Regulation of spinophilin Ser94 phosphorylation in neostriatal neurons involves both DARPP-32-dependent and independent pathways.
Spinophilin is a protein phosphatase-1 (PP-1)- and actin-binding protein that is enriched in dendritic spines. Phosphorylation of the actin-binding domain of rat spinophilin at one or more sites by protein kinase A (PKA) inhibits actin binding. Here, we investigated the regulation of mouse spinophilin that contains only a single PKA-site (Ser94) within its actin-binding domain. In vitro phosphorylation of Ser94 resulted in the dissociation of spinophilin from actin filaments. In mouse neostriatal slices, phospho-Ser94 (p-Ser94) was dephosphorylated mainly by PP-1 and also by PP-2A. Activation of dopamine D1 receptors in striatonigral medium spiny neurons, and of adenosine A 2A receptors in striatopallidal medium spiny neurons increased, whereas activation of dopamine D2 receptors in striatopallidal neurons decreased, spinophilin Ser94 phosphorylation. In neostriatal slices from DARPP-32 (dopamine- and cAMP-regulated phosphoprotein of 32 kDa) knockout mice, the effects of D1, D2 and A 2A receptors were largely attenuated. Activation of NMDA receptors decreased Ser94 phosphorylation in a PP-2A-dependent, but DARPP-32-independent, manner. These results suggest that PKA-dependent phosphorylation of spinophilin at Ser94 in both striatonigral and striatopallidal neurons requires synergistic contributions from the PKA and DARPP-32/PP-1 pathways. In addition, PP-2A plays a role in Ser94 dephosphorylation in response to activation of both D2 and NMDA receptors.
Uematsu
Ken
K
Department of Physiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, Japan.
Futter
Marie
M
Hsieh-Wilson
Linda C
LC
Higashi
Hideho
H
Maeda
Hisao
H
Nairn
Angus C
AC
Greengard
Paul
P
Nishi
Akinori
A
D000199:Actins / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000235:genetics / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005917:Globus Pallidus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015151:Immunoblotting; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics* / Q000378:metabolism*; D017072:Neostriatum / Q000166:cytology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D054645:Protein Phosphatase 1; D043705:Receptor, Adenosine A2A / Q000187:drug effects / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D017470:Receptors, Glutamate / Q000187:drug effects; D012694:Serine / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D000099273:Neurabins
D000199:Actins; D017868:Cyclic AMP-Dependent Protein Kinases; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D018690:Excitatory Amino Acid Agonists; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D043705:Receptor, Adenosine A2A; D017447:Receptors, Dopamine D1; D017470:Receptors, Glutamate; D012694:Serine; D000099273:Neurabins