MOLECULAR NEUROSCIENCEUp-regulation of the Ire1-mediated signaling molecule, Bip, in ischemic rat brainIto, DaisukeCA; Tanaka, Kortaro; Suzuki, Shigeaki; Dembo, Tomohisa; Kosakai, Arifumi; Fukuuchi, YasuoAuthor Information Department of Neurology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan CACorresponding Author Received 6 September 2001; accepted 17 October 2001 Neuroreport: December 21st, 2001 - Volume 12 - Issue 18 - p 4023-4028 Buy SDC Abstract The endoplasmic reticulum (ER) is thought to play important roles in various neurological diseases via multifactorial and complex mechanisms. The Ire1-mediated signal is part of one ER signaling pathways; the signal induces the expression of an ER-resident protein, Bip/GRP78, and is thought to be involved in cell death under ER stress. In this study, we examined time-dependent Bip expression after transient middle cerebral artery occlusion and characterized the Bip-positive cells. Ire1- mediated molecules, Bip, were rapidly up-regulated in the ischemic area after 3.5 h recirculation. Their immunoreactivity continued to increase until 24–48 h. Immunofluorescence staining revealed Bip up-regulation in ischemic neurons, which were TUNEL positive. Our studies suggest that the Ire1-mediated signal might be associated with ischemic neuronal damage. © 2001 Lippincott Williams & Wilkins, Inc.