β-防御素是天然免疫系統(tǒng)中一類重要的抗菌肽,，其在生物體抵抗外界病原微生物感染過程中起著非常重要的作用,。最近,，中國科學(xué)院水生生物研究所桂建芳研究員主持的實驗室從石斑魚中克隆鑒定出一個同時在垂體和精巢中表達(dá)的β-防御素，這是首次發(fā)現(xiàn)防御素共同存在于脊椎動物的垂體和精巢中,。
研究發(fā)現(xiàn),，在石斑魚由雌向雄轉(zhuǎn)變的性逆轉(zhuǎn)進(jìn)程中，該β-防御素在性腺中的表達(dá)不斷上調(diào),；序列分析表明,，該β-防御素啟動子上有一個特異于垂體表達(dá)的POU1F1a結(jié)合位點和一個特異于精巢表達(dá)的SRY結(jié)合位點；體外和體內(nèi)抗菌實驗均表明,，該β-防御素具有抑制革蘭氏陰性菌生長的作用,，且該作用與鹽離子濃度相關(guān)；體外抗病毒實驗還揭示出其抗病毒作用,。
以上發(fā)現(xiàn)意味著魚類β-防御素可能在天然免疫和生殖內(nèi)分泌調(diào)控中起了重要作用,，從而打開了認(rèn)知β-防御素在生殖內(nèi)分泌調(diào)控中功能作用的大門。
該研究得到國家基礎(chǔ)研究973計劃和國家重點基金等項目的資助,，主要是由博士研究生金俊琰等完成,，研究論文12月20日在PLoS ONE在線發(fā)表。（生物谷Bioon.com）
生物谷推薦原文出處：
PLoS ONE doi:10.1371/journal.pone.0012883
Antibacterial and Antiviral Roles of a Fish β-Defensin Expressed Both in Pituitary and Testis
Jun-Yan Jin, Li Zhou, Yang Wang, Zhi Li, Jiu-Gang Zhao, Qi-Ya Zhang, Jian-Fang Gui*
State Key Laboratory of Freshwater Ecology and Biotechnology, Wuhan Center for Developmental Biology, Institute of Hydrobiology, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Wuhan, China
Abstract
Defensins are a group of cationic peptides that exhibit broad-spectrum antimicrobial activity. In this study, we cloned and characterized a β-defensin from pituitary cDNA library of a protogynous hermaphroditic orange-spotted grouper (Epinephelus coioides). Interestingly, the β-defensin was shown to be dominantly expressed in pituitary and testis by RT-PCR and Western blot analysis, and its transcript level is significantly upregulated in reproduction organs from intersexual gonad to testis during the natural and artificial sex reversal. Promoter sequence and the responsible activity region analyses revealed the pituitary-specific POU1F1a transcription binding site and testis-specific SRY responsible site, and demonstrated that the pituitary-specific POU1F1a transcription binding site that locates between ?180 and ?208 bp is the major responsible region of grouper β-defensin promoter activity. Immunofluorescence localization observed its pituicyte expression in pituitary and spermatogonic cell expression in testis. Moreover, both in vitro antibacterial activity assay of the recombinant β-defensin and in vivo embryo microinjection of the β-defensin mRNA were shown to be effective in killing Gram-negative bacteria. And, its antiviral role was also demonstrated in EPC cells transfected with the β-defensin construct. Additionally, the antibacterial activity was sensitive to concentrations of Na+, K+, Ca2+ and Mg2+. The above intriguing findings strongly suggest that the fish β-defensin might play significant roles in both innate immunity defense and reproduction endocrine regulation.
