title: Protein Kinase Cϵ (PKCϵ) Promotes Synaptogenesis through Membrane Accumulation of the Postsynaptic Density Protein PSD-95.
abstract: Protein kinase Cϵ (PKCϵ) promotes synaptic maturation and synaptogenesis via activation of synaptic growth factors such as BDNF, NGF, and IGF. However, many of the detailed mechanisms by which PKCϵ induces synaptogenesis are not fully understood. Accumulation of PSD-95 to the postsynaptic density (PSD) is known to lead to synaptic maturation and strengthening of excitatory synapses. Here we investigated the relationship between PKCϵ and PSD-95. We show that the PKCϵ activators dicyclopropanated linoleic acid methyl ester and bryostatin 1 induce phosphorylation of PSD-95 at the serine 295 residue, increase the levels of PSD-95, and enhance its membrane localization. Elimination of the serine 295 residue in PSD-95 abolished PKCϵ-induced membrane accumulation. Knockdown of either PKCϵ or JNK1 prevented PKCϵ activator-mediated membrane accumulation of PSD-95. PKCϵ directly phosphorylated PSD-95 and JNK1 in vitro Inhibiting PKCϵ, JNK, or calcium/calmodulin-dependent kinase II activity prevented the effects of PKCϵ activators on PSD-95 phosphorylation. Increase in membrane accumulation of PKCϵ and phosphorylated PSD-95 (p-PSD-95(S295)) coincided with an increased number of synapses and increased amplitudes of excitatory post-synaptic potentials (EPSPs) in adult rat hippocampal slices. Knockdown of PKCϵ also reduced the synthesis of PSD-95 and the presynaptic protein synaptophysin by 30 and 44%, respectively. Prolonged activation of PKCϵ increased synapse number by 2-fold, increased presynaptic vesicle density, and greatly increased PSD-95 clustering. These results indicate that PKCϵ promotes synaptogenesis by activating PSD-95 phosphorylation directly through JNK1 and calcium/calmodulin-dependent kinase II and also by inducing expression of PSD-95 and synaptophysin.
authors.affiliation: From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505 asen@brni.org.
authors.forename: Abhik
authors.initials: A
authors.lastname: Sen
authors.affiliation: From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505.
authors.forename: Jarin
authors.initials: J
authors.lastname: Hongpaisan
authors.affiliation: From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505.
authors.forename: Desheng
authors.initials: D
authors.lastname: Wang
authors.affiliation: From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Nelson
authors.affiliation: From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Alkon
mesh_terms: D000818:Animals; D054713:Bryostatins / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000235:genetics / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D057809:HEK293 Cells; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D048055:Mitogen-Activated Protein Kinase 8 / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D051744:Protein Kinase C-epsilon / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D013570:Synaptic Membranes / Q000235:genetics / Q000378:metabolism*; D016708:Synaptophysin / Q000096:biosynthesis / Q000235:genetics
chemical_list: D054713:Bryostatins; C501444:DLG4 protein, human; D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C569014:SYP protein, human; D016708:Synaptophysin; C569016:Syp protein, rat; C046785:bryostatin 1; C497257:Prkce protein, rat; C497255:PRKCE protein, human; D051744:Protein Kinase C-epsilon; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D048055:Mitogen-Activated Protein Kinase 8
keywords: PSD-95; phosphorylation; protein kinase CϵPKC); protein translocation; scaffold protein; synapse