
Current lab members:
- Véronique Paquis-Flucklinger, PU-PH (EC), PI
- Mélanie Abou-Ali, PhD student
- Samira Ait El Mkadem-Saadi, IR CHU
- Gaelle Augé, technician CHU
- Sylvie Bannwarth, PU-PH
- Aurore Bernardin, postdoc
- Annabelle Chaussenot, PH CHU
- Konstantina Fragaki, IR CHU
- Emmanuelle Genin, CRCN Inserm
- Justine Labory, PhD student
- Alessandra Mauri-Crouzet, IA UniCA
- Anna Requena, IE Inserm
- Cécile Rouzier, PH CHU
- Loan Vaillant-Beuchot, postdoc
Links:
https://www.chu-nice.fr/offre-de-soins/maladies-rares/maladies-mitochondriales
The goal of the team concerns the identification of new genes and mechanisms responsible for mitochondrial diseases (MD), rare disorders characterized by an energy defect. Patients with MD develop a wide spectrum of severe disorders including early-onset symptoms in children and late-onset neurodegenerative pathologies. MD are caused by pathogenic variants in nuclear-encoded mitochondrial genes (>400 reported disease genes) or in mitochondrial DNA (mtDNA). Today, the responsible gene is unknown in one patient out of 2 leading to diagnosis deadlock, despite the development of Next Generation Sequencing (NGS) technologies.
Our attention also focuses on aging-associated mitochondrial dysfunction and its involvement in neurodegenerative disorders. Ten years ago, the identification of a point mutation (p.S59L) in the CHCHD10 gene, encoding a mitochondrial protein, was the first genetic evidence that mitochondrial dysfunction can trigger motor neuron disease (MND), leading to amyotrophic lateral sclerosis (ALS). In CHCHD10-related disease, we demonstrated that instability of the MICOS complex, responsible for mitochondrial cristae junction maintenance, contributes to neuronal death via disorganization of the inner mitochondrial membrane (IMM). This discovery led us to identify repositionable molecules (nifuroxazide (NFX) and analogues) able to rescue defects found in in vitro models generated from patient cells.
The work of the team is performed in close collaboration with the CHU of Nice : the Reference Centre for Mitochondrial Diseases “CALISSON”, the Department of Medical Genetics and the Rare Diseases Expertise Plateform “RESILIENCE”. This collaboration enables us to build a continuum between upstream and clinical research, with the aim of fighting diagnostic and therapeutic deadlocks in mitochondrial defects, particularly those responsible for neurodegenerative disorders.
Current Projects
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MITODRUG
Identifying candidate drugs in mitochondrial cardiomyopathies: From mouse to human. 2021-2025, AFM-Strategic Project, Partner Véronique Paquis-Flucklinger. The MITODRUG project aims to understand the mechanisms of action and in vivo proof of concept for a selection of 5 FDA-approved drug candidates identified by our consortium (researchers ranging from basic science to the clinic). Cardiac damage is present in 80% of adults with mitochondrial diseases. The experimental strategy will combine both mouse models and iPSC-derived cardiomyocytes, targeting 3 pathologies associated with mitochondrial cardiomyopathies (Barth’s syndrome, CHCHD10 and complex I-associated diseases). We will pursue the analysis of these drugs and test their effectiveness and…
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Decipher molecular mechanisms responsible for mitochondrial dysfunction leading to motor neuron death
Decipher molecular mechanisms responsible for mitochondrial dysfunction leading to motor neuron death. 2022-2025, FRM-Maladies neurodégénératives, PI Véronique Paquis-Flucklinger The project aims to understand the molecular basis of motor neuron death caused by CHCHD10 mutations. We will explore the hypothesis that respiratory chain deficiency, loss of mitochondrial cristae and destabilization of the inner membrane structure within mitochondria lead to neuromuscular dysfunction and neuronal death. Using the cell and animal models we have generated, this project wants to (i) understand the role of CHCHD10 and the molecular pathways leading to MND, (ii) define the tissue and genetic interactions leading to neuronal death,…
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MITOMICS
MITOMICS: an integrative multi-omics approach to decrease diagnosis deadlock of mitochondrial diseases and dissect crosstalk between mtDNA and nuclear genome. 2022-2027, ANR, co-PI Sylvie Bannwarth. The MITOMICS project aims to understand the molecular mechanisms responsible for the clinical heterogeneity of MDs. The integration of multi-Omics data (transcriptomics / proteomics / metabolomics) combined with clinical and genomic data (WES, WGS) in Mitomatcher, a database implemented by the whole French network of reference centers on MDs, should help to better understand physiopathological mechanisms and specific pathways responsible for these disorders. The cross-analysis of this data will require the development of in silico…
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Mitochondrial cristae disorganization and neuroinflammation
Mitochondrial cristae disorganization and neuroinflammation: a deleterious link leading to neuronal death. 2024-2026, FRM-Maladies neurodégénératives, PI Sylvie Bannwarth Our project seeks to explore molecular mechanisms linking mitochondrial cristae loss, neuroinflammation and neurodegenerative diseases. Mitochondrial cristae architecture is critical to maintain ATP production through respiratory chain integrity. Loss of cristae is observed in various mitochondrial diseases dues to mutations in genes encoding proteins essential for cristae architecture. Patients develop neurodegenerative pathologies with energy defect and neuroinflammation. Using various cellular and mice models, all of which showing disorganization of mitochondrial cristae due to mutations in different genes, we will (i) compare molecular…
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MIM-IR
MIM-IR: Characterization of the links between inner mitochondrial membrane homeostasis and interferon signaling. 2025-2027, ANR, PI Sylvie Bannwarth Mitochondrial cristae disorganization can lead to mitochondrial nucleic acid release into cytosol inducing an up-regulation of the type I interferon (IFN) signaling via the cGAS-STING pathway. Thus, some mitochondrial diseases may be considered as an autoinflammatory disease (type I interferonopathy) and neurological signs may be caused by this inflammation. Our project aims to determine how the interferon signaling contributes to pathophysiology in patients with mitochondrial disease. We will characterize (i) key partners responsible of inner mitochondrial membrane maintenance, (ii) stress responses to…
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MitoCOSMIC
MitoCOSMIC: Loss of mitochondrial cristae structure in motor neuron disease: mechanistic and therapeutic approaches. 2025-2027, ANR Our results suggest that a mitochondrial transport defect along axons may be involved in CHCHD10-associated neuronal degeneration, in connection with the disorganization of MICOS. The positive effects of NFX on mitochondrial settings in CHCHD10S59L/+ cells seem to depend on KIF5B, a protein involved in mitochondrial transport. Our project aims (1) to analyze mitochondrial trafficking and understand the link with cristae disorganization via NFX mechanism of action and (2) to characterize interactions between MICOS, and transport machinery. We generated a KI Chchd10S59L/+ mouse that recapitulates…
Top Publications
- par Emmanuelle C GeninAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive loss of motor neurons. ALS often overlaps clinically and pathologically with frontotemporal dementia (FTD), the second most common form of dementia. Like many neurodegenerative disorders, both ALS and FTD share a crucial pathological hallmark, the aggregation of misfolded proteins into insoluble inclusions in degenerating neurons. This process is referred to as proteinopathy. This review…
- par Emmanuelle C GeninAmyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder characterized by motor neuron (MN) degeneration, frequently overlapping with frontotemporal dementia (FTD). Protein aggregation is a hallmark of these disorders, yet the role of aggregates in ALS pathogenesis remains unclear. Previously, stomatin-like protein 2 (SLP2) and prohibitin (PHB) aggregates were identified in a model of CHCHD10-related ALS (Chchd10^(S59L/+) mice). This study raises the question of the presence and…
- par Sylvie BannwarthNo abstract
- par Baptiste RopertThe identification of a point mutation (p.Ser59Leu) in the CHCHD10 gene was the first genetic evidence that mitochondrial dysfunction can trigger motor neuron disease. Since then, we have shown that this mutation leads to the disorganization of the MItochondrial contact site and Cristae Organizing System (MICOS) complex that maintains the mitochondrial cristae structure. Here, we generated yeast mutant strains mimicking MICOS instability and used them to test the ability of more than 1600…
- par Emmanuelle C GeninMitochondrial dysfunction occurs in numerous neurodegenerative diseases, particularly amyotrophic lateral sclerosis (ALS), where it contributes to motor neuron (MN) death. Of all the factors involved in ALS, mitochondria have been considered as a major player, as secondary mitochondrial dysfunction has been found in various models and patients. Abnormal mitochondrial morphology, defects in mitochondrial dynamics, altered activities of respiratory chain enzymes and increased production of…
- par Emmanuelle C GeninCHCHD10 is an amyotrophic lateral sclerosis/frontotemporal dementia gene that encodes a mitochondrial protein whose precise function is unclear. Here we show that Coiled-Coil-Helix-Coiled-Coil-Helix Domain Containing protein 10 interacts with the Stomatin-Like Protein 2 and participates in the stability of the prohibitin complex in the inner mitochondrial membrane. By using patient fibroblasts and mouse models expressing the same CHCHD10 variant (p.Ser59Leu), we show that Stomatin-Like Protein 2…
- par C RouzierSpinal muscular atrophy (SMA) is a neuromuscular autosomal recessive disorder caused by bi-allelic pathogenic variants in the SMN1 gene. 95% of SMA patients have a SMN1 homozygous deletion. In the 5% remaining affected patients, a heterozygous SMN1 deletion is associated with an intragenic SMN1 rare inactivating pathogenic variant on the other allele. The clinical phenotype of SMA is heterogeneous and severity is inversely correlated with the number of SMN2 copies, a non-functional SMN1 copy….
- par Konstantina FragakiAmong mitochondrial diseases, isolated complex V (CV) deficiency represents a rare cause of respiratory chain (RC) dysfunction. In mammalian mitochondrial DNA (mtDNA), MT-ATP6 partly overlaps with MT-ATP8 making double mutations possible, yet extremely rarely reported principally in patients with cardiomyopathy. Here, we report a novel m.8561 C>T substitution in the overlapping region of MT-ATP6 and MT-ATP8 in a child with early-onset ataxia, psychomotor delay and microcephaly, enlarging the…
- par Emmanuelle C GeninRecently, we provided genetic basis showing that mitochondrial dysfunction can trigger motor neuron degeneration, through identification of CHCHD10 encoding a mitochondrial protein. We reported patients, carrying the p.Ser59Leu heterozygous mutation in CHCHD10, from a large family with a mitochondrial myopathy associated with motor neuron disease (MND). Rapidly, our group and others reported CHCHD10 mutations in amyotrophic lateral sclerosis (ALS), frontotemporal dementia-ALS and other…
- par Emmanuelle C GeninFollowing the involvement of CHCHD10 in FrontoTemporal-Dementia-Amyotrophic Lateral Sclerosis (FTD-ALS) clinical spectrum, a founder mutation (p.Gly66Val) in the same gene was identified in Finnish families with late-onset spinal motor neuronopathy (SMAJ). SMAJ is a slowly progressive form of spinal muscular atrophy with a life expectancy within normal range. In order to understand why the p.Ser59Leu mutation, responsible for severe FTD-ALS, and the p.Gly66Val mutation could lead to different…
- par Konstantina FragakiPatients carrying Acyl-CoA dehydrogenase 9 (ACAD9) mutations reported to date mainly present with severe hypertrophic cardiomyopathy and isolated complex I (CI) dysfunction. Here we report a novel ACAD9 mutation in a young girl presenting with severe hypertrophic cardiomyopathy, isolated CI deficiency and interestingly multiple respiratory chain complexes assembly defects. We show that ACAD9 analysis has to be performed in first intention in patients presenting with cardiac hypertrophy even in…
- par Cécile RouzierNo abstract
- par Cécile RouzierWolfram syndrome (WS) is a progressive neurodegenerative disease characterized by early-onset optic atrophy and diabetes mellitus, which can be associated with more extensive central nervous system and endocrine complications. The majority of patients harbour pathogenic WFS1 mutations, but recessive mutations in a second gene, CISD2, have been described in a small number of families with Wolfram syndrome type 2 (WFS2). The defining diagnostic criteria for WFS2 also consist of optic atrophy and…
- par Godelieve MorelAn 11-year-old boy with psychomotor delay, exercise intolerance, ptosis and growth delay had a muscle biopsy showing typical mitochondrial alterations (60% of ragged-red fibers and 90% of cytochrome-c oxidase-deficient fibers). Next-generation sequencing revealed a novel heteroplasmic mutation (m.15958A>T) in the MTTP gene that encodes tRNA^(Pro). The mutation was not present in the accessible non-muscle tissues of the patient's asymptomatic mother. Mutations in the rarely affected MTTP gene are…
- par Konstantina FragakiCONCLUSION: Our data suggest that a major defect of CI assembly is not responsible for a severe phenotype. Muscle Nerve 55: 919-922, 2017.
- par Sylvie BannwarthMutations in genes coding for mitochondrial helicases such as TWINKLE and DNA2 are involved in mitochondrial myopathies with mtDNA instability in both human and mouse. We show that inactivation of Pif1, a third member of the mitochondrial helicase family, causes a similar phenotype in mouse. pif1-/- animals develop a mitochondrial myopathy with respiratory chain deficiency. Pif1 inactivation is responsible for a deficiency to repair oxidative stress-induced mtDNA damage in mouse embryonic…
- par Konstantina FragakiCONCLUSIONS: Our study shows that CoQ10 defect can be associated with MRC deficiency. This could be of major importance in clinical practice for the diagnosis of a disease that can be improved by CoQ10 supplementation.
- par Sylvie BannwarthNo abstract
- par Emmanuelle C GeninCHCHD10-related diseases include mitochondrial DNA instability disorder, frontotemporal dementia-amyotrophic lateral sclerosis (FTD-ALS) clinical spectrum, late-onset spinal motor neuropathy (SMAJ), and Charcot-Marie-Tooth disease type 2 (CMT2). Here, we show that CHCHD10 resides with mitofilin, CHCHD3 and CHCHD6 within the "mitochondrial contact site and cristae organizing system" (MICOS) complex. CHCHD10 mutations lead to MICOS complex disassembly and loss of mitochondrial cristae with a…
- par Godelieve MorelNo abstract
Lab News
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Véronique PAQUIS-FLUCKLINGER awarded the Prix Claude Pompidou 2024 for her advances in neurodegenerative diseases
In 2024, the Claude Pompidou Prize broadened its scope to include brain pathologies similar to Alzheimer’s disease: Parkinson’s disease, Lewy body dementia, Huntington’s disease, Amyotrophic Lateral Sclerosis (also known as Charcot’s disease) and fronto-temporal lobar degeneration.This year, the Prize was awarded to the research project led by the team of Pr Véronique Paquis-Flucklinger, Head of…
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A major step forward…
Article published in Nice Matin on 12 November 2024
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