0000000000084372
AUTHOR
Beatriz Llamusi
showing 22 related works from this author
Pentamidine rescues contractility and rhythmicity in a Drosophila model of myotonic dystrophy heart dysfunction
2015
Up to 80% of individuals with myotonic dystrophy type 1 (DM1) will develop cardiac abnormalities at some point during the progression of their disease, the most common of which is heart blockage of varying degrees. Such blockage is characterized by conduction defects and supraventricular and ventricular tachycardia, and carries a high risk of sudden cardiac death. Despite its importance, very few animal model studies have focused on the heart dysfunction in DM1. Here, we describe the characterization of the heart phenotype in a Drosophila model expressing pure expanded CUG repeats under the control of the cardiomyocyte-specific driver GMH5-Gal4. Morphologically, expression of 250 CUG repeat…
Two Enhancers Control Transcription of Drosophila muscleblind in the Embryonic Somatic Musculature and in the Central Nervous System
2014
The phylogenetically conserved family of Muscleblind proteins are RNA-binding factors involved in a variety of gene expression processes including alternative splicing regulation, RNA stability and subcellular localization, and miRNA biogenesis, which typically contribute to cell-type specific differentiation. In humans, sequestration of Muscleblind-like proteins MBNL1 and MBNL2 has been implicated in degenerative disorders, particularly expansion diseases such as myotonic dystrophy type 1 and 2. Drosophila muscleblind was previously shown to be expressed in embryonic somatic and visceral muscle subtypes, and in the central nervous system, and to depend on Mef2 for transcriptional activatio…
rbFOX1/MBNL1 competition for CCUG RNA repeats binding contributes to myotonic dystrophy type 1/type 2 differences
2018
Myotonic dystrophy type 1 and type 2 (DM1, DM2) are caused by expansions of CTG and CCTG repeats, respectively. RNAs containing expanded CUG or CCUG repeats interfere with the metabolism of other RNAs through titration of the Muscleblind-like (MBNL) RNA binding proteins. DM2 follows a more favorable clinical course than DM1, suggesting that specific modifiers may modulate DM severity. Here, we report that the rbFOX1 RNA binding protein binds to expanded CCUG RNA repeats, but not to expanded CUG RNA repeats. Interestingly, rbFOX1 competes with MBNL1 for binding to CCUG expanded repeats and overexpression of rbFOX1 partly releases MBNL1 from sequestration within CCUG RNA foci in DM2 muscle ce…
Modeling of Myotonic Dystrophy Cardiac Phenotypes in Drosophila
2018
After respiratory distress, cardiac dysfunction is the second most common cause of fatality associated with the myotonic dystrophy (DM) disease. Despite the prevalance of heart failure in DM, physiopathological studies on heart symptoms have been relatively scarce because few murine models faithfully reproduce the cardiac disease. Consequently, only a small number of candidate compounds have been evaluated in this specific phenotype. To help cover this gap Drosophila combines the amenability of its invertebrate genetics with the possibility of quickly acquiring physiological parameters suitable for meaningful comparisons with vertebrate animal models and humans. Here we review available des…
Expanded CCUG repeat RNA expression in Drosophila heart and muscle trigger Myotonic Dystrophy type 1-like phenotypes and activate autophagocytosis ge…
2016
AbstractMyotonic dystrophies (DM1–2) are neuromuscular genetic disorders caused by the pathological expansion of untranslated microsatellites. DM1 and DM2, are caused by expanded CTG repeats in the 3′UTR of the DMPK gene and CCTG repeats in the first intron of the CNBP gene, respectively. Mutant RNAs containing expanded repeats are retained in the cell nucleus, where they sequester nuclear factors and cause alterations in RNA metabolism. However, for unknown reasons, DM1 is more severe than DM2. To study the differences and similarities in the pathogenesis of DM1 and DM2, we generated model flies by expressing pure expanded CUG ([250]×) or CCUG ([1100]×) repeats, respectively, and compared …
In vivo discovery of a peptide that prevents CUG-RNA hairpin formation and reverses RNA toxicity in myotonic dystrophy models
2011
6 pages, 5 figures. PMID:21730182[PubMed] PMCID: PMC3141925[Available on 2012/1/19]
Optical Cross-Sectional Muscle Area Determination of <em>Drosophila Melanogaster</em> Adult Indirect Flight Muscles
2018
Muscle mass wasting, known as muscle atrophy, is a common phenotype in Drosophila models of neuromuscular diseases. We have used the indirect flight muscles (IFMs) of flies, specifically the dorso-longitudinal muscles (DLM), as the experimental subject to measure the atrophic phenotype brought about by different genetic causes. In this protocol, we describe how to embed fly thorax muscles for semi thin sectioning, how to obtain a good contrast between muscle and the surrounding tissue, and how to process optical microscope images for semiautomatic acquisition of quantifiable data and analysis. We describe three specific applications of the methodological pipeline. First, we show how the met…
Daunorubicin reduces MBNL1 titration by expanded CUG repeat RNA and rescues cardiac dysfunctions in a Drosophila model of myotonic dystrophy
2018
International audience; Myotonic dystrophy (DM) is a dominantly inherited neuromuscular disorder caused by expression of mutant DMPK transcripts containing expanded CUG repeats. Pathogenic RNA sequesters the muscleblind-like (MBNL) proteins, causing alterations of RNA metabolism. Cardiac dysfunction represents the second most common cause of death in DM1 patients. However, the contribution of MBNL titration in DM1 cardiac dysfunction is unclear. We overexpressed Muscleblind (Mbl), Drosophila MBNL orthologue, in cardiomyocytes of DM1 model flies and observed a rescue of heart dysfunctions, which are characteristic of these model flies and resemble cardiac defects observed in patients. We als…
RNA-mediated therapies in myotonic dystrophy
2018
Myotonic dystrophy 1 (DM1) is a multisystemic neuromuscular disease caused by a dominantly inherited 'CTG' repeat expansion in the gene encoding DM Protein Kinase (DMPK). The repeats are transcribed into mRNA, which forms hairpins and binds with high affinity to the Muscleblind-like (MBNL) family of proteins, sequestering them from their normal function. The loss of function of MBNL proteins causes numerous downstream effects, primarily the appearance of nuclear foci, mis-splicing, and ultimately myotonia and other clinical symptoms. Antisense and other RNA-mediated technologies have been applied to target toxic-repeat mRNA transcripts to restore MBNL protein function in DM1 models, such as…
In silico discovery of substituted pyrido[2,3-d]pyrimidines and pentamidine-like compounds with biological activity in myotonic dystrophy models
2016
Myotonic dystrophy type 1 (DM1) is a rare multisystemic disorder associated with an expansion of CUG repeats in mutant DMPK (dystrophia myotonica protein kinase) transcripts; the main effect of these expansions is the induction of pre-mRNA splicing defects by sequestering muscleblind-like family proteins (e.g. MBNL1). Disruption of the CUG repeats and the MBNL1 protein complex has been established as the best therapeutic approach for DM1, hence two main strategies have been proposed: targeted degradation of mutant DMPK transcripts and the development of CUG-binding molecules that prevent MBNL1 sequestration. Herein, suitable CUG-binding small molecules were selected using in silico approach…
Six Serum miRNAs Fail to Validate as Myotonic Dystrophy Type 1 Biomarkers.
2016
Myotonic dystrophy type 1 (DM1) is an autosomal dominant genetic disease caused by expansion of a CTG microsatellite in the 3' untranslated region of the DMPK gene. Despite characteristic muscular, cardiac, and neuropsychological symptoms, CTG trinucleotide repeats are unstable both in the somatic and germinal lines, making the age of onset, clinical presentation, and disease severity very variable. A molecular biomarker to stratify patients and to follow disease progression is, thus, an unmet medical need. Looking for a novel biomarker, and given that specific miRNAs have been found to be misregulated in DM1 heart and muscle tissues, we profiled the expression of 175 known serum miRNAs in …
The use of whole-mountin situhybridization to illustrate gene expression regulation
2014
In situ hybridization is a widely used technique for studying gene expression. Here, we describe two experiments addressed to postgraduate genetics students in which the effect of transcription factors on gene expression is analyzed in Drosophila embryos of different genotypes by whole-mount in situ hybridization. In one of the experiments, students analyzed the repressive effect of Snail over rhomboid expression using reporter lines containing different constructs of the rhomboid neuroectodermal enhancer fused to the lacZ gene. In the second experiment, the epistatic relationship between the cabut and decapentaplegic genes was analyzed. These simple experiments allowed students to (1) unde…
Rabphilin involvement in filtration and molecular uptake in Drosophila nephrocytes suggests a similar role in human podocytes
2020
ABSTRACT Drosophila nephrocytes share functional, structural and molecular similarities with human podocytes. It is known that podocytes express the rabphilin 3A (RPH3A)-RAB3A complex, and its expression is altered in mouse and human proteinuric disease. Furthermore, we previously identified a polymorphism that suggested a role for RPH3A protein in the development of urinary albumin excretion. As endocytosis and vesicle trafficking are fundamental pathways for nephrocytes, the objective of this study was to assess the role of the RPH3A orthologue in Drosophila, Rabphilin (Rph), in the structure and function of nephrocytes. We confirmed that Rph is required for the correct function of the en…
Preclinical characterization of antagomiR-218 as a potential treatment for myotonic dystrophy
2021
Myotonic dystrophy type 1 (DM1) is a rare neuromuscular disease caused by expansion of unstable CTG repeats in a non-coding region of the DMPK gene. CUG expansions in mutant DMPK transcripts sequester MBNL1 proteins in ribonuclear foci. Depletion of this protein is a primary contributor to disease symptoms such as muscle weakness and atrophy and myotonia, yet upregulation of endogenous MBNL1 levels may compensate for this sequestration. Having previously demonstrated that antisense oligonucleotides against miR-218 boost MBNL1 expression and rescue phenotypes in disease models, here we provide preclinical characterization of an antagomiR-218 molecule using the HSALR mouse model and patient-d…
Therapeutic Potential of AntagomiR-23b for Treating Myotonic Dystrophy
2020
Myotonic dystrophy type 1 (DM1) is a chronically debilitating, rare genetic disease that originates from an expansion of a noncoding CTG repeat in the dystrophia myotonica protein kinase (DMPK) gene. The expansion becomes pathogenic when DMPK transcripts contain 50 or more repetitions due to the sequestration of the muscleblind-like (MBNL) family of proteins. Depletion of MBNLs causes alterations in splicing patterns in transcripts that contribute to clinical symptoms such as myotonia and muscle weakness and wasting. We previously found that microRNA (miR)-23b directly regulates MBNL1 in DM1 myoblasts and mice and that antisense technology (“antagomiRs”) blocking this microRNA (miRNA) boost…
The Drosophila junctophilin gene is functionally equivalent to its four mammalian counterparts and is a modifier of a Huntingtin poly-Q expansion and…
2018
[EN] Members of the Junctophilin (JPH) protein family have emerged as key actors in all excitable cells, with crucial implications for human pathophysiology. In mammals, this family consists of four members (JPH1-JPH4) that are differentially expressed throughout excitable cells. The analysis of knockout mice lacking JPH subtypes has demonstrated their essential contribution to physiological functions in skeletal and cardiac muscles and in neurons. Moreover, mutations in the human JPH2 gene are associated with hypertrophic and dilated cardiomyopathies; mutations in JPH3 are responsible for the neurodegenerative Huntington's disease-like-2 (HDL2), whereas JPH1 acts as a genetic modifier in C…
Derepressing muscleblind expression by miRNA sponges ameliorates myotonic dystrophy-like phenotypes in Drosophila
2016
AbstractMyotonic Dystrophy type 1 (DM1) originates from alleles of the DMPK gene with hundreds of extra CTG repeats in the 3′ untranslated region (3′ UTR). CUG repeat RNAs accumulate in foci that sequester Muscleblind-like (MBNL) proteins away from their functional target transcripts. Endogenous upregulation of MBNL proteins is, thus, a potential therapeutic approach to DM1. Here we identify two miRNAs, dme-miR-277 and dme-miR-304, that differentially regulate muscleblind RNA isoforms in miRNA sensor constructs. We also show that their sequestration by sponge constructs derepresses endogenous muscleblind not only in a wild type background but also in a DM1 Drosophila model expressing non-co…
Increased autophagy and apoptosis contribute to muscle atrophy in a myotonic dystrophy type 1 Drosophila model
2015
ABSTRACT Muscle mass wasting is one of the most debilitating symptoms of myotonic dystrophy type 1 (DM1) disease, ultimately leading to immobility, respiratory defects, dysarthria, dysphagia and death in advanced stages of the disease. In order to study the molecular mechanisms leading to the degenerative loss of adult muscle tissue in DM1, we generated an inducible Drosophila model of expanded CTG trinucleotide repeat toxicity that resembles an adult-onset form of the disease. Heat-shock induced expression of 480 CUG repeats in adult flies resulted in a reduction in the area of the indirect flight muscles. In these model flies, reduction of muscle area was concomitant with increased apopto…
miR-23b and miR-218 silencing increase Muscleblind-like expression and alleviate myotonic dystrophy phenotypes in mammalian models
2018
Functional depletion of the alternative splicing factors Muscleblind-like (MBNL 1 and 2) is at the basis of the neuromuscular disease myotonic dystrophy type 1 (DM1). We previously showed the efficacy of miRNA downregulation in Drosophila DM1 model. Here, we screen for miRNAs that regulate MBNL1 and MBNL2 in HeLa cells. We thus identify miR-23b and miR-218, and confirm that they downregulate MBNL proteins in this cell line. Antagonists of miR-23b and miR-218 miRNAs enhance MBNL protein levels and rescue pathogenic missplicing events in DM1 myoblasts. Systemic delivery of these “antagomiRs” similarly boost MBNL expression and improve DM1-like phenotypes, including splicing alterations, histo…
Molecular Effects of the CTG Repeats in Mutant Dystrophia Myotonica Protein Kinase Gene
2008
Myotonic Dystrophy type 1 (DM1) is a multi-system disorder characterized by muscle wasting, myotonia, cardiac conduction defects, cataracts, and neuropsychological dysfunction. DM1 is caused by expansion of a CTG repeat in the 3 untranslated region (UTR) of the Dystrophia Myotonica Protein Kinase (DMPK) gene. A body of work demonstrates that DMPK mRNAs containing abnormally expanded CUG repeats are toxic to several cell types. A core mechanism underlying symptoms of DM1 is that mutant DMPK RNA interferes with the developmentally regulated alternative splicing of defined pre-mRNAs. Expanded CUG repeats fold into ds(CUG) hairpins that sequester nuclear proteins including human Muscleblind-lik…
Muscleblind, BSF and TBPH are mislocalized in the muscle sarcomere of a Drosophila myotonic dystrophy model
2012
SummaryMyotonic dystrophy type 1 (DM1) is a genetic disease caused by the pathological expansion of a CTG trinucleotide repeat in the 3' UTR of the DMPK gene. In the DMPK transcripts, the CUG expansions sequester RNA-binding proteins into nuclear foci, including transcription factors and alternative splicing regulators such as MBNL1. MBNL1 sequestration has been associated with key features of DM1. However, the basis behind a number of molecular and histological alterations in DM1 remain unclear. To help identify new pathogenic components of the disease, we carried out a genetic screen using a Drosophila model of DM1 that expresses 480 interrupted CTG repeats, i(CTG)480, and a collection of…
A GFP-tagged Muscleblind C protein isoform reporter construct
2010
Drosophila muscleblind (mbl), the ortholog of human Muscleblind-like 1 (MBNL1) gene involved in Myotonic Dystrophy (DM), gives raise to protein isoforms MblA to G. The specific functions and subcellular distribution of isoforms are still largely unknown. To overcome the lack of isoform-specific antibodies we generated transgenic flies that express a GFP:MblC fusion protein under the control of the Gal4/UAS system. The reporter fusion protein was able to functionally complement mbl loss of function mutations, demonstrating activity, and accumulated predominantly in adult muscle nuclei. The fluorescent nature of the reporter makes it appropriate for live imaging detection of MblC protein isof…