A new knockin mouse carrying the E364X patient mutation for CDKL5 deficiency disorder: neurological, behavioral and
C Quadalti1, M Sannia2, N E Humphreys3
1Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
Abstract:
CDKL5 deficiency disorder (CDD) is a rare neurodevelopmental syndrome caused by mutations in the X-linked CDKL5 gene. Hundreds of pathogenic variants have been described, associated with a significant phenotypic heterogeneity observed among patients. To date, different knockout mouse models have been generated. Here we present a new knockin CDKL5 mouse model carrying a humanized, well-characterized nonsense variant (c.1090G > T; p.E364X) described in the C-terminal domain of the CDKL5 protein in a female patient with a milder phenotype. Both male and female Cdkl5 E364X mice were analyzed. The novel Cdkl5 E364X mouse showed altered neurological and motor neuron maturation, hyperactivity, defective coordination and impaired memory and cognition. Gene expression analysis highlighted an unexpected reduction of Cdkl5 expression in Cdkl5 E364X mice brain tissues, with a significant increase in overall neuron-specific gene expression and an area-dependent alteration of astrocyte- and oligodendrocyte-specific transcripts. Moreover, our results showed that the loss of CDKL5 protein had the most significant impact on the cerebellum and hippocampus, compared to other analyzed tissues. A targeted analysis to study synaptic plasticity in cerebellum and hippocampus showed reduced Gabra1 and Gabra5 expression levels in females, whereas Gabra1 expression was increased in males, suggesting an opposite, sex-dependent regulation of the GABA receptor expression already described in humans. In conclusion, the novel Cdkl5E364X mouse model is characterized by robust neurological and neurobehavioral alterations, associated with a molecular profile related to synaptic function indicative of a cerebellar GABAergic hypofunction, pointing to Gabra1 and Gabra5 as novel druggable target candidates for CDD.
Insights
A new CDKL5 deficiency disorder (CDD) mouse model exhibits neurological and behavioral deficits, revealing sex-specific gene expression changes and potential therapeutic targets like Gabra1 and Gabra5.
Area of Science:
- Neuroscience
- Genetics
- Developmental Biology
Background:
- CDKL5 deficiency disorder (CDD) is a rare X-linked neurodevelopmental syndrome with varied patient phenotypes.
- Existing CDKL5 knockout mouse models do not fully recapitulate human disease complexity.
- Pathogenic variants in CDKL5 lead to significant phenotypic heterogeneity.
Purpose of the Study:
- To develop and characterize a novel humanized knockin mouse model (Cdkl5E364X) for CDD.
- To investigate the neurological and neurobehavioral consequences of the p.E364X CDKL5 variant.
- To explore sex-dependent molecular alterations in the brain related to CDD.
Main Methods:
- Generation of a knockin mouse model carrying the human CDKL5 nonsense variant c.1090G>T (p.E364X).
- Comprehensive analysis of neurological, motor, and cognitive functions in male and female mice.
- Gene expression profiling in brain tissues to assess neuronal, astrocyte, and oligodendrocyte-specific transcripts.
- Targeted analysis of synaptic plasticity and GABA receptor subunit expression in the cerebellum and hippocampus.
Main Results:
- The Cdkl5E364X mice displayed hyperactivity, impaired coordination, memory deficits, and altered motor neuron maturation.
- Gene expression analysis revealed reduced CDKL5 expression, increased neuron-specific genes, and altered glial transcripts in affected brain regions.
- Significant impacts were observed in the cerebellum and hippocampus, with sex-dependent regulation of Gabra1 and Gabra5 expression.
Conclusions:
- The novel Cdkl5E364X mouse model accurately reflects key neurological and behavioral aspects of CDD.
- The study identifies cerebellar GABAergic hypofunction and sex-specific alterations in GABA receptor expression as critical features of CDD.
- Gabra1 and Gabra5 emerge as potential novel druggable targets for therapeutic intervention in CDD.
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