生物谷報(bào)道：耶魯大學(xué)的研究人員鑒定出一個(gè)重要的調(diào)節(jié)植物中的重要免疫反應(yīng)——程序性細(xì)胞死亡（ＰＣＤ,，凋亡apoptosis）的基因BECLIN-1,，研究結(jié)果發(fā)布在5月20日出版的Cell雜志上（去年5月份生物谷也報(bào)道了一篇類似的文章，也是研究BECLIN-1基因與凋亡的關(guān)系,，見(jiàn)附錄《任小二快報(bào)》：Caspase, 踏住死亡天平的兩端）,。
為了避免病毒的感染，植物會(huì)在感染位點(diǎn)形成一個(gè)死細(xì)胞區(qū)域,，這種地帶能夠阻止感染的擴(kuò)散,。耶魯大學(xué)的Savithramma Dinesh-Kumar和同事發(fā)現(xiàn)了植物在它們出現(xiàn)細(xì)胞自殺過(guò)程——凋亡后避免殺死自己的機(jī)制。
Dinesh-Kumar首先發(fā)明了一種沉默或失活植物基因的技術(shù),，目前這種技術(shù)已經(jīng)被其他幾個(gè)研究團(tuán)體所采用,。利用煙草作為模型系統(tǒng)，他的研究組研究了植物和病毒之間的反應(yīng),。
他們確定并沉默了一種叫做BECLIN-1的“pro-survival”基因,，這種基因在程序性細(xì)胞死亡過(guò)程（PCD）中非常重要。當(dāng)BECLIN-1活躍時(shí),，感染只限于小數(shù)量的細(xì)胞,，而且這些細(xì)胞之后會(huì)死亡并在葉子上形成離散的棕色傷口；當(dāng)這個(gè)基因被失活時(shí),，植物就不能再調(diào)節(jié)程序性細(xì)胞死亡過(guò)程,，從而導(dǎo)致整個(gè)葉子和植物的死亡。
程序性細(xì)胞死亡發(fā)生在植物和動(dòng)物的所有細(xì)胞類型中,，它是許多生物過(guò)程如免疫系統(tǒng)功能,、胚胎發(fā)育和缺陷性細(xì)胞清除過(guò)程的一個(gè)重要的方面。PCD的障礙能夠?qū)е聡?yán)重疾病如癌癥,、阿爾茨海默癥和艾滋病的發(fā)生,。
這項(xiàng)研究進(jìn)一步了解了植物通過(guò)精細(xì)控制感染細(xì)胞的破壞來(lái)抵御微生物攻擊的機(jī)制。這些新發(fā)現(xiàn)揭示出了一個(gè)與動(dòng)物中類似的過(guò)程,，并可能最終促進(jìn)人們更好地了解人類健康,。
生物谷評(píng)論認(rèn)為：細(xì)胞凋亡區(qū)別細(xì)胞壞死的最主要特點(diǎn)在于，細(xì)胞凋亡是主動(dòng)過(guò)程,。因此人們一直認(rèn)為細(xì)胞凋亡可能具有重要的生理和病理意義,。新近觀點(diǎn)認(rèn)為,，細(xì)胞凋亡，染色質(zhì)和胞質(zhì)濃縮,，這樣可以避免細(xì)胞內(nèi)容物釋放出來(lái),，因?yàn)榧?xì)胞內(nèi)容物內(nèi)有大量酶類，同時(shí)還含有大量能引起免疫反應(yīng)的物質(zhì),，因此細(xì)胞一旦出現(xiàn)凋亡,，這些物質(zhì)將被包裹在細(xì)胞內(nèi)而逐漸濃縮最終被吞噬，相反如果是壞死,，則細(xì)胞內(nèi)容物會(huì)漏出,，從而引發(fā)免疫炎性反應(yīng)。因此人們一直認(rèn)為細(xì)胞凋亡在某種程度上是機(jī)體對(duì)外界刺激的主動(dòng)反應(yīng)的結(jié)果,?？赡軐?duì)機(jī)體是一種保護(hù)性，有益的反應(yīng),，而并非傳統(tǒng)想法,，凋亡是有害的過(guò)程。而且在發(fā)育過(guò)程中,，常常伴隨凋亡的存在,，這些細(xì)胞凋亡現(xiàn)象可能具有兩方面的作用，一是優(yōu)化和篩選,，將一些“功能不佳”的細(xì)胞凋亡掉,，從而有利于其它細(xì)胞更好地生長(zhǎng)；二是細(xì)胞凋亡有利于發(fā)育過(guò)程中器官和組織的分化,，如蝌蚪的尾巴在發(fā)育過(guò)程中,，細(xì)胞漸漸凋亡而使尾巴消失。這些新近的觀點(diǎn)促使人們意識(shí)到,，面向凋亡時(shí)應(yīng)該如何處理,？是否是采取什么手段干預(yù)凋亡或減輕凋亡還是想法設(shè)法阻止凋亡的發(fā)生？這還需要更深入的研究和追蹤,，用科學(xué)的證據(jù)來(lái)回答,。
Researchers at Yale have identified a gene that regulates the major immune response in plants, programmed cell death (PCD), according to a recent report in the journal Cell.
To protect themselves from viruses, plants create a zone of dead cells around an infection site that prevents the infection from spreading. Savithramma Dinesh-Kumar, associate professor of Molecular, Cellular and Developmental Biology at Yale and his colleagues discovered how the plants keep from killing themselves after they turn on the cell-suicide PCD process.
Dinesh-Kumar first developed a technique for silencing or inactivating plant genes -- a technique that is now used by several research groups. His group studies the interaction between plants and viruses using tobacco as a model system.
They identified and silenced a "pro-survival" gene, BECLIN-1, that is important in the PCD response. When BECLIN-1 is active, infection is localized to a small number of cells that later die and form discrete brown lesions on the leaves. When the gene is inactivated, the plant can no longer regulate PCD, leading to cell death throughout the leaf and plant.
PCD has been described in virtually all cell types, both plant and animal. It is an important aspect of many biological processes including immune system function, embryonic development and elimination of defective cells. Failure of PCD can result in devastating diseases such as cancer, Alzheimer's and AIDS.
"This work gives us a better understanding of how plants fend off microbial attacks through carefully controlled destruction of infected cells," said James Anderson, of the Division of Genetics and Developmental Biology at the National Institute of General Medical Sciences (NIGMS). "Like other studies carried out in model organisms, these findings shed light on similar processes that occur in mammals, and may eventually be used to better human health."
生物谷內(nèi)凋亡相關(guān)文章共222篇，現(xiàn)精選如下：
《任小二快報(bào)》：Caspase, 踏住死亡天平的兩端
蛋白酶抑制劑抑制HIV感染細(xì)胞的凋亡
雌激素受體拮抗劑他莫西芬誘導(dǎo)細(xì)胞凋亡的機(jī)理圖
線粒體的細(xì)胞凋亡通路模式圖
哈爾濱醫(yī)科大學(xué)研究發(fā)現(xiàn)青蒿素有促進(jìn)白血病細(xì)胞凋亡作用
日本學(xué)者發(fā)現(xiàn)稱活性氧可誘導(dǎo)細(xì)胞凋亡
乳腺癌發(fā)生與凋亡相關(guān)基因有關(guān)
生物谷精華第四期：細(xì)胞凋亡研究進(jìn)展
細(xì)胞凋亡調(diào)節(jié)的分子機(jī)制與抗癌先導(dǎo)物的篩選
抗凋亡策略在細(xì)胞大規(guī)模培養(yǎng)中的應(yīng)用
一種抗凋亡蛋白——存活素的研究
研究細(xì)胞凋亡的幾種光鏡形態(tài)學(xué)檢測(cè)方法比較
細(xì)胞抗凋亡作用及其信號(hào)轉(zhuǎn)導(dǎo)途徑
NF-κB信號(hào)轉(zhuǎn)導(dǎo)途徑與腫瘤抗凋亡關(guān)系的研究進(jìn)展
吞噬凋亡細(xì)胞的機(jī)制
新的凋亡抑制因子Livin
Bcl-2家族蛋白與線粒體凋亡路徑研究進(jìn)展
更多的凋亡相關(guān)文章
原始出處：
Liu Y, Schiff M, Czymmek K, Talloczy Z, Levine B, Dinesh-Kumar SP. Autophagy regulates programmed cell death during the plant innate immune response.
Cell. 2005 May 20;121(4):567-77. 全文下載
