Rosario Osta

Skeletal muscle undergoes structural and functional decline due to aging and neuromuscular disorders such as amyotrophic lateral sclerosis (ALS), both of which impact protein expression and contribute to muscle atrophy. This study investigates how aging and the SOD1^G93A ALS-related mutation affect the expression of eight genes previously linked to sarcopenia (PF4, OIT3, MMRN1, MASP1, C1R, SVEP1, VCAN and SPTB) but not yet characterized in muscle tissue. To this end, we analyzed their expression (1) during muscle aging in WT mice (5 and 24 months), (2) in SOD1^G93A-transfected myotube cells in vitro, (3) in a muscle-specific SOD1^G93A mouse model (5 and 24 months), and (4) in a systemic SOD1^G93A transgenic mouse at different disease stages (60 and 120 days) by quantitative PCR. All eight target genes were expressed in skeletal muscle and most of them showed increased transcription with aging. In ALS models, gene expression was significantly overexpressed at early stages, particularly in muscle-specific (MLC/SOD1^G93A) and systemic (SOD1^G93A) models, mimicking aging-related profiles. These alterations attenuated with disease progression, suggesting an early transient muscle response to ALS-linked SOD1 mutations. Hence, this study demonstrates that sarcopenia-associated proteins are actively expressed and modulated in skeletal muscle during aging and ALS and suggests convergent response mechanisms.

TAR DNA-binding protein 43 (TDP-43) dysfunction is a hallmark of amyotrophic lateral sclerosis (ALS) and related disorders, yet its role in skeletal muscle stem cells, the satellite cells (SC), remains incompletely understood. Here, we investigated ALS-associated gain- and loss-of-function TDP-43 mutations together with inducible SC-specific TDP-43 deletion. While TDP-43 ^Q331K and heterozygous TDP-43 ^F210I mice displayed normal muscle homeostasis, SC abundance, and regenerative capacity, complete TDP-43 loss caused a marked reduction of the SC pool, particularly in females, and shifted SCs from a CD34 ^high stem-like state toward a CD34 ^low primed population. TDP-43-deficient SCs failed to clonally expand, proliferate, and differentiate, resulting in severe regenerative failure following muscle injury. Notably, the SC pool failed to recover after injury and was nearly depleted 30 days post-injury, accompanied by muscle loss, fibrosis and fat infiltration. Transcriptomic analyses revealed activation of stress and aging-associated programs in uninjured TDP-43-deficient SCs, indicating the premature acquisition of an aging-like state. Consistently, chronological aging further exacerbated SC depletion, establishing TDP-43 as a critical regulator of SC stemness, regeneration, and resistance to age-related decline.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease whose diagnosis often remains delayed. Skeletal muscle is increasingly recognized as an early contributor to ALS pathology. Using lipid imaging mass spectrometry (LIMS) in Tibialis anterior muscle from hSOD1 ^G93A mice across disease stages, we identified fiber-type-specific and sex-dependent lipid remodeling. Lipid alterations were detected at the presymptomatic stage, preceding motor neuron loss and clinical symptoms. LIMS distinguished fast-twitch oxidative-glycolytic (type IIA) and glycolytic (type IIB/IIX) fibers and revealed their differential vulnerability to disease. Presymptomatic mutant muscles showed loss of physiological lipid signatures alongside disease-specific lipid changes. Although lipid profiles differed between sexes, ALS-associated alterations enabled accurate discrimination of mutant mice before symptom onset. Importantly, similar disease-related lipid changes were detected in serum, enabling accurate classification of presymptomatic animals. These findings establish lipid remodeling as an early ALS event and highlight novel biomarkers with potential for diagnosis and disease monitoring.

The absence of accessible and reliable biomarkers constitutes a critical barrier for the early diagnosis and stratification of neurodegenerative diseases. While peripheral blood offers a minimally invasive window into systemic pathophysiology, identifying molecular signatures that survive biological heterogeneity and technical noise remains an unresolved challenge. In this study, this issue was addressed through a comparative systemic transcriptomic analysis of Amyotrophic Lateral Sclerosis (ALS), Alzheimer’s disease (AD), and Parkinson’s disease (PD) in whole blood, implementing a comprehensive workflow integrating unsupervised network analysis and supervised machine-learning methods. By employing LASSO regression and cross-validation across independent external cohorts, a stable and specific transcriptomic signature for ALS was identified, comprising key crosstalk genes involved in systemic immune dysregulation and microglial function, including CTSS, PTEN, IL18, PTPRC, and CSF1R. In contrast, AD and PD exhibited weak transcriptomic signatures with poor predictive reproducibility, suggesting a distinctive systemic pathology in ALS. In addition, the study confirms the superiority of linear modeling for this genomic signature: while complex non-linear algorithms, specifically Radial Basis Function (RBF) kernel Support Vector Machine (SVM) and Random Forest, displayed high initial performance, they collapsed due to overfitting during external validation. Conversely, the linear LASSO model demonstrated superior robustness and generalizability (AUC 0.74). In conclusion, this study not only defines a unique systemic immunotranscriptomic signature for ALS, distinguishable from other neurodegenerative pathologies, but also establishes interpretability and linear simplicity as essential factors for developing reproducible blood-based biomarkers with clinical translational potential. AbstractSection Graphical Abstract The alternative text for this image may have been generated using AI.

Increasing evidence demonstrates that long noncoding RNAs (lncRNAs) are crucial for brain evolution and proper development and function of the central nervous system (CNS), exhibiting specific time-, spatial-, and sex-biassed expression patterns. This study investigated whether region-specific spatial expression patterns of brain-relevant lncRNAs are conserved between the mouse and human CNS. Demonstrating such cross-species conservation informs the translational value of mouse models for lncRNA biology. To test this, the expression of 14 lncRNAs was studied in the adult CNS of mice and humans across three different regions (spinal cord, brainstem, and frontal cortex), and age effects were assessed in mice. The results demonstrated conserved expression patterns between the two species, with region-specific changes. The frontal cortex exhibited high expression of Meg3, Miat, and Pvt1 lncRNAs, while the spinal cord showed high levels of Hotair and Gas5. Additionally, Malat1 displayed lower levels in females compared to males in the spinal cord compared to other regions. Finally, through GO functional enrichment analysis and literature review, this study emphasizes the role of lncRNAs in CNS physiology and disease, suggesting their involvement in neurological processes and conditions such as cortical development, neuronal synapsis, schizophrenia, Alzheimer’s, Parkinson’s, and amyotrophic lateral sclerosis. Overall, this research highlights the importance of further investigating the role of lncRNAs in brain function and their potential as key players in neurological disorders, opening the door to explaining the high region- and sex-specific effects of these disorders.

Sarcopenia, the loss of muscle mass and function generally associated to age, leads to increased dependence and mortality in older adults. Despite its clinical significance, unclear molecular mechanisms hinder the development of universal diagnostic and therapeutic monitoring methods. Recent research suggests long non-coding RNAs (lncRNAs) as potential biomarkers for muscle damage and sarcopenia. This study investigates the role of six specific lncRNAs as biomarkers for diagnosing and monitoring sarcopenia following physical training. For this purpose, an initial cohort of participants was divided into two experiments: Trial 1, a cross-sectional study comprising 54 sarcopenic patients and 29 robust controls, both including men and women; Trial 2, a non-randomized controlled trial, where the same sarcopenic patients from Trial 1 were divided in two groups: a Control Group (CG, n = 15); and a Trained Group (TG, n = 22). RNA was extracted from serum samples for all the participants, and the expression of 6 lncRNA (PVT1, HOTAIR, MALAT1, NEAT1, GAS5, H19), selected from the literature, was quantified by RT-PCR and compared between the different groups. Statistical evaluation uncovered four lncRNAs with significantly distinct expression in Trial 1: PVT1 (LOG2FC = 1.194), GAS5 (LOG2FC = 0.8224), NEAT1 (LOG2FC = 1.497) and H19 (LOG2FC = −0.9958) and three lncRNA significantly different between TG and CG in Trial 2 (PVT1 (LOG2FC = −1.796), MALAT1 (LOG2FC = 2.834) and H19 (LOG2FC = 1.355). Among them, NEAT 1 stands aout as promissing diagnostic marker ans PVT1 and H19 may serve as both diagnosis and treatment monitoring, altough further validation in larger cohorts is needed to confirm these results.

Research in amyotrophic lateral sclerosis (ALS) faces major burdens, including the urgent need for sensitive and specific biomarkers, the identification of novel and effective therapeutic targets and a deeper understanding of the mechanisms driving the disease. In this line, long non-coding RNAs (lncRNAs) have emerged as promising candidates due to their regulatory role in a variety of important biological processes such as RNA metabolism, neuroinflammation, apoptosis or proteostasis.

There is increasing evidence on the role of circular RNAs (circRNAs) in neuronal and muscular processes. Accordingly, their dysregulation is associated with neurodegenerative diseases and myopathies. We investigated circRNA expression in the central nervous system (CNS) and skeletal muscle, the two main tissues affected in amyotrophic lateral sclerosis (ALS). Based on circRNA sequencing analysis in spinal cord from ALS mice (SOD1G93A) followed by a literature search, 30 circRNAs potentially involved in ALS were tested. All selected circRNAs were downregulated in the SOD1G93A spinal cord, whereas only half of these were quantifiable and were generally upregulated in quadriceps muscle of SOD1G93A mice. Such tissue-dependent expression pattern was observed in both sexes and circRNA abundance in the spinal cord was higher than in the muscle, both in wild type and in SOD1G93A mice. Finally, we assessed the 18 circRNAs with the largest expression differences and the highest degree of interspecies conservation in brain samples from sporadic ALS (sALS) patients and healthy controls. Similar to the mouse model, circRNA levels tended to decrease in the CNS of sALS patients. Expression of circRNAs may be systematically altered in the two tissues most affected by ALS in a progressive and opposed manner. Although more detailed studies are warranted, circRNAs are potentially related to ALS etiopathogenesis and could possibly serve as future biomarkers, therapeutic targets, or customized therapeutic tools to modulate the pathology.

Background and Purpose: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease with limited treatment options. ALS pathogenesis involves intricate processes within motor neurons, characterized by dysregulated Ca²⁺ influx and buffering in early ALS‐affected motor neurones. This study proposes the modulation of ryanodine receptors (RyRs), key mediators of intracellular Ca²⁺, as a therapeutic target.Experimental Approach: A novel class of novel FKBP12 ligands that show activity as cytosolic calcium modulators through stabilizing RyR channel activity, were tested in the superoxide dismutase 1 (SOD1)^G93A mouse model of ALS. Different outcomes were used to assess treatment efficacy, including electrophysiology, histopathology, neuromuscular function and survival.Key Results: Among the novel FKBP12 ligands, MP‐010 was chosen for its central nervous system availability and favourable in vitro pharmaco‐toxicological profile. Chronic administration of MP‐010 to SOD1^G93A mice produced preservation of motor nerve conduction, with the 61‐mg·kg⁻¹ dose significantly delaying the onset of motor impairment. This was accompanied by improved motor coordination, increased innervated endplates and significant preservation of motor neurones in the spinal cord of treated mice. Notably, MP‐010 treatment significantly extended lifespan by an average of 10 days compared to vehicle.Conclusions and Implications: FKBP12 ligands, particularly MP‐010, exhibit promising neuroprotective effects in ALS, highlighting their potential as novel therapeutic agents. Further investigations into the molecular mechanisms and clinical translatability of these compounds are needed for their application in ALS treatment.