Abstract
Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel type of trophic factor. Recent studies indicate that the MANF gene is induced in response to endoplasmic reticulum (ER) stress through ER stress response element II (ERSE-II) in its 5'-flanking region. In this study, we evaluated the roles of six ER stress response transcription factors in the regulation of the promoter activities of the mouse MANF gene via ERSE-II using various types of mutant MANF luciferase reporter constructs. Treatment with thapsigargin (Tg) induced MANF mRNA generation in parallel with the elevation of ATF6α, sXBP and Luman mRNA levels in Neuro2a cells. Of the six transcription factors, ATF6β most strongly increased the MANF promoter activity via ERSE-II, while the effects of ATF6β and sXBP1 were moderate. However, overexpression of Luman or OASIS did not enhance ERSE-II-dependent MANF promoter activity in Neuro2a cells. To evaluate the relationships between transcription factors in the regulation of ERSE-II-dependent MANF promoter activity, we transfected two effective transcription factor constructs chosen from ATF6α, ATF6β, uXBP1 and sXBP1 into Neuro2a cells with the MANF reporter construct. The MANF promoter activity induced by co-transfection of ATF6α with ATF6β was significantly lower than that induced by ATF6α alone, while other combinations did not show any effect on the ERSE-II-dependent MANF promoter activity in Neuro2a cells. Our study is the first to show the efficiency of ER stress-related transcription factors for ERSE-II in activating the transcription of the mouse MANF gene in Neuro2a cells.