Distribution of Kiaa0319-like immunoreactivity in the adult mouse brain--a novel protein encoded by the putative dyslexia susceptibility gene KIAA0319-like

Kiaa0319L is a novel protein encoded by a recently discovered gene KIAA0319-like(L) that may be associated with reading disability. Little is known about the characteristics of this protein and its distribution in the brain. We investigated here expression of this protein in adult mice, using an antibody specific for human and rodent Kiaa0319L. In the brain, Kiaa0319L was localized strongly in the olfactory bulb, and strong expression was found in other regions, including hippocampus, cerebellum, diencephalon and the cerebral cortex. Immunohistochemistry confirmed expression in these brain regions, and showed further that the protein was expressed preferentially in neurons in layer IV and VI of the neocortex, CA1 and CA2 subfields of the hippocampus and a subpopulation of neurons in CA3 and dentate gyrus. Furthermore, the protein was confined to dendrites of CA1 neurons in the stratum radiatum, but not those in the stratum oriens, and in astrocytes within the hippocampus. In the cerebellum, the protein was observed in the molecular layer and a fraction of Purkinje neurons. These findings confirmed expression of Kiaa0319L in brain regions that are involved in reading performance, supporting its possible involvement in reading disability. The specific patterns of localization in the neocortex, hippocampus and cerebellum suggest further that this protein may be related to other biological processes in a subpopulation of neurons within these regions, eg. formation and maintenance of polarity in the neuron.