Gisèle Bonne - Academia.edu (original) (raw)

Papers by Gisèle Bonne

Research paper thumbnail of Solving patients with rare diseases through programmatic reanalysis of genome-phenome data

European Journal of Human Genetics, 2021

Reanalysis of inconclusive exome/genome sequencing data increases the diagnosis yield of patients... more Reanalysis of inconclusive exome/genome sequencing data increases the diagnosis yield of patients with rare diseases. However, the cost and efforts required for reanalysis prevent its routine implementation in research and clinical environments. The Solve-RD project aims to reveal the molecular causes underlying undiagnosed rare diseases. One of the goals is to implement innovative approaches to reanalyse the exomes and genomes from thousands of well-studied undiagnosed cases. The raw genomic data is submitted to Solve-RD through the RD-Connect Genome-Phenome Analysis Platform (GPAP) together with standardised phenotypic and pedigree data. We have developed a programmatic workflow to reanalyse genome-phenome data. It uses the RD-Connect GPAP’s Application Programming Interface (API) and relies on the big-data technologies upon which the system is built. We have applied the workflow to prioritise rare known pathogenic variants from 4411 undiagnosed cases. The queries returned an aver...

Research paper thumbnail of Solving unsolved rare neurological diseases—a Solve-RD viewpoint

European Journal of Human Genetics, 2021

Systematic re-analysis of coding variation Unsolved WES datasets (fastq) from 2048 families with ... more Systematic re-analysis of coding variation Unsolved WES datasets (fastq) from 2048 families with RNDs were submitted by clinical sites of ERN-RND [4] to the RD-Connect Genome-Phenome Analysis Platform. Genomic data were processed and filtered as detailed [5]. The Solve-RD SNV/Indel working group reported back 74,456 variants in Members of the Solve-RD-DITF-RND and The Solve-RD Consortium are listed in below Acknowledgements.

Research paper thumbnail of N-acetyl cysteine alleviates oxidative stress and protects mice from dilated cardiomyopathy caused by mutations in nuclear A-type lamins gene

Human molecular genetics, 2018

Cardiomyopathy caused by lamin A/C gene (LMNA) mutations (hereafter referred as LMNA cardiomyopat... more Cardiomyopathy caused by lamin A/C gene (LMNA) mutations (hereafter referred as LMNA cardiomyopathy) is an anatomic and pathologic condition associated with muscular and electrical dysfunction of the heart, often leading to heart failure-related disability. There is currently no specific therapy available for patients that target the molecular pathophysiology of LMNA cardiomyopathy. We showed here an increase in oxidative stress levels in the hearts of mice carrying LMNA mutation, associated with a decrease of the key cellular antioxidant glutathione (GHS). Oral administration of N-acetyl cysteine, a GHS precursor, led to a marked improvement of GHS content, a decrease in oxidative stress markers including protein carbonyls and an improvement of left ventricular structure and function in a model of LMNA cardiomyopathy. Collectively, our novel results provide therapeutic insights into LMNA cardiomyopathy.

Research paper thumbnail of Autophagic degradation of nuclear components in mammalian cells

Autophagy, 2009

Autophagy is an evolutionarily conserved intracellular mechanism for the degradation of organelle... more Autophagy is an evolutionarily conserved intracellular mechanism for the degradation of organelles and proteins. Here we demonstrate the presence of perinuclear autophagosomes/ autolysosomes containing nuclear components in nuclear envelopathies caused by mutations in the genes encoding A-type lamins (LMNA) and emerin (EMD). These autophagosomes/ autolysosomes were sometimes bigger than a nucleus. The autophagic nature is further supported by upregulation of LC3-II in Lmna H222P/H222P fibroblasts. In addition, inhibition of autophagy led to the accumulation of nuclear abnormalities and reduced cell viability, strongly suggesting a beneficial role of autophagy, at least in these cells. Similar giant autophagosomes/ autolysosomes were seen even in wild-type cells, albeit rarely, implying that this "nucleophagy" is not confined to the diseased condition, but may be seen even in physiologic conditions to clean up nuclear wastes produced by nuclear damage.

Research paper thumbnail of Truncated prelamin A expression in HGPS-like patients: a transcriptional study

European Journal of Human Genetics, 2015

Premature aging syndromes are rare genetic disorders mimicking clinical and molecular features of... more Premature aging syndromes are rare genetic disorders mimicking clinical and molecular features of aging. A recently identified group of premature aging syndromes is linked to mutation of the LMNA gene encoding lamins A and C, and is associated with nuclear deformation and dysfunction. Hutchinson-Gilford progeria syndrome (HGPS) was the first premature aging syndrome linked to LMNA mutation and its molecular bases have been deeply investigated. It is due to a recurrent de novo mutation leading to aberrant splicing and the production of a truncated and toxic nuclear lamin A precursor (prelamin AΔ50), also called progerin. In this work and based on the literature data, we propose to distinguish two main groups of premature aging laminopathies: (1) HGPS and HGP-like syndromes, which share clinical features due to hampered processing and intranuclear toxic accumulation of prelamin A isoforms; and (2) APS (atypical progeria syndromes), due to dominant or recessive missense mutations affecting lamins A and C. Among HGPS-like patients, several deleted prelamin A transcripts (prelamin AΔ50, AΔ35 and AΔ90) have been described. The purpose of this work was to characterize those transcripts in eight patients affected with HGP-like rare syndromes. When fibroblasts were available, the relationships between the presence and ratios of these transcripts and other parameters were studied, aiming to increase our understanding of genotype-phenotype relationships in HGPS-like patients. Altogether our results evidence that progerin accumulation is the major pathogenetic mechanism responsible for HGP-like syndromes due to mutations near the donor splice site of exon 11.

Research paper thumbnail of ColVI myopathies: where do we stand, where do we go?

Skeletal Muscle, 2011

Collagen VI myopathies, caused by mutations in the genes encoding collagen type VI (ColVI), repre... more Collagen VI myopathies, caused by mutations in the genes encoding collagen type VI (ColVI), represent a clinical continuum with Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy (BM) at each end of the spectrum, and less well-defined intermediate phenotypes in between. ColVI myopathies also share common features with other disorders associated with prominent muscle contractures, making differential diagnosis difficult. This group of disorders, under-recognized for a long time, has aroused much interest over the past decade, with important advances made in understanding its molecular pathogenesis. Indeed, numerous mutations have now been reported in the COL6A1, COL6A2 and COL6A3 genes, a large proportion of which are de novo and exert dominant-negative effects. Genotype-phenotype correlations have also started to emerge, which reflect the various pathogenic mechanisms at play in these disorders: dominant de novo exon splicing that enables the synthesis and secretion of mutant tetramers and homozygous nonsense mutations that lead to premature termination of translation and complete loss of function are associated with early-onset, severe phenotypes. In this review, we present the current state of diagnosis and research in the field of ColVI myopathies. The past decade has provided significant advances, with the identification of altered cellular functions in animal models of ColVI myopathies and in patient samples. In particular, mitochondrial dysfunction and a defect in the autophagic clearance system of skeletal muscle have recently been reported, thereby opening potential therapeutic avenues.

Research paper thumbnail of Complex Interactions between Human Myoblasts and the Surrounding 3D Fibrin-Based Matrix

PLoS ONE, 2012

Anchorage of muscle cells to the extracellular matrix is crucial for a range of fundamental biolo... more Anchorage of muscle cells to the extracellular matrix is crucial for a range of fundamental biological processes including migration, survival and differentiation. Three-dimensional (3D) culture has been proposed to provide a more physiological in vitro model of muscle growth and differentiation than routine 2D cultures. However, muscle cell adhesion and cell-matrix interplay of engineered muscle tissue remain to be determined. We have characterized cell-matrix interactions in 3D muscle culture and analyzed their consequences on cell differentiation. Human myoblasts were embedded in a fibrin matrix cast between two posts, cultured until confluence, and then induced to differentiate. Myoblasts in 3D aligned along the longitudinal axis of the gel. They displayed actin stress fibers evenly distributed around the nucleus and a cortical mesh of thin actin filaments. Adhesion sites in 3D were smaller in size than in rigid 2D culture but expression of adhesion site proteins, including a5 integrin and vinculin, was higher in 3D compared with 2D (p,0.05). Myoblasts and myotubes in 3D exhibited thicker and ellipsoid nuclei instead of the thin disk-like shape of the nuclei in 2D (p,0.001). Differentiation kinetics were faster in 3D as demonstrated by higher mRNA concentrations of a-actinin and myosin. More important, the elastic modulus of engineered muscle tissues increased significantly from 3.560.8 to 7.464.7 kPa during proliferation (p,0.05) and reached 12.266.0 kPa during differentiation (p,0.05), thus attesting the increase of matrix stiffness during proliferation and differentiation of the myocytes. In conclusion, we reported modulations of the adhesion complexes, the actin cytoskeleton and nuclear shape in 3D compared with routine 2D muscle culture. These findings point to complex interactions between muscle cells and the surrounding matrix with dynamic regulation of the cell-matrix stiffness.

Research paper thumbnail of El Pyruvate Dehydrogenase Deficiency in a Child with Motor Neuropathy

Pediatric Research, 1993

Supported by thc AFM (Association Fran~aise contre les Myopathies): a fellow-Was a bilateral and ... more Supported by thc AFM (Association Fran~aise contre les Myopathies): a fellow-Was a bilateral and distal lower limb weakness, but no sensory ship to v.G. and grants to C.M. symptoms or pain. The deep tendon reflexes were absent, and

Research paper thumbnail of G.P.5.04 Autosomal recessive Emery–Dreifuss muscular dystrophy caused by a homozygous lamin A/C mutation

Neuromuscular Disorders, 2007

Research paper thumbnail of 199th ENMC international workshop: FHL1 related myopathies, June 7–9, 2013, Naarden, The Netherlands

Neuromuscular Disorders, 2014

Research paper thumbnail of 141st ENMC International Workshop Inaugural Meeting of the EURO-Laminopathies Project Nuclear Envelope-linked Rare Human Diseases: From Molecular Pathophysiology towards Clinical Applications 10–12 March 2006, Naarden, The Netherlands

Neuromuscular Disorders, 2007

Research paper thumbnail of LMNA mutations in atypical Werner's syndrome

Research paper thumbnail of Guiding the molecular diagnosis of hypertrophic cardiomyopathy

The Journal of Thoracic and Cardiovascular Surgery, 2012

Research paper thumbnail of Meta-analysis of clinical characteristics of 299 carriers of LMNA gene mutations: do lamin A/C mutations portend a high risk of sudden death?

Journal of Molecular Medicine, 2004

Meta-analysis of clinical characteristics of 299 carriers of LMNA gene mutations: do lamin A/C mu... more Meta-analysis of clinical characteristics of 299 carriers of LMNA gene mutations: do lamin A/C mutations portend a high risk of sudden death?

Research paper thumbnail of Cellular micro-environments reveal defective mechanosensing responses and elevated YAP signaling in LMNA-mutated muscle precursors

Journal of Cell Science, 2014

The mechanisms underlying cell response to mechanical forces are critical for muscle development ... more The mechanisms underlying cell response to mechanical forces are critical for muscle development and functionality. We aim to determine whether mutations of the LMNA gene causing congenital muscular dystrophy impair the ability of muscle precursors to sense tissue stiffness and to respond to mechanical challenge. We found that LMNA-mutated myoblasts (LMNA) embedded in soft matrix did not align along the gel axis whereas control myoblasts did. LMNA myoblasts were unable to tune their cytoskeletal tension to the tissue stiffness as attested by inappropriate cell-matrix adhesion sites and cytoskeletal tension in soft versus rigid substrates or after mechanical challenge. Importantly, in soft 2D and/or static 3D conditions, LMNA myoblasts demonstrated enhanced activation of Yes-Associated Protein (YAP) signaling pathway that was paradoxically reduced after cyclic stretch. SiRNA-mediated downregulation of YAP reduced adhesion and actin stress fibers in LMNA myoblasts. This is the first d...

Research paper thumbnail of N-terminal Pro brain natriuretic peptide is a reliable biomarker of reduced myocardial contractility in patients with lamin A/C gene mutations

International Journal of Cardiology, 2011

Background: Recently, concerns have been raised about a possible lack of sensitivity of biomarker... more Background: Recently, concerns have been raised about a possible lack of sensitivity of biomarkers to detect left ventricular (LV) dysfunction in patients with myopathies. We examined the ability of the N-terminal brain natriuretic peptide (NT-proBNP) to detect LV or right ventricular (RV) dysfunction in patients with lamin A/C (LMNA) gene mutations. Methods: We prospectively measured plasma NT-proBNP in consecutive patients with documented LMNA mutations and age-sex matched controls. All patients underwent standard echocardiography implemented by pulsed tissue-Doppler echocardiography (TDE). Results: Twenty-three patients were included (10 males, mean age 39.2±18.9 years);10 had previous atrial arrhythmias, 8 had been implanted with cardioverter defibrillator for primary prevention of sudden death, 5 patients were of NYHA class II and 18 of NHYA class I. Sinus rhythm was recorded in all. NT-proBNP was increased in LMNA patients versus controls (123±229 versus 26 ±78 pg/ml, p=0.0004); 7 patients had depressed LV and/or RV contractility. Patients with reduced LV or RV contractility had increased mean NT-proBNP (341±1032 pg/ml versus 80±79 pg/ml in patients with normal myocardial contractility, p=0.004). Receiver-operating-characteristics analysis shows that NT-proBNP reliably detected depressed contractility (area under the curve 0.889 [0.697-1.000]). Sensitivity and specificity were 88% and 83% respectively, applying manufacturer's recommended cutoff concentration of 125 pg/ml. Conclusion: NT-proBNP reliably detected the presence of reduced LV/RV contractility in LMNA patients.

Research paper thumbnail of Mouse model carrying H222P- Lmna mutation develops muscular dystrophy and dilated cardiomyopathy similar to human striated muscle laminopathies

Human Molecular Genetics, 2004

Laminopathies are a group of disorders caused by mutations in the LMNA gene encoding A-type lamin... more Laminopathies are a group of disorders caused by mutations in the LMNA gene encoding A-type lamins, components of the nuclear lamina. Three of these disorders affect specifically the skeletal and/or cardiac muscles, and their pathogenic mechanisms are still unknown. We chose the LMNA H222P missense mutation identified in a family with autosomal dominant Emery-Dreifuss muscular dystrophy, one of the striated muscle-specific laminopathies, to create a faithful mouse model of this type of laminopathy. The mutant mice exhibit overtly normal embryonic development and sexual maturity. At adulthood, male homozygous mice display reduced locomotion activity with abnormal stiff walking posture and all of them die by 9 months of age. As for cardiac phenotype, they develop chamber dilation and hypokinesia with conduction defects. These abnormal skeletal and cardiac features were also observed in the female homozygous mice but with a later-onset than in males. Histopathological analysis of the mice revealed muscle degeneration with fibrosis associated with dislocation of heterochromatin and activation of Smad signalling in heart and skeletal muscles. These results demonstrate that Lmna H222P/H222P mice represent a good model for studying laminopathies affecting striated muscles as they develop a dystrophic condition of both skeletal and cardiac muscles similar to the human diseases.

Research paper thumbnail of Evidence for FHL1 as a novel disease gene for isolated hypertrophic cardiomyopathy

Human Molecular Genetics, 2012

Hypertrophic cardiomyopathy (HCM) is characterized by asymmetric left ventricular hypertrophy, di... more Hypertrophic cardiomyopathy (HCM) is characterized by asymmetric left ventricular hypertrophy, diastolic dysfunction and myocardial disarray. HCM is caused by mutations in sarcomeric genes, but in >40% of patients, the mutation is not yet identified. We hypothesized that FHL1, encoding four-and-a-half-LIM domains 1, could be another disease gene since it has been shown to cause distinct myopathies, sometimes associated with cardiomyopathy. We evaluated 121 HCM patients, devoid of a mutation in known disease genes. We identified three novel variants in FHL1 (c.134delA/K45Sfs, c.459C>A/C153X and c.827G>C/ C276S). Whereas the c.459C>A variant was associated with muscle weakness in some patients, the c.134delA and c.827G>C variants were associated with isolated HCM. Gene transfer of the latter variants in C2C12 myoblasts and cardiac myocytes revealed reduced levels of FHL1 mutant proteins, which could be rescued by proteasome inhibition. Contractility measurements after adeno-associated virus transduction in rat-engineered heart tissue (EHT) showed: (i) higher and lower forces of contraction with K45Sfs and C276S, respectively, and (ii) prolonged contraction and relaxation with both mutants. All mutants except one activated the fetal hypertrophic gene program in EHT. In conclusion, this study provides evidence for FHL1 to be a novel gene for isolated HCM. These data, together with previous findings of proteasome impairment in HCM, suggest that FHL1 mutant proteins may act as poison peptides, leading to hypertrophy, diastolic dysfunction and/or altered contractility, all features of HCM.

Research paper thumbnail of A centronuclear myopathy-dynamin 2 mutation impairs autophagy in mice

Traffic (Copenhagen, Denmark), 2012

Dynamin 2 (Dnm2) is involved in endocytosis and intracellular membrane trafficking through its fu... more Dynamin 2 (Dnm2) is involved in endocytosis and intracellular membrane trafficking through its function in vesicle formation from distinct membrane compartments. Heterozygous mutations in the DNM2 gene cause dominant centronuclear myopathy or Charcot-Marie-Tooth neuropathy. We generated a knock-in KI-Dnm2(R465W) mouse model expressing the most frequent human mutation and recently reported that heterozygous mice progressively developed a myopathy. We investigated here the cause of neonatal lethality occurring in homozygous mice. We show that homozygous mice present at birth with a reduced body weight, hypoglycemia, increased liver glycogen content and hepatomegaly, in agreement with a defect in neonatal autophagy. In vitro studies performed in homozygous embryonic fibroblasts point out to a decrease in the autophagy flux prior to degradation at the autolysosome. We show that starved homozygous cells have a higher number of immature autophagy-related structures probably due to a defec...

Research paper thumbnail of Emery-Dreifuss muscular dystrophy

European Journal of Human Genetics, 2002

Emery-Dreifuss muscular dystrophy (EDMD) is characterised by early contractures, slowly progressi... more Emery-Dreifuss muscular dystrophy (EDMD) is characterised by early contractures, slowly progressive muscle wasting and weakness with a distinctive humero-peroneal distribution and cardiac conduction defects leading to dilated cardiomyopathy. The genes known to be responsible for EDMD encode proteins associated with the nuclear envelope: the emerin and the lamins A and C.

Research paper thumbnail of Solving patients with rare diseases through programmatic reanalysis of genome-phenome data

European Journal of Human Genetics, 2021

Reanalysis of inconclusive exome/genome sequencing data increases the diagnosis yield of patients... more Reanalysis of inconclusive exome/genome sequencing data increases the diagnosis yield of patients with rare diseases. However, the cost and efforts required for reanalysis prevent its routine implementation in research and clinical environments. The Solve-RD project aims to reveal the molecular causes underlying undiagnosed rare diseases. One of the goals is to implement innovative approaches to reanalyse the exomes and genomes from thousands of well-studied undiagnosed cases. The raw genomic data is submitted to Solve-RD through the RD-Connect Genome-Phenome Analysis Platform (GPAP) together with standardised phenotypic and pedigree data. We have developed a programmatic workflow to reanalyse genome-phenome data. It uses the RD-Connect GPAP’s Application Programming Interface (API) and relies on the big-data technologies upon which the system is built. We have applied the workflow to prioritise rare known pathogenic variants from 4411 undiagnosed cases. The queries returned an aver...

Research paper thumbnail of Solving unsolved rare neurological diseases—a Solve-RD viewpoint

European Journal of Human Genetics, 2021

Systematic re-analysis of coding variation Unsolved WES datasets (fastq) from 2048 families with ... more Systematic re-analysis of coding variation Unsolved WES datasets (fastq) from 2048 families with RNDs were submitted by clinical sites of ERN-RND [4] to the RD-Connect Genome-Phenome Analysis Platform. Genomic data were processed and filtered as detailed [5]. The Solve-RD SNV/Indel working group reported back 74,456 variants in Members of the Solve-RD-DITF-RND and The Solve-RD Consortium are listed in below Acknowledgements.

Research paper thumbnail of N-acetyl cysteine alleviates oxidative stress and protects mice from dilated cardiomyopathy caused by mutations in nuclear A-type lamins gene

Human molecular genetics, 2018

Cardiomyopathy caused by lamin A/C gene (LMNA) mutations (hereafter referred as LMNA cardiomyopat... more Cardiomyopathy caused by lamin A/C gene (LMNA) mutations (hereafter referred as LMNA cardiomyopathy) is an anatomic and pathologic condition associated with muscular and electrical dysfunction of the heart, often leading to heart failure-related disability. There is currently no specific therapy available for patients that target the molecular pathophysiology of LMNA cardiomyopathy. We showed here an increase in oxidative stress levels in the hearts of mice carrying LMNA mutation, associated with a decrease of the key cellular antioxidant glutathione (GHS). Oral administration of N-acetyl cysteine, a GHS precursor, led to a marked improvement of GHS content, a decrease in oxidative stress markers including protein carbonyls and an improvement of left ventricular structure and function in a model of LMNA cardiomyopathy. Collectively, our novel results provide therapeutic insights into LMNA cardiomyopathy.

Research paper thumbnail of Autophagic degradation of nuclear components in mammalian cells

Autophagy, 2009

Autophagy is an evolutionarily conserved intracellular mechanism for the degradation of organelle... more Autophagy is an evolutionarily conserved intracellular mechanism for the degradation of organelles and proteins. Here we demonstrate the presence of perinuclear autophagosomes/ autolysosomes containing nuclear components in nuclear envelopathies caused by mutations in the genes encoding A-type lamins (LMNA) and emerin (EMD). These autophagosomes/ autolysosomes were sometimes bigger than a nucleus. The autophagic nature is further supported by upregulation of LC3-II in Lmna H222P/H222P fibroblasts. In addition, inhibition of autophagy led to the accumulation of nuclear abnormalities and reduced cell viability, strongly suggesting a beneficial role of autophagy, at least in these cells. Similar giant autophagosomes/ autolysosomes were seen even in wild-type cells, albeit rarely, implying that this "nucleophagy" is not confined to the diseased condition, but may be seen even in physiologic conditions to clean up nuclear wastes produced by nuclear damage.

Research paper thumbnail of Truncated prelamin A expression in HGPS-like patients: a transcriptional study

European Journal of Human Genetics, 2015

Premature aging syndromes are rare genetic disorders mimicking clinical and molecular features of... more Premature aging syndromes are rare genetic disorders mimicking clinical and molecular features of aging. A recently identified group of premature aging syndromes is linked to mutation of the LMNA gene encoding lamins A and C, and is associated with nuclear deformation and dysfunction. Hutchinson-Gilford progeria syndrome (HGPS) was the first premature aging syndrome linked to LMNA mutation and its molecular bases have been deeply investigated. It is due to a recurrent de novo mutation leading to aberrant splicing and the production of a truncated and toxic nuclear lamin A precursor (prelamin AΔ50), also called progerin. In this work and based on the literature data, we propose to distinguish two main groups of premature aging laminopathies: (1) HGPS and HGP-like syndromes, which share clinical features due to hampered processing and intranuclear toxic accumulation of prelamin A isoforms; and (2) APS (atypical progeria syndromes), due to dominant or recessive missense mutations affecting lamins A and C. Among HGPS-like patients, several deleted prelamin A transcripts (prelamin AΔ50, AΔ35 and AΔ90) have been described. The purpose of this work was to characterize those transcripts in eight patients affected with HGP-like rare syndromes. When fibroblasts were available, the relationships between the presence and ratios of these transcripts and other parameters were studied, aiming to increase our understanding of genotype-phenotype relationships in HGPS-like patients. Altogether our results evidence that progerin accumulation is the major pathogenetic mechanism responsible for HGP-like syndromes due to mutations near the donor splice site of exon 11.

Research paper thumbnail of ColVI myopathies: where do we stand, where do we go?

Skeletal Muscle, 2011

Collagen VI myopathies, caused by mutations in the genes encoding collagen type VI (ColVI), repre... more Collagen VI myopathies, caused by mutations in the genes encoding collagen type VI (ColVI), represent a clinical continuum with Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy (BM) at each end of the spectrum, and less well-defined intermediate phenotypes in between. ColVI myopathies also share common features with other disorders associated with prominent muscle contractures, making differential diagnosis difficult. This group of disorders, under-recognized for a long time, has aroused much interest over the past decade, with important advances made in understanding its molecular pathogenesis. Indeed, numerous mutations have now been reported in the COL6A1, COL6A2 and COL6A3 genes, a large proportion of which are de novo and exert dominant-negative effects. Genotype-phenotype correlations have also started to emerge, which reflect the various pathogenic mechanisms at play in these disorders: dominant de novo exon splicing that enables the synthesis and secretion of mutant tetramers and homozygous nonsense mutations that lead to premature termination of translation and complete loss of function are associated with early-onset, severe phenotypes. In this review, we present the current state of diagnosis and research in the field of ColVI myopathies. The past decade has provided significant advances, with the identification of altered cellular functions in animal models of ColVI myopathies and in patient samples. In particular, mitochondrial dysfunction and a defect in the autophagic clearance system of skeletal muscle have recently been reported, thereby opening potential therapeutic avenues.

Research paper thumbnail of Complex Interactions between Human Myoblasts and the Surrounding 3D Fibrin-Based Matrix

PLoS ONE, 2012

Anchorage of muscle cells to the extracellular matrix is crucial for a range of fundamental biolo... more Anchorage of muscle cells to the extracellular matrix is crucial for a range of fundamental biological processes including migration, survival and differentiation. Three-dimensional (3D) culture has been proposed to provide a more physiological in vitro model of muscle growth and differentiation than routine 2D cultures. However, muscle cell adhesion and cell-matrix interplay of engineered muscle tissue remain to be determined. We have characterized cell-matrix interactions in 3D muscle culture and analyzed their consequences on cell differentiation. Human myoblasts were embedded in a fibrin matrix cast between two posts, cultured until confluence, and then induced to differentiate. Myoblasts in 3D aligned along the longitudinal axis of the gel. They displayed actin stress fibers evenly distributed around the nucleus and a cortical mesh of thin actin filaments. Adhesion sites in 3D were smaller in size than in rigid 2D culture but expression of adhesion site proteins, including a5 integrin and vinculin, was higher in 3D compared with 2D (p,0.05). Myoblasts and myotubes in 3D exhibited thicker and ellipsoid nuclei instead of the thin disk-like shape of the nuclei in 2D (p,0.001). Differentiation kinetics were faster in 3D as demonstrated by higher mRNA concentrations of a-actinin and myosin. More important, the elastic modulus of engineered muscle tissues increased significantly from 3.560.8 to 7.464.7 kPa during proliferation (p,0.05) and reached 12.266.0 kPa during differentiation (p,0.05), thus attesting the increase of matrix stiffness during proliferation and differentiation of the myocytes. In conclusion, we reported modulations of the adhesion complexes, the actin cytoskeleton and nuclear shape in 3D compared with routine 2D muscle culture. These findings point to complex interactions between muscle cells and the surrounding matrix with dynamic regulation of the cell-matrix stiffness.

Research paper thumbnail of El Pyruvate Dehydrogenase Deficiency in a Child with Motor Neuropathy

Pediatric Research, 1993

Supported by thc AFM (Association Fran~aise contre les Myopathies): a fellow-Was a bilateral and ... more Supported by thc AFM (Association Fran~aise contre les Myopathies): a fellow-Was a bilateral and distal lower limb weakness, but no sensory ship to v.G. and grants to C.M. symptoms or pain. The deep tendon reflexes were absent, and

Research paper thumbnail of G.P.5.04 Autosomal recessive Emery–Dreifuss muscular dystrophy caused by a homozygous lamin A/C mutation

Neuromuscular Disorders, 2007

Research paper thumbnail of 199th ENMC international workshop: FHL1 related myopathies, June 7–9, 2013, Naarden, The Netherlands

Neuromuscular Disorders, 2014

Research paper thumbnail of 141st ENMC International Workshop Inaugural Meeting of the EURO-Laminopathies Project Nuclear Envelope-linked Rare Human Diseases: From Molecular Pathophysiology towards Clinical Applications 10–12 March 2006, Naarden, The Netherlands

Neuromuscular Disorders, 2007

Research paper thumbnail of LMNA mutations in atypical Werner's syndrome

Research paper thumbnail of Guiding the molecular diagnosis of hypertrophic cardiomyopathy

The Journal of Thoracic and Cardiovascular Surgery, 2012

Research paper thumbnail of Meta-analysis of clinical characteristics of 299 carriers of LMNA gene mutations: do lamin A/C mutations portend a high risk of sudden death?

Journal of Molecular Medicine, 2004

Meta-analysis of clinical characteristics of 299 carriers of LMNA gene mutations: do lamin A/C mu... more Meta-analysis of clinical characteristics of 299 carriers of LMNA gene mutations: do lamin A/C mutations portend a high risk of sudden death?

Research paper thumbnail of Cellular micro-environments reveal defective mechanosensing responses and elevated YAP signaling in LMNA-mutated muscle precursors

Journal of Cell Science, 2014

The mechanisms underlying cell response to mechanical forces are critical for muscle development ... more The mechanisms underlying cell response to mechanical forces are critical for muscle development and functionality. We aim to determine whether mutations of the LMNA gene causing congenital muscular dystrophy impair the ability of muscle precursors to sense tissue stiffness and to respond to mechanical challenge. We found that LMNA-mutated myoblasts (LMNA) embedded in soft matrix did not align along the gel axis whereas control myoblasts did. LMNA myoblasts were unable to tune their cytoskeletal tension to the tissue stiffness as attested by inappropriate cell-matrix adhesion sites and cytoskeletal tension in soft versus rigid substrates or after mechanical challenge. Importantly, in soft 2D and/or static 3D conditions, LMNA myoblasts demonstrated enhanced activation of Yes-Associated Protein (YAP) signaling pathway that was paradoxically reduced after cyclic stretch. SiRNA-mediated downregulation of YAP reduced adhesion and actin stress fibers in LMNA myoblasts. This is the first d...

Research paper thumbnail of N-terminal Pro brain natriuretic peptide is a reliable biomarker of reduced myocardial contractility in patients with lamin A/C gene mutations

International Journal of Cardiology, 2011

Background: Recently, concerns have been raised about a possible lack of sensitivity of biomarker... more Background: Recently, concerns have been raised about a possible lack of sensitivity of biomarkers to detect left ventricular (LV) dysfunction in patients with myopathies. We examined the ability of the N-terminal brain natriuretic peptide (NT-proBNP) to detect LV or right ventricular (RV) dysfunction in patients with lamin A/C (LMNA) gene mutations. Methods: We prospectively measured plasma NT-proBNP in consecutive patients with documented LMNA mutations and age-sex matched controls. All patients underwent standard echocardiography implemented by pulsed tissue-Doppler echocardiography (TDE). Results: Twenty-three patients were included (10 males, mean age 39.2±18.9 years);10 had previous atrial arrhythmias, 8 had been implanted with cardioverter defibrillator for primary prevention of sudden death, 5 patients were of NYHA class II and 18 of NHYA class I. Sinus rhythm was recorded in all. NT-proBNP was increased in LMNA patients versus controls (123±229 versus 26 ±78 pg/ml, p=0.0004); 7 patients had depressed LV and/or RV contractility. Patients with reduced LV or RV contractility had increased mean NT-proBNP (341±1032 pg/ml versus 80±79 pg/ml in patients with normal myocardial contractility, p=0.004). Receiver-operating-characteristics analysis shows that NT-proBNP reliably detected depressed contractility (area under the curve 0.889 [0.697-1.000]). Sensitivity and specificity were 88% and 83% respectively, applying manufacturer's recommended cutoff concentration of 125 pg/ml. Conclusion: NT-proBNP reliably detected the presence of reduced LV/RV contractility in LMNA patients.

Research paper thumbnail of Mouse model carrying H222P- Lmna mutation develops muscular dystrophy and dilated cardiomyopathy similar to human striated muscle laminopathies

Human Molecular Genetics, 2004

Laminopathies are a group of disorders caused by mutations in the LMNA gene encoding A-type lamin... more Laminopathies are a group of disorders caused by mutations in the LMNA gene encoding A-type lamins, components of the nuclear lamina. Three of these disorders affect specifically the skeletal and/or cardiac muscles, and their pathogenic mechanisms are still unknown. We chose the LMNA H222P missense mutation identified in a family with autosomal dominant Emery-Dreifuss muscular dystrophy, one of the striated muscle-specific laminopathies, to create a faithful mouse model of this type of laminopathy. The mutant mice exhibit overtly normal embryonic development and sexual maturity. At adulthood, male homozygous mice display reduced locomotion activity with abnormal stiff walking posture and all of them die by 9 months of age. As for cardiac phenotype, they develop chamber dilation and hypokinesia with conduction defects. These abnormal skeletal and cardiac features were also observed in the female homozygous mice but with a later-onset than in males. Histopathological analysis of the mice revealed muscle degeneration with fibrosis associated with dislocation of heterochromatin and activation of Smad signalling in heart and skeletal muscles. These results demonstrate that Lmna H222P/H222P mice represent a good model for studying laminopathies affecting striated muscles as they develop a dystrophic condition of both skeletal and cardiac muscles similar to the human diseases.

Research paper thumbnail of Evidence for FHL1 as a novel disease gene for isolated hypertrophic cardiomyopathy

Human Molecular Genetics, 2012

Hypertrophic cardiomyopathy (HCM) is characterized by asymmetric left ventricular hypertrophy, di... more Hypertrophic cardiomyopathy (HCM) is characterized by asymmetric left ventricular hypertrophy, diastolic dysfunction and myocardial disarray. HCM is caused by mutations in sarcomeric genes, but in >40% of patients, the mutation is not yet identified. We hypothesized that FHL1, encoding four-and-a-half-LIM domains 1, could be another disease gene since it has been shown to cause distinct myopathies, sometimes associated with cardiomyopathy. We evaluated 121 HCM patients, devoid of a mutation in known disease genes. We identified three novel variants in FHL1 (c.134delA/K45Sfs, c.459C>A/C153X and c.827G>C/ C276S). Whereas the c.459C>A variant was associated with muscle weakness in some patients, the c.134delA and c.827G>C variants were associated with isolated HCM. Gene transfer of the latter variants in C2C12 myoblasts and cardiac myocytes revealed reduced levels of FHL1 mutant proteins, which could be rescued by proteasome inhibition. Contractility measurements after adeno-associated virus transduction in rat-engineered heart tissue (EHT) showed: (i) higher and lower forces of contraction with K45Sfs and C276S, respectively, and (ii) prolonged contraction and relaxation with both mutants. All mutants except one activated the fetal hypertrophic gene program in EHT. In conclusion, this study provides evidence for FHL1 to be a novel gene for isolated HCM. These data, together with previous findings of proteasome impairment in HCM, suggest that FHL1 mutant proteins may act as poison peptides, leading to hypertrophy, diastolic dysfunction and/or altered contractility, all features of HCM.

Research paper thumbnail of A centronuclear myopathy-dynamin 2 mutation impairs autophagy in mice

Traffic (Copenhagen, Denmark), 2012

Dynamin 2 (Dnm2) is involved in endocytosis and intracellular membrane trafficking through its fu... more Dynamin 2 (Dnm2) is involved in endocytosis and intracellular membrane trafficking through its function in vesicle formation from distinct membrane compartments. Heterozygous mutations in the DNM2 gene cause dominant centronuclear myopathy or Charcot-Marie-Tooth neuropathy. We generated a knock-in KI-Dnm2(R465W) mouse model expressing the most frequent human mutation and recently reported that heterozygous mice progressively developed a myopathy. We investigated here the cause of neonatal lethality occurring in homozygous mice. We show that homozygous mice present at birth with a reduced body weight, hypoglycemia, increased liver glycogen content and hepatomegaly, in agreement with a defect in neonatal autophagy. In vitro studies performed in homozygous embryonic fibroblasts point out to a decrease in the autophagy flux prior to degradation at the autolysosome. We show that starved homozygous cells have a higher number of immature autophagy-related structures probably due to a defec...

Research paper thumbnail of Emery-Dreifuss muscular dystrophy

European Journal of Human Genetics, 2002

Emery-Dreifuss muscular dystrophy (EDMD) is characterised by early contractures, slowly progressi... more Emery-Dreifuss muscular dystrophy (EDMD) is characterised by early contractures, slowly progressive muscle wasting and weakness with a distinctive humero-peroneal distribution and cardiac conduction defects leading to dilated cardiomyopathy. The genes known to be responsible for EDMD encode proteins associated with the nuclear envelope: the emerin and the lamins A and C.