Sex differences on constitutive long non-coding RNA expression: Modulatory effect of estradiol and testosterone in muscle cells.

INTRODUCTION: Despite the growing awareness of sexual dimorphism between males and females under pathological and physiological conditions, sex bias in biomedical research in animal models and patients is still present nowadays. The main objective of this work was to investigate sex differences in constitutive long non-coding RNA expression in spinal cord and skeletal muscle from wild-type mice. MATERIALS AND METHODS: To assess the influence of gender on long non-coding RNAs, we extracted RNA from tissues of male and female mice and analyzed the expression on nine long non-coding RNAs, selected for being among the most commonly studied or exerting an important role in muscle, at 50, 60, and 120 days of age. RESULTS AND DISCUSSION: We observed age- and tissue-dependent significant sex differences, being more prominent in skeletal muscle. We also studied the effect of sex steroid hormones on long non-coding RNA expression in vitro, noticing a modulation of long non-coding RNA levels upon estradiol and dihydrotestosterone treatment in muscle. CONCLUSIONS: Taken together, results obtained evidenced sex differences on constitutive long non-coding RNA expression and suggested an influence of steroid hormones complementary to other possible factors. These findings emphasize the importance of including both sexes in experimental design to minimize any potential sex bias.

Inflammasome in ALS Skeletal Muscle: NLRP3 as a Potential Biomarker.

Since NLRP3 inflammasome plays a pivotal role in several neurodegenerative disorders, we hypothesized that levels of inflammasome components could help in diagnosis or prognosis of amyotrophic lateral sclerosis (ALS). Gene and protein expression was assayed by RT-PCR and Western blot. Spearman's correlation coefficient was used to determine the linear correlation of transcriptional expression levels with longevity throughout disease progression in mice models. Kaplan-Meier analysis was performed to evaluate MCC950 effects (NLRP3 inhibitor) on lifespan of SOD1G93A mice. The results showed significant alterations in NLRP3 inflammasome gene and protein levels in the skeletal muscle of SOD1G93A mice. Spearman's correlation coefficient revealed a positive association between Nlrp3 transcriptional levels in skeletal muscle and longevity of SOD1G93A mice (r = 0.506; p = 0.027). Accordingly, NLRP3 inactivation with MCC950 decreased the lifespan of mice. Furthermore, NLRP3 mRNA levels were significantly elevated in the blood of ALS patients compared to healthy controls (p = 0.03). In conclusion, NLRP3 could be involved in skeletal muscle pathogenesis of ALS, either through inflammasome or independently, and may play a dual role during disease progression. NLRP3 gene expression levels could be used as a biomarker to improve diagnosis and prognosis in skeletal muscle from animal models and also to support diagnosis in clinical practice with the blood of ALS patients.

What skeletal muscle has to say in amyotrophic lateral sclerosis: Implications for therapy.

Amyotrophic lateral sclerosis (ALS) is an adult onset disorder characterized by progressive neuromuscular junction (NMJ) dismantling and degeneration of motor neurons leading to atrophy and paralysis of voluntary muscles responsible for motion and breathing. Except for a minority of patients harbouring genetic mutations, the origin of most ALS cases remains elusive. Peripheral tissues, and particularly skeletal muscle, have lately demonstrated an active contribution to disease pathology attracting a growing interest for these tissues as therapeutic targets in ALS. In this sense, molecular mechanisms essential for cell and tissue homeostasis have been shown to be deregulated in the disease. These include muscle metabolism and mitochondrial activity, RNA processing, tissue-resident stem cell function responsible for muscle regeneration, and proteostasis that regulates muscle mass in adulthood. This review aims to compile scientific evidence that demonstrates the role of skeletal muscle in ALS pathology and serves as reference for development of novel therapeutic strategies targeting this tissue to delay disease onset and progression. LINKED ARTICLES: This article is part of a themed issue on Neurochemistry in Japan. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.6/issuetoc.

Competing Endogenous RNA Networks as Biomarkers in Neurodegenerative Diseases.

Protein aggregation is classically considered the main cause of neuronal death in neurodegenerative diseases (NDDs). However, increasing evidence suggests that alteration of RNA metabolism is a key factor in the etiopathogenesis of these complex disorders. Non-coding RNAs are the major contributor to the human transcriptome and are particularly abundant in the central nervous system, where they have been proposed to be involved in the onset and development of NDDs. Interestingly, some ncRNAs (such as lncRNAs, circRNAs and pseudogenes) share a common functionality in their ability to regulate gene expression by modulating miRNAs in a phenomenon known as the competing endogenous RNA mechanism. Moreover, ncRNAs are found in body fluids where their presence and concentration could serve as potential non-invasive biomarkers of NDDs. In this review, we summarize the ceRNA networks described in Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis and spinocerebellar ataxia type 7, and discuss their potential as biomarkers of these NDDs. Although numerous studies have been carried out, further research is needed to validate these complex interactions between RNAs and the alterations in RNA editing that could provide specific ceRNET profiles for neurodegenerative disorders, paving the way to a better understanding of these diseases.

DREAM-Dependent Activation of Astrocytes in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of unknown origin and characterized by a relentless loss of motor neurons that causes a progressive muscle weakness until death. Among the several pathogenic mechanisms that have been related to ALS, a dysregulation of calcium-buffering proteins in motor neurons of the brain and spinal cord can make these neurons more vulnerable to disease progression. Downstream regulatory element antagonist modulator (DREAM) is a neuronal calcium-binding protein that plays multiple roles in the nucleus and cytosol. The main aim of this study was focused on the characterization of DREAM and glial fibrillary acid protein (GFAP) in the brain and spinal cord tissues from transgenic SOD1G93A mice and ALS patients to unravel its potential role under neurodegenerative conditions. The DREAM and GFAP levels in the spinal cord and different brain areas from transgenic SOD1G93A mice and ALS patients were analyzed by Western blot and immunohistochemistry. Our findings suggest that the calcium-dependent excitotoxicity progressively enhanced in the CNS in ALS could modulate the multifunctional nature of DREAM, strengthening its apoptotic way of action in both motor neurons and astrocytes, which could act as an additional factor to increase neuronal damage. The direct crosstalk between astrocytes and motor neurons can become vulnerable under neurodegenerative conditions, and DREAM could act as an additional switch to enhance motor neuron loss. Together, these findings could pave the way to further study the molecular targets of DREAM to find novel therapeutic strategies to fight ALS.