DM1 Pathogenesis Research Articles

Identification and validation of interferon-stimulated gene 15 as a biomarker for dermatomyositis by integrated bioinformatics analysis and machine learning

BackgroundDermatomyositis (DM) is an autoimmune disease that primarily affects the skin and muscles. It can lead to increased mortality, particularly when patients develop associated malignancies or experience fatal complications such as pulmonary fibrosis. Identifying reliable biomarkers is essential for the early diagnosis and treatment of DM. This study aims to identify and validate pivotal diagnostic biomarker for DM through integrated bioinformatics analysis and clinical sample validation.MethodsGene expression datasets GSE46239 and GSE142807 from the Gene Expression Omnibus (GEO) database were merged for analysis. Differentially expressed genes (DEGs) were identified and subjected to enrichment analysis. Advanced machine learning methods were utilized to further pinpoint hub genes. Weighted gene co‐expression network analysis (WGCNA) was also conducted to discover key gene modules. Subsequently, we derived intersection gene from these methods. The diagnostic performance of the candidate biomarker was evaluated using analysis with dataset GSE128314 and confirmed by immunohistochemistry (IHC) in skin lesion biopsy specimens. The CIBERSORT algorithm was used to analyze immune cell infiltration patterns in DM, then the association between the hub gene and immune cells was investigated. Gene set enrichment analysis (GSEA) was performed to understand the biomarker’s biological functions. Finally, the drug-gene interactions were predicted using the DrugRep server.ResultsInterferon-stimulated gene 15 (ISG15) was identified by intersecting DEGs, advanced machine learning-selected genes and key module genes from WGCNA. ROC analysis showed ISG15 had a high Area under the curve (AUC) of 0.950. IHC findings confirmed uniformly positive expression of ISG15, particularly in perivascular regions and lymphocytes, contrasting with universally negative expression in controls. Further analysis revealed that ISG15 is involved in abnormalities in various immune cells and inflammation-related pathways. We also predicted three drugs targeting ISG15, supported by molecular docking studies.ConclusionOur study identifies ISG15 as a highly specific diagnostic biomarker for DM, ISG15 may be closely related to the pathogenesis of DM, demonstrating promising potential for clinical application.

CUG repeat RNA-dependent proteasomal degradation of MBNL1 in a cellular model of myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is caused by the expansion of a non-coding CTG repeat in DMPK. CUG-repeat-containing transcripts sequester the splicing regulator MBNL1 into nuclear RNA foci, causing aberrant splicing of many genes. Although the mislocalization of MBNL1 represents a causal event in DM1 pathogenesis, the effect of CUG repeat RNA on the protein level of MBNL1 remains unclear. Using a DM1 model cell line, we found that CUG repeat RNA caused a significant decrease in the protein, but not mRNA levels, of MBNL1. As CUG repeats did not decrease MBNL1 translation, we investigated protein degradation pathways. Although autophagy-related reagents induced little change, proteasome inhibitors partially recovered MBNL1 protein expression levels under conditions of CUG repeat expression and induced a slight, but significant, reversal of splicing dysregulation. MBNL1 was detected in the polyubiquitinated protein fraction, but MBNL1 polyubiquitination was not detected. Moreover, inhibition of the ubiquitin-activating enzyme E1 did not increase MBNL1 levels, suggesting that MBNL1 is a substrate of polyubiquitin-independent proteasomal degradation. These results suggest that CUG-repeat-induced proteasomal degradation partially contributes to the functional decline of MBNL1.

The role of genetic factors in likelihood of type 2 diabetes mellitus

Type 2 diabetes mellitus (DM2) is the ninth leading cause of worldwide mortality. To predict likelihood of the disease and its unfavorable clinical course with developing complications, it is necessary to consider genetic and molecular factors of DM2 pathogenesis. Therefore, the aim of this review was to analyze the role that belongs to genetic factors in molecular mechanisms of DM2 development and to establish the most significant single nucleotide polymorphisms (SNP) in DM2 pathogenesis. The authors have analyzed literature sources found in such databases as CYBERLENINKA, E-library, and National Center for Biotechnology Information over the last 10 years as well as the integrated database GeneCards. By now, Genome-Wide Association Studies (GWAS) have identified about 100 genes and more than 700 polymorphisms that influence DM2 risks and its likelihood. Classifications of candidate genes with their effects and expression being limited by external and internal transcription factors are rather tentative. Literature analysis has established certain ambiguousness of the role that belongs to genetic markers in DM2 pathogenesis. It is advisable to add new genetic markers of the PPARγ, TLR4, IRS and IL-6 genes to the existing test-systems. This will increase the likelihood of detecting hereditary predisposition to diabetes mellitus according to the key molecular-genetic mechanisms of its development and ensure implementation of relevant measures aimed at preventing the disease and early identification of genetic risk groups.

Роль генетических факторов в вероятности развития сахарного диабета 2-го типа

Type 2 diabetes mellitus (DM2) is the ninth leading cause of worldwide mortality. To predict likelihood of the disease and its unfavorable clinical course with developing complications, it is necessary to consider genetic and molecular factors of DM2 pathogenesis. Therefore, the aim of this review was to analyze the role that belongs to genetic factors in molecular mechanisms of DM2 development and to establish the most significant single nucleotide polymorphisms (SNP) in DM2 pathogenesis. The authors have analyzed literature sources found in such databases as CYBERLENINKA, E-library, and National Center for Biotechnology Information over the last 10 years as well as the integrated database GeneCards. By now, Genome-Wide Association Studies (GWAS) have identified about 100 genes and more than 700 polymorphisms that influence DM2 risks and its likelihood. Classifications of candidate genes with their effects and expression being limited by external and internal transcription factors are rather tentative. Literature analysis has established certain ambiguousness of the role that belongs to genetic markers in DM2 pathogenesis. It is advisable to add new genetic markers of the PPARγ, TLR4, IRS and IL-6 genes to the existing test-systems. This will increase the likelihood of detecting hereditary predisposition to diabetes mellitus according to the key molecular-genetic mechanisms of its development and ensure implementation of relevant measures aimed at preventing the disease and early identification of genetic risk groups.

Progeroid dermatological manifestations in myotonic dystrophy type 1. Case report

Introduction: myotonic dystrophy type 1 is an autosomal dominant genetic disease with highly variable expressivity. Among the systemic alterations that are part of the clinical manifestations are neurodegeneration and premature aging, which is why it is part of progeroid syndromes. Objective: to describe progeroid dermatological manifestations in type 1 myotonic dystrophy. Case report: 44-year-old patient who, at the age of 9, confirmed a clinical diagnosis of myotonic dystrophy type 1. A family history with the same genetic disorder was collected. It presents dysmorphic signs in the skull, face, extremities and in different organs, among which are bilateral sensorineural deafness, early-onset cataracts, as well as dermatological manifestations such as seborrheic dermatitis and other lesions reminiscent of ichthyosis. Conclusions: DM1 is often referred to as a progeroid syndrome, which implies assuming that it exposes the usual underlying mechanisms of aging that are also those that participate in the pathogenesis of DM1 and in turn justify the dermatological manifestations observed

MicroRNA-mRNA expression profiles in the skeletal muscle of myotonic dystrophy type 1

ABSTRACT Objectives Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy in adults, yet there are currently no disease-modifying treatments. Disrupted miRNA expressions may lead to dysregulation of target mRNAs and dysfunction involved in DM1 pathogenic mechanism. Methods We used microarray platforms to examine the miRNA/mRNA expression profiles in skeletal muscle biopsies derived from DM1 patients and matched controls. Bioinformatics analysis and dual-luciferase reporter assay were conducted to provide insight into miRNA-mRNA regulatory networks altered in DM1. Results Twenty-three differentially expressed miRNAs and 135 differentially expressed genes were identified. qPCR confirmed that miR-3201, myogenic factor 5 (MYF5), myogenic differentiation 1 (MYOD1), CUGBP, Elav-like family member 1 (CELF1), and CELF2 were significantly up-regulated, while miR-196a, miR-200c, and miR-146a were significantly down-regulated. Enriched functions and pathways such as multicellular organismal development, RNA splicing, cell differentiation, and spliceosome are relevant to DM1. The miRNA-mRNA interaction network revealed that miR-182, miR-30c-2, and miR-200c were the critical nodes that potentially interacted with hub genes. Luciferase reporter assay confirmed the direct interaction between miR-196a and CELF2. Conclusion Those results implied that the observed miRNA/mRNA dysregulation could contribute to specific functions and pathways related to DM1 pathogenesis, highlighting the dysfunction of miR-196a and CELF2.

Insulin resistance, type 2 diabetes mellitus and sarcopenia

Sarcopenia is a chronic age-associated disease, the prevalence of which increases with aging. The primary form is associated with aging, when no other causes have been identified, the cause of secondary sarcopenia may be various diseases, including type 2 diabetes mellitus (DM2). One of the common links in the pathogenesis of DM2 and sarcopenia is insulin resistance. A combination of sarcopenia and obesity is often observed. The interrelation of these pathological processes, etiology and pathogenesis are presented in this literature review.

From metabolism to pathology: тhe role of sodium-glucose cotransporter-1 in the pathogenesis of type 2 diabetes mellitus

Type 2 diabetes mellitus (DM2) is one of the most common metabolic diseases of our time, affecting millions of people around the world. In recent years, the attention of researchers has been attracted by type 1 sodium-glucose cotransporter inhibitors (NGL-1), which open up new horizons in the treatment of this disease. Currently, there is data on the location of NGL-1 in many organs and tissues. Excessive activity of these transporters may contribute to an increase in blood glucose levels, which makes inhibition of this cotransporter a promising approach for glycemia management. This article will consider the effects of inhibition of iSGLT-1, their effect on the pathogenesis of DM2, and will also present the results of clinical studies confirming the effectiveness and safety of inhibition of iSGLT-1 in patients with DM2.

Myotonic Dystrophy Type 1: A Comprehensive Literary Review

Myotonic Dystrophy Type 1 (DM1) is a degenerative neuromuscular disease that costs 448 million dollars in the US annually to combat. Caused by the abnormal expansion of the CTG sequence located along the Dystrophia Myotonica Protein Kinase (DMPK) gene of chromosome 19, DM1 results in several different observable effects that include, but are not limited to cataracts, facial weakness, hypersomnia, cardiomyopathy, and arrhythmias. Symptoms are attributed to the rapid degeneration of muscles that leads to weakened control over the heart, lungs, gastrointestinal systems, and face. Treatments for DM1 are limited to minimizing morbidity such as through assistive mobility devices. In pursuit of a cure, pre-clinical models have provided a foundation for deeper investigations into the pathogenesis of DM1. Ongoing studies utilize molecular genetics and pharmacology to target the underlying molecular mechanisms, fortunately, many of these studies have shown potential in pre-clinical trials. Antisense therapy targets expanded trinucleotide regions and has demonstrated recovery of cardiac muscle in mice. CRISPR/SpCas9, when injected, has shown beneficial effects in several DM1 animal models. Furthermore, given the pre-clinical success of the novel pharmacologic agent AOC 1001, clinical trials have been initiated and are ongoing. Unfortunately, due to the nuances and difficulties in treating DM1, there is currently no Food and Drug Administration-approved disease-modifying therapies, and as such DM1 represents a growing public health concern.

Modeling Myotonic Dystrophy Type 2 Using Drosophila melanogaster.

Myotonic dystrophy 2 (DM2) is a genetic multi-systemic disease primarily affecting skeletal muscle. It is caused by CCTGn expansion in intron 1 of the CNBP gene, which encodes a zinc finger protein. DM2 disease has been successfully modeled in Drosophila melanogaster, allowing the identification and validation of new pathogenic mechanisms and potential therapeutic strategies. Here, we describe the principal tools used in Drosophila to study and dissect molecular pathways related to muscular dystrophies and summarize the main findings in DM2 pathogenesis based on DM2 Drosophila models. We also illustrate how Drosophila may be successfully used to generate a tractable animal model to identify novel genes able to affect and/or modify the pathogenic pathway and to discover new potential drugs.

The role and mechanism of myeloperoxidase in dermatomyositis

ObjectiveDermatomyositis (DM) is the best known subtype of idiopathic inflammatory myopathies. The hallmarks of DM muscle pathology including microangiopathy, inflammatory infiltration, and perifascicular atrophy. Recent findings have revealed pathogenetic effects of myeloperoxidase (MPO) by causing oxidative damage and regulating abnormal immunity in multiple disease conditions. In this study, we aimed to explore the role of MPO in the pathogenesis of DM. MethodsThe peripheral blood mononuclear cell (PBMC) mRNA expression and DNA methylation of MPO were verified using real-time qPCR and bisulfite pyrosequencing, respectively. Plasma MPO levels were measured with enzyme-linked immunosorbent assay, and their relationships with clinical characteristics were analyzed. The expression and distribution of MPO in muscle were tested by immunofluorescence. Purified human native MPO protein was used to stimulate human dermal microvascular endothelial cells (HDMECs) and skeletal muscle myotubes. The cell viability, tube forming capacity, permeability, adhesion molecule expressions in HDMECs, and atrophy and programmed cell death pathways in myotubes were then observed. ResultsMPO gene methylation was decreased, while mRNA expression and plasma levels were increased in DM. Plasma MPO of DM patients was positively correlated with serum creatine kinase (CK). MPO mainly distributed around endomysia capillaries and perifascicular atrophy in DM muscle biopsies, and was co-localized with CD4+, CD8+ T cells and CD19+ B cells. MPO not only could influence the cell viability, tube forming capacity, permeability and expression of adhesion molecules (including ICAM 1, VCAM 1 and E-selectin) of HDMECs, but also could cause atrophy of myotubes. ConclusionsOur study disclosed, for the first time, that MPO plays an important role in promoting inflammatory infiltration and inducing muscle damage in DM patients. MPO may be a potential biomarker for DM muscle involvement and MPO targeted drugs may be promising in DM treatment.

Afterdischarges in myotonic dystrophy type 1.

Electrodiagnostic testing is an important screening test for myotonic dystrophy type 1 (DM1). Although myotonic discharges are observed on electromyography in cases of DM1, it is difficult to distinguish DM1 from other myotonic disorders clinically. In the present study, afterdischarges, another type of pathological potential revealed by electrodiagnostic testing, were analyzed, and their role in distinguishing DM1 from other myotonic disorders was explored. Data from 33 patients with myotonic discharges on electromyography were analyzed retrospectively. According to gene testing, the patients were divided into DM1 (n = 20) and non-DM1 myotonia (n = 13) groups. Afterdischarges were investigated by retrospectively evaluating the electrodiagnostic findings of motor nerve conduction studies, F-waves, and repetitive nerve stimulations. Afterdischarges were observed in 17 of the 20 patients with DM1, with an occurrence rate of approximately 85%. However, afterdischarges were absent in all patients with non-DM1 myotonia. There were significant differences in the occurrence rate between the two groups (P < 0.01). Afterdischarges may serve as a suggestive role in clinical diagnosis of DM1. The discovery that DM1 can present with afterdischarges may pave a new way to study the pathogenesis of DM1.

Is Diabetes Pre-coded in the Brain? Role of Hypothalamus, Addiction Network and Social Cognition

The hypothalamus, the master regulator of circadian rhythm, in association with peripheral clocks, play crucial roles in glucose metabolism. Impairment in cerebral sensing, uptake and processing of glucose has been suggested in various animal and human diabetic models. Diabetes Mellitus has been largely superseded by the discovery of insulin and insulin resistance. Expanding horizons of knowledge of the roles of the hypothalamus in glucose metabolism and the overlapping neural pathways of sugar addictionwith other classically described substance and behavioral addictions networks have again thrown some light on the cerebral theory of DM pathogenesis.

High‐throughput transcriptomic profiling of mRNAs and lncRNAs in the dermatomyositis muscle by RNA sequencing

AbstractBackgroundDermatomyositis (DM) is an idiopathic inflammatory myopathy (IIM). In this study, we investigated the mRNAs and long noncoding RNAs (lncRNAs) in muscle biopsy specimens that are differentially expressed among patients with DM, patients with other IIM, and healthy controls (HCs).MethodsIn total, three patients with DM, 10 patients with other IIM, and three HCs were included. Muscle biopsy specimens were collected for RNA‐sequencing. Gene ontology and pathway analyses were employed to characterize the biological processes and signaling pathways.ResultsCompared with HCs, 372 differentially expressed mRNAs were identified within the DM group, including 275 upregulated and 97 downregulated ones. Moreover, 692 differentially expressed lncRNAs were identified in the DM group compared with HCs, of which 407 were upregulated and 285 were downregulated. Bioinformatic analysis indicated that the type‐I interferon signaling pathway and biological processes of innate immunity were significantly influenced by the differentially expressed mRNAs. Notably, 11 of the top 20 upregulated mRNAs were involved in the type‐I interferon signaling pathway. Reverse transcription polymerase chain reaction analysis verified the RNA‐sequencing data. Target gene prediction analysis suggested that the lncRNA NONHSAG043573.2 potentially targeting transporter associated with antigen processing 1, a key regulator of interferon signaling genes, might play an important role in the pathogenesis of DM.ConclusionsOur study assessed the transcriptomic profiles of differentially expressed mRNAs and lncRNAs in the DM muscle tissue and revealed that the upregulated mRNAs are significantly involved in the innate immune response and the type‐I interferon signaling pathway, which might play important roles in the pathogenesis of DM.

ВОЗМОЖНОСТИ ПРИМЕНЕНИЯ АНТИ-CD20 ИММУНОТЕРАПИИ ДЛЯ ЛЕЧЕНИЯ САХАРНОГО ДИАБЕТА 1 ТИПА У ДЕТЕЙ И ПОДРОСТКОВ (АНАЛИТИЧЕСКИЙ ОБЗОР)

Type 1 diabetes mellitus (DM1) is a world- and widespread disease in children and adolescents caused by the destruction of insulin-producing β-cells in the pancreas. As of today there is only one generally accepted approach to treating DM1, which is the insulin therapy, which in fact is a symptomatic therapy since it is aimed at correcting the outcome of the DM1 pathogenesis through compensation of insulin deficiency and elimination of hyperglycemia. The insulin therapy makes it possible to maintain the acceptable blood glucose levels for decades, but does not prevent the development of severe chronic complications of DM1, which in its turn are the main causes for disability cases and early deaths in such patients. Practitioners and scientists in diabetology are therefore actively searching for the ways to treating DM1 etiologically and pathogenetically. Among such methods there are various promising variants of immunotherapy aimed at prevention or suppression of an autoimmune reaction against β-cells. This review provides the basic information on DM1 and considers the modern approaches to its immunotherapy. The particular attention is paid to immunotherapy using cytotoxic monoclonal antibodies against B-lymphocytes autoreactive towards β-cells.

Antidiabetic and in vitro antioxidant potential of Mormodica charantia L. fruit in Experimentally Induced Wistar Rat Model of Type 2 Diabetes

BACKGROUND: The liver is a vital organ responsible for regulating the normal glucose homeostasis in the body system, and hepatic glucose metabolic dysregulation is one of the most critical elements in the pathogenesis of DM. METHOD: Twenty-five healthy rats aged seven weeks were divided into the following main groups; non-diabetic, diabetic untreated, diabetic treated with 250 mg/kg and 500 mg/kg of MC fruit, and diabetic treated with Metformin (500 mg/kg). Different models of in vitro antioxidant assays of MC fruit were also determined. RESULTS: The results showed that MC fruit has high antioxidant potential against DPPH, hydrogen peroxide, hydroxyl radicals, good reducing ferric power, significant Inhibition of lipid peroxidation and total antioxidant activities. The FBG levels decreased significantly in MC fruit treatment groups compared to diabetes control (DC) rats. The histology of the hepatic tissue of the diabetic untreated rats revealed a marked depletion in glycogen granules and hepatic DNA. These negative features were ameliorated in the MC fruit treated rats, as consistent glycogen granule storage and improved hepatic DNA presence were observed in the MC fruit treated rats. CONCLUSION: MC fruit reduces blood glucose levels in a diabetic rat model, and it also preserves the hepatic DNA and glycogen granules. MC fruit has a significant in vitro antioxidant activity.

Deregulations of miR‐1 and its target Multiplexin promote dilated cardiomyopathy associated with myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy in adults. It is caused by the excessive expansion of noncoding CTG repeats, which when transcribed affects the functions of RNA‐binding factors with adverse effects on alternative splicing, processing, and stability of a large set of muscular and cardiac transcripts. Among these effects, inefficient processing and down‐regulation of muscle‐ and heart‐specific miRNA, miR‐1, have been reported in DM1 patients, but the impact of reduced miR‐1 on DM1 pathogenesis has been unknown. Here, we use Drosophila DM1 models to explore the role of miR‐1 in cardiac dysfunction in DM1. We show that miR‐1 down‐regulation in the heart leads to dilated cardiomyopathy (DCM), a DM1‐associated phenotype. We combined in silico screening for miR‐1 targets with transcriptional profiling of DM1 cardiac cells to identify miR‐1 target genes with potential roles in DCM. We identify Multiplexin (Mp) as a new cardiac miR‐1 target involved in DM1. Mp encodes a collagen protein involved in cardiac tube formation in Drosophila. Mp and its human ortholog Col15A1 are both highly enriched in cardiac cells of DCM‐developing DM1 flies and in heart samples from DM1 patients with DCM, respectively. When overexpressed in the heart, Mp induces DCM, whereas its attenuation rescues the DCM phenotype of aged DM1 flies. Reduced levels of miR‐1 and consecutive up‐regulation of its target Mp/Col15A1 might be critical in DM1‐associated DCM.

Vorinostat Improves Myotonic Dystrophy Type 1 Splicing Abnormalities in DM1 Muscle Cell Lines and Skeletal Muscle from a DM1 Mouse Model.

Myotonic dystrophy type 1 (DM1), the most common form of adult muscular dystrophy, is caused by an abnormal expansion of CTG repeats in the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene. The expanded repeats of the DMPK mRNA form hairpin structures in vitro, which cause misregulation and/or sequestration of proteins including the splicing regulator muscleblind-like 1 (MBNL1). In turn, misregulation and sequestration of such proteins result in the aberrant alternative splicing of diverse mRNAs and underlie, at least in part, DM1 pathogenesis. It has been previously shown that disaggregating RNA foci repletes free MBNL1, rescues DM1 spliceopathy, and alleviates associated symptoms such as myotonia. Using an FDA-approved drug library, we have screened for a reduction of CUG foci in patient muscle cells and identified the HDAC inhibitor, vorinostat, as an inhibitor of foci formation; SERCA1 (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) spliceopathy was also improved by vorinostat treatment. Vorinostat treatment in a mouse model of DM1 (human skeletal actin-long repeat; HSALR) improved several spliceopathies, reduced muscle central nucleation, and restored chloride channel levels at the sarcolemma. Our in vitro and in vivo evidence showing amelioration of several DM1 disease markers marks vorinostat as a promising novel DM1 therapy.

Automatic Text-Mining Approach to Identify Molecular Target Candidates Associated with Metabolic Processes for Myotonic Dystrophy Type 1.

Myotonic dystrophy type 1 (DM1) is an autosomal dominant hereditary disease caused by abnormal expansion of unstable CTG repeats in the 3' untranslated region of the myotonic dystrophy protein kinase (DMPK) gene. This disease mainly affects skeletal muscle, resulting in myotonia, progressive distal muscle weakness, and atrophy, but also affects other tissues and systems, such as the heart and central nervous system. Despite some studies reporting therapeutic strategies for DM1, many issues remain unsolved, such as the contribution of metabolic and mitochondrial dysfunctions to DM1 pathogenesis. Therefore, it is crucial to identify molecular target candidates associated with metabolic processes for DM1. In this study, resorting to a bibliometric analysis, articles combining DM1, and metabolic/metabolism terms were identified and further analyzed using an unbiased strategy of automatic text mining with VOSviewer software. A list of candidate molecular targets for DM1 associated with metabolic/metabolism was generated and compared with genes previously associated with DM1 in the DisGeNET database. Furthermore, g:Profiler was used to perform a functional enrichment analysis using the Gene Ontology (GO) and REAC databases. Enriched signaling pathways were identified using integrated bioinformatics enrichment analyses. The results revealed that only 15 of the genes identified in the bibliometric analysis were previously associated with DM1 in the DisGeNET database. Of note, we identified 71 genes not previously associated with DM1, which are of particular interest and should be further explored. The functional enrichment analysis of these genes revealed that regulation of cellular metabolic and metabolic processes were the most associated biological processes. Additionally, a number of signaling pathways were found to be enriched, e.g., signaling by receptor tyrosine kinases, signaling by NRTK1 (TRKA), TRKA activation by NGF, PI3K-AKT activation, prolonged ERK activation events, and axon guidance. Overall, several valuable target candidates related to metabolic processes for DM1 were identified, such as NGF, NTRK1, RhoA, ROCK1, ROCK2, DAG, ACTA, ID1, ID2 MYOD, and MYOG. Therefore, our study strengthens the hypothesis that metabolic dysfunctions contribute to DM1 pathogenesis, and the exploitation of metabolic dysfunction targets is crucial for the development of future therapeutic interventions for DM1.

Establishment of quantitative and consistent in vitro skeletal muscle pathological models of myotonic dystrophy type 1 using patient-derived iPSCs

Myotonic dystrophy type 1 (DM1) is caused by expanded CTG repeats (CTGexp) in the dystrophia myotonica protein kinase (DMPK) gene, and the transcription products, expanded CUG repeats, sequester muscleblind like splicing regulator 1 (MBNL1), resulting in the nuclear MBNL1 aggregation in the DM1 cells. Loss of MBNL1 function is the pivotal mechanism underlying the pathogenesis of DM1. To develop therapeutics for DM1, proper human in vitro models based on the pathologic mechanism of DM1 are required. In this study, we established robust in vitro skeletal muscle cell models of DM1 with patient-derived induced pluripotent stem cells (iPSCs) using the MyoD1-induced system and iPSCs-derived muscle stem cell (iMuSC) differentiation system. Our newly established DM1 models enable simple quantitative evaluation of nuclear MBNL1 aggregation and the downstream splicing defects. Quantitative analyses using the MyoD1-induced myotubes showed that CTGexp-deleted DM1 skeletal myotubes exhibited a reversal of MBNL1-related pathologies, and antisense oligonucleotide treatment recovered these disease phenotypes in the DM1-iPSCs-derived myotubes. Furthermore, iMuSC-derived myotubes exhibited higher maturity than the MyoD1-induced myotubes, which enabled us to recapitulate the SERCA1 splicing defect in the DM1-iMuSC-derived myotubes. Our quantitative and reproducible in vitro models for DM1 established using human iPSCs are promising for drug discovery against DM1.