Bécsi Bálint, Kónya Zoltán, Boratkó Anita, Kovács Katalin, Erdődi Ferenc
Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
Cells. 2022 May 20;11(10):1704. doi: 10.3390/cells11101704.
Epigallocatechin-3-gallate (EGCG) has widespread effects on adipocyte development. However, the molecular mechanisms of EGCG are not fully understood. We investigate the adipogenic differentiation of human-derived mesenchymal stem cells, including lipid deposition and changes in the expression and phosphorylation of key transcription factors, myosin, protein phosphatase-2A (PP2A), and myosin phosphatase (MP). On day 6 of adipogenic differentiation, EGCG (1-20 µM) suppressed lipid droplet formation, which was counteracted by an EGCG-binding peptide for the 67 kDa laminin receptor (67LR), suggesting that EGCG acts via 67LR. EGCG decreased the phosphorylation of CCAAT-enhancer-binding protein beta via the activation of PP2A in a protein kinase A (PKA)-dependent manner, leading to the partial suppression of peroxisome proliferator-activated receptor gamma (PPARγ) and adiponectin expression. Differentiated cells exhibited a rounded shape, cortical actin filaments, and lipid accumulation. The EGCG treatment induced cell elongation, stress fiber formation, and less lipid accumulation. These effects were accompanied by the degradation of the MP target subunit-1 and increased the phosphorylation of the 20 kDa myosin light chain. Our results suggest that EGCG acts as an agonist of 67LR to inhibit adipogenesis via the activation of PP2A and suppression of MP. These events are coupled with the decreased phosphorylation and expression levels of adipogenic transcription factors and changes in cell shape, culminating in curtailed adipogenesis.
表没食子儿茶素-3-没食子酸酯（EGCG）对脂肪细胞发育具有广泛影响。然而，EGCG的分子机制尚未完全明确。我们研究了人源间充质干细胞的脂肪生成分化，包括脂质沉积以及关键转录因子、肌球蛋白、蛋白磷酸酶-2A（PP2A）和肌球蛋白磷酸酶（MP）的表达及磷酸化变化。在脂肪生成分化的第6天，EGCG（1 - 20 μM）抑制了脂滴形成，而一种针对67 kDa层粘连蛋白受体（67LR）的EGCG结合肽可抵消这种抑制作用，这表明EGCG通过67LR发挥作用。EGCG以蛋白激酶A（PKA）依赖的方式通过激活PP2A降低CCAAT增强子结合蛋白β的磷酸化，导致过氧化物酶体增殖物激活受体γ（PPARγ）和脂联素表达受到部分抑制。分化细胞呈现圆形、皮质肌动蛋白丝和脂质积累。EGCG处理诱导细胞伸长、应力纤维形成且脂质积累减少。这些效应伴随着MP靶亚基-1的降解以及20 kDa肌球蛋白轻链磷酸化增加。我们的结果表明，EGCG作为67LR的激动剂，通过激活PP2A和抑制MP来抑制脂肪生成。这些事件与脂肪生成转录因子的磷酸化和表达水平降低以及细胞形状变化相关联，最终导致脂肪生成减少。
