RhoA and Rho Kinase-dependent Phosphorylation of Moesin at Thr-558 in Hippocampal Neuronal Cells by Glutamate

• Published in: The Journal of biological chemistry 2002-05, Vol.277 (19), p.16576-16584
• Main Authors: Jeon, Songhee, Kim, Sohee, Park, Jong-Bae, Suh, Pann-Ghill, Kim, Yong Sik, Bae, Chang-Dae, Park, Joobae
• Format: Article
• Language: English
• Subjects: Animals; Brain - metabolism; cdc42 GTP-Binding Protein - metabolism; Cross-Linking Reagents - pharmacology; Electrophoresis, Polyacrylamide Gel; Electroshock; Glutamic Acid - chemistry; Glutamic Acid - metabolism; Hippocampus - metabolism; Immunoblotting; Intracellular Signaling Peptides and Proteins; Male; Microfilament Proteins - chemistry; Microfilament Proteins - metabolism; moesin; Neurons - metabolism; Phosphorylation; Precipitin Tests; Protein-Serine-Threonine Kinases - chemistry; Protein-Serine-Threonine Kinases - metabolism; rac1 GTP-Binding Protein - metabolism; Rats; Rats, Sprague-Dawley; Recombinant Proteins - metabolism; rho-Associated Kinases; rhoA GTP-Binding Protein - chemistry; rhoA GTP-Binding Protein - metabolism; RhoA protein; Serine - metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Subcellular Fractions; Threonine - chemistry; Threonine - metabolism; Time Factors; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110380200

When we were studying phosphorylated proteins in the rat brain after electroconvulsive shock (ECS), we observed the rapid phosphorylation of a 75-kDa protein, which cross-reacted with the anti-phospho-p70 S6 kinase antibody. The phosphorylated protein was purified and identified as moesin, a member of the ezrin/radixin/moesin (ERM) family and a general cross-linker between cortical actin filaments and plasma membranes. The purified moesin from rat brain was phosphorylated at serine and threonine residues. Moesin was rapidly phosphorylated at the threonine 558 residue after ECS in the rat hippocampus, peaked at 1 min, and returned to the basal level by 2 min after ECS. To investigate the mechanism of moesin phosphorylation in neuronal cells, we stimulated a rat hippocampal progenitor cell, H19–7/IGF-IR, with glutamate, and observed the increased phosphorylation of moesin at Thr-558. Glutamate transiently activated RhoA, and constitutively active RhoA increased the basal level phosphorylation of moesin. The inhibition of RhoA and its effector, Rho kinase, abolished increased Thr-558 phosphorylation by glutamate in H19–7/IGF-IR cells, suggesting that the phosphorylation of moesin at Thr-558 in H19–7/IGF-IR cells by glutamate is mediated by RhoA and Rho kinase activation.