Annual Report 2003–04

傑出研 O u R e P r o — 醫 F a o f M e 破解精子成熟之謎 Important Breakthrough in Research on Sperm Maturation 上皮細胞生物學研究中心發現了人類精 子成熟的秘密——從附睪頭部分泌的 β -防禦素基因 「Bin1b」 ，能夠黏附到精子 頭部，令到原來不能運動的未成熟精子獲 得動能。 精子在睪丸生成時，沒有游動和授精能 力，亦即精子未成熟。精子是在附睪内成 熟的，但經過近四十年的探索研究，科學 家仍未能了解精子在附睪中成熟的過程。 陳小章敎授（左）領導的研究隊伍找到的 B i n1b 基因，是首個在附睪發現的，可以啟 動精子成熟的分子；若抑制 B i n1b ，精子便 無法獲得運動能力。因此， Bin1b 可作為男 性不育診斷與治療的追蹤及量度的生物學 標示工具，促進相關的研究，更成為發展 新避孕策略的研究基礎。他們正研究 B i n1b 如何影響精子外膜蛋白，並著手研究不育 病人的 Bin1b 基因的表達。 此項研究是該中心與中國科學院上海生物 化學與細胞生物學研究所的合作成果，已 刊於《自然一細胞生物學》雜 誌。該系博士研究生周晨曦 (右）更因此項研究而獲美國 茱勒基金會授與博士後研究基 金。他將在陳敎授的指導下， 完成題為「附睪特異防禦素 Bin1b 對精子成熟的作用」的博士後研 究。 Sperms do not intrinsically possess the ability to swim or fertilize eggs. They acquire these abilities through a process called sperm maturation in the epididymis situated next to the testes. How sperm matures in the epididymis has been puzzling to scientists despite nearly four decades of research. A study conducted by Prof. H.C. Chan (left) of the Epithelial Cell Biology Research Centre in collaboration with the Shanghai Institute of Biochemistry and Cell Biology of the Chinese Academy of Sciences reveals the first secret of sperm maturation. It has been found that Bin1b, a β -defensi ngene found in the head region of the epidigymis, can attach itself to the sper m head and induce progressive sperm motility in originally immotile immature sperm. β -defensin is the first molecule found in the epididymis that is involved in initiating sperm maturation. It can be used as a biomarker for the diagnosis or treat- ment of male infertility. The findings, p u b l i s h e d i n Nature Cell Biology, also provide a basis for the development of new contraceptive strategies. Studies on the detailed mechanisms of β -defensin's interactions with sperm membrane proteins are already in the pipeline and there are plans to examine Bin1b expression in infertile patients. The Lalor Foundation in the US has awarded a Lalor Foundation Postdoctoral Fellowship to Mr. Zhou Chenxi (right), a doctoral candidate under the supervision of Prof. H.C. Chan, to undertake a study, entitled 'The Role of Epididymis-specific Definsin, Bin1b, in Sperm Maturation'. 51