ニシマツ　シンイチロウ   Shinichiro Nishimatsu   西松　伸一郎    所属   川崎医科大学  医学部 一般教養　自然科学    職種   教授
言語種別	日本語
発表タイトル	Wnt signaling via the endoplasmic reticulum, a new pathway highlighted by a study of the organizer formation of Xenopus embryos.
会議名	第60回日本細胞生物学会大会
学会区分	全国規模の学会
発表形式	ポスター掲示
講演区分	一般
発表者・共同発表者	◎Narita Tomohiro, Motomura Eriko, Nishimatsu Shin-ichiro, Sakai Masao, Nohno Tsutomu
発表年月日	2008/07/01
開催地 （都市, 国名）	横浜
学会抄録	第60回日本細胞生物学会大会要旨集 158
概要	Wnts are secreted proteins and activate the intracellular signaling of neighboring cells via the plasma membrane. However, Wnts might also trigger the signaling on the way of the secretion in the expressing cell. We have examined distribution of Xwnt8 and differentiation by Xwnt8 in Xenopus embryos, since the Wnt signaling is key to the formation of the Spemann organizer. Injection of Xwnt8 mRNA generates a secondary axis of embryos and rescues the axes of egg fragments, which develop into non-axial embryos. When Xwnt8 mRNA was injected with a lineage tracer, cells labeled were expressed dorsal maker genes and differentiated into dorsal cells, suggesting that Xwnt8 acts autonomously. Using confocal laser microscope, we found that Xwnt8 protein was localized in the endoplasmic reticulum (ER) of the cells labeled. When injected with Xwnt8 and Frzb a Wnt binding protein, Xwnt8 was released from the ER and localized on the plasma membrane and the extracellular space. Furthermore, when embryos injected with Xwnt8 were dissociated with 1 mM EDTA, Xwnt8 was discharged from the ER and expression of dorsal marker genes was not detected. Autonomous differentiation by Xwnt8 was interfered with the dissociation as well as Frzb. These results suggest that accumulation of Xwnt8 in the ER was involved in the dorsal determination and generate the organizer activity in Xenopus embryos.