Mice lacking <i>Brinp2</i> or <i>Brinp3</i>, or both, exhibit behaviors consistent with neurodevelopmental disorders

Background: Brinps 1 – 3, and Astrotactins (Astn) 1 and 2, are members of the Membrane Attack Complex / Perforin (MACPF) superfamily that are predominantly expressed in the mammalian brain during development. Genetic variation at the human BRINP2/ASTN1 and BRINP1/ASTN2 loci has been implicated in neurodevelopmental disorders. We, and others, have previously shown that Brinp1-/- mice exhibit behaviour reminiscent of autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD).Method: We created Brinp2-/- mice and Brinp3-/- mice via the Cre-mediated LoxP system to investigate the effect of gene deletion on anatomy and behaviour. Additionally, Brinp2-/-Brinp3-/- double knock-out mice were generated by interbreeding Brinp2-/- and Brinp3-/- mice. Genomic validation was carried out for each knock-out line, followed by histological, weight and behavioural examination. Brinp1-/-Brinp2-/-Brinp3-/- triple knock-out mice were also generated by crossing Brinp2/3 double knock-out mice with previously generated Brinp1-/- mice, and examined by weight and histological analysis.Results: Brinp2-/- and Brinp3-/- mice differ in their behaviour: Brinp2-/- mice are hyperactive, whereas Brinp3-/- mice exhibit marked changes in anxiety-response on the elevated plus maze. Brinp3-/- mice also show evidence of altered sociability. Both Brinp2-/- and Brinp3-/- mice have normal short-term memory, olfactory responses, pre-pulse inhibition and motor learning. The double knock-out mice show behaviours of Brinp2-/- and Brinp3-/- mice, without evidence of new or exacerbated phenotypes. Conclusion: Brinp3 is important in moderation of anxiety, with potential relevance to anxiety disorders. Brinp2 dysfunction resulting in hyperactivity may be relevant to the association of ADHD with chromosome locus 1q25.2. Brinp2-/- and Brinp3-/- genes do not compensate in the mammalian brain and likely have distinct molecular or cell-type specific functions

P. Baehni, professeur en médecine dentaire

P. Baehni, professeur en médecine dentair

Additional file 4: Figure S4. of Brinp1 −/− mice exhibit autism-like behaviour, altered memory, hyperactivity and increased parvalbumin-positive cortical interneuron density

Up-regulation of Astrotactin 1 and Astrotactin 2 mRNA in the embryonic brain and adult hippocampus of Brinp1 knock-out mice (normalised with actin). a qPCR showing a significant increase in Astn2 mRNA, t(9) = 2.829, p = 0.0222, in the developing (E18.5) mouse brain. Levels of exon 3-deleted Brinp1 mRNA (Brinp1Δe3) also increase t(9) = 2.733, p = 0.0231, unpaired Student’s t tests. No significant changes overserved for Brinp2 mRNA levels or Brinp3 mRNA levels. b An increase in Astn1 and Astn2 expression was also detectable in the hippocampus at 6 weeks of the Brinp1 −/− mice: Astn1: t(9) = 3.384, p = 0.0081, Astn2: t(9) = 2.821, p = 0.0200, unpaired Student’s t tests. No significant changes were detected in levels of Brinp1Δe3 mRNA, Brinp2 mRNA or Brinp3 mRNA. c No significant change in expression of Brinps or Astrotactins in the 6-week-old Brinp1 −/− cortex. N = 3 WT, 4 Brinp1 −/−, *p < 0.05, **p < 0.01. Normalisation against actin expression levels. All data represented as the mean ± SE. (PNG 70 kb

Additional file 3: Figure S3. of Brinp1 −/− mice exhibit autism-like behaviour, altered memory, hyperactivity and increased parvalbumin-positive cortical interneuron density

Pyramidal neuron distribution in the adult Brinp1 −/− somatosensory neocortex. a Normal density of NeuN+ cells in the Brinp1 −/− somatosensory neocortex. b No significant change in distribution of NeuN+ cells through somatosensory cortical layers, F(1,6) = 1.423, p = 0.278, repeat measures two-way ANOVA. Sections counterstained with DAPI. c No significant changes in Cux1 cell number or distribution were detected in the Brinp1 −/− somatosensory neocortex, F(1,6) = 2.027, p = 0.204, repeat measures two-way ANOVA. N = 4 WT, 4 Brinp1 −/− mice. *p < 0.05, **p < 0.01. All data represented as the mean ± SD. (PNG 2569 kb

Stuttering associated with a pathogenic variant in the chaperone protein cyclophilin 40

Stuttering is a common speech disorder that interrupts speech fluency and tends to cluster in families. Typically, stuttering is characterized by speech sounds, words or syllables which may be repeated or prolonged and speech that may be further interrupted by hesitations or 'blocks'. Rare variants in a small number of genes encoding lysosomal pathway proteins have been linked to stuttering. We studied a large four-generation family in which persistent stuttering was inherited in an autosomal dominant manner with disruption of the cortico-basal-ganglia-thalamo-cortical network found on imaging. Exome sequencing of three affected family members revealed the PPID c.808C>T (p.Pro270Ser) variant that segregated with stuttering in the family. We generated a Ppid p.Pro270Ser knock-in mouse model and performed ex vivo imaging to assess for brain changes. Diffusion-weighted MRI in the mouse revealed significant microstructural changes in the left corticospinal tract, as previously implicated in stuttering. Quantitative susceptibility mapping also detected changes in cortico-striatal-thalamo-cortical loop tissue composition, consistent with findings in affected family members. This is the first report to implicate a chaperone protein in the pathogenesis of stuttering. The humanized Ppid murine model recapitulates network findings observed in affected family members