The role of prolonged excessive activation of unfolded protein response pathway in the pathogenesis of leukoencephalopathy with vanishing white matter

Objective Intolerance to endoplasmic reticulum stress (ERS) and biomarkers in unfolded protein response (UPR) were measured, which provided clues to the investigation of potential pathogenesis. Methods Human oligodendrocytes cell lines transfected with full length EIF2B3 cDNA of the wild type or c. 1037T>C, were used as the cell model.Thapsigargin induced ERS condition.Cleaved Caspase-3 and cell viability assays (cell counting kit-8) were applied to reflect ERS tolerance between the wild type and mutant oligodendrocytes under baseline (0 h) or diffe-rent time points after ERS induction.The components in UPR pancreatic ER kinase-like ER kinase(UPR-PERK) pathway were also measured under baseline condition and after ERS induction. Results (1)Oligodendrocytes transfected with the mutant EIF2B3 showed less tolerance to ERS than the wild type, with declined cell viability and increased apoptosis rates.(2)UPR pathway was over activated in human oligodendrocyte cell line transfected with EIF2B3 mutation.(3)Western blot showed UPR biomarkers of phosphorylated eukaryotic translation initiation factor 2α(P-eIF2α), activating transcription factor 4, CCAAT enhancer-binding homologous protein (CHOP) and growth arrest and DNA damage inducible gene 34(GADD34) were expressed at a higher level in the mutant cells under basal condition.(4)The expression of apoptosis related UPR factors (CHOP, GADD34) and P-eIF2α stayed at a higher level from 24 to 72 hours with the time of ERS stimulation in the mutant cells, but decreased in the wild type group. Conclusions Oligodendrocytes with EIF2B3 were less tolerable to ERS. The ERS susceptibility is related to UPR mediated apoptotic cell death. The relief of the endoplasmic reticulum burden and stabilization of the over-activated UPR are the potential approaches for the delay of the progressive aggravation of the disease. Key words: Vanishing white matter disease; EIF2B3; Unfolded protein response; Endoplasmic reticulum stress