Mutant eIF eIF 2B leads to impaired mitochondrial oxidative phosphorylation in vanishing white matter disease

摘要

Abstract Eukaryotic translation initiation factor 2B ( eIF 2B) is a master regulator of protein synthesis under normal and stress conditions. Mutations in any of the five genes encoding its subunits lead to vanishing white matter ( VWM ) disease, a recessive genetic deadly illness caused by progressive loss of white matter in the brain. In this study we used fibroblasts, which are not involved in the disease, to demonstrate the involvement of eIF 2B in mitochondrial function and abundance. Mass spectrometry of total proteome of mouse embryonic fibroblasts ( MEF s) isolated from Eif2b5 R132H/R132H mice revealed unbalanced stoichiometry of proteins involved in oxidative phosphorylation and of mitochondrial translation machinery components, among others. Mutant MEF s exhibit 55% decrease in oxygen consumption rate per mt DNA content and 47% increase in mitochondrial abundance ( p ??0.005), reflecting adaptation to energy requirements. A more robust eIF 2B‐associated oxidative respiration deficiency was found in mutant primary astrocytes, which exhibit ?3‐fold lower ATP ‐linked respiration per cell despite a 2‐fold increase in mt DNA content ( p ??0.03). The 2‐fold increase in basal and stimulated glycolysis in mutant astrocytes ( p ?≤?0.03), but not in MEF s, demonstrates their higher energetic needs and further explicates their involvement in the disease. The data demonstrate the critical role of eIF 2B in tight coordination of expression from nuclear and mitochondrial genomes and illuminates the importance of mitochondrial function in VWM pathology. Further dissection of the signaling network associated with eIF 2B function will help generating therapeutic strategies for VWM disease and possibly other neurodegenerative disorders.