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1.
Lancet Reg Health Southeast Asia ; 25: 100395, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38586062

RESUMO

Background: Emerging research indicates growing concern over long COVID globally, although there have been limited studies that estimate population burden. We aimed to estimate the burden of long COVID in three districts of Haryana, India, using an opportunity to link a seroprevalence study to follow-up survey of symptoms associated with long COVID. Methods: We used a population-based seroprevalence survey for COVID-19 conducted in September 2021 across Haryana, India. Adults from three purposively selected districts (Rohtak, Gurugram, and Jhajjar) were eligible to participate; 2205 of 3213 consented to participate in a survey on health status. Trained investigators administered a structured questionnaire that included demographic characteristics, self-reported symptoms of illness in the last six months before the survey, mental health, and history of COVID-19. Findings: Unadjusted regression estimates indicated positive correlations between symptomatic complaints and COVID-19 exposure, suggesting lingering effects of COVID-19 in this population. The overall physical morbidity index was higher among those who tested positive for COVID-19, as was the incidence of new cases. However, both morbidity and incidence became statistically insignificant after adjustment for multiple comparisons. Cough emerged as the only statistically significant individual persistent symptom. Sex-stratified analyses indicated significant estimates only for physical morbidity in women. Interpretation: This study is one of the first from India that uses a large population-based sample to examine longer term repercussions of COVID infections. The burden of long COVID should primarily be addressed in clinical settings, where specialised treatment for individual cases continues to evolve. Our analyses also provide insight into the size and nature of studies required to assess the population-level burden of long COVID. Funding: This paper was produced under the auspices of the Lancet COVID 19 Commission India Task Force, which was supported financially by the Reliance Foundation. The Lancet COVID 19 Commission was set up in July 2020 and submitted its final report by October 2022. This report by the India Task Force was prepared during the same period.

2.
PLOS Glob Public Health ; 3(11): e0002601, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38032861

RESUMO

The COVID-19 pandemic has brought about valuable insights regarding models, data, and experiments. In this narrative review, we summarised the existing literature on these three themes, exploring the challenges of providing forecasts, the requirement for real-time linkage of health-related datasets, and the role of 'experimentation' in evaluating interventions. This literature review encourages us to broaden our perspective for the future, acknowledging the significance of investing in models, data, and experimentation, but also to invest in areas that are conceptually more abstract: the value of 'team science', the need for public trust in science, and in establishing processes for using science in policy. Policy-makers rely on model forecasts early in a pandemic when there is little data, and it is vital to communicate the assumptions, limitations, and uncertainties (theme 1). Linked routine data can provide critical information, for example, in establishing risk factors for adverse outcomes but are often not available quickly enough to make a real-time impact. The interoperability of data resources internationally is required to facilitate sharing across jurisdictions (theme 2). Randomised controlled trials (RCTs) provided timely evidence on the efficacy and safety of vaccinations and pharmaceuticals but were largely conducted in higher income countries, restricting generalisability to low- and middle-income countries (LMIC). Trials for non-pharmaceutical interventions (NPIs) were almost non-existent which was a missed opportunity (theme 3). Building on these themes from the narrative review, we underscore the importance of three other areas that need investment for effective evidence-driven policy-making. The COVID-19 response relied on strong multidisciplinary research infrastructures, but funders and academic institutions need to do more to incentivise team science (4). To enhance public trust in the use of scientific evidence for policy, researchers and policy-makers must work together to clearly communicate uncertainties in current evidence and any need to change policy as evidence evolves (5). Timely policy decisions require an established two-way process between scientists and policy makers to make the best use of evidence (6). For effective preparedness against future pandemics, it is essential to establish models, data, and experiments as fundamental pillars, complemented by efforts in planning and investment towards team science, public trust, and evidence-based policy-making across international communities. The paper concludes with a 'call to actions' for both policy-makers and researchers.

3.
iScience ; 25(11): 104993, 2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36299999

RESUMO

The MetaSUB Consortium, founded in 2015, is a global consortium with an interdisciplinary team of clinicians, scientists, bioinformaticians, engineers, and designers, with members from more than 100 countries across the globe. This network has continually collected samples from urban and rural sites including subways and transit systems, sewage systems, hospitals, and other environmental sampling. These collections have been ongoing since 2015 and have continued when possible, even throughout the COVID-19 pandemic. The consortium has optimized their workflow for the collection, isolation, and sequencing of DNA and RNA collected from these various sites and processing them for metagenomics analysis, including the identification of SARS-CoV-2 and its variants. Here, the Consortium describes its foundations, and its ongoing work to expand on this network and to focus its scope on the mapping, annotation, and prediction of emerging pathogens, mapping microbial evolution and antibiotic resistance, and the discovery of novel organisms and biosynthetic gene clusters.

4.
Genes (Basel) ; 13(10)2022 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-36292799

RESUMO

The recent increase in publicly available metagenomic datasets with geospatial metadata has made it possible to determine location-specific, microbial fingerprints from around the world. Such fingerprints can be useful for comparing microbial niches for environmental research, as well as for applications within forensic science and public health. To determine the regional specificity for environmental metagenomes, we examined 4305 shotgun-sequenced samples from the MetaSUB Consortium dataset-the most extensive public collection of urban microbiomes, spanning 60 different cities, 30 countries, and 6 continents. We were able to identify city-specific microbial fingerprints using supervised machine learning (SML) on the taxonomic classifications, and we also compared the performance of ten SML classifiers. We then further evaluated the five algorithms with the highest accuracy, with the city and continental accuracy ranging from 85-89% to 90-94%, respectively. Thereafter, we used these results to develop Cassandra, a random-forest-based classifier that identifies bioindicator species to aid in fingerprinting and can infer higher-order microbial interactions at each site. We further tested the Cassandra algorithm on the Tara Oceans dataset, the largest collection of marine-based microbial genomes, where it classified the oceanic sample locations with 83% accuracy. These results and code show the utility of SML methods and Cassandra to identify bioindicator species across both oceanic and urban environments, which can help guide ongoing efforts in biotracing, environmental monitoring, and microbial forensics (MF).


Assuntos
Metagenômica , Microbiota , Metagenômica/métodos , Metagenoma , Microbiota/genética , Aprendizado de Máquina Supervisionado , Cidades
5.
Trans Indian Natl Acad Eng ; 7(1): 365-374, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35837004

RESUMO

A network is often an obvious choice for modeling real-life interconnected systems, where the nodes represent interacting objects and the edges represent their associations. There has been immense progress in complex network analysis with methods and tools that can provide important insights into the respective scenario. In the advancement of information technology and globalization, the amount of data is increasing day by day, and it is indeed incomprehensible without the help of network science. This work highlights how we can model multiple interaction scenarios under a single umbrella to uncover novel insights. We show that a varying scenario gets reflected by the change of topological patterns in interaction networks. We construct multi-scenario graphs, a novel framework proposed by us, from real-life environments followed by topological analysis. We focus on two different application areas: analyzing geographical variations in SARS-CoV-2 and studying topic similarity in citation patterns.

6.
Environ Res ; 207: 112183, 2022 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-34637759

RESUMO

In urban ecosystems, microbes play a key role in maintaining major ecological functions that directly support human health and city life. However, the knowledge about the species composition and functions involved in urban environments is still limited, which is largely due to the lack of reference genomes in metagenomic studies comprises more than half of unclassified reads. Here we uncovered 732 novel bacterial species from 4728 samples collected from various common surface with the matching materials in the mass transit system across 60 cities by the MetaSUB Consortium. The number of novel species is significantly and positively correlated with the city population, and more novel species can be identified in the skin-associated samples. The in-depth analysis of the new gene catalog showed that the functional terms have a significant geographical distinguishability. Moreover, we revealed that more biosynthetic gene clusters (BGCs) can be found in novel species. The co-occurrence relationship between BGCs and genera and the geographical specificity of BGCs can also provide us more information for the synthesis pathways of natural products. Expanded the known urban microbiome diversity and suggested additional mechanisms for taxonomic and functional characterization of the urban microbiome. Considering the great impact of urban microbiomes on human life, our study can also facilitate the microbial interaction analysis between human and urban environment.


Assuntos
Metagenoma , Microbiota , Bactérias/genética , Humanos , Metagenômica , Interações Microbianas , Microbiota/genética
7.
Soc Netw Anal Min ; 11(1): 53, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34122667

RESUMO

The recent pandemic of COVID-19 has not only shaken the healthcare but also economic structure around the world. In addition to these direct effects, it has also brought in some indirect difficulties owing to the information epidemic (hereafter termed as infodemic) on social media. We aimed to understand the nature of panic social media users in India are experiencing due to the flow of (mis)information. We further extend this investigation to other countries. We performed a cross-sectional study on 1075 social media users from India and 29 other countries. This revealed a significant increase in social media usage and the rise of panic (symbolizing a sense of alarm and/or fear) over time in India. Several of these behaviors are unique to social media users in India possibly because of later outbreak of COVID-19 and a prolonged uninterrupted lockdown. The amount of social media usage might not be causal but has a significant role in generating panic among the people in India. As multiple countries are entering into the second phase of lockdown, this study focused on India might provide a unique perspective of how various factors, including infodemic, affect the mental state of individuals around the globe. SUPPLEMENTARY INFORMATION: The online version supplementary material available at 10.1007/s13278-021-00750-2.

8.
Cell ; 184(13): 3376-3393.e17, 2021 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-34043940

RESUMO

We present a global atlas of 4,728 metagenomic samples from mass-transit systems in 60 cities over 3 years, representing the first systematic, worldwide catalog of the urban microbial ecosystem. This atlas provides an annotated, geospatial profile of microbial strains, functional characteristics, antimicrobial resistance (AMR) markers, and genetic elements, including 10,928 viruses, 1,302 bacteria, 2 archaea, and 838,532 CRISPR arrays not found in reference databases. We identified 4,246 known species of urban microorganisms and a consistent set of 31 species found in 97% of samples that were distinct from human commensal organisms. Profiles of AMR genes varied widely in type and density across cities. Cities showed distinct microbial taxonomic signatures that were driven by climate and geographic differences. These results constitute a high-resolution global metagenomic atlas that enables discovery of organisms and genes, highlights potential public health and forensic applications, and provides a culture-independent view of AMR burden in cities.


Assuntos
Farmacorresistência Bacteriana/genética , Metagenômica , Microbiota/genética , População Urbana , Biodiversidade , Bases de Dados Genéticas , Humanos
10.
BMC Genomics ; 18(1): 721, 2017 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-28899360

RESUMO

BACKGROUND: Parkinson's disease (PD) is the second most prevalent neurodegenerative disorders in the world. Studying PD from systems biology perspective involving genes and their regulators might provide deeper insights into the complex molecular interactions associated with this disease. RESULT: We have studied gene co-expression network obtained from a PD-specific microarray data. The co-expression network identified 11 hub genes, of which eight genes are not previously known to be associated with PD. Further study on the functionality of these eight novel hub genes revealed that these genes play important roles in several neurodegenerative diseases. Furthermore, we have studied the tissue-specific expression and histone modification patterns of the novel hub genes. Most of these genes possess several histone modification sites those are already known to be associated with neurodegenerative diseases. Regulatory network namely mTF-miRNA-gene-gTF involves microRNA Transcription Factor (mTF), microRNA (miRNA), gene and gene Transcription Factor (gTF). Whereas long noncoding RNA (lncRNA) mediated regulatory network involves miRNA, gene, mTF and lncRNA. mTF-miRNA-gene-gTF regulatory network identified a novel feed-forward loop. lncRNA-mediated regulatory network identified novel lncRNAs of PD and revealed the two-way regulatory pattern of PD-specific miRNAs where miRNAs can be regulated by both the TFs and lncRNAs. SNP analysis of the most significant genes of the co-expression network identified 20 SNPs. These SNPs are present in the 3' UTR of known PD genes and are controlled by those miRNAs which are also involved in PD. CONCLUSION: Our study identified eight novel hub genes which can be considered as possible candidates for future biomarker identification studies for PD. The two regulatory networks studied in our work provide a detailed overview of the cellular regulatory mechanisms where the non-coding RNAs namely miRNA and lncRNA, can act as epigenetic regulators of PD. SNPs identified in our study can be helpful for identifying PD at an earlier stage. Overall, this study may impart a better comprehension of the complex molecular interactions associated with PD from systems biology perspective.


Assuntos
Epigênese Genética , Redes Reguladoras de Genes , Doença de Parkinson/genética , Polimorfismo de Nucleotídeo Único , Biologia de Sistemas
11.
Mol Phylogenet Evol ; 109: 404-408, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28216014

RESUMO

The proliferation and intensification of diseases have forced every researcher to take actions for a robust understanding of the organisms. This demands deep knowledge about the cells and tissues in an organ and its entire surroundings, more precisely the microbiome community which involves viruses, bacteria, archaea, among others. They play an important role in the function of our body, and act both as a deterrent as well as shelter for diseases. Therefore, it is pertinent to study the relation within the microbiome in a human body. In this work, we analyze the sequence data provided through the Human Microbiome Project to explore evolutionary relations within blood microbiome. The objective is to analyze the common proteins present in the different microbes in the blood and find their phylogeny. The analysis of the phylogenetic relation between these species provides important insights about the conservedness of phylogeny of blood microbiome. Interestingly, the co-existence of five of those common proteins is observed in human too.


Assuntos
Bactérias/classificação , Evolução Biológica , Sangue/microbiologia , Microbiota , Archaea/classificação , Proteínas de Bactérias/genética , Proteínas Fúngicas/genética , Humanos , Filogenia
12.
IEEE Trans Nanobioscience ; 16(3): 226-238, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28103559

RESUMO

Disease dietomics is an emerging area of systems biology that attempts to explore the connections between the dietary habits and diseases. Some of the topical studies highlight that foods might have different impacts over an organism either in progressing a disease (negative association) or in fighting against it (positive association). The association of foods with different diseases can be put together to build a network that might provide a global view of the entire system. Again, such disease-food networks might emerge in a more complex form while considering the disease subtypes individually. Some foods might have positive association with a particular subtype of a disease, whereas it might have no association or negative association with another subtype of the same disease. Therefore, the subtypes might have completely different network patterns. On the other hand, the same food may be helpful for a disease and harmful for another disease or even for a subtype. Analyzing such disease-food networks in different forms might give us important information about the relations between different diseases. In this paper, we have analyzed a large-scale disease-food network comprising 162 different diseases and 455 types of foods for gaining knowledge about the connection between these diseases and their subtypes. We have measured the similarity between diseases based on their patterns of association with foods. In addition to observing a high similarity between several disease subtypes, particularly for cancer, we have found strong relations between constipation-dysphagia and cancer-cardiovascular disease, which are rarely known. Tendency of occurrence of different diseases can be predicted based on such information.


Assuntos
Comportamento Alimentar , Neoplasias , Biologia de Sistemas , Doenças Cardiovasculares , Constipação Intestinal , Transtornos de Deglutição , Humanos , Neoplasias/genética , Neoplasias/metabolismo , Risco
13.
Mol Biol Rep ; 43(7): 591-9, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27245063

RESUMO

MicroRNAs (miRNAs) are small non-coding RNAs that help in post-transcriptional gene silencing. These endogenous RNAs develop a post-transcriptional gene-regulatory network by binding to complementary sequences of target mRNAs and essentially degrade them. Cancer is a class of diseases that is caused by the uncontrolled cell growth, thereby resulting into a gradual degradation of cell structure. Earlier researches have shown that miRNAs have significant biological involvement in cancer. Prolonged research in this genre has led to the identification of the functions of numerous miRNAs in cancer development. Studying the differential expression profiles of miRNAs and mRNAs together could help us in recognizing the significant miRNA-mRNA pairs from cancer samples. In this paper, we have analyzed the simultaneous over-expression of miRNAs and under-expression of mRNAs and vice versa to establish their association with cancer. This study focuses on breast tumor samples and the miRNA-mRNA target pairs that have a visible signature in such breast tumor samples. We have been able to identify the differentially expressed miRNAs and mRNAs, and further established relations between them to extract the miRNA-mRNA pairs that might be significant in the breast cancer types. This gives us the clue about the potential biomarkers for the breast cancer subtypes that can further help in understanding the progression of each of the subtypes separately. This might be helpful for the joint miRNA-mRNA biomarker identification.


Assuntos
Biomarcadores Tumorais/genética , MicroRNAs/genética , RNA Mensageiro/genética , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Redes Reguladoras de Genes , Humanos , MicroRNAs/metabolismo , RNA Mensageiro/metabolismo , Transcriptoma
14.
Gene ; 556(2): 192-8, 2015 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-25485717

RESUMO

MicroRNAs (miRNAs) are a kind of short non-coding RNAs, of about 22 nucleotides in length, which modulate and sometimes degrade the target mRNAs thereby regulating a number of cellular functions. Recent research in this area establishes the involvement of miRNAs in various disease progressions, including certain types of cancer development. Further, genome-wide expression profiling of miRNAs has been proven to be useful for differentiating various cancer types. In this paper, we have used miRNA expression profiles over a large set of breast cancer tumor samples for identifying subtypes of breast cancers. The experimental results demonstrate that miRNAs carry a unique signature that distinguishes cancer subtypes and reveal new cancer subtypes. Additional survival analyses based on clinical data also strengthen this claim.


Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/patologia , MicroRNAs/genética , Biologia Computacional/métodos , Bases de Dados Genéticas , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Análise de Sobrevida
15.
PLoS One ; 9(4): e93751, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24690883

RESUMO

BACKGROUND: Parkinson's Disease (PD) is a progressive neurologic disorder that affects movement and balance. Recent studies have revealed the importance of microRNA (miR) in PD. However, the detailed role of miR and its regulation by Transcription Factor (TF) remain unexplored. In this work for the first time we have studied TF-miR-mRNA regulatory network as well as miR co-expression network in PD. RESULT: We compared the 204 differentially expressed miRs from microarray data with 73 PD related miRs obtained from literature, Human MicroRNA Disease Database and found a significant overlap of 47 PD related miRs (p-value<0.05). Functional enrichment analyses of these 47 common (Group1) miRs and the remaining 157 (Group2) miRs revealed similar kinds of over-representative GO Biological Processes and KEGG pathways. This strengthens the possibility that some of the Group 2 miRs can have functional roles in PD progression, hitherto unidentified in any study. In order to explore the cross talk between TF, miR and target mRNA, regulatory networks were constructed. Study of these networks resulted in 14 Inter-Regulatory hub miRs whereas miR co-expression network revealed 18 co-expressed hub miRs. Of these 32 hub miRs, 23 miRs were previously unidentified with respect to their association with PD. Hierarchical clustering analysis further strengthens the roles of these novel miRs in different PD pathways. Furthermore hsa-miR-92a appeared as novel hub miR in both regulatory and co-expression network indicating its strong functional role in PD. High conservation patterns were observed for most of these 23 novel hub miRs across different species including human. Thus these 23 novel hub miRs can be considered as potential biomarkers for PD. CONCLUSION: Our study identified 23 novel miR markers which can open up new avenues for future studies and shed lights on potential therapeutic targets for PD.


Assuntos
Redes Reguladoras de Genes , MicroRNAs/genética , Doença de Parkinson/genética , Transcrição Gênica , Análise por Conglomerados , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Humanos , MicroRNAs/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno/genética , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Doença de Parkinson/patologia , RNA Mensageiro
16.
Artigo em Inglês | MEDLINE | ID: mdl-23929866

RESUMO

In this work, we model the problem of mining quasi-bicliques from weighted viral-host protein-protein interaction network as a biclustering problem for identifying strong interaction modules. In this regard, a multiobjective genetic algorithm-based biclustering technique is proposed that simultaneously optimizes three objective functions to obtain dense biclusters having high mean interaction strengths. The performance of the proposed technique has been compared with that of other existing biclustering methods on an artificial data. Subsequently, the proposed biclustering method is applied on the records of biologically validated and predicted interactions between a set of HIV-1 proteins and a set of human proteins to identify strong interaction modules. For this, the entire interaction information is realized as a bipartite graph. We have further investigated the biological significance of the obtained biclusters. The human proteins involved in the strong interaction module have been found to share common biological properties and they are identified as the gateways of viral infection leading to various diseases. These human proteins can be potential drug targets for developing anti-HIV drugs.


Assuntos
Infecções por HIV/metabolismo , Infecções por HIV/virologia , HIV-1/metabolismo , Mapeamento de Interação de Proteínas/métodos , Mapas de Interação de Proteínas , Algoritmos , Análise por Conglomerados , Biologia Computacional , Bases de Dados Factuais , Interações Hospedeiro-Patógeno , Humanos , Modelos Biológicos , Reprodutibilidade dos Testes , Transdução de Sinais , Proteínas Virais/análise , Proteínas Virais/química , Proteínas Virais/metabolismo
17.
PLoS One ; 8(6): e66722, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23826117

RESUMO

Predicting the transcription start sites (TSSs) of microRNAs (miRNAs) is important for understanding how these small RNA molecules, known to regulate translation and stability of protein-coding genes, are regulated themselves. Previous approaches are primarily based on genetic features, trained on TSSs of protein-coding genes, and have low prediction accuracy. Recently, a support vector machine based technique has been proposed for miRNA TSS prediction that uses known miRNA TSS for training the classifier along with a set of existing and novel CpG island based features. Current progress in epigenetics research has provided genomewide and tissue-specific reports about various phenotypic traits. We hypothesize that incorporating epigenetic characteristics into statistical models may lead to better prediction of primary transcripts of human miRNAs. In this paper, we have tested our hypothesis on brain-specific miRNAs by using epigenetic as well as genetic features to predict the primary transcripts. For this, we have used a sophisticated feature selection technique and a robust classification model. Our prediction model achieves an accuracy of more than 80% and establishes the potential of epigenetic analysis for in silico prediction of TSSs.


Assuntos
Metilação de DNA , MicroRNAs/genética , Transcrição Gênica , Epigênese Genética , Humanos , Máquina de Vetores de Suporte
18.
IEEE Trans Biomed Eng ; 60(8): 2167-73, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23475332

RESUMO

MicroRNAs (miRNAs) are a class of small noncoding RNAs that are known to have critical functions across various biological processes. Simultaneous activities of multiple miRNAs can be monitored from their expression profiles under various conditions. We often build up coexpression networks from such profiles. Unfortunately, due to the change of experimental setups (or conditions), the expression profiles do change, and consequently, the patterns of the coexpression networks vary. To obtain a robust functional relationship between miRNAs, by integrating different coexpression networks in a systems biology approach, we have to combine them properly. Here, we evaluate the state-of-the-art techniques and propose a novel integrative measure, and a corresponding methodology, that might be useful for identifying the dependence between coexpression and functional similarity. We establish the results by evaluating the expression profiles of miRNAs taken from bone marrow samples of patients with leukemia. The findings highlight the potential of the integrative algorithm in analyzing the expression profiles of miRNAs for further study.


Assuntos
Algoritmos , Medula Óssea/metabolismo , Regulação Neoplásica da Expressão Gênica , MicroRNAs/metabolismo , Modelos Biológicos , Transdução de Sinais , Simulação por Computador , Humanos , Armazenamento e Recuperação da Informação/métodos , Leucemia , MicroRNAs/genética
19.
Mol Biosyst ; 9(3): 457-66, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23344858

RESUMO

MicroRNAs (miRNAs) are a class of short non-coding RNAs, which show tissue-specific regulatory activity on genes. Expression profiling of miRNAs is an important step for understanding the pathology of Alzheimer's disease (AD), a neurodegenerative disorder originating in the brain. Recent studies highlight that miRNAs enriched in gray matter (GM) and white matter (WM) of AD brains show differential expression. However, no in-depth study has yet been conducted on analysing the differential co-expression of pairs of miRNAs over GM and WM. Two genes (or miRNAs) are said to be co-expressed if their expression profiles change similarly over a number of samples. A pair of co-expressed genes under a condition type (or phenotype) may not remain co-expressed, or get contra-expressed, under another condition. Such pairs of genes are referred to as differentially co-expressed. Such an investigation in the early stage of AD is reported in this article. A network of differentially co-expressed miRNAs in GM and WM is first built. Analysis of the differential co-expression property reveals that such a network can not have any cycle. We use the notion of switching to distinguish two distinct types of differential co-expression patterns - a pair of miRNAs that are highly co-expressed in GM but does not remain so in WM, and vice versa. Based on this, we find the substructures, referred to as differentially co-expressed switching tree (DCST), that throughout have similar pattern of switching. The miR-423-5p emerges as a hub of the network. We extract subtrees of these DCSTs that have similar switching pattern throughout. These substructures are found to be both statistically and biologically significant. A large number of miRNAs obtained from the DCSTs are found to have association with AD, most of which are enriched in WM. This computational study therefore indicates a significant role of WM in early AD progression, a hitherto less acknowledged fact.


Assuntos
Doença de Alzheimer/metabolismo , Córtex Cerebral/metabolismo , MicroRNAs/genética , Idoso de 80 Anos ou mais , Algoritmos , Doença de Alzheimer/patologia , Progressão da Doença , Feminino , Redes Reguladoras de Genes , Humanos , Redes e Vias Metabólicas , MicroRNAs/metabolismo , Modelos Biológicos , Fenótipo , Transcriptoma
20.
Genomics Proteomics Bioinformatics ; 10(5): 310-6, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23200141

RESUMO

MicroRNAs (miRNAs) are small endogenous non-coding RNAs of about 22 nt in length that take crucial roles in many biological processes. These short RNAs regulate the expression of mRNAs by binding to their 3'-UTRs or by translational repression. Many of the current studies focus on how mature miRNAs regulate mRNAs, however, very limited knowledge is available regarding their transcriptional loci. It is known that primary miRNAs (pri-miRs) are first transcribed from the DNA, followed by the formation of precursor miRNAs (pre-miRs) by endonuclease activity, which finally produces the mature miRNAs. Till date, many of the pre-miRs and mature miRNAs have been experimentally verified. But unfortunately, identification of the loci of pri-miRs, promoters and associated transcription start sites (TSSs) are still in progress. TSSs of only about 40% of the known mature miRNAs in human have been reported. This information, albeit limited, may be useful for further study of the regulation of miRNAs. In this paper, we provide a novel database of validated miRNA TSSs, miRT, by collecting data from several experimental studies that validate miRNA TSSs and are available for full download. We present miRT as a web server and it is also possible to convert the TSS loci between different genome built. miRT might be a valuable resource for advanced research on miRNA regulation, which is freely accessible at: http://www.isical.ac.in/~bioinfo_miu/miRT/miRT.php.


Assuntos
Bases de Dados de Ácidos Nucleicos , MicroRNAs/genética , Sítio de Iniciação de Transcrição , Regiões 3' não Traduzidas , Genoma Humano , Humanos , MicroRNAs/metabolismo , RNA Mensageiro/genética
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