The role of microRNAs in amyotrophic lateral sclerosis

Dissertação para obtenção do Grau de Mestre em Genética Molecular e BiomedicinaMicroRNAs (miRNAs) are emerging as a primary mediator of gene regulation in many different cell types. There is increasing evidence that specific subsets of miRNA play a prominent role in the nervous system, both in development and in specific neurodegenerative diseases. This study aims to elucidate the role of microRNA in selective motor neuron death that is the hallmark of amyotrophic Lateral sclerosis (ALS). Pre-symptomatic time-point was chosen since the levels of miRNAs are highly likely to be altered as a secondary consequence of cell injury and death in ALS. Laser capture microdissection (LCM) was used to study miRNA profiles in motor neurons of spinal cord tissue from SOD1G93A mice, the best characterized model of ALS. In preliminary work, using miRNA specific chips we have identified 2 miRNAs which are dramatically upregulated before disease onset. In this study, high RNA quality was achieved from laser captured cells, which consist in a major advance towards obtaining meaningful results of these miRNAs expression in downstream applications. Despite LCM technology has become increasingly sophisticated; rapidly obtaining enough amount of starting material for downstream applications is still extremely challenging. The combination of this optimized technique with microarrays, followed by RT-qPCR may provide insights into potential contribution of microRNAs to progression of neurodegeneration of motor neurons in ALS

Understanding Neuromuscular Health and Disease: Advances in Genetics, Omics, and Molecular Function

This compilation focuses on recent advances in the molecular and cellular understandingof neuromuscular biology, and the treatment of neuromuscular disease.These advances are at the forefront of modern molecular methodologies, oftenintegrating across wet-lab cell and tissue models, dry-lab computational approaches,and clinical studies. The continuing development and application ofmultiomics methods offer particular challenges and opportunities in the field,not least in the potential for personalized medicine

Differential expression of microRNAs and other small RNAs in muscle tissue of patients with ALS and healthy age-matched controls

Amyotrophic lateral sclerosis is a late-onset disorder primarily affecting motor neurons and leading to progressive and lethal skeletal muscle atrophy. Small RNAs, including microRNAs (miRNAs), can serve as important regulators of gene expression and can act both globally and in a tissue-/cell-type-specific manner. In muscle, miRNAs called myomiRs govern important processes and are deregulated in various disorders. Several myomiRs have shown promise for therapeutic use in cellular and animal models of ALS; however, the exact miRNA species differentially expressed in muscle tissue of ALS patients remain unknown. Following small RNA-Seq, we compared the expression of small RNAs in muscle tissue of ALS patients and healthy age-matched controls. The identified snoRNAs, mtRNAs and other small RNAs provide possible molecular links between insulin signaling and ALS. Furthermore, the identified miRNAs are predicted to target proteins that are involved in both normal processes and various muscle disorders and indicate muscle tissue is undergoing active reinnervation/compensatory attempts thus providing targets for further research and therapy development in ALS

Dysregulation of MicroRNAs and Target Genes Networks in Peripheral Blood of Patients With Sporadic Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurodegenerative disease. While genetics and other factors contribute to ALS pathogenesis, critical knowledge is still missing and validated biomarkers for monitoring the disease activity have not yet been identified. To address those aspects we carried out this study with the primary aim of identifying possible miRNAs/mRNAs dysregulation associated with the sporadic form of the disease (sALS). Additionally, we explored miRNAs as modulating factors of the observed clinical features. Study included 56 sALS and 20 healthy controls (HCs). We analyzed the peripheral blood samples of sALS patients and HCs with a high-throughput next-generation sequencing followed by an integrated bioinformatics/biostatistics analysis. Results showed that 38 miRNAs (let-7a-5p, let-7d-5p, let-7f-5p, let-7g-5p, let-7i-5p, miR-103a-3p, miR-106b-3p, miR-128-3p, miR-130a-3p, miR-130b-3p, miR-144-5p, miR-148a-3p, miR-148b-3p, miR-15a-5p, miR-15b-5p, miR-151a-5p, miR-151b, miR-16-5p, miR-182-5p, miR-183-5p, miR-186-5p, miR-22-3p, miR-221-3p, miR-223-3p, miR-23a-3p, miR-26a-5p, miR-26b-5p, miR-27b-3p, miR-28-3p, miR-30b-5p, miR-30c-5p, miR-342-3p, miR-425-5p, miR-451a, miR-532-5p, miR-550a-3p, miR-584-5p, miR-93-5p) were significantly downregulated in sALS. We also found that different miRNAs profiles characterized the bulbar/spinal onset and the progression rate. This observation supports the hypothesis that miRNAs may impact the phenotypic expression of the disease. Genes known to be associated with ALS (e.g., PARK7, C9orf72, ALS2, MATR3, SPG11, ATXN2) were confirmed to be dysregulated in our study. We also identified other potential candidate genes like LGALS3 (implicated in neuroinflammation) and PRKCD (activated in mitochondrial-induced apoptosis). Some of the downregulated genes are involved in molecular bindings to ions (i.e., metals, zinc, magnesium) and in ions-related functions. The genes that we found upregulated were involved in the immune response, oxidation–reduction, and apoptosis. These findings may have important implication for the monitoring, e.g., of sALS progression and therefore represent a significant advance in the elucidation of the disease’s underlying molecular mechanisms. The extensive multidisciplinary approach we applied in this study was critically important for its success, especially in complex disorders such as sALS, wherein access to genetic background is a major limitation

Genetic Regulation Of Tmem106b In The Pathogenesis Of Frontotemporal Lobar Degeneration

Neurodegenerative diseases are an emerging global health crisis, with the projected global cost of dementia alone expected to exceed $1 trillion, or \u3e1% of world GDP, by 2018. However, there are no disease-modifying treatments for the major neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, frontotemporal lobar degeneration (FTLD), and amyotrophic lateral sclerosis. Therefore, there is an urgent need for a better understanding of the pathophysiology underlying these diseases. While genome-wide association studies (GWAS) have identified ~200 genetic variants that are associated with risk of developing neurodegenerative disease, the biological mechanisms underlying these associations are largely unknown. This dissertation investigates the mechanisms by which common genetic variation at TMEM106B, a GWAS-identified risk locus for FTLD, influences disease risk. First, using genetic and clinical data from thirty American and European medical centers, I demonstrate that the TMEM106B locus acts as a genetic modifier of a common Mendelian form of FTLD. Second, I investigate the role of increased TMEM106B expression levels, which have been reported both in FTLD patients and in individuals carrying the TMEM106B risk allele, in FTLD pathogenesis. I demonstrate that microRNA-132, the most dysregulated microRNA in a genome-wide screen of FTLD and control brains, directly represses TMEM106B expression in human cells, and likely contributes to the elevated TMEM106B levels seen in disease. I then combine statistical approaches, bioinformatics, and experimental approaches in order to functionally characterize all candidate GWAS causal variants at the TMEM106B locus. This approach identifies a noncoding variant, rs1990620, which affects CTCF-mediated long-range chromatin interactions between distal regulatory elements, as the likely causal variant responsible for altering TMEM106B expression levels and disease risk. These results provide a plausible mechanism by which TMEM106B genotype and expression levels influence FTLD risk and clinical progression, and provide a general framework for elucidating the biological mechanisms underlying a disease-associated risk locus. Such an approach will be necessary in order to translate the thousands of loci associated with disease risk by GWAS into mechanistic understanding and therapeutic advances

Topological Analysis of Biological Pathways: Genes, MicroRNAs and Pathways Involved in Hepatocellular Carcinoma

abstract: Rewired biological pathways and/or rewired microRNA (miRNA)-mRNA interactions might also influence the activity of biological pathways. Here, rewired biological pathways is defined as differential (rewiring) effect of genes on the topology of biological pathways between controls and cases. Similarly, rewired miRNA-mRNA interactions are defined as the differential (rewiring) effects of miRNAs on the topology of biological pathways between controls and cases. In the dissertation, it is discussed that how rewired biological pathways (Chapter 1) and/or rewired miRNA-mRNA interactions (Chapter 2) aberrantly influence the activity of biological pathways and their association with disease. This dissertation proposes two PageRank-based analytical methods, Pathways of Topological Rank Analysis (PoTRA) and miR2Pathway, discussed in Chapter 1 and Chapter 2, respectively. PoTRA focuses on detecting pathways with an altered number of hub genes in corresponding pathways between two phenotypes. The basis for PoTRA is that the loss of connectivity is a common topological trait of cancer networks, as well as the prior knowledge that a normal biological network is a scale-free network whose degree distribution follows a power law where a small number of nodes are hubs and a large number of nodes are non-hubs. However, from normal to cancer, the process of the network losing connectivity might be the process of disrupting the scale-free structure of the network, namely, the number of hub genes might be altered in cancer compared to that in normal samples. Hence, it is hypothesized that if the number of hub genes is different in a pathway between normal and cancer, this pathway might be involved in cancer. MiR2Pathway focuses on quantifying the differential effects of miRNAs on the activity of a biological pathway when miRNA-mRNA connections are altered from normal to disease and rank disease risk of rewired miRNA-mediated biological pathways. This dissertation explores how rewired gene-gene interactions and rewired miRNA-mRNA interactions lead to aberrant activity of biological pathways, and rank pathways for their disease risk. The two methods proposed here can be used to complement existing genomics analysis methods to facilitate the study of biological mechanisms behind disease at the systems-level.Dissertation/ThesisDoctoral Dissertation Molecular and Cellular Biology 201

Whole transcriptome approach to evaluate the effect of aluminium hydroxide in ovine encephalon

Aluminium hydroxide adjuvants are crucial for livestock and human vaccines. Few studies have analysed their effect on the central nervous system in vivo. In this work, lambs received three different treatments of parallel subcutaneous inoculations during 16 months with aluminium-containing commercial vaccines, an equivalent dose of aluminium hydroxide or mock injections. Brain samples were sequenced by RNA-seq and miRNA-seq for the expression analysis of mRNAs, long non-coding RNAs and microRNAs and three expression comparisons were made. Although few differentially expressed genes were identified, some dysregulated genes by aluminium hydroxide alone were linked to neurological functions, the lncRNA TUNA among them, or were enriched in mitochondrial energy metabolism related functions. In the same way, the miRNA expression was mainly disrupted by the adjuvant alone treatment. Some differentially expressed miRNAs had been previously linked to neurological diseases, oxidative stress and apoptosis. In brief, in this study aluminium hydroxide alone altered the transcriptome of the encephalon to a higher degree than commercial vaccines that present a milder effect. The expression changes in the animals inoculated with aluminium hydroxide suggest mitochondrial disfunction. Further research is needed to elucidate to which extent these changes could have pathological consequences

Whole Transcriptome Approach to Evaluate the Effect of Aluminium Hydroxide in Ovine Encephalon

Aluminium hydroxide adjuvants are crucial for livestock and human vaccines. Few studies have analysed their effect on the central nervous system in vivo. In this work, lambs received three different treatments of parallel subcutaneous inoculations during 16 months with aluminium-containing commercial vaccines, an equivalent dose of aluminium hydroxide or mock injections. Brain samples were sequenced by RNA-seq and miRNA-seq for the expression analysis of mRNAs, long non-coding RNAs and microRNAs and three expression comparisons were made. Although few differentially expressed genes were identified, some dysregulated genes by aluminium hydroxide alone were linked to neurological functions, the lncRNA TUNA among them, or were enriched in mitochondrial energy metabolism related functions. In the same way, the miRNA expression was mainly disrupted by the adjuvant alone treatment. Some differentially expressed miRNAs had been previously linked to neurological diseases, oxidative stress and apoptosis. In brief, in this study aluminium hydroxide alone altered the transcriptome of the encephalon to a higher degree than commercial vaccines that present a milder effect. The expression changes in the animals inoculated with aluminium hydroxide suggest mitochondrial disfunction. Further research is needed to elucidate to which extent these changes could have pathological consequences.This work was supported by the Spanish Ministry of Economy grant [MINECO project AGL2013-49137-C3 to BMJ, LL and DA]; University of the Basque Country (UPV/EHU) predoctoral fellowships [PIF15/361 to EV-M and PIF17/306 to MB-A]; and University of the Basque Country (UPV/EHU) postdoctoral fellowship [ESPDOC16/43 to NA]. Thanks to M. Ortega for technical help

Naprt expression regulation mechanisms: novel functions predicted by a bioinformatics approach

The nicotinate phosphoribosyltransferase (NAPRT) gene has gained relevance in the research of cancer therapeutic strategies due to its main role as a NAD biosynthetic enzyme. NAD metabolism is an attractive target for the development of anti-cancer therapies, given the high energy requirements of proliferating cancer cells and NAD-dependent signaling. A few studies have shown that NAPRT expression varies in different cancer types, making it imperative to assess NAPRT expression and functionality status prior to the application of therapeutic strategies targeting NAD. In addition, the recent finding of NAPRT extracellular form (eNAPRT) suggested the involvement of NAPRT in inflammation and signaling. However, the mechanisms regulating NAPRT gene expression have never been thoroughly addressed. In this study, we searched for NAPRT gene expression regulatory mechanisms in transcription factors (TFs), RNA binding proteins (RBPs) and microRNA (miRNAs) databases. We identified several potential regulators of NAPRT transcription activation, downregulation and alternative splicing and performed GO and expression analyses. The results of the functional analysis of TFs, RBPs and miRNAs suggest new, unexpected functions for the NAPRT gene in cell differentiation, development and neuronal biology.info:eu-repo/semantics/publishedVersio