Faculty Bibliography

BACKGROUND: Fibers containing galanin (GAL) enlarge and hyperinnervate cholinergic basal forebrain (CBF) nucleus basalis (NB) neurons in late-stage Alzheimer's disease (AD), yet the physiological consequences of this phenomenon are unclear. OBJECTIVE: To determine whether GAL hyperinnervation of cholinergic NB neurons modulates the expression of genes critical to cholinergic transmission [e.g. acetylcholine (ACh) metabolism and ACh receptors] in AD. METHODS: Single-cell gene expression profiling was used to compare cholinergic mRNA levels in non-GAL-hyperinnervated NB neurons in tissue autopsied from cases classified as having no cognitive impairment (NCI) or late-stage AD (AD/GAL-) and in GAL-hyperinnervated (AD/GAL+) NB neurons from the same AD subjects. RESULTS: AD/GAL+ cells displayed a significant upregulation in choline acetyltransferase (ChAT) mRNA expression compared to NCI and AD/GAL- cells. CONCLUSION: GAL fiber hyperinnervation of cholinergic NB neurons upregulates the expression of ChAT, the synthetic enzyme for ACh, suggesting that GAL regulates the cholinergic tone of CBF neurons in AD

BACKGROUND: Mutations in eukaryotic translation initiation factor 2B (eIF2B) cause Childhood Ataxia with CNS Hypomyelination (CACH), also known as Vanishing White Matter disease (VWM). The disease is manifested by loss of brain myelin upon physiological stress. In a previous study, we showed that fibroblasts isolated from CACH/VWM patients are hypersensitive to pharmacologically-induced endoplasmic reticulum (ER) stress. Since brain cells from affected individuals are not available for research, we wished to assess the effect of eIF2B mutation on oligodendroglial-derived cells. METHODOLOGY/PRINCIPAL FINDINGS: A rat oligodendroglial-derived cell line was used for a stable knock-down of eIF2B5 followed by stable expression of mutated eIF2B5(R195H) cDNA. In response to a pharmacological ER-stress agent, eIF2B5(R195H) expressing cells exhibited heightened ER-stress response demonstrated by hyper induction of ATF4, GADD34, Bip, PDIA1, PDIA3, PDIA4 and PDIA6 proteins. Moreover, even in the absence of a pharmacological stress agent, eIF2B5(R195H)-expressing cells exhibited high basal levels of ATF4, GADD34 and ER-associated Bip, PDIA1 and PDIA3. SIGNIFICANCE: The data provide evidence that oligodendroglial-derived cells expressing a mutated eIF2B constantly use their stress response mechanism as an adaptation mean in order to survive. The current study is the first to demonstrate the effects of eIF2B5 mutation on ER homeostasis in oligodendroglial-derived cells.