Migration defects by DISC1 knockdown in C57BL/6, 129X1/SvJ, and ICR strains via in utero gene transfer and virus-mediated RNAi

Abstract

Disrupted-in-Schizophrenia 1 (DISC1) is a promising genetic risk factor for major mental disorders. Many groups repeatedly reported a role for DISC1 in brain development in various strains of mice and rats by using RNA interference (RNAi) approach. Nonetheless, due to the complexity of its molecular disposition, such as many splice variants and a spontaneous deletion in a coding exon of the DISC1 gene in some mouse strains, there have been debates on the interpretation on these published data. Thus, in this study, we address this question by DISC1 knockdown via short-hairpin RNAs (shRNAs) against several distinct target sequences with more than one delivery methodologies into several mouse strains, including C57BL/6, ICR, and 129X1/SvJ. Here, we show that DISC1 knockdown by in utero electroporation of shRNA against exons 2, 6, and 10 consistently results in neuronal migration defects in the developing cerebral cortex, which are successfully rescued by coexpression of full-length DISC1. Furthermore, lentivirus-mediated shRNA also led to migration defects, which is consistent with two other methodologies already published, such as plasmidmediated and retrovirus-mediated ones. The previous study by Song's group also reported that, in the adult hippocampus, the phenotype elicited by DISC1 knockdown with shRNA targeting exon 2 was consistently seen in both C57BL/6 and 129S6 mice. Taken together, we propose that some of DISC1 isoforms that are feasible to be knocked down by shRNAs to exon 2, 6, and 10 of the DISC1 gene play a key role for neuronal migration commonly in various mouse strains and rats.

Disrupted-in-schizophrenia 1 regulates transport of ITPR1 mRNA for synaptic plasticity

“…In addition, other Disc1 RNAi tools that confer a defective phenotype in the 129 and outbred ICR strain backgrounds require verification of the knockdown specificity. Some groups have reported that Disc1 knockdown in the brains of 129 and outbred ICR mice leads to extensive disruption of cortical migration and adult neurogenesis 14,[17][18][19] . One of the Disc1 shRNAs used in these studies is shRNA-D1.…”

PAKs inhibitors ameliorate schizophrenia-associated dendritic spine deterioration in vitro and in vivo during late adolescence

“…This procedure was performed according the published protocol with minor modifications (24,25). Briefly, pregnant C57BL/6 mice were anesthetized at embryonic day 14.5 (E14.5) by isoflurane, and shRNA plasmids (control or DISC1 shRNA) together with CAG::Venus vector were injected into the bilateral ventricles.…”

“…6A). In this model, by in utero electroporation, DISC1 shRNA is selectively targeted to the cells in a lineage of the pyramidal neurons in the layer II/III of the prefrontal cortex (24,25). Among the PAK inhibitors tested above, FRAX486 displayed the highest penetrance of blood-brain barrier (Fig.…”

DISC1 a key molecular lead in psychiatry and neurodevelopment: No-More Disrupted-in-Schizophrenia 1

“…Furthermore, the present study precludes potential off-target effects elicited by an RNAi construct 12, 13 that was used to show the involvement of DISC1 in progenitor cell proliferation and neuronal migration: The DISC1 RNAi construct does not affect the migration of Disc1 LI mice in which the target sequences of RNAi were genetically depleted (Supplementary Figure 3). …”