Missplicing resulting from a short deletion in the reelin gene causes reeler‐like neuronal disorders in the mutant shaking rat Kawasaki

Abstract

The shaking rat Kawasaki (SRK) is an autosomal recessive mutant that exhibits reeler-like abnormal locomotor behaviors. The murine reeler mutants arise from several mutations in the specific gene called reelin, which result in defects of Reelin expression or secretion in the cerebral cortex and other regions of CNS. To address the issue of whether the SRK mutation also arises from a mutation in reelin, we analyzed the reelin gene in SRK. Northern analysis of reelin mRNA from normal rats showed that rat reelin was expressed as a approximately 12-kb transcript in both the cerebrum and the cerebellum, whereas reelin expression was markedly reduced in the SRK brains. In situ hybridization analysis showed that reelin mRNA in the SRK brains was expressed in Cajal-Retzius cells in the marginal zone of the cerebral cortex and outer granular cells in the cerebellar cortex in similar manners to normal controls, but its expression was considerably reduced. On Western blotting and immunohistochemical analyses using antibodies specific for the Reelin protein, no immunoproduct was recognized in the cerebral and cerebellar cortices. From the cDNA sequences, we found a 64-base heterologous sequence in SRK reelin, which contains a termination codon in the reading frame. Furthermore, genomic DNA analysis revealed that a 10-base deletion, which contains a predicted splice donor site, occurred in the SRK genomic reelin gene, resulting in "read through" into the following intron in SRK. Thus, the SRK mutation is another type of mutation that lacks expression of the functional Reelin protein and, therefore, causes the reeler phenotype.

Kinetic Properties of Cl−Uptake Mediated by Na+-Dependent K+-2Cl−Cotransport in Immature Rat Neocortical Neurons

“…In situ hybridization protocols and antisense mRNA probes for NKCC1 are described in detail previously (Kanaka et al, 2001). The sequence of reelin antisense probe was CAC-GACAACATGGGCTCAGGCACTTCTACAAC (GenBank accession number AB049473) (Kikkawa et al, 2003). Detection of hybridization probes was performed using emulsion microautoradiography on thionin-stained sections to allow morphological identification.…”

Regulation of Cortical Neuron Migration by the Reelin Signaling Pathway

“…Based on these results, reelin was conclusively identified as the responsible gene for the reeler brain phenotype. At present, non-mouse reeler mutations have also been reported in humans [30] and rats (shaking rat Kawasaki [SRK]) [31]. a Schematic drawing of embryonic mouse brain.…”

Postnatal Development of Entorhinodentate Projection of the <i>Reeler</i> Mutant Mouse

“…Therefore, it appears that the malpositioning of hippocampal pyramidal cells and dentate granule cells has an effect on the final distribution of the afferents upon the target cells, so that the terminal endings of entorhinal afferents are quite markedly disturbed in some specific areas. Woodhams and Terashima [2000] showed that entorhinodentate axons in the SRK rat, a neurological mutant rat caused by a rat reelin mutation [Kikkawa et al, 2003], fail to cross the hippocampal fissure, moving instead parallel to it until they curve around the deepest point of this fissure in the CA3 sector. In the present study, we have .…”

“…The duplication and disruption of pyramidal cells in the area CA1 of the reeler hippocampus are mirrored by the duplication and disruption of the perforant pathway, suggesting that the normal laminar organization of the perforant pathway depends on positional cues presented by their target cells [Deller et al, 1999a, b]. The shaking rat Kawasaki (SRK) is caused by 10-base deletion of the genomic reelin gene that contains a splice donor consensus [Kikkawa et al, 2003]. Woodhams and Terashima [2000] reported that in the SRK rat, fibers of the perforant pathway take an anomalous course in parallel with the hippocampal fissure and terminate in the dentate gyrus instead of crossing the hippocampal fissure due to the barrier formation caused by accumulation of astroglia along this fissure.…”