title: Regulation and function of the calcium/calmodulin-dependent protein kinase IV/protein serine/threonine phosphatase 2A signaling complex.
abstract: Calcium/calmodulin-dependent protein kinase IV (CaMKIV) is a member of the broad substrate specificity class of Ca(2+)/calmodulin (CaM)-dependent protein kinases and functions as a potent stimulator of Ca(2+)-dependent gene expression. Activation of CaMKIV is a transient, tightly regulated event requiring both Ca(2+)/CaM binding and phosphorylation of the kinase on T200 by an upstream CaMK kinase (CaMKK). Previously, CaMKIV was shown to stably associate with protein serine/threonine phosphatase 2A (PP2A), which was proposed to play a role in negatively regulating the kinase. Here we report that the Ca(2+)/CaM binding-autoinhibitory domain of CaMKIV is required for association of the kinase with PP2A and that binding of PP2A and Ca(2+)/CaM appears to be mutually exclusive. We demonstrate that inhibition of the CaMKIV/PP2A association in cells results in enhanced CaMKIV-mediated gene transcription that is independent of Ca(2+)/CaM. The enhanced transcriptional activity correlates with the elevated level of phospho-T200 that accumulates when CaMKIV is prevented from interacting with PP2A. Collectively, these data suggest a molecular basis for the sequential activation and inactivation of CaMKIV. First, in response to an increase in intracellular Ca(2+), CaMKIV binds Ca(2+)/CaM and becomes phosphorylated on T200 by CaMKK. These events result in the generation of autonomous activity required for CaMKIV-mediated transcriptional regulation. The CaMKIV-associated PP2A then dephosphorylates CaMKIV T200, thereby terminating autonomous activity and CaMKIV-mediated gene transcription.
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Kristin A
authors.initials: KA
authors.lastname: Anderson
authors.forename: Pamela K
authors.initials: PK
authors.lastname: Noeldner
authors.forename: Kelie
authors.initials: K
authors.lastname: Reece
authors.forename: Brian E
authors.initials: BE
authors.lastname: Wadzinski
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Means
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D020013:Calcium Signaling; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases; C517683:CAMK4 protein, human; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2