Study for protein binding to the cholesterol-rich secretory granule membrane in neuroendocrine cells

2015 Fiscal Year Final Research Report

• Project/Area Number: 25440052
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Functional biochemistry
• Research Institution: Akita Prefectural University
• Principal Investigator: HOSAKA Masahiro 秋田県立大学, 生物資源科学部, 教授 (80311603)
• Co-Investigator(Renkei-kenkyūsha): WATANABE Tsuyoshi 旭川医科大学, 医学部, 教授 (80220903) ; Bochimoto Hiroki 旭川医科大学, 医学部, 助教 (60632841) ; YAMADA Keiichi 群馬大学, 工学研究院, 助教 (70323334)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 分泌顆粒 / コレステロール / グラニンタンパク質

Outline of Final Research Achievements

Prior to secretion, regulated peptide hormones are selectively sorted to secretory granules (SGs) at the trans-Golgi network (TGN) in endocrine cells. Secretogranin III (SgIII) appears to facilitate SG sorting process by tethering of protein aggregates containing chromogranin A (CgA) and peptide hormones to the cholesterol-rich SG membrane (SGM).
In this study, we evaluated the role of cholesterol binding protein, especially on SgIII, in SG sorting. In the SgIII-knockout mice, plasma ACTH was considerably impaired under highly stress condition. Similarly, plasma glucose level in the SgIII-knockout mice under highly stress condition were highly elevated at glucorse tolerance test. These data indicated SgIII works as sorting receptor in living animals.
Biochemical protein screening for binding to cholesterol at the SGM indicated that several candidate proteins, including granins and processing enzyme, bound directly to the SGM in a cholesterol-dependent manner.

Free Research Field

生化学