Is the sequential model for regulated exocytosis really correct?

2014 Fiscal Year Final Research Report

• Project/Area Number: 26670133
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: General medical chemistry
• Research Institution: Gunma University
• Principal Investigator: IZUMI Tetsuto 群馬大学, 生体調節研究所, 教授 (00212952)
• Research Collaborator: MIZUNO Kouichi
• Project Period (FY): 2014-04-01 – 2015-03-31
• Keywords: インスリン / 分泌顆粒 / 開口放出 / 細胞内膜輸送

Outline of Final Research Achievements

Regulated exocytosis has evolved as the main means of intercellular communication. It is generally assumed that vesicles must first dock at the plasma membrane and then undergo preparatory priming reactions before they become fusion-competent. However, the functional relationship among docking, priming, and fusion has not been sufficiently explored. In the present study, we visualized each individual step in living cells, and showed that docked granules are fusion-reluctant but fuse with the dissociation of a docking factor by recruiting a priming factor, after the stimulus-induced Ca2+ increase. These findings suggest that stable docking is neither a prerequisite nor a dead-end for fusion, but instead represents a temporal fusion-reluctant state to inhibit spontaneous fusion, whereas priming is not a step to acquire fusion competence before stimulation, but instead occurs after sensing a stimulus-induced Ca2+ increase.

Free Research Field

医歯薬学