title: Functional and Physical Interaction of Diacylglycerol Kinase ζ with Protein Kinase Cα Is Required for Cerebellar Long-Term Depression.
abstract: The balance between positive and negative regulators required for synaptic plasticity must be well organized at synapses. Protein kinase Cα (PKCα) is a major mediator that triggers long-term depression (LTD) at synapses between parallel fibers and Purkinje cells in the cerebellum. However, the precise mechanisms involved in PKCα regulation are not clearly understood. Here, we analyzed the role of diacylglycerol kinase ζ (DGKζ), a kinase that physically interacts with PKCα as well as postsynaptic density protein 95 (PSD-95) family proteins and functionally suppresses PKCα by metabolizing diacylglycerol (DAG), in the regulation of cerebellar LTD. In Purkinje cells of DGKζ-deficient mice, LTD was impaired and PKCα was less localized in dendrites and synapses. This impaired LTD was rescued by virus-driven expression of wild-type DGKζ, but not by a kinase-dead mutant DGKζ or a mutant lacking the ability to localize at synapses, indicating that both the kinase activity and synaptic anchoring functions of DGKζ are necessary for LTD. In addition, experiments using another DGKζ mutant and immunoprecipitation analysis revealed an inverse regulatory mechanism, in which PKCα phosphorylates, inactivates, and then is released from DGKζ, is required for LTD. These results indicate that DGKζ is localized to synapses, through its interaction with PSD-95 family proteins, to promote synaptic localization of PKCα, but maintains PKCα in a minimally activated state by suppressing local DAG until its activation and release from DGKζ during LTD. Such local and reciprocal regulation of positive and negative regulators may contribute to the fine-tuning of synaptic signaling.
  
  
  CONCLUSIONS
  Many studies have identified signaling molecules that mediate long-term synaptic plasticity. In the basal state, the activities and concentrations of these signaling molecules must be maintained at low levels, yet be ready to be boosted, so that synapses can undergo synaptic plasticity only when they are stimulated. However, the mechanisms involved in creating such conditions are not well understood. Here, we show that diacylglycerol kinase ζ (DGKζ) creates optimal conditions for the induction of cerebellar long-term depression (LTD). DGKζ works by regulating localization and activity of protein kinase Cα (PKCα), an important mediator of LTD, so that PKCα effectively responds to the stimulation that triggers LTD.
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea, Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul 136-791, Korea, and.
authors.forename: Dongwon
authors.initials: D
authors.lastname: Lee
authors.affiliation: Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul 136-791, Korea, and.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea, Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon 305-701, Korea.
authors.forename: Eunjoon
authors.identifier: http://orcid.org/0000-0001-5518-6584
authors.initials: E
authors.lastname: Kim
authors.affiliation: Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul 136-791, Korea, and keikoyamat@gmail.com.
authors.forename: Keiko
authors.initials: K
authors.lastname: Tanaka-Yamamoto
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D002531:Cerebellum / Q000166:cytology*; D019852:Diacylglycerol Kinase / Q000235:genetics / Q000378:metabolism*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D017490:Ichthyosis, Lamellar; D066298:In Vitro Techniques; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000235:genetics*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008822:Mice, Transgenic; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology; D051571:Protein Kinase C-alpha / Q000378:metabolism*; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
chemical_list: D018691:Excitatory Amino Acid Antagonists; D049452:Green Fluorescent Proteins; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D019852:Diacylglycerol Kinase; C512480:diacylglycerol kinase zeta, mouse; D051571:Protein Kinase C-alpha
keywords: DGKζ; PKCα; Purkinje cells; cerebellum; long-term depression