Protein from neuronal death by regulation ER stress response.

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Various neurodegenerative diseases are reported to be associated with be endoplasmic reticulum (ER) stress. To develop therapeutic strategies for these diseases, the whole aspects of ER stress response should be made clear. In the present study, we demonstrated the following issues ;1) We identified a novel ER stress sensor BBF2H7, which is expressed in neurons of ischemic brains. The molecules are cleaved at the transmembrane domain in response to ER stress. N-terminal fragments of cleaved BBF2H7 are translocated into the nucleus and activates the transcription of target genes.2) The formation of autophagosomes that are recognized as the double membrane structure with cytoplasmic contents was promoted in the neurons that were exposed to ER stress. Disturbance of autophagy rendered cells vulnerable to ER stress, suggesting that autophagy plays important roles in cell survival after ER stress.3) In screening for compounds that induce the ER-mediated chaperone BiP, we identified BiP Inducer X (BIX). Pretreatment of neuroblastoma cells with BIX reduced cell death induced by ER stress. Intracerebroventricular pretreatment with BIX reduced the area of infarction due to focal cerebral ischemia in mice, suggesting that it may be a potential therapeutic agent for cerebral diseases caused by ER stress.4) We demonstrated that ER stress sensors, IRE1, PERK, and ATF6 exist in the ER of both soma and dendrites in primary cultured neurons, and that BiP and phosphoryrated eIF2a are induced. These results indicate that the ER in dendrites could respond to ER stress and retain the capacity of protein quality control.