title: Embryonic forebrain transcriptome of mice with polyalanine expansion mutations in the ARX homeobox gene.
abstract: The Aristaless-related homeobox (ARX) gene encodes a paired-type homeodomain transcription factor with critical roles in embryonic development. Mutations in ARX give rise to intellectual disability (ID), epilepsy and brain malformation syndromes. To capture the genetics and molecular disruptions that underpin the ARX-associated clinical phenotypes, we undertook a transcriptome wide RNASeq approach to analyse developing (12.5 dpc) telencephalon of mice modelling two recurrent polyalanine expansion mutations with different phenotypic severities in the ARX gene. Here we report 238 genes significantly deregulated (Log2FC  > +/-1.1, P-value <0.05) when both mutations are compared to wild-type (WT) animals. When each mutation is considered separately, a greater number of genes were deregulated in the severe PA1 mice (825) than in the PA2 animals (78). Analysing genes deregulated in either or both mutant strains, we identified 12% as implicated in ID, epilepsy and autism (99/858), with ∼5% of them as putative or known direct targets of ARX transcriptional regulation. We propose a core pathway of transcription regulators, including Hdac4, involved in chromatin condensation and transcriptional repression, and one of its targets, the transcription factor Twist1, as potential drivers of the ID and infantile spasms in patients with ARX polyalanine expansion mutations. We predict that the subsequent disturbance to this pathway is a consequence of ARX protein reduction with a broader and more significant level of disruption in the PA1 in comparison to the PA2 mice. Identifying early triggers of ARX-associated phenotypes contributes to our understanding of particular clusters/pathways underpinning comorbid phenotypes that are shared by many neurodevelopmental disorders.
authors: Department of Paediatrics, Adelaide Medical School.|Robinson Research Institute, University of Adelaide, SA, Australia.
authors: Tessa
authors: T
authors: Mattiske
authors: Department of Paediatrics, Adelaide Medical School.|Robinson Research Institute, University of Adelaide, SA, Australia.
authors: Kristie
authors: K
authors: Lee
authors: Department of Paediatrics, Adelaide Medical School.|Robinson Research Institute, University of Adelaide, SA, Australia.
authors: Jozef
authors: J
authors: Gecz
authors: Inserm, UMR1078, Brest, France.|Brest University, Faculté de Médecine et des Sciences de la Santé, Sfr ScInBioS, Brest, France.
authors: Gaelle
authors: G
authors: Friocourt
authors: Department of Paediatrics, Adelaide Medical School.|Robinson Research Institute, University of Adelaide, SA, Australia.
authors: Cheryl
authors: C
authors: Shoubridge
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004827:Epilepsy / Q000235:genetics* / Q000473:pathology; D018507:Gene Expression Regulation, Developmental; D006655:Histone Deacetylases / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics* / Q000473:pathology; D051379:Mice; D009154:Mutation; D010455:Peptides / Q000235:genetics*; D010641:Phenotype; D016548:Prosencephalon / Q000196:embryology / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics; D015398:Signal Transduction; D013687:Telencephalon / Q000196:embryology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics*; D059467:Transcriptome / Q000235:genetics*
chemical_list: C469265:ARX protein, mouse; D018398:Homeodomain Proteins; D010455:Peptides; D014157:Transcription Factors; C019529:polyalanine; C498618:Hdac5 protein, mouse; D006655:Histone Deacetylases