The effects of behavioral tasks on the in vitro phosphorylation of intermediate filament subunits of rat hippocampus are mediated by CaMKII and PKA.
Neurofilaments (NF) are the most abundant constituents of the neuronal cytoskeleton, while glial fibrillary acidic protein (GFAP) is a major component of the glial astrocyte cytoskeleton. These proteins can be phosphorylated by different protein kinases and they are regulated in a complex way by phosphorylation. Using a hippocampal cytoskeletal fraction we demonstrated that the behavioral tasks of inhibitory avoidance and habituation can differently alter the in vitro phosphorylation of the 150 kDa (NF-M) and the 68 kDa (NF-L) neurofilament subunits and of the GFAP. In order to verify the effect of habituation and inhibitory avoidance training on the phosphatase activity, we performed the time course-dephosphorylation assay (5-30 min of incubation of the cytoskeletal fraction with 32P-ATP). Subsequently we investigated the effect of these behavioral tasks on the protein kinase activities associated with the cytoskeletal fraction, carring out the 32P incorporation assays in the presence of specific kinase inhibitors. Results suggest that phosphatase activity is not altered in the cytoskeletal fraction by the behavioral tasks and that the increased in vitro phosphorylation of NF-M and NF-L caused by habituation is probably mediated by the Ca2+/calmodulin dependent protein kinase (CaMKII). However, the inhibition of GFAP in vitro phosphorylation caused by inhibitory avoidance training is probably related to the cAMP dependent protein kinase (PKA).
Schröder
N
N
Universidade Federal do Rio Grande do Sul, Departamento de Bioquímica,Porto Alegre, Brasil.
de Mattos-Dutra
A
A
Sampaio de Freitas
M
M
Fogaça Lisboa
C S
CS
Zilles
A C
AC
Pessoa-Pureur
R
R
Izquierdo
I
I
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D004597:Electroshock; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006624:Hippocampus / Q000201:enzymology / Q000502:physiology*; D007381:Intermediate Filament Proteins / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D016900:Neurofilament Proteins / Q000378:metabolism; D009474:Neurons / Q000201:enzymology / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D005904:Glial Fibrillary Acidic Protein; D007381:Intermediate Filament Proteins; D016900:Neurofilament Proteins; C044882:neurofilament protein L; C061195:neurofilament protein M; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases