Publications by authors named "Claire Chevalier"

19 Publications

  • Page 1 of 1

Primary mouse osteoblast and osteoclast culturing and analysis.

STAR Protoc 2021 Jun 13;2(2):100452. Epub 2021 Apr 13.

Department of Cell Physiology and Metabolism, Centre Médical Universitaire (CMU), Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland.

Mesenchymal-derived osteoblasts play a key role in bone formation via synthesis and mineralization of the bone and bone remodeling. Osteoclasts are multinucleated cells of hematopoietic origin with a role in bone resorption. Here, we describe a protocol for generating primary cultures of these two cell types from bone tissue including the femur, tibia, and humerus of young mice. We describe methods for addressing their activity and/or differentiation, enabling studying the effects of various treatments during or following differentiation . For further practical example of using these protocols, please refer to Chevalier et al. (2020).
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http://dx.doi.org/10.1016/j.xpro.2021.100452DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8065294PMC
June 2021

Multi-influential genetic interactions alter behaviour and cognition through six main biological cascades in Down syndrome mouse models.

Hum Mol Genet 2021 May;30(9):771-788

Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), department of translational medicine and neurogenetics 1 rue Laurent Fries, 67404 Illkirch Graffenstaden, France.

Down syndrome (DS) is the most common genetic form of intellectual disability caused by the presence of an additional copy of human chromosome 21 (Hsa21). To provide novel insights into genotype-phenotype correlations, we used standardized behavioural tests, magnetic resonance imaging and hippocampal gene expression to screen several DS mouse models for the mouse chromosome 16 region homologous to Hsa21. First, we unravelled several genetic interactions between different regions of chromosome 16 and how they contribute significantly to altering the outcome of the phenotypes in brain cognition, function and structure. Then, in-depth analysis of misregulated expressed genes involved in synaptic dysfunction highlighted six biological cascades centred around DYRK1A, GSK3β, NPY, SNARE, RHOA and NPAS4. Finally, we provide a novel vision of the existing altered gene-gene crosstalk and molecular mechanisms targeting specific hubs in DS models that should become central to better understanding of DS and improving the development of therapies.
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http://dx.doi.org/10.1093/hmg/ddab012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8161522PMC
May 2021

Targeting the RHOA pathway improves learning and memory in adult Kctd13 and 16p11.2 deletion mouse models.

Mol Autism 2021 01 13;12(1). Epub 2021 Jan 13.

Université de Strasbourg, CNRS, INSERM, Institut de Génétique Biologie Moléculaire et Cellulaire - UMR 7104 - U1258, IGBMC, 1 rue Laurent Fries, 67404, Illkirch Cedex, France.

Background: Gene copy number variants play an important role in the occurrence of neurodevelopmental disorders. Particularly, the deletion of the 16p11.2 locus is associated with autism spectrum disorder, intellectual disability, and several other features. Earlier studies highlighted the implication of Kctd13 genetic imbalance in 16p11.2 deletion through the regulation of the RHOA pathway.

Methods: Here, we generated a new mouse model with a small deletion of two key exons in Kctd13. Then, we targeted the RHOA pathway to rescue the cognitive phenotypes of the Kctd13 and 16p11.2 deletion mouse models in a pure genetic background. We used a chronic administration of fasudil (HA1077), an inhibitor of the Rho-associated protein kinase, for six weeks in mouse models carrying a heterozygous inactivation of Kctd13, or the deletion of the entire 16p11.2 BP4-BP5 homologous region.

Results: We found that the small Kctd13 heterozygous deletion induced a cognitive phenotype similar to the whole deletion of the 16p11.2 homologous region, in the Del/+ mice. We then showed that chronic fasudil treatment can restore object recognition memory in adult heterozygous mutant mice for Kctd13 and for 16p11.2 deletion. In addition, learning and memory improvement occurred in parallel to change in the RHOA pathway.

Limitations: The Kcdt13 mutant line does not recapitulate all the phenotypes found in the 16p11.2 Del/+ model. In particular, the locomotor activity was not altered at 12 and 18 weeks of age and the object location memory was not defective in 18-week old mutants. Similarly, the increase in locomotor activity was not modified by the treatment in the 16p11.2 Del/+ mouse model, suggesting that other loci were involved in such defects. Rescue was observed only after four weeks of treatment but no long-term experiment has been carried out so far. Finally, we did not check the social behaviour, which requires working in another hybrid genetic background.

Conclusion: These findings confirm KCTD13 as one target gene causing cognitive deficits in 16p11.2 deletion patients, and the relevance of the RHOA pathway as a therapeutic path for 16p11.2 deletion. In addition, they reinforce the contribution of other gene(s) involved in cognitive defects found in the 16p11.2 models in older mice.
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http://dx.doi.org/10.1186/s13229-020-00405-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7805198PMC
January 2021

Warmth Prevents Bone Loss Through the Gut Microbiota.

Cell Metab 2020 10 10;32(4):575-590.e7. Epub 2020 Sep 10.

Department of Cell Physiology and Metabolism, Centre Médical Universitaire (CMU), Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland; Diabetes Center, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland. Electronic address:

Osteoporosis is the most prevalent metabolic bone disease, characterized by low bone mass and microarchitectural deterioration. Here, we show that warmth exposure (34°C) protects against ovariectomy-induced bone loss by increasing trabecular bone volume, connectivity density, and thickness, leading to improved biomechanical bone strength in adult female, as well as in young male mice. Transplantation of the warm-adapted microbiota phenocopies the warmth-induced bone effects. Both warmth and warm microbiota transplantation revert the ovariectomy-induced transcriptomics changes of the tibia and increase periosteal bone formation. Combinatorial metagenomics/metabolomics analysis shows that warmth enhances bacterial polyamine biosynthesis, resulting in higher total polyamine levels in vivo. Spermine and spermidine supplementation increases bone strength, while inhibiting polyamine biosynthesis in vivo limits the beneficial warmth effects on the bone. Our data suggest warmth exposure as a potential treatment option for osteoporosis while providing a mechanistic framework for its benefits in bone disease.
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http://dx.doi.org/10.1016/j.cmet.2020.08.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7116155PMC
October 2020

Oligogenic Effects of 16p11.2 Copy-Number Variation on Craniofacial Development.

Cell Rep 2019 09;28(13):3320-3328.e4

Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093, USA; Beyster Center for Genomics of Psychiatric Diseases, University of California, San Diego, La Jolla, CA 92093, USA; Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA. Electronic address:

A copy-number variant (CNV) of 16p11.2 encompassing 30 genes is associated with developmental and psychiatric disorders, head size, and body mass. The genetic mechanisms that underlie these associations are not understood. To determine the influence of 16p11.2 genes on development, we investigated the effects of CNV on craniofacial structure in humans and model organisms. We show that deletion and duplication of 16p11.2 have "mirror" effects on specific craniofacial features that are conserved between human and rodent models of the CNV. By testing dosage effects of individual genes on the shape of the mandible in zebrafish, we identify seven genes with significant effects individually and find evidence for others when genes were tested in combination. The craniofacial phenotypes of 16p11.2 CNVs represent a model for studying the effects of genes on development, and our results suggest that the associated facial gestalts are attributable to the combined effects of multiple genes.
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http://dx.doi.org/10.1016/j.celrep.2019.08.071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6988705PMC
September 2019

Prenatal treatment with EGCG enriched green tea extract rescues GAD67 related developmental and cognitive defects in Down syndrome mouse models.

Sci Rep 2019 03 8;9(1):3914. Epub 2019 Mar 8.

Université Paris-Diderot, Sorbonne Paris Cité, Adaptive Functional Biology, National Centre for Scientific Research (CNRS), UMR 8251, Paris, France.

Down syndrome is a common genetic disorder caused by trisomy of chromosome 21. Brain development in affected foetuses might be improved through prenatal treatment. One potential target is DYRK1A, a multifunctional kinase encoded by chromosome 21 that, when overexpressed, alters neuronal excitation-inhibition balance and increases GAD67 interneuron density. We used a green tea extract enriched in EGCG to inhibit DYRK1A function only during gestation of transgenic mice overexpressing Dyrk1a (mBACtgDyrk1a). Adult mice treated prenatally displayed reduced levels of inhibitory markers, restored VGAT1/VGLUT1 balance, and rescued density of GAD67 interneurons. Similar results for gabaergic and glutamatergic markers and interneuron density were obtained in Dp(16)1Yey mice, trisomic for 140 chromosome 21 orthologs; thus, prenatal EGCG exhibits efficacy in a more complex DS model. Finally, cognitive and behaviour testing showed that adult Dp(16)1Yey mice treated prenatally had improved novel object recognition memory but do not show improvement with Y maze paradigm. These findings provide empirical support for a prenatal intervention that targets specific neural circuitries.
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http://dx.doi.org/10.1038/s41598-019-40328-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6408590PMC
March 2019

Functional Gut Microbiota Remodeling Contributes to the Caloric Restriction-Induced Metabolic Improvements.

Cell Metab 2018 12 30;28(6):907-921.e7. Epub 2018 Aug 30.

Department of Cell Physiology and Metabolism, Centre Médical Universitaire, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland; Diabetes Centre, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland; Institute of Genetics and Genomics in Geneva, University of Geneva, 1211 Geneva, Switzerland. Electronic address:

Caloric restriction (CR) stimulates development of functional beige fat and extends healthy lifespan. Here we show that compositional and functional changes in the gut microbiota contribute to a number of CR-induced metabolic improvements and promote fat browning. Mechanistically, these effects are linked to a lower expression of the key bacterial enzymes necessary for the lipid A biosynthesis, a critical lipopolysaccharide (LPS) building component. The decreased LPS dictates the tone of the innate immune response during CR, leading to increased eosinophil infiltration and anti-inflammatory macrophage polarization in fat of the CR animals. Genetic and pharmacological suppression of the LPS-TLR4 pathway or transplantation with Tlr4 bone-marrow-derived hematopoietic cells increases beige fat development and ameliorates diet-induced fatty liver, while Tlr4 or microbiota-depleted mice are resistant to further CR-stimulated metabolic alterations. These data reveal signals critical for our understanding of the microbiota-fat signaling axis during CR and provide potential new anti-obesity therapeutics.
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http://dx.doi.org/10.1016/j.cmet.2018.08.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288182PMC
December 2018

WD40-repeat 47, a microtubule-associated protein, is essential for brain development and autophagy.

Proc Natl Acad Sci U S A 2017 10 12;114(44):E9308-E9317. Epub 2017 Oct 12.

Department of Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France;

The family of WD40-repeat (WDR) proteins is one of the largest in eukaryotes, but little is known about their function in brain development. Among 26 WDR genes assessed, we found 7 displaying a major impact in neuronal morphology when inactivated in mice. Remarkably, all seven genes showed corpus callosum defects, including thicker (, , , and ), thinner ( and ), or absent corpus callosum (), revealing a common role for WDR genes in brain connectivity. We focused on the poorly studied WDR47 protein sharing structural homology with LIS1, which causes lissencephaly. In a dosage-dependent manner, mice lacking showed lethality, extensive fiber defects, microcephaly, thinner cortices, and sensory motor gating abnormalities. We showed that WDR47 shares functional characteristics with LIS1 and participates in key microtubule-mediated processes, including neural stem cell proliferation, radial migration, and growth cone dynamics. In absence of WDR47, the exhaustion of late cortical progenitors and the consequent decrease of neurogenesis together with the impaired survival of late-born neurons are likely yielding to the worsening of the microcephaly phenotype postnatally. Interestingly, the WDR47-specific C-terminal to LisH (CTLH) domain was associated with functions in autophagy described in mammals. Silencing WDR47 in hypothalamic GT1-7 neuronal cells and yeast models independently recapitulated these findings, showing conserved mechanisms. Finally, our data identified superior cervical ganglion-10 (SCG10) as an interacting partner of WDR47. Taken together, these results provide a starting point for studying the implications of WDR proteins in neuronal regulation of microtubules and autophagy.
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http://dx.doi.org/10.1073/pnas.1713625114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5676932PMC
October 2017

Mouse models of 17q21.31 microdeletion and microduplication syndromes highlight the importance of Kansl1 for cognition.

PLoS Genet 2017 Jul 13;13(7):e1006886. Epub 2017 Jul 13.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Illkirch, France.

Koolen-de Vries syndrome (KdVS) is a multi-system disorder characterized by intellectual disability, friendly behavior, and congenital malformations. The syndrome is caused either by microdeletions in the 17q21.31 chromosomal region or by variants in the KANSL1 gene. The reciprocal 17q21.31 microduplication syndrome is associated with psychomotor delay, and reduced social interaction. To investigate the pathophysiology of 17q21.31 microdeletion and microduplication syndromes, we generated three mouse models: 1) the deletion (Del/+); or 2) the reciprocal duplication (Dup/+) of the 17q21.31 syntenic region; and 3) a heterozygous Kansl1 (Kans1+/-) model. We found altered weight, general activity, social behaviors, object recognition, and fear conditioning memory associated with craniofacial and brain structural changes observed in both Del/+ and Dup/+ animals. By investigating hippocampus function, we showed synaptic transmission defects in Del/+ and Dup/+ mice. Mutant mice with a heterozygous loss-of-function mutation in Kansl1 displayed similar behavioral and anatomical phenotypes compared to Del/+ mice with the exception of sociability phenotypes. Genes controlling chromatin organization, synaptic transmission and neurogenesis were upregulated in the hippocampus of Del/+ and Kansl1+/- animals. Our results demonstrate the implication of KANSL1 in the manifestation of KdVS phenotypes and extend substantially our knowledge about biological processes affected by these mutations. Clear differences in social behavior and gene expression profiles between Del/+ and Kansl1+/- mice suggested potential roles of other genes affected by the 17q21.31 deletion. Together, these novel mouse models provide new genetic tools valuable for the development of therapeutic approaches.
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http://dx.doi.org/10.1371/journal.pgen.1006886DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5531616PMC
July 2017

Reciprocal Effects on Neurocognitive and Metabolic Phenotypes in Mouse Models of 16p11.2 Deletion and Duplication Syndromes.

PLoS Genet 2016 Feb 12;12(2):e1005709. Epub 2016 Feb 12.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.

The 16p11.2 600 kb BP4-BP5 deletion and duplication syndromes have been associated with developmental delay; autism spectrum disorders; and reciprocal effects on the body mass index, head circumference and brain volumes. Here, we explored these relationships using novel engineered mouse models carrying a deletion (Del/+) or a duplication (Dup/+) of the Sult1a1-Spn region homologous to the human 16p11.2 BP4-BP5 locus. On a C57BL/6N inbred genetic background, Del/+ mice exhibited reduced weight and impaired adipogenesis, hyperactivity, repetitive behaviors, and recognition memory deficits. In contrast, Dup/+ mice showed largely opposite phenotypes. On a F1 C57BL/6N × C3B hybrid genetic background, we also observed alterations in social interaction in the Del/+ and the Dup/+ animals, with other robust phenotypes affecting recognition memory and weight. To explore the dosage effect of the 16p11.2 genes on metabolism, Del/+ and Dup/+ models were challenged with high fat and high sugar diet, which revealed opposite energy imbalance. Transcriptomic analysis revealed that the majority of the genes located in the Sult1a1-Spn region were sensitive to dosage with a major effect on several pathways associated with neurocognitive and metabolic phenotypes. Whereas the behavioral consequence of the 16p11 region genetic dosage was similar in mice and humans with activity and memory alterations, the metabolic defects were opposite: adult Del/+ mice are lean in comparison to the human obese phenotype and the Dup/+ mice are overweight in comparison to the human underweight phenotype. Together, these data indicate that the dosage imbalance at the 16p11.2 locus perturbs the expression of modifiers outside the CNV that can modulate the penetrance, expressivity and direction of effects in both humans and mice.
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http://dx.doi.org/10.1371/journal.pgen.1005709DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4752317PMC
February 2016

Gut Microbiota Orchestrates Energy Homeostasis during Cold.

Cell 2015 Dec;163(6):1360-74

Department of Cell Physiology and Metabolism, Centre Médical Universitaire (CMU), Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland; Diabetes Centre, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland; Division of Biosciences, Institute of Structural and Molecular Biology, University College London (UCL), London WC1E 6BT, UK. Electronic address:

Microbial functions in the host physiology are a result of the microbiota-host co-evolution. We show that cold exposure leads to marked shift of the microbiota composition, referred to as cold microbiota. Transplantation of the cold microbiota to germ-free mice is sufficient to increase insulin sensitivity of the host and enable tolerance to cold partly by promoting the white fat browning, leading to increased energy expenditure and fat loss. During prolonged cold, however, the body weight loss is attenuated, caused by adaptive mechanisms maximizing caloric uptake and increasing intestinal, villi, and microvilli lengths. This increased absorptive surface is transferable with the cold microbiota, leading to altered intestinal gene expression promoting tissue remodeling and suppression of apoptosis-the effect diminished by co-transplanting the most cold-downregulated strain Akkermansia muciniphila during the cold microbiota transfer. Our results demonstrate the microbiota as a key factor orchestrating the overall energy homeostasis during increased demand.
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http://dx.doi.org/10.1016/j.cell.2015.11.004DOI Listing
December 2015

Microbiota depletion promotes browning of white adipose tissue and reduces obesity.

Nat Med 2015 Dec 16;21(12):1497-1501. Epub 2015 Nov 16.

University of Geneva, Faculty of Medicine, Department of Cell Physiology and Metabolism, Centre Médical Universitaire (CMU), Geneva, Switzerland.

Brown adipose tissue (BAT) promotes a lean and healthy phenotype and improves insulin sensitivity. In response to cold or exercise, brown fat cells also emerge in the white adipose tissue (WAT; also known as beige cells), a process known as browning. Here we show that the development of functional beige fat in the inguinal subcutaneous adipose tissue (ingSAT) and perigonadal visceral adipose tissue (pgVAT) is promoted by the depletion of microbiota either by means of antibiotic treatment or in germ-free mice. This leads to improved glucose tolerance and insulin sensitivity and decreased white fat and adipocyte size in lean mice, obese leptin-deficient (ob/ob) mice and high-fat diet (HFD)-fed mice. Such metabolic improvements are mediated by eosinophil infiltration, enhanced type 2 cytokine signaling and M2 macrophage polarization in the subcutaneous white fat depots of microbiota-depleted animals. The metabolic phenotype and the browning of the subcutaneous fat are impaired by the suppression of type 2 cytokine signaling, and they are reversed by recolonization of the antibiotic-treated or germ-free mice with microbes. These results provide insight into the microbiota-fat signaling axis and beige-fat development in health and metabolic disease.
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http://dx.doi.org/10.1038/nm.3994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4675088PMC
December 2015

Analysis of mammalian gene function through broad-based phenotypic screens across a consortium of mouse clinics.

Nat Genet 2015 Sep 27;47(9):969-978. Epub 2015 Jul 27.

Institute for Medical Microbiology, Immunology and Hygiene, Technische Universität München, Munich, Germany.

The function of the majority of genes in the mouse and human genomes remains unknown. The mouse embryonic stem cell knockout resource provides a basis for the characterization of relationships between genes and phenotypes. The EUMODIC consortium developed and validated robust methodologies for the broad-based phenotyping of knockouts through a pipeline comprising 20 disease-oriented platforms. We developed new statistical methods for pipeline design and data analysis aimed at detecting reproducible phenotypes with high power. We acquired phenotype data from 449 mutant alleles, representing 320 unique genes, of which half had no previous functional annotation. We captured data from over 27,000 mice, finding that 83% of the mutant lines are phenodeviant, with 65% demonstrating pleiotropy. Surprisingly, we found significant differences in phenotype annotation according to zygosity. New phenotypes were uncovered for many genes with previously unknown function, providing a powerful basis for hypothesis generation and further investigation in diverse systems.
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http://dx.doi.org/10.1038/ng.3360DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4564951PMC
September 2015

Deletion of the App-Runx1 region in mice models human partial monosomy 21.

Dis Model Mech 2015 Jun 16;8(6):623-34. Epub 2015 Apr 16.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Department of Translational Medicine and Neurogenetics, 1 rue Laurent Fries, Illkirch 67404, France Centre National de la Recherche Scientifique, UMR7104, Illkirch 67404, France Institut National de la Santé et de la Recherche Médicale, U964, Illkirch 67404, France Université de Strasbourg, Illkirch 67404, France Institut Clinique de la Souris, PHENOMIN-ICS, CNRS, INSERM, Université de Strasbourg, 1 rue Laurent Fries, Illkirch 67404, France

Partial monosomy 21 (PM21) is a rare chromosomal abnormality that is characterized by the loss of a variable segment along human chromosome 21 (Hsa21). The clinical phenotypes of this loss are heterogeneous and range from mild alterations to lethal consequences, depending on the affected region of Hsa21. The most common features include intellectual disabilities, craniofacial dysmorphology, short stature, and muscular and cardiac defects. As a complement to human genetic approaches, our team has developed new monosomic mouse models that carry deletions on Hsa21 syntenic regions in order to identify the dosage-sensitive genes that are responsible for the symptoms. We focus here on the Ms5Yah mouse model, in which a 7.7-Mb region has been deleted from the App to Runx1 genes. Ms5Yah mice display high postnatal lethality, with a few surviving individuals showing growth retardation, motor coordination deficits, and spatial learning and memory impairments. Further studies confirmed a gene dosage effect in the Ms5Yah hippocampus, and pinpointed disruptions of pathways related to cell adhesion (involving App, Cntnap5b, Lgals3bp, Mag, Mcam, Npnt, Pcdhb2, Pcdhb3, Pcdhb4, Pcdhb6, Pcdhb7, Pcdhb8, Pcdhb16 and Vwf). Our PM21 mouse model is the first to display morphological abnormalities and behavioural phenotypes similar to those found in affected humans, and it therefore demonstrates the major contribution that the App-Runx1 region has in the pathophysiology of PM21.
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http://dx.doi.org/10.1242/dmm.017814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4457029PMC
June 2015

IGF2 promotes growth of adrenocortical carcinoma cells, but its overexpression does not modify phenotypic and molecular features of adrenocortical carcinoma.

PLoS One 2014 4;9(8):e103744. Epub 2014 Aug 4.

Paris Cardiovascular Center, Institut National de la Santé et de la Recherche Médicale U970, Université Paris Descartes, Paris, France; Département de Biologie Hormonale, Assistance Publique Hôpitaux de Paris, Hôpital Cochin, Paris, France.

Insulin-like growth factor 2 (IGF2) overexpression is an important molecular marker of adrenocortical carcinoma (ACC), which is a rare but devastating endocrine cancer. It is not clear whether IGF2 overexpression modifies the biology and growth of this cancer, thus more studies are required before IGF2 can be considered as a major therapeutic target. We compared the phenotypical, clinical, biological, and molecular characteristics of ACC with or without the overexpression of IGF2, to address these issues. We also carried out a similar analysis in an ACC cell line (H295R) in which IGF2 expression was knocked down with si- or shRNA. We found no significant differences in the clinical, biological and molecular (transcriptomic) traits between IGF2-high and IGF2-low ACC. The absence of IGF2 overexpression had little influence on the activation of tyrosine kinase pathways both in tumors and in H295 cells that express low levels of IGF2. In IGF2-low tumors, other growth factors (FGF9, PDGFA) are more expressed than in IGF2-high tumors, suggesting that they play a compensatory role in tumor progression. In addition, IGF2 knock-down in H295R cells substantially impaired growth (>50% inhibition), blocked cells in G1 phase, and promoted apoptosis (>2-fold). Finally, analysis of the 11p15 locus showed a paternal uniparental disomy in both IGF2-high and IGF2-low tumors, but low IGF2 expression could be explained in most IGF2-low ACC by an additional epigenetic modification at the 11p15 locus. Altogether, these observations confirm the active role of IGF2 in adrenocortical tumor growth, but also suggest that other growth promoting pathways may be involved in a subset of ACC with low IGF2 expression, which creates opportunities for the use of other targeted therapies.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0103744PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4121173PMC
April 2015

Domains of genome-wide gene expression dysregulation in Down's syndrome.

Nature 2014 Apr;508(7496):345-50

1] Department of Genetic Medicine and Development, University of Geneva Medical School, University Hospitals of Geneva, 1211 Geneva, Switzerland [2] iGE3 Institute of Genetics and Genomics of Geneva, 1211 Geneva, Switzerland.

Trisomy 21 is the most frequent genetic cause of cognitive impairment. To assess the perturbations of gene expression in trisomy 21, and to eliminate the noise of genomic variability, we studied the transcriptome of fetal fibroblasts from a pair of monozygotic twins discordant for trisomy 21. Here we show that the differential expression between the twins is organized in domains along all chromosomes that are either upregulated or downregulated. These gene expression dysregulation domains (GEDDs) can be defined by the expression level of their gene content, and are well conserved in induced pluripotent stem cells derived from the twins' fibroblasts. Comparison of the transcriptome of the Ts65Dn mouse model of Down's syndrome and normal littermate mouse fibroblasts also showed GEDDs along the mouse chromosomes that were syntenic in human. The GEDDs correlate with the lamina-associated (LADs) and replication domains of mammalian cells. The overall position of LADs was not altered in trisomic cells; however, the H3K4me3 profile of the trisomic fibroblasts was modified and accurately followed the GEDD pattern. These results indicate that the nuclear compartments of trisomic cells undergo modifications of the chromatin environment influencing the overall transcriptome, and that GEDDs may therefore contribute to some trisomy 21 phenotypes.
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http://dx.doi.org/10.1038/nature13200DOI Listing
April 2014

Missense mutation in the second RNA binding domain reveals a role for Prkra (PACT/RAX) during skull development.

PLoS One 2011 14;6(12):e28537. Epub 2011 Dec 14.

Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America.

Random chemical mutagenesis of the mouse genome can causally connect genes to specific phenotypes. Using this approach, reduced pinna (rep) or microtia, a defect in ear development, was mapped to a small region of mouse chromosome 2. Sequencing of this region established co-segregation of the phenotype (rep) with a mutation in the Prkra gene, which encodes the protein PACT/RAX. Mice homozygous for the mutant Prkra allele had defects not only in ear development but also growth, craniofacial development and ovarian structure. The rep mutation was identified as a missense mutation (Serine 130 to Proline) that did not affect mRNA expression, however the steady state level of RAX protein was significantly lower in the brains of rep mice. The mutant protein, while normal in most biochemical functions, was unable to bind dsRNA. In addition, rep mice displayed altered morphology of the skull that was consistent with a targeted deletion of Prkra showing a contribution of the gene to craniofacial development. These observations identified a specific mutation that reduces steady-state levels of RAX protein and disrupts the dsRNA binding function of the protein, demonstrating the importance of the Prkra gene in various aspects of mouse development.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0028537PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3237451PMC
August 2012

Identification of the translocation breakpoints in the Ts65Dn and Ts1Cje mouse lines: relevance for modeling Down syndrome.

Mamm Genome 2011 Dec 28;22(11-12):674-84. Epub 2011 Sep 28.

Institut de Génétique Biologie Moléculaire et Cellulaire, Translational Medicine and Neuroscience Program, Université de Strasbourg, Illkirch, France.

Down syndrome (DS) is the most frequent genetic disorder leading to intellectual disabilities and is caused by three copies of human chromosome 21. Mouse models are widely used to better understand the physiopathology in DS or to test new therapeutic approaches. The older and the most widely used mouse models are the trisomic Ts65Dn and the Ts1Cje mice. They display deficits similar to those observed in DS people, such as those in behavior and cognition or in neuronal abnormalities. The Ts65Dn model is currently used for further therapeutic assessment of candidate drugs. In both models, the trisomy was induced by reciprocal chromosomal translocations that were not further characterized. Using a comparative genomic approach, we have been able to locate precisely the translocation breakpoint in these two models and we took advantage of this finding to derive a new and more efficient Ts65Dn genotyping strategy. Furthermore, we found that the translocations introduce additional aneuploidy in both models, with a monosomy of seven genes in the most telomeric part of mouse chromosome 12 in the Ts1Cje and a trisomy of 60 centromeric genes on mouse chromosome 17 in the Ts65Dn. Finally, we report here the overexpression of the newly found aneuploid genes in the Ts65Dn heart and we discuss their potential impact on the validity of the DS model.
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http://dx.doi.org/10.1007/s00335-011-9356-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3224224PMC
December 2011
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