Effects of fermented soybean extracts on differentiation of 3T3-L1 preadipocytes and glucose utilization : 3T3-L1지방세포 모델에서 발효 대두 추출물이 지방세포 분화와 당 이용능력에 미치는 영향 연구

다국어 초록 (Multilingual Abstract)

Obesity is a serious public health problem worldwide for continuously increasing the morbidity and mortality of a variety of acute and chronic diseases. This study aimed to examine the antiobesity effect of soybean extracts fermented by Bacillus subtilis MORI and to elucidate the mechanisms underlying such effects using 3T3-L1 preadipocytes. The 3T3-L1 preadipocytes were induced to differentiate in the presence of fermented soybean extracts for 7 days and the cells were treated with either DW (Distilled water) or fermented soybean extracts at various concentrations (0-100 g/ml) during adipogenesis. Oil red O staining, triglyceride (TG) contents, glycerol release and glucose uptake level were measured on differentiated adipocytes. Levels of adipogenesis-related protein expression were evaluated using immunoblotting. Lipid accumulations as measured by Oil Red O staining were significantly inhibited by fermented soybean extracts treatment in a dose dependent manner. In addition, intracellular TG contents and glycerol release level were dramatically decreased by fermented soybean extracts treatment, which were accompanied by the decreased expression of CCAAT element binding protein α (C/EBPα) protein expression and the increased phosphorylation of acetyl-CoA carboxylase (ACC) protein expression. Also, fermented soybean extracts treatment increased the expression of glucose transporter 4 (GLUT4) along with a significant increase in glucose uptake into the adipocytes based on results of a 2-deoxy-D-[3H] glucose uptake assay. Several studies showed that C/EBPα and peroxisome proliferator-activated receptor γ (PPARγ) are known as a cross-regulator on adipogenesis, which partly differs with our results showing that fermented soybean extracts act as an agonistic ligand of PPARγ, thereby PPARγ contributing to glucose uptake through improving insulin sensitivity. Our findings suggest that fermented soybean extracts may suppress the differentiation of 3T3-L1 adipocytes and greatly facilitated glucose uptake into the adipocytes. Based on these results, fermented soybean extracts may have potential to develop therapeutic agent for the prevention or treatment of obesity and related metabolic disorders.

목차 (Table of Contents)

• CONTENTS
• Page
• ABSTRACT................................................................................ i
• CONTENTS ............................................................................. iii
• LIST OF FIGURES...................................................................... vi
• LIST OF ABBREVIATIONS.......................................................... iii
• I. INTRODUCTION
• 1.1. Preface............................................................................ 1
• 1.2. Bacillus subtilis MORI-fermented soybean extracts....................... 4
• 1.3. Adipogenesis..................................................................... 6
• 1.4. Glucose uptake in adipocytes.................................................. 8
• 1.5. Endocrine function in adipocytes.............................................. 9
• II. MATERIALS AND METHODS
• 2.1. Chemicals........................................................................ 11
• 2.2. Preparation of fermented soybean extracts.................................. 11
• 2.3. Cell culture and adipocyte differentiation................................... 12
• 2.4. MTT assay....................................................................... 13
• 2.5. Oil red O staining............................................................... 14
• 2.6. Quantification of TG contents................................................ 14
• 2.7. Glycerol release assay..........................................................15
• 2.8. Immunoblot assay...............................................................15
• 2.9. Glucose uptake assay...........................................................16
• 2.10. Statistical analysis.............................................................16
• III. RESULTS
• 3.1. Effect of fermented soybean extracts on inhibition of lipid accumulation
• in 3T3-L1 cells.................................................................. 17
• 3.2. Effect of fermented soybean extracts on adipogenic transcriptional factor
• protein expression in 3T3-L1 cells............................................ 21
• 3.3. Effect of fermented soybean extracts on AMPK signaling in 3T3-L1 cells
• .................................................................................... 23
• 3.4. Effect of fermented soybean extracts on glucose uptake and GLUT4 protein expression in 3T3-L1 cells............................................ 25
• IV. DISCUSSIONS...................................................................... 27
• V. REFERENCES....................................................................... 33
• ABSTRACT IN KOREAN ........................................................... 42