Evaluation of the endoplasmic reticulum-stress response in eIF2B-mutated lymphocytes and lymphoblasts from CACH/VWM patients

• Published in: BMC neurology Vol. 10; no. 1; p. 94
• Main Authors: Horzinski, Laetitia, Kantor, Liraz, Huyghe, Aurélia, Schiffmann, Raphael, Elroy-Stein, Orna, Boespflug-Tanguy, Odile, Fogli, Anne
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 19.10.2010; BioMed Central; BMC
• Subjects: Activating Transcription Factor 4; Activating Transcription Factor 4 - genetics; Activating Transcription Factor 4 - metabolism; Adolescent; Ataxia; Blotting, Western; Cell Line; Cellular signal transduction; Child; Child, Preschool; Development and progression; Endoplasmic Reticulum; Endoplasmic Reticulum - drug effects; Endoplasmic Reticulum - genetics; Endoplasmic Reticulum - metabolism; Enzyme Inhibitors; Enzyme Inhibitors - toxicity; Epstein-Barr virus; Eukaryotic Initiation Factor-2B; Eukaryotic Initiation Factor-2B - genetics; Eukaryotic Initiation Factor-2B - metabolism; Female; Human subjects; Humans; Infant; Leukoencephalopathies; Leukoencephalopathies - genetics; Leukoencephalopathies - metabolism; Life Sciences; Lymphocytes; Lymphocytes - metabolism; Male; Metabolic disorders; Mutation; Neurons and Cognition; Phosphorylation; Physiological aspects; Protein Biosynthesis; Protein Biosynthesis - drug effects; Protein Biosynthesis - physiology; Protein synthesis; Reverse Transcriptase Polymerase Chain Reaction; Stress response; Stress, Physiological; Stress, Physiological - physiology; Thapsigargin; Thapsigargin - toxicity; Yeast
• ISSN: 1471-2377; 1471-2377
• DOI: 10.1186/1471-2377-10-94

Eukaryotic translation initiation factor 2B (eIF2B), a guanine nucleotide exchange factor (GEF) and a key regulator of translation initiation under normal and stress conditions, causes an autosomal recessive leukodystrophy of a wide clinical spectrum. EBV-immortalised lymphocytes (EIL) from eIF2B-mutated patients exhibit a decrease in eIF2B GEF activity. eIF2B-mutated primary fibroblasts have a hyper-induction of activating transcription factor 4 (ATF4) which is involved in the protective unfolded protein response (UPR), also known as the ER-stress response. We tested the hypothesis that EIL from eIF2B-mutated patients also exhibit a heightened ER-stress response. We used thapsigargin as an ER-stress agent and looked at polysomal profiles, rate of protein synthesis, translational activation of ATF4, and transcriptional induction of stress-specific mRNAs (ATF4, CHOP, ASNS, GRP78) in normal and eIF2B-mutated EIL. We also compared the level of stress-specific mRNAs between EIL and primary lymphocytes (PL). Despite the low eIF2B GEF activity in the 12 eIF2B-mutated EIL cell lines tested (range 40-70% of normal), these cell lines did not differ from normal EIL in their ATF4-mediated ER-stress response. The absence of hyper-induction of ATF4-mediated ER-stress response in eIF2B-mutated EIL in contrast to primary fibroblasts is not related to their transformation by EBV. Indeed, PL exhibited a higher induction of the stress-specific mRNAs in comparison to EIL, but no hyper-induction of the UPR was noticed in the eIF2B-mutated cell lines in comparison to controls. Taken together with work of others, our results demonstrate the absence of a major difference in ER-stress response between controls and eIF2B-mutated cells. Therefore, components of the ER-stress response cannot be used as discriminatory markers in eIF2B-related disorders.