オクニシ　カツヒデ   Okunishi Katsuhide   奥西　勝秀    所属   東邦大学  医学部 医学科    職種   教授
論文種別	原著
言語種別	英語
査読の有無	査読なし
表題	Functional hierarchy among different Rab27 effectors involved in secretory granule exocytosis.
掲載誌名	正式名：eLife
掲載区分	国外
巻・号・頁	12
著者・共著者	Kunli Zhao,Kohichi Matsunaga,Kouichi Mizuno,Hao Wang,Katsuhide Okunishi,Tetsuro Izumi
発行年月	2023/02/21
概要	The Rab27 effectors are known to play versatile roles in regulated exocytosis. In pancreatic beta cells, exophilin-8 anchors granules in the peripheral actin cortex, whereas granuphilin and melanophilin mediate granule fusion with and without stable docking to the plasma membrane, respectively. However, it is unknown whether these coexisting effectors function in parallel or in sequence to support the whole insulin secretory process. Here, we investigate their functional relationships by comparing the exocytic phenotypes in mouse beta cells simultaneously lacking two effectors with those lacking just one of them. Analyses of prefusion profiles by total internal reflection fluorescence microscopy suggest that melanophilin exclusively functions downstream of exophilin-8 to mobilize granules for fusion from the actin network to the plasma membrane after stimulation. The two effectors are physically linked via the exocyst complex. Downregulation of the exocyst component affects granule exocytosis only in the presence of exophilin-8. The exocyst and exophilin-8 also promote fusion of granules residing beneath the plasma membrane prior to stimulation, although they differentially act on freely diffusible granules and those stably docked to the plasma membrane by granuphilin, respectively. This is the first study to diagram the multiple intracellular pathways of granule exocytosis and the functional hierarchy among different Rab27 effectors within the same cell.
DOI	10.7554/eLife.82821
PMID	36803984