【摘要】： 內(nèi)質(zhì)網(wǎng)是真核細胞一種重要的細胞器,是細胞內(nèi)蛋白質(zhì)合成,修飾,折疊的場所。由于各種原因引起的內(nèi)質(zhì)網(wǎng)平衡的紊亂,稱為內(nèi)質(zhì)網(wǎng)應(yīng)激。內(nèi)質(zhì)網(wǎng)應(yīng)激會引起從內(nèi)質(zhì)網(wǎng)到細胞質(zhì)和細胞核的信號傳導(dǎo),最終幫助細胞恢復(fù)穩(wěn)態(tài)并得以存活。然而,嚴重的內(nèi)質(zhì)網(wǎng)應(yīng)激可導(dǎo)致細胞發(fā)生自噬和凋亡。對于調(diào)控這一過程的精確機制目前知之甚少。本研究表明,內(nèi)質(zhì)網(wǎng)應(yīng)激通過抑制mTOR通路引起細胞自噬,進而誘導(dǎo)細胞死亡。 本實驗中,三種廣泛使用的內(nèi)質(zhì)網(wǎng)應(yīng)激的誘導(dǎo)劑,包括衣霉素,DTT和MG132均引起了LC3-Ⅰ向LC3-Ⅱ的轉(zhuǎn)化。該轉(zhuǎn)化是細胞出現(xiàn)自噬的重要指標。同時,三種藥物也導(dǎo)致mTOR的活性大幅度下降。而抑制自噬可以顯著提高細胞在內(nèi)質(zhì)網(wǎng)應(yīng)激下的存活率。已知TSC缺失的細胞中mTOR被組成型激活。而本實驗表明,在內(nèi)質(zhì)網(wǎng)應(yīng)激中,TSC缺失細胞的自噬水平顯著低于其對照組細胞。由此可見,內(nèi)質(zhì)網(wǎng)應(yīng)激導(dǎo)致的mTOR活性降低,是由于其對AKT/TSC/mTOR信號通路的下調(diào)所致。作為該通路中的兩個重要調(diào)節(jié)蛋白,PTEN及AMPK并未參與該調(diào)控。4-PBA作為一種幫助蛋白質(zhì)正確折疊的化學(xué)伴侶分子,部分恢復(fù)了由內(nèi)質(zhì)網(wǎng)應(yīng)激下調(diào)的AKT/TSC/mTOR通路。 另外,根據(jù)相關(guān)文獻報道,組成型激活的mTOR可導(dǎo)致內(nèi)質(zhì)網(wǎng)應(yīng)激。本實驗結(jié)果表明,由組成型激活的mTOR所導(dǎo)致的內(nèi)質(zhì)網(wǎng)應(yīng)激,減弱了RTK/PI3K/AKT通路對多種生長因子的反應(yīng)。同時,4-PBA可以恢復(fù)該反應(yīng)。據(jù)此,本實驗提出一種新的機制用以解釋內(nèi)質(zhì)網(wǎng)應(yīng)激引起的自噬,以及由mTOR到AKT的負反饋作用。
[Abstract]:Endoplasmic reticulum (ER) is an important organelle of eukaryotic cells. It is a place for protein synthesis, modification and folding. The disorder of endoplasmic reticulum balance caused by various reasons is called endoplasmic reticulum stress. Endoplasmic reticulum stress induces signal transduction from endoplasmic reticulum to cytoplasm and nucleus, which ultimately helps the cell to recover homeostasis and survive. However, severe endoplasmic reticulum stress can lead to autophagy and apoptosis. Little is known about the precise mechanism for regulating this process. This study suggests that endoplasmic reticulum stress induces autophagy and cell death by inhibiting mTOR pathway. In this study, three widely used endoplasmic reticulum (ER) stress inducers, including chlortetracycline DTT and MG132, caused the transformation of LC3- 鈪，

本文編號：2252910