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哈哈大姑爺至尊木蟲 (知名作家)
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[交流]
Genes & Development:細胞凋亡研究領(lǐng)域獲新進展 已有3人參與
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清華大學(xué)生命科學(xué)學(xué)院施一公教授實驗室在《Genes&Development》發(fā)表名為“Mechanistic insights into CED-4-mediated activation of CED-3”的學(xué)術(shù)論文。本文的第一作者黃渭蛟為生命學(xué)院的博士研究生。 細胞凋亡(程序性細胞死亡)與人的生長、發(fā)育、衰老以及死亡息息相關(guān)。臨床數(shù)據(jù)表明細胞凋亡的異常會導(dǎo)致嚴重病變,比如癌癥、老年癡呆癥等等。因此揭示細胞凋亡的分子機理不僅可以加深我們對這一基本生命過程的了解,還可以對 開發(fā)新型抗癌、預(yù)防老年癡呆的藥物提供重要線索。 研究細胞凋亡的一個重要模式生物是秀麗線蟲(Caenorhabditis elegans),MIT的Bob Horvitz教授領(lǐng)導(dǎo)的研究組因為通過遺傳學(xué)揭示egl-1、ced-9、ced-4和ced-3構(gòu)成的程序性細胞死亡的線性調(diào)控通路而獲得2002年的諾貝爾生理與醫(yī)學(xué)獎。 細胞凋亡從線蟲到人類都高度保守,當細胞接收到凋亡信號后,通過一系列精細調(diào)控和傳遞后,下游的凋亡執(zhí)行者caspase家族蛋白(CED-3是其中一員)被激活從而誘導(dǎo)凋亡的發(fā)生。施一公教授領(lǐng)導(dǎo)的實驗室十五年來一直致力于對細胞凋亡調(diào)控機理的研究。但是這條通路上caspase蛋白被激活的具體機制至今仍不清晰。2010年施一公實驗室解析了CED-4細胞凋亡小體八聚體的晶體結(jié)構(gòu),是對CED-4介導(dǎo)的CED-3激活機制研究的重要突破,但是CED-3與CED-4的相互作用界面及機制仍然有待揭示。 施一公實驗室最新論文通過解析CED-4凋亡小體與CED-3片段復(fù)合體的晶體結(jié)構(gòu),結(jié)合大量生物化學(xué)分析首次鑒定并證實了CED-4與CED-3相互作用的界面,發(fā)現(xiàn)CED-3通過L2’ loop上的一段疏水氨基酸與CED-4碗狀八聚體內(nèi)部的疏水空腔結(jié)合。這一實驗證據(jù)改變了該領(lǐng)域此前一直認為的Caspase與其激活蛋白僅僅通過各自N端CARD結(jié)構(gòu)域結(jié)合這一固有觀念。后續(xù)一系列生物化學(xué)研究證實CED-3-CED-4形成的穩(wěn)定復(fù)合體可以激活CED-3并提高其酶切活性,進而執(zhí)行下游凋亡活動。CED-3激活機制的研究為人類caspase家族蛋白激活機制提供了重要線索。 Genes & Development doi: 10.1101/gad.224428.113 英文摘要 Mechanistic insights into CED-4-mediated activation of CED-3 Weijiao Huang1,2, Tianyu Jiang1,2, Wooyoung Choi1,2, Shiqian Qi1,2, Yuxuan Pang1,2, Qi Hu1,2, Yanhui Xu3, Xinqi Gong1,2, Philip D. Jeffrey4, Jiawei Wang5 and Yigong Shi1,2,6 Programmed cell death in Caenorhabditis elegans requires activation of the caspase CED-3, which strictly depends on CED-4. CED-4 forms an octameric apoptosome, which binds the CED-3 zymogen and facilitates its autocatalytic maturation. Despite recent advances, major questions remain unanswered. Importantly, how CED-4 recognizes CED-3 and how such binding facilitates CED-3 activation remain completely unknown. Here we demonstrate that the L2′ loop of CED-3 directly binds CED-4 and plays a major role in the formation of an active CED-4–CED-3 holoenzyme. The crystal structure of the CED-4 apoptosome bound to the L2′ loop fragment of CED-3, determined at 3.2 ? resolution, reveals specific interactions between a stretch of five hydrophobic amino acids from CED-3 and a shallow surface pocket within the hutch of the funnel-shaped CED-4 apoptosome. Structure-guided biochemical analysis confirms the functional importance of the observed CED-4–CED-3 interface. Structural analysis together with published evidence strongly suggest a working model in which two molecules of CED-3 zymogen, through specific recognition, are forced into the hutch of the CED-4 apoptosome, consequently undergoing dimerization and autocatalytic maturation. The mechanism of CED-3 activation represents a major revision of the prevailing model for initiator caspase activation. [ Last edited by 哈哈大姑爺 on 2013-10-20 at 09:06 ] |

銅蟲 (小有名氣)

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新蟲 (初入文壇)
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