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Idiopathic pulmonary fibrosis (IPF) is a fatal disorder characterised by progressive, destructive lung scarring. Despite substantial progress, the genetic determinants of this disease remain incompletely defined. Using whole genome and whole exome sequencing data from 752 individuals with sporadic IPF and 119,055 UK Biobank controls, we performed a variant-level exome-wide association study (ExWAS) and gene-level collapsing analyses. Our variant-level analysis revealed a novel association between a rare missense variant in SPDL1 and IPF (NM_017785.5:g.169588475 G > A p.Arg20Gln; p = 2.4 × 10-7, odds ratio = 2.87, 95% confidence interval: 2.03-4.07). This signal was independently replicated in the FinnGen cohort, which contains 1028 cases and 196,986 controls (combined p = 2.2 × 10-20), firmly associating this variant as an IPF risk allele. SPDL1 encodes Spindly, a protein involved in mitotic checkpoint signalling during cell division that has not been previously described in fibrosis. To the best of our knowledge, these results highlight a novel mechanism underlying IPF, providing the potential for new therapeutic discoveries in a disease of great unmet need.

Neurogenesis in the adult brain gives rise to functional neurons, which integrate into neuronal circuits and modulate neural plasticity. Sustained neurogenesis throughout life occurs in the subgranular zone (SGZ) of the dentate gyrus in the hippocampus and is hypothesized to be involved in behavioral/cognitive processes such as memory and in diseases. Genomic imprinting is of critical importance to brain development and normal behavior, and exemplifies how epigenetic states regulate genome function and gene dosage. While most genes are expressed from both alleles, imprinted genes are usually expressed from either the maternally or the paternally inherited chromosome. Here, we show that in contrast to its canonical imprinting in nonneurogenic regions, Delta-like homolog 1 (Dlk1) is expressed biallelically in the SGZ, and both parental alleles are required for stem cell behavior and normal adult neurogenesis in the hippocampus. To evaluate the effects of maternally, paternally, and biallelically inherited mutations within the Dlk1 gene in specific behavioral domains, we subjected Dlk1-mutant mice to a battery of tests that dissociate and evaluate the effects of Dlk1 dosage on spatial learning ability and on anxiety traits. Importantly, reduction in Dlk1 levels triggers specific cognitive abnormalities that affect aspects of discriminating differences in environmental stimuli, emphasizing the importance of selective absence of imprinting in this neurogenic niche.

Neurogenesis in the adult brain gives rise to functional neurons, which integrate into neuronal circuits and modulate neural plasticity. Sustained neurogenesis throughout life occurs in the subgranular zone (SGZ) of the dentate gyrus in the hippocampus and is hypothesized to be involved in behavioral/cognitive processes such as memory and in diseases. Genomic imprinting is of critical importance to brain development and normal behavior, and exemplifies how epigenetic states regulate genome function and gene dosage. While most genes are expressed from both alleles, imprinted genes are usually expressed from either the maternally or the paternally inherited chromosome. Here, we show that in contrast to its canonical imprinting in nonneurogenic regions, Delta-like homolog 1 (Dlk1) is expressed biallelically in the SGZ, and both parental alleles are required for stem cell behavior and normal adult neurogenesis in the hippocampus. To evaluate the effects of maternally, paternally, and biallelically inherited mutations within the Dlk1 gene in specific behavioral domains, we subjected Dlk1-mutant mice to a battery of tests that dissociate and evaluate the effects of Dlk1 dosage on spatial learning ability and on anxiety traits. Importantly, reduction in Dlk1 levels triggers specific cognitive abnormalities that affect aspects of discriminating differences in environmental stimuli, emphasizing the importance of selective absence of imprinting in this neurogenic niche.

Contains fulltext : 137817.pdf (publisher's version ) (Open Access), The recent identification of multiple dominant mutations in the gene encoding beta-catenin in both humans and mice has enabled exploration of the molecular and cellular basis of beta-catenin function in cognitive impairment. In humans, beta-catenin mutations that cause a spectrum of neurodevelopmental disorders have been identified. We identified de novo beta-catenin mutations in patients with intellectual disability, carefully characterized their phenotypes, and were able to define a recognizable intellectual disability syndrome. In parallel, characterization of a chemically mutagenized mouse line that displays features similar to those of human patients with beta-catenin mutations enabled us to investigate the consequences of beta-catenin dysfunction through development and into adulthood. The mouse mutant, designated batface (Bfc), carries a Thr653Lys substitution in the C-terminal armadillo repeat of beta-catenin and displayed a reduced affinity for membrane-associated cadherins. In association with this decreased cadherin interaction, we found that the mutation results in decreased intrahemispheric connections, with deficits in dendritic branching, long-term potentiation, and cognitive function. Our study provides in vivo evidence that dominant mutations in beta-catenin underlie losses in its adhesion-related functions, which leads to severe consequences, including intellectual disability, childhood hypotonia, progressive spasticity of lower limbs, and abnormal craniofacial features in adults.

Contains fulltext : 137817.pdf (publisher's version ) (Open Access), The recent identification of multiple dominant mutations in the gene encoding beta-catenin in both humans and mice has enabled exploration of the molecular and cellular basis of beta-catenin function in cognitive impairment. In humans, beta-catenin mutations that cause a spectrum of neurodevelopmental disorders have been identified. We identified de novo beta-catenin mutations in patients with intellectual disability, carefully characterized their phenotypes, and were able to define a recognizable intellectual disability syndrome. In parallel, characterization of a chemically mutagenized mouse line that displays features similar to those of human patients with beta-catenin mutations enabled us to investigate the consequences of beta-catenin dysfunction through development and into adulthood. The mouse mutant, designated batface (Bfc), carries a Thr653Lys substitution in the C-terminal armadillo repeat of beta-catenin and displayed a reduced affinity for membrane-associated cadherins. In association with this decreased cadherin interaction, we found that the mutation results in decreased intrahemispheric connections, with deficits in dendritic branching, long-term potentiation, and cognitive function. Our study provides in vivo evidence that dominant mutations in beta-catenin underlie losses in its adhesion-related functions, which leads to severe consequences, including intellectual disability, childhood hypotonia, progressive spasticity of lower limbs, and abnormal craniofacial features in adults.

Contains fulltext : 137817.pdf (publisher's version ) (Open Access), The recent identification of multiple dominant mutations in the gene encoding beta-catenin in both humans and mice has enabled exploration of the molecular and cellular basis of beta-catenin function in cognitive impairment. In humans, beta-catenin mutations that cause a spectrum of neurodevelopmental disorders have been identified. We identified de novo beta-catenin mutations in patients with intellectual disability, carefully characterized their phenotypes, and were able to define a recognizable intellectual disability syndrome. In parallel, characterization of a chemically mutagenized mouse line that displays features similar to those of human patients with beta-catenin mutations enabled us to investigate the consequences of beta-catenin dysfunction through development and into adulthood. The mouse mutant, designated batface (Bfc), carries a Thr653Lys substitution in the C-terminal armadillo repeat of beta-catenin and displayed a reduced affinity for membrane-associated cadherins. In association with this decreased cadherin interaction, we found that the mutation results in decreased intrahemispheric connections, with deficits in dendritic branching, long-term potentiation, and cognitive function. Our study provides in vivo evidence that dominant mutations in beta-catenin underlie losses in its adhesion-related functions, which leads to severe consequences, including intellectual disability, childhood hypotonia, progressive spasticity of lower limbs, and abnormal craniofacial features in adults.