The gene encoding disabled-1 (DAB1), the intracellular adaptor of the Reelin pathway, reveals unusual complexity in human and mouse.
The Disabled-1 (Dab1) gene encodes a key regulator of Reelin signaling. Reelin is a large glycoprotein secreted by neurons of the developing brain, particularly Cajal-Retzius cells. The DAB1 protein docks to the intracellular part of the Reelin very low density lipoprotein receptor and apoE receptor type 2 and becomes tyrosine-phosphorylated following binding of Reelin to cortical neurons. In mice, mutations of Dab1 and Reelin generate identical phenotypes. In humans, Reelin mutations are associated with brain malformations and mental retardation; mutations in DAB1 have not been identified. Here, we define the organization of Dab1, which is similar in human and mouse. The Dab1 gene spreads over 1100 kb of genomic DNA and is composed of 14 exons encoding the major protein form, some alternative internal exons, and multiple 5'-exons. Alternative polyadenylation and splicing events generate DAB1 isoforms. Several 5'-untranslated regions (UTRs) correspond to different promoters. Two 5'-UTRs (1A and 1B) are predominantly used in the developing brain. 5'-UTR 1B is composed of 10 small exons spread over 800 kb. With a genomic length of 1.1 Mbp for a coding region of 5.5 kb, Dab1 provides a rare example of genomic complexity, which will impede the identification of human mutations.
Bar
Isabelle
I
Neurobiology Unit, University of Namur Medical School, 61, rue de Bruxelles, B5000 Namur, Belgium. isabelle.bar@fundp.ac.be
Tissir
Fadel
F
Lambert de Rouvroit
Catherine
C
De Backer
Olivier
O
Goffinet
Andre M
AM
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000166:cytology / Q000502:physiology*; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics*; D002874:Chromosome Mapping; D002878:Chromosomes, Human, Pair 1; D017931:DNA Primers; D005091:Exons; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D017403:In Situ Hybridization; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010446:Peptide Fragments; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic; D000091042:Reelin Protein; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases
D048868:Adaptor Proteins, Signal Transducing; D015816:Cell Adhesion Molecules, Neuronal; C115785:DAB1 protein, human; D017931:DNA Primers; C103773:Dab1 protein, mouse; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D000091042:Reelin Protein; C000717127:RELN protein, human; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases