Stimulation of MAP kinase by v-raf transformation of fibroblasts fails to induce hyperphosphorylation of transfected tau.
A proportion of the microtubule-associated protein, tau, is in an elevated state of phosphorylation in foetal and adult brain whereas all of the tau in paired helical filaments, which are characteristic of Alzheimer's disease is hyperphosphorylated; it is important therefore to elucidate the mechanisms that regulate tau phosphorylation. Here we describe results that show that although MAP kinase can hyperphosphorylate tau in vitro, activation of MAP kinase in transformed fibroblasts does not result in hyperphosphorylation of transfected tau, whereas glycogen synthase kinase-3 beta (GSK-3 beta) when co-transfected with tau does result in tau hyperphosphorylation. The findings imply that GSK-3 beta may be a stronger candidate than MAP kinase for inducing tau hyperphosphorylation in vivo.
Latimer
D A
DA
Department of Neuroscience, Institute of Psychiatry, London, UK.
Gallo
J M
JM
Lovestone
S
S
Miller
C C
CC
Reynolds
C H
CH
Marquardt
B
B
Stabel
S
S
Woodgett
J R
JR
Anderton
B H
BH
D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D027384:Oncogene Proteins v-raf; D010766:Phosphorylation; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic; D016875:tau Proteins / Q000235:genetics / Q000378:metabolism*
D015682:Retroviridae Proteins, Oncogenic; D016875:tau Proteins; D038341:Glycogen Synthase Kinases; D027384:Oncogene Proteins v-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D038362:Glycogen Synthase Kinase 3