In vivo transgenic expression of collybistin in neurons of the rat cerebral cortex.

Collybistin (CB) is a guanine nucleotide exchange factor selectively localized to γ-aminobutyric acid (GABA)ergic and glycinergic postsynapses. Active CB interacts with gephyrin, inducing the submembranous clustering and the postsynaptic accumulation of gephyrin, which is a scaffold protein that recruits GABA receptors (GABA Rs) at the postsynapse. CB is expressed with or without a src homology 3 (SH3) domain.

In vivo clonal overexpression of neuroligin 3 and neuroligin 2 in neurons of the rat cerebral cortex: Differential effects on GABAergic synapses and neuronal migration.

We studied the effect of clonal overexpression of neuroligin 3 (NL3) or neuroligin 2 (NL2) in the adult rat cerebral cortex following in utero electroporation (IUEP) at embryonic stage E14. Overexpression of NL3 leads to a large increase in vesicular gamma-aminobutyric acid (GABA) transporter (vGAT) and glutamic acid decarboxylase (GAD)65 in the GABAergic contacts that the overexpressing neurons receive. Overexpression of NL2 produced a similar effect but to a lesser extent.

Fate mapping by piggyBac transposase reveals that neocortical GLAST+ progenitors generate more astrocytes than Nestin+ progenitors in rat neocortex.

Progenitors within the neocortical ventricular zone (VZ) first generate pyramidal neurons and then astrocytes. We applied novel piggyBac transposase lineage tracking methods to fate-map progenitor populations positive for Nestin or glutamate and aspartate transpoter (GLAST) promoter activities in the rat neocortex. GLAST+ and Nestin+ progenitors at embryonic day 13 (E13) produce lineages containing similar rations of neurons and astrocytes.

Neocortical disruption and behavioral impairments in rats following in utero RNAi of candidate dyslexia risk gene Kiaa0319.

Within the last decade several genes have been identified as candidate risk genes for developmental dyslexia. Recent research using animal models and embryonic RNA interference (RNAi) has shown that a subset of the candidate dyslexia risk genes--DYX1C1, ROBO1, DCDC2, KIAA0319--regulate critical parameters of neocortical development, such as neuronal migration. For example, embryonic disruption of the rodent homolog of DYX1C1 disrupts neuronal migration and produces deficits in rapid auditory processing (RAP) and working memory--phenotypes that have been reported to be associated with developmental dyslexia.

Repressor element 1 silencing transcription factor (REST) controls radial migration and temporal neuronal specification during neocortical development.

Neurogenesis requires mechanisms that coordinate early cell-fate decisions, migration, and terminal differentiation. Here, we show that the transcriptional repressor, repressor element 1 silencing transcription factor (REST), regulates radial migration and the timing of neural progenitor differentiation during neocortical development, and that the regulation is contingent upon differential REST levels. Specifically, a sustained presence of REST blocks migration and greatly delays--but does not prevent--neuronal differentiation, resulting in a subcortical band heterotopia-like phenotype, reminiscent of loss of doublecortin.

Synaptic and nonsynaptic localization of protocadherin-gammaC5 in the rat brain.

It has been proposed that gamma-protocadherins (Pcdh-gammas) are involved in the establishment of specific patterns of neuronal connectivity. Contrary to the other Pcdh-gammas, which are expressed in the embryo, Pcdh-gammaC5 is expressed postnatally in the brain, coinciding with the peak of synaptogenesis. We have developed an antibody specific for Pcdh-gammaC5 to study the expression and localization of Pcdh-gammaC5 in brain.

Disruption of neuronal migration by RNAi of Dyx1c1 results in neocortical and hippocampal malformations.

The brains of individuals with developmental dyslexia have neocortical neuronal migration abnormalities including molecular layer heterotopias, laminar dysplasias, and periventricular nodular heterotopias (PNH). RNA interference (RNAi) of Dyx1c1, a candidate dyslexia susceptibility gene, disrupts neuronal migration in developing embryonic neocortex. Using in utero electroporation, we cotransfected cells in the rat neocortical ventricular zone (VZ) at E14/15 with short hairpin RNA vectors targeting Dyx1c1 along with either plasmids encoding enhanced green fluorescent protein or plasmids encoding monomeric red fluorescent protein only.