| 摘要: | 中文摘要
自噬作用是細胞中蛋白質聚集體、多餘脂肪和受損線粒體的回收過程。它可以保護細胞免受壓力條件（如飢餓和氧化應激）的影響，並且通過營養物質進行調節。EGCG是綠茶兒茶素的主要成分之一，已知其可作為肥胖和癌細胞自噬的調節劑，但關於EGCG 對脂肪細胞自噬的影響知之甚少。從我們的研究中，發現 EGCG 在所有血清條件（0%、2% 和 10% FBS）中處理 12、24、36 和 48 小時後會抑制 HIB1B 棕色前脂肪細胞的細胞生長，並且發現與正常血清條件（10% FBS）下相比，較長的治療時間和較低的血清條件（0% 和 2% FBS）中抑制細胞數量甚至更多。處理 12 小時後，我們觀察到 EGCG 在無血清和低血清條件（0% 和 2% FBS）下抑制自噬的啟動以及自噬體的降解，但在正常血清條件下（10% FBS）則不同。特別是，EGCG 在0% FBS 中調節了 Atg3、Atg5、Atg7、Atg13、Atg16L1、LC3B-II/LC3B-I、pp62/p62、pAMPK、AMPK、pAKT 和AKT蛋白的水平。而在 2% FBS 中調節了 Atg7、Atg16L1、LC3B-II/LC3B-I、pp62/p62、pAMPK、pAKT 和AKT 的水平。在 10% FBS 中，發現 EGCG 會調節 Atg3、Atg7、LC3B-II/LC3B-I 和 pp62/p62。基於斑點形成測定，觀察到 EGCG 在 0% FBS 中降低自噬形成能力，導致細胞在早期自噬抑制，但在 2% 和 10% FBS 中則不同。綜上所述，發現EGCG在無血清的條件下通過AMPK和自噬體降解（自噬的後期）抑制自噬的起始（自噬的早期）。此外血清的增加似乎降低了EGCG對自噬的影響。最後，這些發現表明EGCG對HIB1B棕色前脂肪細胞自噬過程的影響取決於血清的比例。
;Abstract
Autophagy is a recycling process for protein aggregates, excess fat, and damaged mitochondria in cells. It protects the cells from stressful conditions (such as starvation and oxidative stress) and can be regulated by nutrients. EGCG, the major component of green tea catechins, has been known to act as a regulator of autophagy of cancer cells. But little information is known about the effect of EGCG on autophagy of fat cells. From our study, EGCG was found to suppress the cell growth in HIB1B brown preadipocytes after 12, 24, 36, and 48 hours of treatment in 0%, 2%, and 10% FBS, and was found to be dependent on the duration of treatment, the dose of EGCG, and the proportion of serum. Upon 12 hours of treatment, EGCG was observed to inhibit the initiation of autophagy as well as the degradation of autophagosomes in no to less serum conditions (0% and 2% FBS), but not in normal serum condition (10% FBS). In particular, EGCG altered the level of Atg3, Atg5, Atg7, Atg13, Atg16L1, LC3B-II/LC3B-I, pp62/p62, pAMPK, AMPK, pAKT, and AKT proteins in 0% FBS. And it altered the level of Atg7, Atg16L1, LC3B-II/LC3B-I, pp62/p62, pAMPK, pAKT, and AKT in 2% FBS. In 10% FBS, EGCG was found to alter Atg3, Atg7, LC3B-II/LC3B-I, and pp62/p62. Based on the puncta formation assay, EGCG was observed to decrease autophagy flux in 0% FBS, causing the cell to undergo an early phase autophagy suppression, but not in 2% and 10% FBS. Taken together, EGCG was found to inhibit the autophagy initiation (early phase of autophagy) through AMPK and autophagosome degradation (late phase of autophagy) in no serum condition (0% FBS). The increase presence of the serum seemed to decrease the effect of EGCG on autophagy. These findings suggest that the effect of EGCG on the autophagy process of HIB1B brown preadipocytes is dependent on the proportion of serum.
Keywords: Autophagy, EGCG, brown preadipocytes |
