibits adipogenesis and key adipogenic transactivators but activates two energy expenditure genes in 3T3-L1 cells.