title: Apolipoprotein E4 and Insulin Resistance Interact to Impair Cognition and Alter the Epigenome and Metabolome.
abstract: Apolipoprotein E4 (E4) and type 2 diabetes are major risk factors for cognitive decline and late onset Alzheimer's disease (AD). E4-associated phenotypes and insulin resistance (IR) share several features and appear to interact in driving cognitive dysfunction. However, shared mechanisms that could explain their overlapping pathophysiology have yet to be found. We hypothesized that, compared to E3 mice, E4 mice would be more susceptible to the harmful cognitive effects of high fat diet (HFD)-induced IR due to apoE isoform-specific differences in brain metabolism. While both E3 and E4 mice fed HFD displayed impairments in peripheral metabolism and cognition, deficits in hippocampal-dependent spatial learning and memory were exaggerated in E4 mice. Combining genome-wide measures of DNA hydroxymethylation with comprehensive untargeted metabolomics, we identified novel alterations in purine metabolism, glutamate metabolism, and the pentose phosphate pathway. Finally, in E4 mice, the metabolic and cognitive deficiencies caused by HFD were rescued by switching to a low fat diet for one month, suggesting a functional role was associated with reversal of the same metabolic pathways described above. These results suggest a susceptibility of E4 carriers to metabolic impairments brought on by IR, and may guide development of novel therapies for cognitive decline and dementia.
authors.affiliation: Department of Behavioral Neuroscience, Oregon Health &Science University, Portland, OR 97239, USA.
authors.forename: Lance A
authors.initials: LA
authors.lastname: Johnson
authors.affiliation: Department of Behavioral Neuroscience, Oregon Health &Science University, Portland, OR 97239, USA.
authors.forename: Eileen Ruth S
authors.initials: ER
authors.lastname: Torres
authors.affiliation: Oregon Stem Cell Center and Department of Pediatrics, Oregon Health &Science University, Portland, OR 97239, USA.|Department of Cell, Developmental and Cancer Biology, Oregon Health &Science University, Portland, OR 97239 USA.
authors.forename: Soren
authors.initials: S
authors.lastname: Impey
authors.affiliation: Department of Pharmaceutical Sciences, Oregon State University, Corvallis, OR 97331 USA.|Linus Pauling Institute, Oregon State University, Corvallis, OR 97331 USA.
authors.forename: Jan F
authors.initials: JF
authors.lastname: Stevens
authors.affiliation: Department of Behavioral Neuroscience, Oregon Health &Science University, Portland, OR 97239, USA.|Departments of Neurology and Radiation Medicine, Division of Neuroscience, ONPRC, Oregon Health &Science University, Portland, OR 97239 USA.
authors.forename: Jacob
authors.initials: J
authors.lastname: Raber
mesh_terms: D000818:Animals; D053327:Apolipoprotein E4 / Q000235:genetics / Q000378:metabolism*; D001835:Body Weight; D060825:Cognitive Dysfunction / Q000209:etiology* / Q000378:metabolism* / Q000503:physiopathology; D019175:DNA Methylation; D059305:Diet, High-Fat; D004198:Disease Susceptibility; D044127:Epigenesis, Genetic; D005838:Genotype; D018149:Glucose Intolerance; D006624:Hippocampus / Q000378:metabolism; D007333:Insulin Resistance / Q000235:genetics; D053858:Metabolic Networks and Pathways; D055442:Metabolome; D051379:Mice; D008954:Models, Biological; D065853:Spatial Learning; D065852:Spatial Memory
chemical_list: D053327:Apolipoprotein E4