High-throughput analysis of the RNA-induced silencing complex in myotonic dystrophy type 1 patients identifies the dysregulation of miR-29c and its target ASB2

Myotonic dystrophy type 1 (DM1) is a multi-systemic disorder caused by abnormally expanded stretches of CTG DNA triplets in the DMPK gene, leading to mutated-transcript RNA-toxicity. MicroRNAs (miRNAs) are short non-coding RNAs that, after maturation, are loaded onto the RISC effector complex that destabilizes target mRNAs and represses their translation. In DM1 muscle biopsies not only the expression, but also the intracellular localization of specific miRNAs is disrupted, leading to the dysregulation of the relevant mRNA targets. To investigate the functional alterations of the miRNA/target interactions in DM1, we analyzed by RNA-sequencing the RISC-associated RNAs in skeletal muscle biopsies derived from DM1 patients and matched controls. The mRNAs found deregulated in DM1 biopsies were involved in pathways and functions relevant for the disease, such as energetic metabolism, calcium signaling, muscle contraction and p53-dependent apoptosis. Bioinformatic analysis of the miRNA/mRNA interactions based on the RISC enrichment profiles, identified 24 miRNA/mRNA correlations. Following validation in 21 independent samples, we focused on the couple miR-29c/ASB2 because of the role of miR-29c in fibrosis (a feature of late-stage DM1 patients) and of ASB2 in the regulation of muscle mass. Luciferase reporter assay confirmed the direct interaction between miR-29c and ASB2. Moreover, decreased miR-29c and increased ASB2 levels were verified also in immortalized myogenic cells and primary fibroblasts, derived from biopsies of DM1 patients and controls. CRISPR/Cas9-mediated deletion of CTG expansions rescued normal miR-29c and ASB2 levels, indicating a direct link between the mutant repeats and the miRNA/target expression. In conclusion, functionally relevant miRNA/mRNA interactions were identified in skeletal muscles of DM1 patients, highlighting the dysfunction of miR-29c and ASB2

Tibialis anterior muscle needle biopsy and sensitive biomolecular methods: A useful tool in myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a neuromuscular disorder caused by a CTG repeat expansion in 3\u2019UTR of DMPK gene. This mutation causes accumulation of toxic RNA in nuclear foci leading to splicing misregulation of specific genes. In view of future clinical trials with antisense oligonucleotides in DM1 patients, it is important to set up sensitive and minimally-invasive tools to monitor the efficacy of treatments on skeletal muscle. A tibialis anterior (TA) muscle sample of about 60 mg was obtained from 5 DM1 patients and 5 healthy subjects through a needle biopsy. A fragment of about 40 mg was used for histological examination and a fragment of about 20 mg was used for biomolecular analysis. The TA fragments obtained with the minimally-invasive needle biopsy technique is enough to perform all the histopathological and biomolecular evaluations useful to monitor a clinical trial on DM1 patients

Neuropsychological and psychological functioning aspects in myotonic dystrophy type 1 patients in Italy

Introduction: Myotonic Dystrophy Type 1 (DM1) is an autosomal dominant genetic illness, characterized by a progressive loss of strength. Important deficits in cognitive functioning and a significant prevalence of psychiatric disorders have been previously reported. Methods: A neuropsychological and psychological assessment was carried out in 31 DM1 patients (61% males) in order to measure the cognitive functioning and explore their personality profiles. The MMSE Mini-Mental State Examination, Frontal Assessment Battery (FAB), ENB-2 Battery assessing memory (short term, long term and working memory), integration capacities, visual-spatial ability, attention (selective, divided, shifting/switching) executive functions, praxis, discrimination and logic capabilities and psychopathology Symptom Check List 90-R (SCL-90-R) were administered. The neuropsychological and psychological evaluation of DM1 patients was carried out taking into consideration the clinical parameters (CTG repeat, age at onset, disease duration, Muscular Impairment Rate Scale (MIRS), Medical Research Council Scale (MRC) and the Epworth Sleepiness Scales (EPS)). Results: Regarding psychopathology 19.4% of patients scored a moderate or high level of symptoms intensity index (GSI), 12.9% reported a high number of symptoms (PST) and 16.1% reported a high intensity level of the perceived symptoms (PSDI). Fatigue and daytime sleepiness resulted as being associated with higher levels of psychoticism (PSY). Only 1 patient reported a severe impairment in the spatial and temporal orientation, memory, language, praxis, attention and calculation. Longer disease duration was also associated with cognitive impairment evaluated through ENB-2 (p < 0.05). Discussions and Conclusions: There are indications of the utility of neuropsychological and psychological screening and support for these patients and their families due to the link between disease duration and cognitive performances. A proposal of a clinical protocol, with an illustration of a clinical case report of a family is presented

Cell environment shapes TDP-43 function with implications in neuronal and muscle disease

TDP-43 (TAR DNA-binding protein 43) aggregation and redistribution are recognised as a hallmark of amyotrophic lateral sclerosis and frontotemporal dementia. As TDP-43 inclusions have recently been described in the muscle of inclusion body myositis patients, this highlights the need to understand the role of TDP-43 beyond the central nervous system. Using RNA-seq, we directly compare TDP-43-mediated RNA processing in muscle (C2C12) and neuronal (NSC34) mouse cells. TDP-43 displays a cell-type-characteristic behaviour targeting unique transcripts in each cell-type, which is due to characteristic expression of RNA-binding proteins, that influence TDP-43's performance and define cell-type specific splicing. Among splicing events commonly dysregulated in both cell lines, we identify some that are TDP-43-dependent also in human cells. Inclusion levels of these alternative exons are altered in tissues of patients suffering from FTLD and IBM. We therefore propose that TDP-43 dysfunction contributes to disease development either in a common or a tissue-specific manner

A 14-Year Italian Experience in DM2 Genetic Testing: Frequency and Distribution of Normal and Premutated CNBP Alleles

Myotonic dystrophy type 2 (DM2) is a multisystemic disorder caused by a (CCTG)n in intron 1 of the CNBP gene. The CCTG repeat tract is part of a complex (TG)v(TCTG)w(CCTG)x(NCTG)y(CCTG)z motif generally interrupted in CNBP healthy range alleles. Here we report our 14-year experience of DM2 postnatal genetic testing in a total of 570 individuals. The DM2 locus has been analyzed by a combination of SR-PCR, TP-PCR, LR-PCR, and Sanger sequencing of CNBP alleles. DM2 molecular diagnosis has been confirmed in 187/570 samples analyzed (32.8%) and is mainly associated with the presence of myotonia in patients. This set of CNBP alleles showed unimodal distribution with 25 different alleles ranging from 108 to 168 bp, in accordance with previous studies on European populations. The most frequent CNBP alleles consisted of 138, 134, 140, and 136 bps with an overall locus heterozygosity of 90%. Sequencing of 103 unexpanded CNBP alleles in DM2-positive patients revealed that (CCTG)5(NCTG)3(CCTG)7 and (CCTG)6(NCTG)3(CCTG)7 are the most common interruption motifs. We also characterized five CNBP premutated alleles with (CCTG)n repetitions from n = 36 to n = 53. However, the molecular and clinical consequences in our cohort of samples are not unequivocal. Data that emerged from this study are representative of the Italian population and are useful tools for National and European centers offering DM2 genetic testing and counseling

Deregulated MicroRNAs in Myotonic Dystrophy Type 2

Myotonic Dystrophy Type-2 (DM2) is an autosomal dominant disease caused by the expansion of a CCTG tetraplet repeat. It is a multisystemic disorder, affecting skeletal muscles, the heart, the eye, the central nervous system and the endocrine system. Since microRNA (miRNA) expression is disrupted in Myotonic Dystrophy Type-1 and many other myopathies, miRNAs deregulation was studied in skeletal muscle biopsies of 13 DM2 patients and 13 controls. Eleven miRNAs were deregulated: 9 displayed higher levels compared to controls (miR-34a-5p, miR-34b-3p, miR-34c-5p, miR-146b-5p, miR-208a, miR-221-3p and miR-381), while 4 were decreased (miR-125b-5p, miR-193a-3p, miR-193b-3p and miR-378a-3p). To explore the relevance of DM2 miRNA deregulation, the predicted interactions between miRNA and mRNA were investigated. Global gene expression was analyzed in DM2 and controls and bioinformatic analysis identified more than 1,000 miRNA/mRNA interactions. Pathway and function analysis highlighted the involvement of the miRNA-deregulated mRNAs in multiple aspects of DM2 pathophysiology. In conclusion, the observed miRNA dysregulations may contribute to DM2 pathogenetic mechanisms

Covid-19-Associated Coagulopathy: Biomarkers of Thrombin Generation and Fibrinolysis Leading the Outcome

Background: Coronavirus Disease 2019 (COVID-19)-associated coagulopathy is characterized by a prothrombotic state not yet comprehensively studied. We investigated the coagulation pattern of patients with COVID-19 acute respiratory distress syndrome (ARDS), comparing patients who survived to those who did not. Methods: In this prospective cohort study on 20 COVID-19 ARDS patients, the following biomarkers were measured: thrombin generation (prothrombin fragment 1 + 2 (PF 1 + 2)), fibrinolysis activation (tissue plasminogen activator (tPA)) and inhibition (plasminogen activator inhibitor 2 (PAI-2)), fibrin synthesis (fibrinopeptide A) and fibrinolysis magnitude (plasmin&ndash;antiplasmin complex (PAP) and D-dimers). Measurements were done upon intensive care unit (ICU) admission and after 10&ndash;14 days. Results: There was increased thrombin generation; modest or null release of t-PA; and increased levels of PAI-2, fibrinopeptide A, PAP and D-dimers. At baseline, nonsurvivors had a significantly (p = 0.014) higher PAI-2/PAP ratio than survivors (109, interquartile range (IQR) 18.1&ndash;216, vs. 8.7, IQR 2.9&ndash;12.6). At follow-up, thrombin generation was significantly (p = 0.025) reduced in survivors (PF 1 + 2 from 396 pg/mL, IQR 185&ndash;585 to 237 pg/mL, IQR 120&ndash;393), whereas it increased in nonsurvivors. Fibrinolysis inhibition at follow-up remained stable in survivors and increased in nonsurvivors, leading to a significant (p = 0.026) difference in PAI-2 levels (161 pg/mL, IQR 50&ndash;334, vs. 1088 pg/mL, IQR 177&ndash;1565). Conclusion: Severe patterns of COVID-19 ARDS are characterized by a thrombin burst and the consequent coagulation activation. Mechanisms of fibrinolysis regulation appear unbalanced toward fibrinolysis inhibition. This pattern ameliorates in survivors, whereas it worsens in nonsurvivors

CRISPR/Cas9-Mediated Deletion of CTG Expansions Recovers Normal Phenotype in Myogenic Cells Derived from Myotonic Dystrophy 1 Patients

Myotonic dystrophy type 1 (DM1) is the most common adult-onset muscular dystrophy, characterized by progressive myopathy, myotonia, and multi-organ involvement. This dystrophy is an inherited autosomal dominant disease caused by a (CTG)n expansion within the 3′ untranslated region of the DMPK gene. Expression of the mutated gene results in production of toxic transcripts that aggregate as nuclear foci and sequester RNA-binding proteins, resulting in mis-splicing of several transcripts, defective translation, and microRNA dysregulation. No effective therapy is yet available for treatment of the disease. In this study, myogenic cell models were generated from myotonic dystrophy patient-derived fibroblasts. These cells exhibit typical disease-associated ribonuclear aggregates, containing CUG repeats and muscleblind-like 1 protein, and alternative splicing alterations. We exploited these cell models to develop new gene therapy strategies aimed at eliminating the toxic mutant repeats. Using the CRISPR/Cas9 gene-editing system, the repeat expansions were removed, therefore preventing nuclear foci formation and splicing alterations. Compared with the previously reported strategies of inhibition/degradation of CUG expanded transcripts by various techniques, the advantage of this approach is that affected cells can be permanently reverted to a normal phenotype

Plasma microRNAs as biomarkers for myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) lacks non-invasive and easy to measure biomarkers, still largely relying on semi-quantitative tests for diagnostic and prognostic purposes. Muscle biopsies provide valuable data, but their use is limited by their invasiveness. microRNA (miRNAs) are small non-coding RNAs regulating gene expression that are also present in biological fluids and may serve as diseases biomarkers. Thus, we tested plasma miRNAs in the blood of 36 DM1 patients and 36 controls. First, a wide miRNA panel was profiled in a patient subset, followed by validation using all recruited subjects. We identified a signature of nine deregulated miRNAs in DM1 patients: eight miRNAs were increased (miR-133a, miR-193b, miR-191, miR-140-3p, miR-454, miR-574, miR-885-5p, miR-886-3p) and one (miR-27b) was decreased. Next, the levels of these miRNAs were used to calculate a "DM1-miRNAs score". We found that both miR-133a levels and DM1-miRNAs score discriminated DM1 from controls significantly and Receiver-Operator Characteristic curves displayed an area under the curve of 0.94 and 0.97, respectively. Interestingly, both miR-133a levels and DM1-miRNAs score displayed an inverse correlation with skeletal muscle strength and displayed higher values in more compromised patients. In conclusion, we identified a characteristic plasma miRNA signature of DM1. Although preliminary, this study indicates miRNAs as potential DM1 humoral biomarkers