干擾素是脊椎動(dòng)物抗病毒免疫系統(tǒng)的關(guān)鍵因子,。干擾素家族包括I型,、II型和III型干擾素,。在爬行類,，鳥類和哺乳類中,，I型和III型干擾素的結(jié)構(gòu)和功能極為相似，但它們需要與不同受體的結(jié)合,，且在基因結(jié)構(gòu)上具有明顯的差異,。
I型干擾素基因不含內(nèi)含子，III型干擾素基因則具有4個(gè)內(nèi)含子,。近年來在低等脊椎動(dòng)物魚類中發(fā)現(xiàn)的干擾素基因具有與III型干擾素相同的基因結(jié)構(gòu),，但是氨基酸序列和功能方面則類似于I型干擾素。魚類的干擾素基因是屬于I型還是III型干擾素,，以及I型和III型干擾素基因在脊椎動(dòng)物中的分化是在該領(lǐng)域研究中的受到關(guān)注的問題之一,。
在中國(guó)科學(xué)院水生生物研究所聶品研究員和蘇格蘭魚類免疫研究中心鄒鈞博士的聯(lián)合指導(dǎo)下，齊志濤博士通過對(duì)脊椎動(dòng)物基因組進(jìn)行分析,，結(jié)合基因功能研究,，發(fā)現(xiàn)兩棲動(dòng)物蟾蜍中同時(shí)具有功能性的含有內(nèi)含子的I型和III型干擾素基因，證實(shí)它們?cè)谀孓D(zhuǎn)座進(jìn)化事件以前就已經(jīng)分化,，提出了“逆轉(zhuǎn)座事件發(fā)生在脊椎動(dòng)物由水生轉(zhuǎn)向陸生環(huán)境的過渡時(shí)期,，這一事件造成爬行類、鳥類和哺乳類中I型干擾素基因內(nèi)含子的丟失”的學(xué)術(shù)觀點(diǎn),。
這一研究成果為全面揭示干擾素系統(tǒng)的演化提供了關(guān)鍵的信息,，相關(guān)研究結(jié)果發(fā)表在The Journal of Immunology 。 (生物谷Bioon.com)
生物谷推薦原文出處：
The Journal of Immunology doi:10.4049/jimmunol.0903374
Intron-Containing Type I and Type III IFN Coexist in Amphibians: Refuting the Concept That a Retroposition Event Gave Rise to Type I IFNs
Zhitao Qi,*, Pin Nie,* Chris J. Secombes, and Jun Zou
*State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei; Chemical and Biological Engineering College, Yancheng Institute of Technology, Jiangsu, China; and Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom
Type I and III IFNs are structurally related cytokines with similar antiviral functions. They have different genomic organizations and bind to distinct receptor complexes. It has been vigorously debated whether the recently identified intron containing IFN genes in fish and amphibians belong to the type I or III IFN family or diverged from a common ancestral gene, that subsequently gave rise to both types. In this report, we have identified intron containing type III IFN genes that are tandemly linked in the Xenopus tropicalis genome and hence demonstrate for the first time that intron containing type I and III genes diverged relatively early in vertebrate evolution, and at least by the appearance of early tetrapods, a transition period when vertebrates migrated from an aquatic environment to land. Our data also suggest that the intronless type I IFN genes seen in reptiles, birds, and mammals have originated from a type I IFN transcript via a retroposition event that led to the disappearance of intron-containing type I IFN genes in modern vertebrates. In vivo and in vitro studies in this paper show that the Xenopus type III IFNs and their cognate receptor are ubiquitously expressed in tissues and primary splenocytes and can be upregulated by stimulation with synthetic double-stranded RNA, suggesting they are involved in antiviral defense in amphibians.
