title: Identification of alternatively spliced Dab1 and Fyn isoforms in pig.
abstract: BACKGROUND
  Disabled-1 (Dab1) is an adaptor protein that is essential for the intracellular transduction of Reelin signaling, which regulates the migration and differentiation of postmitotic neurons during brain development in vertebrates. Dab1 function depends on its tyrosine phosphorylation by Src family kinases, especially Fyn.
  
  
  RESULTS
  We have isolated alternatively spliced forms of porcine Dab1 from brain (sDab1) and liver (sDab1-Li) and Fyn from brain (sFyn-B) and spleen (sFyn-T). Radiation hybrid mapping localized porcine Dab1 (sDab1) and Fyn (sFyn) to chromosomes 6q31-35 and 1p13, respectively. Real-time quantitative RT-PCR (qRT-PCR) demonstrated that different isoforms of Dab1 and Fyn have tissue-specific expression patterns, and sDab1 and sFyn-B display similar temporal expression characteristics in the developing porcine cerebral cortex and cerebellum. Both sDab1 isoforms function as nucleocytoplasmic shuttling proteins. It was further shown that sFyn phosphorylates sDab1 at tyrosyl residues (Tyr) 185, 198/200 and 232, whereas sDab1-Li was phosphorylated at Tyr 185 and Tyr 197 (corresponding to Y232 in sDab1) in vitro.
  
  
  CONCLUSIONS
  Alternative splicing generates natural sDab1-Li that only carries Y185 and Y197 (corresponding to Y232 in sDab1) sites, which can be phosphorylated by Fyn in vitro. sDab1-Li is an isoform that is highly expressed in peripheral organs. Both isoforms are suggested to be nucleocytoplasmic shuttling proteins. Our results imply that the short splice form sDab1-Li might regulate cellular responses to different cell signals by acting as a dominant negative form against the full length sDab1 variant and that both isoforms might serve different signaling functions in different tissues.
authors.affiliation: Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
authors.forename: Huan
authors.initials: H
authors.lastname: Long
authors.forename: Hans H
authors.initials: HH
authors.lastname: Bock
authors.forename: Ting
authors.initials: T
authors.lastname: Lei
authors.forename: Xuejun
authors.initials: X
authors.lastname: Chai
authors.forename: Jihong
authors.initials: J
authors.lastname: Yuan
authors.forename: Joachim
authors.initials: J
authors.lastname: Herz
authors.forename: Michael
authors.initials: M
authors.lastname: Frotscher
authors.forename: Zaiqing
authors.initials: Z
authors.lastname: Yang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000235:genetics*; D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics*; D009474:Neurons / Q000502:physiology; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics; D051076:Proto-Oncogene Proteins c-fyn / Q000737:chemistry / Q000235:genetics*; D051381:Rats; D017208:Rats, Wistar; D000091042:Reelin Protein; D013154:Spleen / Q000378:metabolism; D034421:Sus scrofa
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C115785:DAB1 protein, human; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D000091042:Reelin Protein; C000717129:Reln protein, rat; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; C000717127:RELN protein, human