The X-linked subcortical laminar heterotopia and lissencephaly syndrome is a disorder of neuronal migration caused by a mutation in XLIS, a recently cloned gene on chromosome Xq22.3-q23. The predicted protein product for XLIS, doublecortin (DC), shows high homology to a putative calcium calmodulin-dependent kinase , KIAA0369 protein (KI). Here we identified DC and KI in the brains of human and rat fetuses by immunochemical and immunohistochemical means. In this study , Western blotting demonstrated that both DC and KI are specific to the nervous system and are abundant during the fetal period , around 20 gestational weeks in humans and embryonic days 17 to 20 in rats. Immunostaining of the developing neocortex disclosed localization of DC and KI immunoreactivities in neuronal cell bodies and processes in the zones of ongoing neuronal migration. Although KI showed a somewhat wider distribution than DC , the temporal and spatial patterns of their expression were similar. These results suggest that DC and KI participate in a common signaling pathway regulating neuronal migration. (Am J Pathol 1999, 155:1713-1721)

Immunohistochemical expression of doublecortin (DCX), KIAA0369 (KIA) and LIS1 proteins as well as nestin and vimentin in the cerebral cortices of six patients with Zellweger syndrome (ZS), aged 19 gestational weeks (GW) to 8 months, was compared with that in nine controls, aged 12 GW to 8 months. DCX immunoreactivity was apparently reduced in ZS, particularly in the cortical plate of fetuses, and in the subependymal foci of heterotopic neurons of the infants. Reduced expression of DCX in ZS was confirmed by Western blot analysis. On the other hand, neuronal expression of nestin was high in the cortical plate, migrating cells of the white matter and germinal cells in the ventricular zone in fetuses with ZS. Immunoreactivities for KIA, LIS1 and vimentin in ZS were comparable to those of controls. Reduced expression of DCX may be responsible for the neuronal migration disorder, and increased expression of nestin may be another evidence for delayed neuronal maturation in ZS.

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