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BACKGROUND: Mirror movements are involuntary movements of one hand that mirror intentional movements of the other hand. Congenital mirror movements (CMM) is a rare genetic disorder with autosomal dominant inheritance, in which mirror movements are the main neurological manifestation. CMM is associated with an abnormal decussation of the corticospinal tract, a major motor tract for voluntary movements. RAD51 is known to play a key role in homologous recombination with a critical function in DNA repair. While RAD51 haploinsufficiency was first proposed to explain CMM, other mechanisms could be involved.METHODS: We performed Sanger sequencing of RAD51 in five newly identified CMM families to identify new pathogenic variants. We further investigated the expression of wild-type and mutant RAD51 in the patients' lymphoblasts at mRNA and protein levels. We then characterised the functions of RAD51 altered by non-truncating variants using biochemical approaches.RESULTS: The level of wild-type RAD51 protein was lower in the cells of all patients with CMM compared with their non-carrier relatives. The reduction was less pronounced in asymptomatic carriers. In vitro, mutant RAD51 proteins showed loss-of-function for polymerisation, DNA binding and strand exchange activity.CONCLUSION: Our study demonstrates that RAD51 haploinsufficiency, including loss-of-function of non-truncating variants, results in CMM. The incomplete penetrance likely results from post-transcriptional compensation. Changes in RAD51 levels and/or polymerisation properties could influence guidance of the corticospinal axons during development. Our findings open up new perspectives to understand the role of RAD51 in neurodevelopment.

Figure S4. Unbiased detection of APA for Class I or Class II Olfr 3’UTRs in the male_IS2014 dataset A. Expression levels of Class I Olfr mRNAs (total counts in CDS) related to the number of 3’UTR isoforms per Olfr gene. One-way Kruskal-Wallis test (Chi-squared = 5.5307, df = 3, p-value = 0.136) shows no difference for expression levels between Olfr without APA (single 3’UTR) and others. B. Expression levels of Class II Olfr mRNAs (total counts in CDS) related to the number of 3’UTR isoforms per Olfr gene. One-way Kruskal-Wallis test (Chi-squared = 80.875, df = 4, p

Figure S7. Whole northern blots and demonstration of the probe specificity for Olfr1507 and Olfr15 northern blot experiments. Whole northern blots correspond to Fig. 3g (A) and h (B) and Additional file 4: Figure S2 (C). The specificity of the antisense probes used in northern blots was confirmed by the absence of signals with the sense probes for Olfr1507 (B-C) or Olfr15 (A). See the corresponding figure legends and Table 3 for the detailed description of the probes. (PDF 363 kb)

Figure S3. Unbiased detection of APA for Olfr 3’UTRs in the 4 datasets. A, B, C, D. Expression levels of Olfr mRNAs (total counts in CDS) related to the number of 3’UTR isoforms per Olfr gene. One-way Kruskal-Wallis test (A: Chi square = 88.615, p

Figure S6. Alternative 3’UTR isoforms identified for 2 pilot genes in the 4 datasets. Graphical representation of the alternative 3’UTR isoforms annotated for Olfr1507 or Olfr15 in terms of 3’UTR length (left panels; blue bars) and relative abundance (right panels). (PDF 393 kb)

Figure S5. Comparison of the subsets of annotated Olfr genes between the 4 datasets. A-D. Venn diagrams showing the numbers of Olfr genes with annotated 3’UTR(s) in 2 different datasets. The intersection of the 2 ellipses represent the common Olfr genes retrieved in the 2 datasets. E-H. Correlation of the expression levels between 2 datasets restricted to common Olfr with annotations in both datasets. The expression levels of Olfr genes are similar in the male and female datasets from each experiment (2014 or 2017) as previously shown in [26]. Pearson equation and coefficient were used to estimate the fitting level (p

Figure S1. Set up of IsoSCM min_fold and merge_radius parameters. A-D. Numbers of annotated 3’UTRs are higher when min_fold is set at 0.8 (solid triangles) as compared to default setting at 0.5 min_fold (empty triangles). Blue label = Total numbers of annotated 3’UTRs; grey label = numbers of 3’UTRs merging 3’ends under the 100-nt precision threshold; orange label = numbers of 3’UTRs matching at least one canonical AAUAAA or AUUAAA PAS in a [− 100;+ 100] window. E-F. Increasing merge_radius triggers higher numbers of Olfr genes showing annotation of chimeric exons between adjacent genes (discarded fusions). min_fold is set to 0.8 in E-F. (PDF 392 kb)

Figure S2. Northern blot characterization of the intron-retaining transcript for Olfr1507. Total OM RNAs were separated on an agarose/formaldehyde gel and transferred onto a nitrocellulose membrane. The presence of Olfr1507 mRNAs was detected following hybridization with DIG-labeled antisense probes either in the 5′ exon (5’e), the 5′ intron (5’i), the CDS region (CDS), between the CDS and 3′S ends (3′S) or between the 3′S and 3’M ends (3’M) (see Table 3 for detailed probe description). The major isoform of the Olfr1507 mRNA is characterized by the absence of the 5′ intron that has been excised, and the presence of a short 3’UTR (≈3-kb dark band detected with 5’e, CDS and 3′S probes, not detected with 3’M or 5’i probes); the highest band (indicated with # in Fig. 3g) corresponds to an intron-retaining Olfr1507 mRNA bearing a short 3’UTR (> 7 kb light band detected with 5’e, 5’i, CDS and 3′S probes, not detected with 3’M probe). (PDF 1137 kb)

International audience; BackgroundIn the adult brain, structural plasticity allowing gain or loss of synapses remodels circuits to support learning. In Fragile X Syndrome (FXS), the absence of Fragile X Mental Retardation Protein (FMRP) leads to defects in plasticity and learning deficits. FMRP is a master regulator of local translation but its implication in learning-induced structural plasticity is unknown.MethodsUsing an olfactory learning task requiring adult-born olfactory bulb (OB) neurons and cell-specific ablation of FMRP, we investigated whether learning shapes adult-born neuron morphology during their synaptic integration and its dependence on FMRP. We used αCaMKII mutant mice with altered dendritic localization of αCaMKII mRNA as well as a reporter of αCaMKII local translation to investigate the role of this FMRP mRNA target in learning-dependent structural plasticity.ResultsLearning induces profound changes in dendritic architecture and spine morphology of adult-born neurons that are prevented by ablation of FMRP in adult-born neurons and rescued by an mGLUR5 antagonist. Moreover, dendritically translated αCaMKII is necessary for learning and associated structural modifications and learning triggers an FMRP-dependent increase of αCaMKII dendritic translation in adult-born neurons.ConclusionOur results strongly suggest that FMRP mediates structural plasticity of OB adult-born neurons to support olfactory learning through αCaMKII local translation. This reveals a new role for FMRP-regulated dendritic local translation in learning-induced structural plasticity. This might be of clinical relevance for the understanding of critical periods disruption in autism spectrum disorder patients, among which FXS is the primary monogenic cause.

Rodents contain in their genome more than 1,000 functional odorant receptor genes, which are specifically expressed by the olfactory sensory neurons projecting from the olfactory epithelium to the olfactory bulb. Strong evidence for the presence and local translation of odorant receptor mRNAs in the axon of olfactory sensory neurons was obtained, but no function has been assigned to these axonal mRNAs yet. The aim of this review is to discuss the evidence for the presence and local translation of odorant receptor mRNAs in olfactory sensory axons, and to speculate on their possible function in the wiring of the mouse olfactory sensory projections.

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Background: Autosomal dominant congenital mirror movements (CMM) is a neurodevelopmental disorder characterized by early onset involuntary movements of one side of the body that mirror intentional movements on the contralateral side; these persist throughout life in the absence of other neurological symptoms. The main culprit genes responsible for this condition are RAD51 and DCC. This condition has only been reported in a few families, and the molecular mechanisms linking RAD51 mutations and mirror movements (MM) are poorly understood. Methods: We collected demographic, clinical, and genetic data of a new family with CMM due to a truncating mutation of RAD51. We reviewed the literature to identify all reported patients with CMM due to RAD51 mutations. Results: We identified a heterozygous nonsense mutation c.760C>T (p.Arg254∗) in eight subjects: four with obvious and disabling MM, and four with a mild phenotype. Including our new family, we identified 32 patients from 6 families with CMM linked to RAD51 variants. Discussion: Our findings further support the involvement of RAD51 in CMM pathogenesis. Possible molecular mechanisms involved in CMM pathogenesis are discussed.