第12回 バイオフォーラム2011

 最先端の生命科学研究に触れてみませんか

NEW CONCEPTS OF THE MOUSE SPERM ACROSOMAL EXOCYTOSIS

Mammalian sperm must undergo a process termed capacitation to become competent to fertilize an egg. Capacitation renders the sperm competent by priming the cells to undergo a rapid exocytotic event called acrosomal exocytosis that is stimulated by the zona pellucida (ZP) of the egg or progesterone. Over the years, several biochemical events have been associated with the capacitation process; however, the question that has remained unanswered in investigations of capacitation is: What is the underlying reaction or set of reactions that transform the sperm cell from a state unresponsive to ZP or progesterone- stimulated acrosomal exocytosis to the state primed to respond to these stimuli? Our preliminary results demonstrate that the actin cytoskeleton plays a role in this process. The aim of this research was to understand how mammalian sperm acquire the competence to undergo acrosomal exocytosis during capacitation.
We evaluated the establishment and stabilization of the primed state of acrosomal exocytosis that develops during the course of sperm capacitation through the formation of intermediate stages of exocytosis.
To monitor the formation of intermediate stages of exocytosis, we used sperm from transgenic mouse GFP-Acr (green acrosomes) and the exposure of sp56 (monitored by flow cytometry and immunocytochemistry). We found that the actin polymerization that takes place during capacitation is essential in this process. Additionally, using Blue native gel electrophoresis and purified hybrid vesicles (generated by the fusion of the plasma membrane and the outer acrosomal membrane after exocytosis), we found that actin and several actin-related proteins participate in the formation of these intermediate stages of exocytosis.


There are several human health-related reasons these studies are significant. For example, an understanding this process may lead to a better understanding of certain cases of male infertility and to the development of pharmacological approaches to interfere with this process, leading to new contraceptive agents. Most importantly, since actin has been implicated in exocytosis occurring in many types of somatic cells, information gathered from studying the less complicated sperm system will likely impact our understanding of secretion in other organ systems such as endocrine or digestive tissues.

(和訳:生物の受精が成立するためには、雌雄配偶子の形成と分化、そして成熟が適切に実行される必要があります。哺乳類において、精子が受精能を獲得するためには、さらに雌個体内で起こるキャパシテーションと呼ばれる現象が重要です。キャパシテーションを起こした精子のみが卵との結合の直前あるいは結合時に先体反応(精子頭部の外分泌反応)を起こし、さらには卵との合体(細胞膜融合)を実行することができます。本フォーラムでは、精子内アクチン細胞骨格のキャパシテーションや先体反応における役割を中心に紹介し、受精生物学の最先端にふれてもらいます。)

講師

National Research Council of Argentina (CONICET)
Mariano G. Buffone 博士

日時 2012年2月3日(金)
開場 16:00〜
開演 16:30〜(講演時間:60分)
英語講演・通訳なし
場所 京都産業大学総合生命科学部15号館
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主催 京都産業大学 総合生命科学部

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