title: Differential modulation of Ca2+/calmodulin-dependent protein kinase II activity by regulated interactions with N-methyl-D-aspartate receptor NR2B subunits and alpha-actinin.
abstract: Neuronal Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) interacts with several prominent dendritic spine proteins, which have been termed CaMKII-associated proteins. The NR2B subunit of N-methyl-d-aspartate (NMDA)-type glutamate receptor, densin-180, and alpha-actinin bind comparable, approximately stoichiometric amounts of Thr(286)-autophosphorylated CaMKIIalpha, forming a ternary complex (Robison, A. J., Bass, M. A., Jiao, Y., Macmillan, L. B., Carmody, L. C., Bartlett, R. K., and Colbran, R. J. (2005) J. Biol. Chem. 280, 35329-35336), but their impacts on CaMKII function are poorly understood. Here we show that these interactions are differentially regulated and exert distinct effects on CaMKII activity. Nonphosphorylated and Thr(286)-autophosphorylated CaMKII bind to alpha-actinin with similar efficacy, but autophosphorylation at Thr(305/306) or Ca(2+)/calmodulin binding significantly reduce this binding. Moreover, alpha-actinin antagonizes CaMKII activation by Ca(2+)/calmodulin, as assessed by autophosphorylation and phosphorylation of a peptide substrate. CaMKII binding to densin (1247-1542) is partially independent of Thr(286) autophosphorylation and is unaffected by Ca(2+)-independent autophosphorylation or Ca(2+)/calmodulin. In addition, the CaMKII binding domain of densin-180 has little effect on CaMKII activity. In contrast, the interaction of CaMKIIalpha with NR2B requires either Thr(286) autophosphorylation or the binding of both Ca(2+)/calmodulin and adenine nucleotides. NR2B inhibits both the Ca(2+)/calmodulin-dependent and autonomous activities of CaMKII by a mechanism that is competitive with autocamtide-2 substrate, non-competitive with syntide-2 substrate, and uncompetitive with respect to ATP. In combination, these data suggest that dynamically regulated interactions with CaMKII-associated proteins could play pleiotropic roles in finetuning CaMKII signaling in defined subcellular compartments.
authors.affiliation: Department of Molecular Physiology and Biophysics, Center for Molecular Neurosciences and The Vanderbilt-Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Robison
authors.forename: Ryan K
authors.initials: RK
authors.lastname: Bartlett
authors.forename: Martha A
authors.initials: MA
authors.lastname: Bass
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Colbran
mesh_terms: D000185:Actinin / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D008954:Models, Biological; D010766:Phosphorylation; D021122:Protein Subunits; D016194:Receptors, N-Methyl-D-Aspartate / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012795:Sialoglycoproteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D002147:Calmodulin; C504462:Lrrc7 protein, mouse; C121001:NR2B NMDA receptor; D021122:Protein Subunits; D016194:Receptors, N-Methyl-D-Aspartate; D011993:Recombinant Fusion Proteins; D012795:Sialoglycoproteins; D000185:Actinin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium