title: Neuronal expression of two isoforms of mouse Septin 5.
abstract: Septin 5 (Sept5) is a member of the Septin GTPase family and is thought to be involved in exocytosis through interactions with syntaxin 1 in postmitotic neurons. In rats, Sept5 is alternatively spliced to produce a short (Sept5_v2) and long (Sept5_v1) isoform. We recently identified Sept5 in rat brain as a substrate for Cdk5/p35, which phosphorylates Ser17 of Sept5_v1. To date, however, only the short Sept5_v2 isoform has been reported in the mouse. To determine the general expression of the Sept5_v1 isoform in mammals, we isolated Sept5_v1 cDNA by PCR using mouse brain total RNA. Mouse Sept5_v1 cDNA showed a high degree of nucleotide and amino acid sequence homology to the corresponding isoform of rat and human Sept5. Both isoforms were expressed mainly in brain and testis at the mRNA level, but expression was restricted to brain at the protein level. Whereas Sept5_v1 mRNA was highly expressed in the cortex and hippocampus, Sept5_v2 mRNA was expressed at the similar extent across in various brain regions. The protein ratio of Sept5_v1 to Sept5_v2 was high in the hippocampus, roughly equivalent in the cortex and low in the cerebellum and medulla. Sept5_v2 expression increased gradually from E17 to P30, but expression of Sept5_v1 was delayed until P10. The two isoforms were distinguished by their pattern of N-terminal phosphorylation. Thus, these different expression and phosphorylation patterns suggest isoform-specific functions for Sept5 and that a phosphorylation-specific antibody will be useful to study this idea.
authors: Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan. a7203ki@tmu.ac.jp
authors: Akiko
authors: A
authors: Asada
authors: Junya
authors: J
authors: Takahashi
authors: Makoto
authors: M
authors: Taniguchi
authors: Hiromi
authors: H
authors: Yamamoto
authors: Taeko
authors: T
authors: Kimura
authors: Taro
authors: T
authors: Saito
authors: Shin-Ichi
authors: S
authors: Hisanaga
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism*; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism*; D010766:Phosphorylation; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D058112:Septins
chemical_list: D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D020033:Protein Isoforms; D012333:RNA, Messenger; D019204:GTP-Binding Proteins; C491612:Sept5 protein, mouse; D058112:Septins