李 鹏
论文题目：大鼠附睾特异表达基因Binlb和Bin2a的克隆及其表达调控研究
作者简介：李 鹏，男，1971年12月出生，1996年09月师从于中国科学院上海生命科学研究院张永莲教授，于2001年08月获博士学位。
摘 要
附睾是精子成熟、贮存和受到保护的场所。在睾丸中完成形态分化的精子细胞进入附睾，在通过附睾的过程中，获得了前向运动能力和受精能力。这些能力的获得，是精子表面与附睾区域性表达的基因在管腔中造成的微环境不断相互作用的结果。另外，各种性传播疾病、男性不育一直是威胁人类生殖健康的、全球性问题。人口危机也对安全避孕，尤其是男性避孕也提出了新的要求。因此，对男性生殖机理的研究受到越来越多的重视。
近来，我们实验室在大鼠附睾头部先后克隆了两个基因。其中，Bin1b的全长cDNA为385bp，编码一个68个氨基酸的多肽。它是一个单拷贝基因，有一个大小约为1.3
kb的内含子。在18种不同的组织中，Bin1b只在大鼠附睾头部有表达，表达的组织专一性很高。并且它只表达在附睾头部中段的上皮细胞中。另外，Bin1b在大鼠发育到性成熟时，表达水平最高，并在整个性成熟期维持较高的表达水平。同源性分析表明，它很有可能是哺乳动物体内的一种先天性免疫效应分子b-defensin家族中的一员，在灵长类中也有同源分子存在。与香港中文大学合作，利用附睾上皮细胞的体外培养及反义核酸技术证明了它的抗菌性。同时，Bin1b的表达可以被附睾炎症上调。
Bin2a的全长cDNA为2606bp, 编码637个氨基酸。Bin2a的氨基酸序列中包括Glycosyl
hydrolases family 35家族中的9段相对保守的序列,其中包括210位的活性中心Glu（proton donor）,但是缺少另外一个活性中心，279位的Glu（nucleophile）。并且，Bin2a与大鼠附睾中报道的酸性b-半乳糖苷酶显然不同。所以，Bin2a可能是b-半乳糖苷酶家族的新成员。Bin2a表达受雄激素上调，其表达的组织专一性也很高，只在大鼠附睾有表达，并主要在附睾头部。与Bin1b不同的是，Bin2a
mRNA的水平在45天时，有一个表达高峰。
Bin1b和Bin2a的克隆，为研究附睾中的粘膜免疫过程以及精子成熟提供了线索。
关键词：附睾，精子成熟，男性避孕，b-defensin，b-半乳糖苷酶
Abstract
Epididymis is responsible for sperm maturation,storage and protection. Spermatozoa that emerge from the testes had to traverse the epididymis to acquire motility and fertility. The acquisition results from the interaction between sperm and the optimal microenvironment created by genes which are regionally expressed and regulated along the epididymal tubule. Additionally, sexually transmitted disease, male infertility and male contraception remains world-wide health problem. So more attentions are paid on the research of male reproductive tract.
Our lab have cloned two genes in the caput of rat epididymis recently. The full-length cDNA of Bin1b is 385bp, encoding 68 amino acid. It is a single-copy gene and has a 1.3kb intron. Of 18 organ tissues, Bin1b mRNA was only found in the epididymis and confined to epithelial cells in the middle part of the caput region. It was developmentally regulated and its expression started at 30 days of age and reached a maximum during the sexually active period, and then, decreased in the aged rats. By similarity analysis, Bin1b is probably a new member of mamalian b-defensin family which is involved in host innate immunity. And it has homologs in primate. Its antimicrobial activity was proved using primary cultures of epididymal epithelia and antisense technique under the cooperation of The Chinese University of Hong Kong.
The full-length cDNA of Bin2a is 2606bp, encoding 637 amino acid. Its
amino acid sequence has nine conserved blocks of Glycosyl hydrolases family 35,
including an active site Glu210 of proton donor, but lacking another active
site Glu279 of nucleophile. It is obvious that Bin2a is different from acid b-galactosidase reported in
rat epididymis. Maybe it is a new member of b-galactosidase family. Bin2a
mRNA is upregulated by androgen and also epididymis-specific, majorly in caput
epididymides. There is a marked increase ( approximately fourfold ) of its mRNA
level in rat of 45 days age.
The cloning of Bin1b and Bin2a give us a clue in mucosal immunity and
sperm maturation in epididymis.
Key Words: epididymis, sperm maturation, male controception, b-defensin, b-galactosidase.
