title: Amyloid β oligomer-induced ERK1/2-dependent serine 636/639 phosphorylation of insulin receptor substrate-1 impairs insulin signaling and glycogen storage in human astrocytes.
abstract: OBJECTIVE
  This study is to investigate the effect of amyloid β1-42 oligomers on insulin signaling in astrocytes.
  
  
  METHODS
  Synthetic Aβ1-42 oligomers were prepared and the oligomeric form of Aβ1-42 was verified by an electron microscope. Normal human astrocytes were cultured in Dulbecco's Modified Eagle Medium. Western blotting was employed to measure the amount of lysate proteins. Immunofluorescence was performed to detect the distribution of phosphorylated insulin receptor substrate-1 and expression of P-GSK3β in astrocytes under confocal microscopy and fluorescent microscopy, respectively. Periodic Acid-Schiff staining was used to detect glycogen, the content of which was measured using glycogen assay.
  
  
  RESULTS
  Our data showed that Aβ1-42 oligomers inhibited insulin-induced serine phosphorylation of Akt at 473 and GSK3β at serine 9, as well as glycogen storage. However, the levels of phosphorylated GSK3β at tyrosine 216 were significantly increased in the presence of Aβ1-42 oligomers. In addition, the levels of phosphorylated ERK1/2 and insulin receptor substrate-1 at serine 636/639 were significantly increased in response to treatment with Aβ1-42 oligomers. Of note, the responses and inhibitory effects of Aβ1-42 oligomers on insulin signaling were partially reversed by ERK1/2 upstream inhibitor PD98059.
  
  
  CONCLUSIONS
  Our results demonstrated that Aβ1-42 oligomers impaired insulin signaling and suppressed insulin-induced glycogen storage in human astrocytes, probably due to ERK1/2-dependent serine phosphorylation of insulin receptor substrate-1 at 636/639 induced by Aβ1-42 oligomers.
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China.
authors: Qinghua
authors: Q
authors: Zhang
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China.
authors: Shougang
authors: S
authors: Guo
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China.
authors: Xiao
authors: X
authors: Zhang
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China.
authors: Shi
authors: S
authors: Tang
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China.
authors: Lu
authors: L
authors: Wang
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China.
authors: Xiaojuan
authors: X
authors: Han
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China.
authors: Wen
authors: W
authors: Shao
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China.
authors: Lin
authors: L
authors: Cong
authors: Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan City, Shandong Province, PR China. Electronic address: neurology2014j@163.com.
authors: Yifeng
authors: Y
authors: Du
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism / Q000494:pharmacology*; D001253:Astrocytes; D002460:Cell Line; D048049:Extracellular Signal-Regulated MAP Kinases; D005419:Flavonoids / Q000494:pharmacology; D006003:Glycogen / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000096:biosynthesis; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D016229:Amyloid beta-Peptides; D005419:Flavonoids; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D006003:Glycogen; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D048049:Extracellular Signal-Regulated MAP Kinases; D038362:Glycogen Synthase Kinase 3; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
keywords: Amyloid β(1–42) oligomers; Astrocyte; ERK1/2; Insulin receptor substrate-1; Insulin signaling