title: An anti-diabetes agent protects the mouse brain from defective insulin signaling caused by Alzheimer's disease- associated Aβ oligomers.
abstract: Defective brain insulin signaling has been suggested to contribute to the cognitive deficits in patients with Alzheimer's disease (AD). Although a connection between AD and diabetes has been suggested, a major unknown is the mechanism(s) by which insulin resistance in the brain arises in individuals with AD. Here, we show that serine phosphorylation of IRS-1 (IRS-1pSer) is common to both diseases. Brain tissue from humans with AD had elevated levels of IRS-1pSer and activated JNK, analogous to what occurs in peripheral tissue in patients with diabetes. We found that amyloid-β peptide (Aβ) oligomers, synaptotoxins that accumulate in the brains of AD patients, activated the JNK/TNF-α pathway, induced IRS-1 phosphorylation at multiple serine residues, and inhibited physiological IRS-1pTyr in mature cultured hippocampal neurons. Impaired IRS-1 signaling was also present in the hippocampi of Tg mice with a brain condition that models AD. Importantly, intracerebroventricular injection of Aβ oligomers triggered hippocampal IRS-1pSer and JNK activation in cynomolgus monkeys. The oligomer-induced neuronal pathologies observed in vitro, including impaired axonal transport, were prevented by exposure to exendin-4 (exenatide), an anti-diabetes agent. In Tg mice, exendin-4 decreased levels of hippocampal IRS-1pSer and activated JNK and improved behavioral measures of cognition. By establishing molecular links between the dysregulated insulin signaling in AD and diabetes, our results open avenues for the investigation of new therapeutics in AD.
authors.affiliation: Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Theresa R
authors.initials: TR
authors.lastname: Bomfim
authors.forename: Leticia
authors.initials: L
authors.lastname: Forny-Germano
authors.forename: Luciana B
authors.initials: LB
authors.lastname: Sathler
authors.forename: Jordano
authors.initials: J
authors.lastname: Brito-Moreira
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Houzel
authors.forename: Helena
authors.initials: H
authors.lastname: Decker
authors.forename: Michael A
authors.initials: MA
authors.lastname: Silverman
authors.forename: Hala
authors.initials: H
authors.lastname: Kazi
authors.forename: Helen M
authors.initials: HM
authors.lastname: Melo
authors.forename: Paula L
authors.initials: PL
authors.lastname: McClean
authors.forename: Christian
authors.initials: C
authors.lastname: Holscher
authors.forename: Steven E
authors.initials: SE
authors.lastname: Arnold
authors.forename: Konrad
authors.initials: K
authors.lastname: Talbot
authors.forename: William L
authors.initials: WL
authors.lastname: Klein
authors.forename: Douglas P
authors.initials: DP
authors.lastname: Munoz
authors.forename: Sergio T
authors.initials: ST
authors.lastname: Ferreira
authors.forename: Fernanda G
authors.initials: FG
authors.lastname: De Felice
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism* / Q000517:prevention & control / Q000523:psychology; D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D000077270:Exenatide; D005260:Female; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D000069285:Infliximab; D007328:Insulin / Q000502:physiology*; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism*; D007333:Insulin Resistance; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008252:Macaca fascicularis; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008569:Memory Disorders / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008875:Middle Aged; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology / Q000627:therapeutic use*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051381:Rats; D014688:Venoms / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D016229:Amyloid beta-Peptides; D000911:Antibodies, Monoclonal; D007004:Hypoglycemic Agents; C526292:IRS1 protein, human; C526297:IRS2 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D010455:Peptides; D014688:Venoms; D000077270:Exenatide; D000069285:Infliximab