title: Comparative analysis of protocadherin-11 X-linked expression among postnatal rodents, non-human primates, and songbirds suggests its possible involvement in brain evolution.
abstract: BACKGROUND
  Protocadherin-11 is a cell adhesion molecule of the cadherin superfamily. Since, only in humans, its paralog is found on the Y chromosome, it is expected that protocadherin-11X/Y plays some role in human brain evolution or sex differences. Recently, a genetic mutation of protocadherin-11X/Y was reported to be associated with a language development disorder. Here, we compared the expression of protocadherin-11 X-linked in developing postnatal brains of mouse (rodent) and common marmoset (non-human primate) to explore its possible involvement in mammalian brain evolution. We also investigated its expression in the Bengalese finch (songbird) to explore a possible function in animal vocalization and human language faculties.
  
  
  RESULTS
  Protocadherin-11 X-linked was strongly expressed in the cerebral cortex, hippocampus, amygdala and brainstem. Comparative analysis between mice and marmosets revealed that in certain areas of marmoset brain, the expression was clearly enriched. In Bengalese finches, protocadherin-11 X-linked was expressed not only in nuclei of regions of the vocal production pathway and the tracheosyringeal hypoglossal nucleus, but also in areas homologous to the mammalian amygdala and hippocampus. In both marmosets and Bengalese finches, its expression in pallial vocal control areas was developmentally regulated, and no clear expression was seen in the dorsal striatum, indicating a similarity between songbirds and non-human primates.
  
  
  CONCLUSIONS
  Our results suggest that the enriched expression of protocadherin-11 X-linked is involved in primate brain evolution and that some similarity exists between songbirds and primates regarding the neural basis for vocalization.
authors.affiliation: Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Wako, Japan. Eiji.Matsunaga@brain.riken.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Matsunaga
authors.forename: Sanae
authors.initials: S
authors.lastname: Nambu
authors.forename: Mariko
authors.initials: M
authors.lastname: Oka
authors.forename: Kazuo
authors.initials: K
authors.lastname: Okanoya
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iriki
mesh_terms: D000818:Animals; D001921:Brain / Q000254:growth & development / Q000378:metabolism; D001933:Brain Stem / Q000378:metabolism; D015820:Cadherins / Q000235:genetics*; D002144:Callithrix; D002540:Cerebral Cortex / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism; D004644:Emotions; D005260:Female; D015870:Gene Expression; D005786:Gene Expression Regulation; D050172:Genes, X-Linked; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D008568:Memory; D051379:Mice; D020308:Songbirds
chemical_list: D015820:Cadherins