title: Identification and characterization of a novel Delphilin variant with an alternative N-terminus.
abstract: Delphilin is identified as a Glutamate receptor delta2 (GluRdelta2) subunit interacting protein, consisting of a PDZ domain and formin homology (FH) domains 1 and 2, in addition to a C-terminal coiled-coil structure. Delphilin has been shown to be selectively expressed in cerebellar Purkinje cells where it co-localizes with the GluRdelta2 subunit at the Purkinje cell-parallel fiber synapses. Although Delphilin specifically interacts with the GluRdelta2 C-terminus via its PDZ domain, the physiological role of the interaction is not yet understood. Here, we report that the Delphilin protein exhibits diversity at its N-terminus by variable usage of the first several exons. Interestingly, the two Delphilin mRNAs which correspond to the first one initially identified (now designated as Delphilin alpha) and the second that contains a newly identified first exon (designated as Delphilin beta), show different chronological expression profiles. Delphilin beta mRNA was not decreased throughout the cerebellar development in vivo and in vitro, while in vivo Delphilin alpha mRNA gradually decreases following the first postnatal week. Delphilins alpha and beta also revealed different subcellular distribution with some overlap. Specifically, the cerebellar synaptosomal membrane fraction contained the Delphilin beta protein. Both Delphilin alpha and beta localized at the dendritic spines with GluRdelta2; however, dendritic shafts in cultured Purkinje cells also included Delphilin beta. In MDCK cells upon becoming confluent, Delphilin alpha moved to the cell-cell junction area, whereas Delphilin beta maintained a diffuse distribution pattern throughout the cytoplasm. Taken as a whole, these two different Delphilins seemed to play functionally different roles in developing and matured cerebellar Purkinje cells.
authors.affiliation: Department of Bacteriology, Yokohama City University School of Medicine, 3-9 Fukuura, Yokohama 236-0004, Japan.
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Yamashita
authors.forename: Yohei
authors.initials: Y
authors.lastname: Miyagi
authors.forename: Michio
authors.initials: M
authors.lastname: Ono
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ito
authors.forename: Keiko
authors.initials: K
authors.lastname: Watanabe
authors.forename: Tomoko
authors.initials: T
authors.lastname: Sonoda
authors.forename: Keisuke
authors.initials: K
authors.lastname: Tsuzuki
authors.forename: Seiji
authors.initials: S
authors.lastname: Ozawa
authors.forename: Ichiro
authors.initials: I
authors.lastname: Aoki
authors.forename: Kenji
authors.initials: K
authors.lastname: Okuda
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Mishina
authors.forename: Susumu
authors.initials: S
authors.lastname: Kawamoto
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D005091:Exons; D005822:Genetic Vectors; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D011689:Purkinje Cells / Q000166:cytology / Q000378:metabolism; D017470:Receptors, Glutamate / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D017470:Receptors, Glutamate; D011993:Recombinant Fusion Proteins; C447759:delphilin; C107913:glutamate receptor delta 2