Afadin regulates puncta adherentia junction formation and presynaptic differentiation in hippocampal neurons

• Published in: PloS one 2014-02, Vol.9 (2), p.e89763-e89763
• Main Authors: Toyoshima, Daisaku, Mandai, Kenji, Maruo, Tomohiko, Supriyanto, Irwan, Togashi, Hideru, Inoue, Takahito, Mori, Masahiro, Takai, Yoshimi
• Format: Article
• Language: English
• Subjects: Analysis; Animal models; Animals; Bassoon protein; Biochemistry; Biology; Brain - metabolism; Brain - pathology; Cadherins - metabolism; Cell adhesion; Cell adhesion & migration; Cell adhesion molecules; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Dietary fiber; Differentiation; Excitatory postsynaptic potentials; Gene expression; Hippocampus; Immunofluorescence; Intermediate filament proteins; Learning; Memory; Mice; Mice, Knockout; Microfilament Proteins - genetics; Microfilament Proteins - metabolism; Molecular biology; Mossy Fibers, Hippocampal - metabolism; N-Cadherin; Nectin; Nectins; Nestin; Neurons; Presynaptic Terminals - metabolism; Proteins; Pyramidal Cells - metabolism; Synapses; Synapses - metabolism; Synaptogenesis
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0089763

The formation and remodeling of mossy fiber-CA3 pyramidal cell synapses in the stratum lucidum of the hippocampus are implicated in the cellular basis of learning and memory. Afadin and its binding cell adhesion molecules, nectin-1 and nectin-3, together with N-cadherin, are concentrated at puncta adherentia junctions (PAJs) in these synapses. Here, we investigated the roles of afadin in PAJ formation and presynaptic differentiation in mossy fiber-CA3 pyramidal cell synapses. At these synapses in the mice in which the afadin gene was conditionally inactivated before synaptogenesis by using nestin-Cre mice, the immunofluorescence signals for the PAJ components, nectin-1, nectin-3 and N-cadherin, disappeared almost completely, while those for the presynaptic components, VGLUT1 and bassoon, were markedly decreased. In addition, these signals were significantly decreased in cultured afadin-deficient hippocampal neurons. Furthermore, the interevent interval of miniature excitatory postsynaptic currents was prolonged in the cultured afadin-deficient hippocampal neurons compared with control neurons, indicating that presynaptic functions were suppressed or a number of synapse was reduced in the afadin-deficient neurons. Analyses of presynaptic vesicle recycling and paired recordings revealed that the cultured afadin-deficient neurons showed impaired presynaptic functions. These results indicate that afadin regulates both PAJ formation and presynaptic differentiation in most mossy fiber-CA3 pyramidal cell synapses, while in a considerable population of these neurons, afadin regulates only PAJ formation but not presynaptic differentiation.