title: Amyloid beta peptide specifically promotes phosphorylation and nuclear translocation of the extracellular signal-regulated kinase in cultured rat cortical astrocytes.
abstract: To explore cellular signaling molecules that respond to amyloid beta protein (A beta), we investigated the effect of A beta on tyrosine phosphorylation of cellular proteins in cultured rat cortical astrocytes. Western blotting with the phosphotyrosine-specific monoclonal antibody 4G10 demonstrated that exposure of cultured rat cortical astrocytes to 20 microM A beta 1-40 or A beta 25-35 for 24 h resulted in a prominent increase in the phosphotyrosine content of 44-kDa protein. The A beta-induced increase in tyrosine phosphorylation of 44-kDa protein was blocked by U0126, a specific inhibitor of the extracellular signal-regulated kinase (ERK) kinase MEK. Western blotting with anti-phospho-ERK1/2 antibody and anti-ERK1/2 antibody demonstrated that A beta 1-40 or A beta 25-35 induced an increase in the dually (tyrosine and threonine) phosphorylated form of ERK1 and ERK2, with no change in total ERK1/2 level. In addition, immunofluorescent staining with anti-ERK1/2 antibody revealed that A beta induced a significant increase in the number of cells expressing ERK1/2 mainly in the nucleus. These results suggest that A beta specifically promotes tyrosine phosphorylation and nuclear translocation of ERK in astrocytes.
authors.affiliation: Department of Pharmacology, School of Pharmacy, Hoshi University, Tokyo, Japan. abe@hoshi.ac.jp
authors.forename: Kazuho
authors.initials: K
authors.lastname: Abe
authors.forename: Rie
authors.initials: R
authors.lastname: Hisatomi
authors.forename: Miwa
authors.initials: M
authors.lastname: Misawa
mesh_terms: D016229:Amyloid beta-Peptides / Q000494:pharmacology* / Q000502:physiology; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology*; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000201:enzymology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar
chemical_list: D016229:Amyloid beta-Peptides; D020928:Mitogen-Activated Protein Kinases