Efhc1 deficiency causes spontaneous myoclonus and increased seizure susceptibility

High-speed digital imaging of ependymal cilia in the murine brain

The development and health of mammals requires proper ciliary motility. Ciliated epithelia are found in the airways, the uterus and Fallopian tubes, the efferent ducts of the testes, and the ventricular system of the brain. A technique is described for the motion analysis of ependymal cilia in the murine brain. Vibratome sections of the brain are imaged by differential interference contrast microscopy and recorded by high-speed digital imaging. Side views of individual cilia are traced to establish their bending pattern. Tracking of individual cilia recorded in top view allows determination of bend planarity and beat direction. Ciliary beat frequency is determined from line scans of image sequences. The capacity of the epithelium to move fluid and objects is revealed by analyzing the velocity of polystyrene beads added to brain sections. The technique is useful for detailed assessment of how various conditions or mutations affect the fidelity of ciliary motility at the ependyma. The methods are also applicable to other ciliated epithelia, for example, in airways.

EFHC1 interacts with microtubules to regulate cell division and cortical development

Mutations in the EFHC1 gene are linked to juvenile myoclonic epilepsy (JME), one of the most frequent forms of idiopathic generalized epilepsies. JME is associated with subtle alterations of cortical and subcortical architecture, but the underlying pathological mechanism remains unknown. We found that EFHC1 is a microtubule-associated protein involved in the regulation of cell division. In vitro, EFHC1 loss of function disrupted mitotic spindle organization, impaired M phase progression, induced microtubule bundling and increased apoptosis. EFHC1 impairment in the rat developing neocortex by ex vivo and in utero electroporation caused a marked disruption of radial migration. We found that this effect was a result of cortical progenitors failing to exit the cell cycle and defects in the radial glia scaffold organization and in the locomotion of postmitotic neurons. Therefore, we propose that EFHC1 is a regulator of cell division and neuronal migration during cortical development and that disruption of its functions leads to JME.

Genetic basis in epilepsies caused by malformations of cortical development and in those with structurally normal brain

Epilepsy is the most common neurological disorder affecting young people. The etiologies are multiple and most cases are sporadic. However, some rare families with Mendelian inheritance have provided evidence of genes' important role in epilepsy. Two important but apparently different groups of disorders have been extensively studied: epilepsies associated with malformations of cortical development (MCDs) and epilepsies associated with a structurally normal brain (or with minimal abnormalities only). This review is focused on clinical and molecular aspects of focal cortical dysplasia, polymicrogyria, periventricular nodular heterotopia, subcortical band heterotopia, lissencephaly and schizencephaly as examples of MCDs. Juvenile myoclonic epilepsy, childhood absence epilepsy, some familial forms of focal epilepsy and epilepsies associated with febrile seizures are discussed as examples of epileptic conditions in (apparently) structurally normal brains.