Search Results (96)

Background/Objectives: Myotonic dystrophy type 1 (DM1) is a rare, multisystemic disorder caused by an expanded (CTG)n repeat in the DMPK gene. Although DM1 has been studied in several populations, access to molecular diagnosis and comprehensive care remains limited in many low- and middle-income countries. This study provides an updated overview of DM1 in Mexico, from diagnostic implementation to patient management, describing key clinical and genetic findings. Methods: We conducted a nationwide, 15-year prospective study at Mexico’s National Reference Center for neuromuscular diseases. A total of 853 individuals at risk were subjected to clinical and molecular evaluation using PCR, TP-PCR, and SP-PCR, encompassing symptomatic, pre-symptomatic, prenatal, and preimplantation genetic diagnosis. Socioeconomic, clinical, and molecular variables were analyzed. Results: A total of 488 individuals were confirmed as DM1 carriers, with the most prevalent phenotypes being classic (36.5%) and juvenile (28.5%). Genomic analysis revealed a correlation between CTG tract sizes and phenotypes. Intriguingly, interrupted CTG repeat tracts were identified in 2.8% of DM1 carriers, who exhibited milder clinical phenotypes and a reduced degree of somatic and intergenerational instability. Survival analysis revealed a reduction in symptom-free survival in patients with larger expansions, while interrupted CTG tracts were associated with delayed onset. Conclusions: The centralization of diagnostic services in Mexico resulted in regional disparities, impacting early diagnosis and family planning. This study highlights the clinical and molecular diversity of DM1 in a Latin American population and underscores the urgent need for decentralized diagnostic services, integrated care models, and tailored prognostic tools in underserved settings. Full article

Myotonic Dystrophy Type 1 (DM1) is a complex multisystemic genetic disorder caused by CTG repeat expansions in the DMPK gene, leading to RNA toxicity and widespread splicing defects. These splicing abnormalities affect multiple systems, including the respiratory, skeletal, cardiac, nervous, and endocrine systems, resulting in aggressive symptoms that significantly impact quality of life and survival. Cardiac complications are the second leading cause of deaths in DM1, after respiratory insufficiency. Current research is largely focused on understanding cardiac pathology in DM1. This review highlights recent advancements in the clinical and pathological characterization of DM1 cardiac involvement, preclinical models used to study cardiac dysfunction, and emerging therapeutic strategies that target the molecular basis of DM1. Promising approaches include RNA-targeting strategies such as antisense oligonucleotides (ASOs), gene-editing tools like CRISPR-Cas9, and small molecules that modulate RNA splicing. ASOs aim to reduce toxic RNA accumulation, CRISPR-based approaches aim to excise or correct the expanded CTG repeats, and repurposed small-molecule drugs, such as vorinostat, tideglusib, and metformin, could serve as potential therapeutic agents for DM1 patients with cardiac complications. Despite this progress, several challenges remain: the heterogeneity of cardiac manifestations, unpredictable and often silent progression of arrhythmias, limited therapeutic options beyond implantable cardioverter-defibrillator (ICD)/pacemaker implantations, and complex interplay with the multisystemic nature of DM1. More research and well-designed clinical trials are urgently needed to translate these promising strategies into effective treatments for DM1-associated cardiac disease. Here, we discuss the current knowledge in DM1 cardiac pathology and preclinical models as well as the benefits and pitfalls of the available therapeutic approaches. Full article

Myotonic dystrophy type 1 (DM1) results from the toxicity of RNA produced from the mutant allele of the DMPK gene. The mechanism by which the toxic RNA causes muscular dystrophy in DM1 is unknown. Dystrophy in DM1 is associated with defective muscle regeneration and repair. Here, we used the BaCl₂-induced damage model of muscle injury to study muscle regeneration in the HSALR mouse model of DM1. We have previously shown delayed muscle regeneration and deleterious effects on satellite cell numbers in another mouse model of RNA toxicity using similar experimental approaches. We found that HSALR mice show no apparent deleterious effects on satellite cell number or early markers of muscle regeneration. Further analysis at later time points after damage showed increased numbers of internal nuclei as compared to control mice undergoing the same protocol. Muscle fiber type analysis using immunostaining for type IIA and IIB fibers identified a switch to slower fibers (increased fraction of IIA and reduced fraction of IIB fibers) after regeneration in HSALR mice as compared to regenerated muscle from wildtype mice. Full article

Myotonic dystrophy type 1 (DM1) is a progressive multisystemic disease caused by a CTG repeat expansion in the DMPK gene. The toxic mutant mRNA sequesters MBNL proteins, disrupting global RNA metabolism. Although alternative splicing in DM1 skeletal muscle pathology has been extensively studied, early-stage transcriptomic changes remained uncharacterized. To gain deeper and contextual insight into DM1 transcriptome, we performed the first Weighted Gene Co-expression Network Analysis (WGCNA) on skeletal muscle RNA sequencing data from the widely used DM1 mouse model HSA^LR (~250 CTG repeats). We identified 532 core genes using data from 16-week-old mice, an age before the onset of muscle weakness. Additional differential expression analysis across multiple HSA^LR datasets revealed 42 common up-regulated coding and non-coding genes. Within identified core genes, the pathway gene-pair signature analysis enabled contextual selection of functionally related genes involved in maintaining proteostasis, including endoplasmic reticulum (ER) protein processing, the ubiquitin-proteasome system (UPS), macroautophagy and mitophagy, and muscle contraction. The enrichment of ER protein processing with prevailing core genes related to ER-associated degradation suggests adaptive chaperone and UPS activation, while core genes such as Ambra1, Mfn2, and Usp30 indicate adaptations in mitochondrial quality control. Coordinated early alterations in processes maintaining protein homeostasis, critical for muscle mass and function, possibly reflect a response to cellular stress due to repeat expansion and appears before muscle weakness development. Although the study relies exclusively on transcriptomic analyses, it offers a comprehensive, hypothesis-generating perspective that pinpoints candidate pathways, preceding muscle weakness, for future mechanistic validation. Full article

Myotonic Dystrophy type 1 (DM1) is a complex disease affecting multiple tissues, including skeletal and cardiac muscles, the brain and the eyes. DM1 results from an expansion of CTG repeats in the 3′ UTR of the DMPK gene. Previously, we described that the small-molecule inhibitor of GSK3β, tideglusib (TG), reduces DM1 pathology in DM1 cell and mouse models by correcting the GSK3β-CUGBP1 pathway, decreasing the mutant CUG-containing RNA. Respectively, clinical trials using TG showed promising results for patients with congenital DM1 (CDM1). The drug development in DM1 human studies needs specific and noninvasive biomarkers. We examined the blood levels of active GSK3β in different clinical forms of DM1 and found an increase in active GSK3β in the peripheral blood mononuclear cells (PBMCs) in patients with CDM1, juvenile DM1 and adult-onset DM1 vs. unaffected patients. The blood levels of active GSK3β correlate with the length of CTG repeats and severity of muscle weakness. Thrombospondin and TGFβ, linked to the TG-GSK3β pathway in DM1, are also elevated in the DM1 patients’ blood. These findings show that the blood levels of active GSK3β might be developed as a potential noninvasive biomarker of muscle weakness in DM1. Full article

Head and neck cancer (HNC) is a highly aggressive malignancy with limited treatment options and poor prognosis. Inflammation plays a critical role in HNC progression, with elevated levels of pro-inflammatory cytokines such as TNF, IL-6, IL-8, and IL-1β contributing to tumor development. In this study, a novel series of boronic chalcones was designed and synthesized as potential dual-action anticancer and anti-inflammatory agents. The most potent compounds were evaluated for their cytotoxicity against Squamous Cell Carcinoma (SCC-25), and their selectivity index (SI) was determined. Compound 5 emerged as the most promising, displaying cytotoxicity against cancer cells, with IC₅₀ values of 17.9 µM and a favorable SI (>3). Mechanistic studies revealed that its anticancer activity was independent of p53 status, and annexin V/PI staining indicated cell death via necrosis. Interestingly, compound 5 also significantly reduced pro-inflammatory cytokine levels, as TNF and IL-6. Furthermore, drug metabolism and pharmacokinetics (DMPK) studies demonstrated that compound 5 exhibited moderate solubility and high permeability. These findings underscore the crucial role of the boronic acid moiety in enhancing both anticancer and anti-inflammatory properties. Full article

Background: Carnosine is a multimodal pleotropic endogenous molecule that exhibits properties that make it a compelling therapeutic agent for further evaluation in a number of diseases. However, little data currently exists on its pharmacokinetic profile, maximum tolerated doses, side effects and whether oral administration can lead to elevated brain concentrations. Method: To investigate this, sixteen healthy volunteers underwent a single dose-escalation study of oral carnosine to establish safety, tolerability, and pharmacokinetics. A subset (n = 5) underwent Proton Magnetic Resonance Imaging (MRI) spectroscopy to evaluate the effect of oral dosing on brain carnosine concentrations, and another subset (n = 4) completed a long-term (4-week) dosing study. Results: Oral carnosine was safe and well tolerated up to a dose of 10 g. At doses of 15 g, the frequency of adverse events became unacceptably high, with 77% of participants experiencing side effects, most commonly headache (43.5%), nausea (21.7%) and paraesthesia (21.7%). While pharmacokinetic profiles varied between individuals, peak plasma concentrations occurred within the first hour of dosing. Little circulating carnosine was detectable beyond 4 h. Brain carnosine concentration increased at 1 h post-dose but reverted to baseline values by 5 h. Long-term dosing at 5 g twice daily did not result in any adverse events. Conclusions: Our data will inform dosing interventions in future clinical trials of this exciting agent. Full article

Background/Objectives: Myotonic dystrophy type 1 (DM1) is a rare neuromuscular disorder characterized by respiratory dysfunction that significantly impacts quality of life and longevity. This study aimed to explore the outcomes of pulmonary function tests and sleep-disordered breathing (SDB) workups in children with DM1 and to identify the factors contributing to SDB. Methods: A retrospective study examined patients’ medical records, including genetic analyses, clinical characteristics, and noninvasive pulmonary function testing (PFT), when possible. The Pediatric Sleep Questionnaire (PSQ), arterial blood gases, polygraphy, and overnight transcutaneous capnometry (PtcCO₂) were used to assess SDB. Results: The size of CTG expansion in the DMPK gene directly correlated with the severity of respiratory complications and the need for early tracheostomy tube insertion in 7/20 (35%) patients. A total of 13/20 (65%) children were available for respiratory evaluation during spontaneous breathing. While moderate/severe obstructive sleep apnea syndrome (OSAS) and hypoventilation were confirmed in 4/13 (31%) children, none of the patients had mixed or dominantly central sleep apnea syndrome. There was no correlation between apnea–hypopnea index (AHI) or PtcCO₂ and the presence of SDB-related symptoms or the PSQ score. Although a significant correlation between AHI and PtcCO₂ was not confirmed (p = 0.447), the oxygen desaturation index directly correlated with PtcCO₂ (p = 0.014). Conclusions: While SDB symptoms in children with DM1 may not fully correlate with observed respiratory events or impaired gas exchange during sleep, a comprehensive screening for SDB should be considered for all patients with DM1. Further research into disease-specific recommendations encompassing the standardization of PFT, as well as overnight polygraphic and capnometry recordings, could help to guide timely, personalized treatment. Full article

Background: Extrapolation of intrinsic clearance from in vitro systems such as liver microsomes or hepatocytes is an established approach to predict clearance in preclinical species and in humans. A common discussion in the literature is whether the predictive accuracy of such extrapolations is influenced by the chemotype and whether these methods are also applicable to compounds studied in early drug discovery programs. Compounds in such programs are frequently lipophilic and show low solubility and low free fraction in plasma, which may pose challenges to the extrapolation of clearance different from those of the final clinical candidates. A similar discussion has been raised about compounds residing beyond the traditional small-molecule property space, such as PROTACs© and other molecules incompatible with Lipinski’s rule-of-five. Methods: To further enlighten the field on these matters, we present a study comparing the predictive accuracy between mouse hepatocytes and microsomes for a set of molecules (N = 211) from the Merck Healthcare drug discovery pipeline. This set was dominated by compounds belonging to class 2 and 4 of the extended clearance classification systems (ECCS). It contained a similar proportion of molecules compliant with the Lipinski rule-of-five (N = 127) and molecules lacking such compliance (N = 84). Results: This study showed no or little differences in predictive accuracy nor bias between the two groups, with an average fold error close to 1, an absolute average fold error of just over 2, and around 50% being within 2-fold and >90% being within 5-fold of the predicted unbound clearance in both in vitro systems. Furthermore, no significant differences in accuracy were observed for compounds with an extremely low free fraction (down to 0.05%) in plasma. Conclusions: The accuracy of in vitro–in vivo extrapolation of female CD-1 mouse clearance was not affected by the physicochemical properties. Full article

The complexity of therapeutic proteins like antibody–drug conjugates (ADCs) holds a tremendous analytical challenge. Complementary mass spectrometry approaches such as peptide mapping and intact mass analysis are required for the in-depth characterization of these bioconjugates. Cysteine-linked ADCs have shown a unique challenge for characterization, mainly when the conjugation is carried out on interchain cysteines, because their intact analysis requires native mass spectrometry conditions to preserve non-covalent binding between antibody chains. In this work, two different approaches were proposed. Specifically, a full scan data-independent all ion fragmentation (FS-AIF) and a full scan data-dependent targeted MS2 (FS-ddtMS2) were applied to generate complementary datasets for a cysteine-linked ADC characterization with a highly reactive payload. These two methods were applied to in vitro plasma stability and in vivo PK samples to calculate and refine mean drug-to-antibody ratio over time. Using this approach, we successfully characterized an ADC containing a hydrolysis-sensitive payload and refined the “active” drug-to-antibody ratio on in vitro stability and in vivo samples. These two methods allowed the confirmation of the different ADC species and potential metabolites of conjugated payload attached to the antibody backbone in a single analysis without needing a dedicated method for the conjugated payload metabolite identification. Full article

The cholinergic pathways in the central nervous system (CNS) play a pivotal role in different cognitive functions of the brain, such as memory and learning. This review takes a dive into the pharmacological side of this important part of CNS function, taking into consideration muscarinic receptors and cholinesterase enzymes. Targeting a specific subtype of five primary muscarinic receptor subtypes (M1-M5) through agonism or antagonism may benefit patients; thus, there is a great pharmaceutical research interest. Inhibition of AChE and BChE, orthosteric or allosteric, or partial agonism of M1 mAChR are correlated with Alzheimer’s disease (AD) symptoms improvement. Agonism or antagonism on different muscarinic receptor subunits may lessen schizophrenia symptoms (especially positive allosteric modulation of M4 mAChR). Selective antagonism of M4 mAChR is a promising treatment for Parkinson’s disease and dystonia, and the adverse effects are limited compared to inhibition of all five mAChR. Additionally, selective M5 antagonism plays a role in drug independence behavior. M3 mAChR overexpression is associated with malignancies, and M3R antagonists seem to have a therapeutic potential in cancer, while M1R and M2R inhibition leads to reduction of neoangiogenesis. Depending on the type of cancer, agonism of mAChR may promote cancer cell proliferation (as M3R agonism does) or protection against further tumor development (M1R agonism). Thus, there is an intense need to discover new potent compounds with specific action on muscarinic receptor subtypes. Chemical structures, chemical modification of function groups aiming at action enhancement, reduction of adverse effects, and optimization of Drug Metabolism and Pharmacokinetics (DMPK) will be further discussed, as well as protein–ligand docking. Full article

Background/Objectives: Missplicing caused by toxic DMPK-mRNA is described as a hallmark of myotonic dystrophy type 1 (DM1). Yet, there is an expressional misregulation of additional splicing factors described in DM1, and missplicing has been observed in other myopathies. Here, we compare the expressional misregulation of splicing factors and the resulting splicing profiles between three different hereditary myopathies. Methods: We used publicly available RNA-sequencing datasets for the three muscular dystrophies—DM1, facioscapulohumeral muscular dystrophy (FSHD) and Emery–Dreifuss muscular dystrophy (EDMD)—to compare the splicing factor expression and missplicing genome-wide using DESeq2 and MAJIQ. Results: Upregulation of alternative splicing factors and downregulation of constitutive splicing factors were detected for all three myopathies, but to different degrees. Correspondingly, the missplicing events were mostly alternative exon usage and skipping events. In DM1, most events were alternative exon usage and intron retention, while exon skipping was prevalent in FSHD, with EDMD being in between the two other myopathies in terms of splice factor regulation as well as missplicing. Accordingly, the missplicing events were only partially shared between these three myopathies, sometimes with the same locus being spliced differently. Conclusions: This indicates a combination of primary (toxic RNA) and more downstream effects (splicing factor expression) resulting in the DM1 missplicing phenotype. Furthermore, this analysis allows the distinction between disease-specific missplicing and general myopathic splicing alteration to be used as biomarkers. Full article

Fragile X, Huntington disease, and myotonic dystrophy type 1 are prototypical examples of human disorders caused by short tandem repeat variation, repetitive nucleotide stretches that are highly mutable both in the germline and somatic tissue. As short tandem repeats are unstable, they can expand, contract, and acquire and lose epigenetic marks in somatic tissue. This means within an individual, the genotype and epigenetic state at these loci can vary considerably from cell to cell. This somatic mosaicism may play a key role in clinical pathogenesis, and yet, our understanding of mosaicism in driving clinical phenotypes in short tandem repeat disorders is only just emerging. This review focuses on these three relatively well-studied examples where, given the advent of new technologies and bioinformatic approaches, a critical role for mosaicism is coming into focus both with respect to cellular physiology and clinical phenotypes. Full article

Background/Objectives: Short tandem repeat expansions are the most common cause of inherited neurological diseases. These disorders are clinically and genetically heterogeneous, such as in myotonic dystrophy and spinocerebellar ataxia, and they are caused by different repeat motifs in different genomic locations. Major advances in bioinformatic tools used to detect repeat expansions from short read sequencing data in the last few years have led to the implementation of these workflows into next generation sequencing pipelines in healthcare. Here, we aimed to evaluate the clinical utility of analysing repeat expansions through exome sequencing in a large cohort of genetically undiagnosed patients with neurological disorders. Methods: We here analyse 27 disease-causing DNA repeats found in the coding, intronic and untranslated regions in 12,496 exomes in patients with a range of neurogenetic conditions. Results: We identified—and validated by polymerase chain reaction—29 repeat expansions across a range of loci, 48% (n = 14) of which were diagnostic. We then analysed the genotyping performance across all repeat loci and found that, despite high coverage in most repeats in coding regions, some loci had low genotyping rates, such as those that cause spinocerebellar ataxia 2 (ATXN2, 0.1–8.4%) and Huntington disease (HTT, 0.2–58.2%), depending on the capture kit. Conversely, while most intronic repeats were not genotyped, we found a high genotyping rate in the intronic locus that causes spinocerebellar ataxia 36 (NOP56, 30.1–98.3%) and in the one that causes myotonic dystrophy type 1 (DMPK, myotonic dystrophy type 1). Conclusions: We show that the key factors that influence the genotyping rate of repeat expansion loci analysis are the sequencing read length and exome capture kit. These results provide important information about the performance of exome sequencing as a genetic test for repeat expansion disorders. Full article

AE90015 is a highly specific and effective negative allosteric modulator (NAM) for the human mGlu5 receptor, showing significant promise for treating Parkinson’s disease. An in vivo rat oral dose study was conducted on AE90015, which involved the collection of urine and bile samples over a 24 h period. At the study’s endpoint, plasma, liver, brain, and renal tissues were also collected. A total of 30 metabolites of AE90015 were identified and structurally characterized or detected using high-resolution LC-MS/MSn. These metabolites fall into four categories: mono-hydroxyl, di-hydroxyl, mono-hydroxyl glucuronide, and di-hydroxyl glucuronide. This study provided a comprehensive overview of the metabolism, excretion, and disposition of AE90015, a promising NAM. The primary clearance pathway for AE90015 is mono-oxidation, accounting for 96% of the total, while direct excretion via renal and bile routes accounted for only 0.5%. Bile emerged as the predominant excretion route, at 65%, for metabolites and a minor amount of parent compound, which contrasts with the common assumption that urine would be the primary excretion pathway, which accounted for 26%. Each adamantyl and pyrazine moiety of AE90015 undergoes a one-time oxidation, while the pyridyl portion remains unmetabolized. Secondary metabolites, such as di-hydroxylated forms and glucuronide conjugates, do not contribute to clearance. In this work, a new quantification method combining UV and mass spectra integration was developed, allowing for the quantification of overlapping metabolite peaks. This novel approach proved to be highly effective for metabolite identification in early preclinical studies. Full article