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1.
Medicina (Kaunas) ; 60(3)2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38541118

RESUMO

Macrophage activation syndrome is an uncommon yet dangerous and potentially fatal complication of many rheumatic diseases, inducing multiple organ failure, including, although rarely, acute heart failure. In the following paper, we present a case of a 37-year-old woman who, in a short period of time after a gynecological procedure due to fetal death, developed full-blown lupus erythematosus leading to early stages of macrophage activation syndrome with acute heart failure as its main clinical manifestation. We also include herein a brief literature review of the current understanding of diverse macrophage populations and their functions in various organs (focusing especially on the heart muscle), as well as a summary of different attempts at composing concise criteria for diagnosing macrophage activation syndrome.


Assuntos
Insuficiência Cardíaca , Lúpus Eritematoso Sistêmico , Síndrome de Ativação Macrofágica , Feminino , Humanos , Adulto , Síndrome de Ativação Macrofágica/etiologia , Síndrome de Ativação Macrofágica/complicações , Lúpus Eritematoso Sistêmico/complicações , Lúpus Eritematoso Sistêmico/diagnóstico , Macrófagos , Miocárdio , Insuficiência Cardíaca/complicações
2.
Transl Lung Cancer Res ; 12(10): 2083-2097, 2023 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-38025814

RESUMO

Background: Lung cancer remains a significant public health concern, accounting for a considerable number of cancer-related deaths worldwide. Neural networks have emerged as a promising tool that can aid in the diagnosis and treatment of various cancers. Consequently, there has been a growing interest in exploring the potential of artificial intelligence (AI) methods in medicine. The present study aimed to evaluate the effectiveness of a neural network in predicting lung cancer recurrence. Methods: The study employed retrospective data from 2,296 medical records of patients diagnosed with lung cancer and admitted to the Warminsko-Mazurskie Center for Lung Diseases in Olsztyn, Poland. The statistical software STATISTICA 7.1, equipped with the Neural Networks module (StatSoft Inc., Tulsa, USA), was utilized to analyze the data. The neural network model was trained using patient information regarding gender, treatment, smoking status, family history, and symptoms of cancer. Results: The study employed a multilayer perceptron neural network with a two-phase learning process. The network demonstrated high predictive ability, as indicated by the percentage of correct classifications, which amounted to 87.5%, 89.1%, and 89.9% for the training, validation, and test sets, respectively. Conclusions: The findings of this study support the potential usefulness of a neural network-based predictive model in assessing the risk of lung cancer recurrence. Further research is warranted to validate these findings and to explore AI's broader implications in cancer diagnosis and treatment.

3.
J Clin Med ; 12(19)2023 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-37834893

RESUMO

Systemic connective tissue disorders constitute a heterogenous group of autoimmune diseases with the potential to affect a range of organs. Rheumatoid arthritis (RA) is a chronic, progressive, autoimmune inflammatory disease affecting the joints. Systemic lupus erythematosus (SLE) may manifest with multiple system involvement as a result of inflammatory response to autoantibodies. Spondyloarthropathies (SpAs) such as ankylosing spondylitis (AS) or psoriatic arthritis (PsA) are diseases characterised by the inflammation of spinal joints, paraspinal tissues, peripheral joints and enthesitis as well as inflammatory changes in many other systems and organs. Physiologically, sclerostin helps to maintain balance in bone tissue metabolism through the Wnt/ß-catenin pathway, which represents a major intracellular signalling pathway. This review article aims to present the current knowledge on the role of sclerostin in the Wnt/ß-catenin pathway and its correlation with clinical data from RA, SLE, AS and PsA patients.

4.
Medicina (Kaunas) ; 59(9)2023 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-37763659

RESUMO

Background and Objectives: In the era of the COVID-19 pandemic, telemedicine, so far underestimated, has gained in value. Currently, telemedicine is not only a telephone or chat consultation, but also the possibility of the remote recording of signals (such as ECG, saturation, and heart rate) or even remote auscultation of the lungs. The objective of this review article is to present a potential role for, and disseminate knowledge of, telemedicine during the COVID-19 pandemic. Material and Methods: In order to analyze the research material in accordance with PRISMA guidelines, a systematic search of the ScienceDirect, Web of Science, and PubMed databases was conducted. Out of the total number of 363 papers identified, 22 original articles were subjected to analysis. Results: This article presents the possibilities of remote patient registration, which contributes to an improvement in remote diagnostics and diagnoses. Conclusions: Telemedicine is, although not always and not by everyone, an accepted form of providing medical services. It cannot replace direct patient-doctor contact, but it can undoubtedly contribute to accelerating diagnoses and improving their quality at a distance.


Assuntos
COVID-19 , Telemedicina , Humanos , Pandemias , Bases de Dados Factuais , Frequência Cardíaca
5.
Cells ; 12(3)2023 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-36766810

RESUMO

Aquaporins (AQPs) are selective, transmembrane proteins, which are primarily responsible for the transport of water and small molecules. They have been demonstrated to play a key role in the development and progression of cancer. Lung adenocarcinoma is the most common primary lung cancer diagnosed in patients in Europe and the USA. The research done so far has provided firm evidence that some AQPs can be biomarkers for various diseases. The objective of this review article is to present a potential role of AQP5 in the development of lung adenocarcinoma. Original papers discussing the involvement of AQP5 in carcinogenesis and containing relevant clinical data were identified. In order to analyze the research material in accordance with PRISMA guidelines, a systematic search of the ScienceDirect, Web of Science, and Pubmed databases was conducted. Out of the total number of 199 papers identified, 14 original articles were subject to analysis. This article presents the pathophysiological role of AQP5 in the biology of lung adenocarcinoma as well as its prognostic value. The analysis substantiates the conclusion that the prognostic value of AQP5 in lung cancer requires further research. Another aim of this paper is to disseminate knowledge about AQPs among clinicians.


Assuntos
Adenocarcinoma de Pulmão , Neoplasias Pulmonares , Humanos , Aquaporina 5/metabolismo , Neoplasias Pulmonares/patologia , Proteínas de Membrana/metabolismo , Europa (Continente)
6.
J Clin Med ; 11(19)2022 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-36233821

RESUMO

Aquaporins (AQPs) are highly conserved channel proteins which are mainly responsible for the exchange of water and small molecules and have shown to play a pivotal role in the development and progression of cancer. Lung adenocarcinoma is the most common primary lung cancer seen in patients in Europe and the United States. However, in patients it is often not diagnosed until the advanced tumor stage is present. Previous studies provided strong evidence that some members of the AQP family could serve as clinical biomarkers for different diseases. Therefore, we aimed to investigate how AQP3 and AQP4 protein expression in lung adenocarcinoma (ADC) biopsy samples correlate with clinical and pathological parameters. The protein expression of AQP3 and AQP4 was analyzed based on immunohistochemical staining. AQP3 protein was observed in the cytoplasmic membrane of cancer tissue in 82% of lung samples. Significant differences in relative protein expression of AQP3 were noted between advanced age patients compared to younger counterparts (p = 0.017). A high expression of AQP3 was significant in cancer tissue when compared to the control group (p < 0.001), whereas a low AQP4 membrane expression was noted as significantly common in cancer tissue compared to non-neoplastic lung tissue (p < 0.001). Moreover, a low AQP4 membrane expression was positively correlated with a more advanced disease status, e.g., lymph node metastases (p = 0.046). Based on our findings, AQP3 and AQP4 could be used as biomarkers in ADC patients.

7.
Artigo em Inglês | MEDLINE | ID: mdl-35564663

RESUMO

The COVID-19 pandemic has revealed the high usefulness of telemedicine. To date, no uniform recommendations or diagnostic protocols for long-COVID patients have been developed. This article presents the preliminary results of the examination of patients after SARS-CoV-2 infection who were provided with medical telemonitoring devices in order to oversee their pulmonological and cardiological health. Three cases have been analyzed. Each patient underwent a 10-day registration of basic vital signs, in three 15-min sessions daily: RR (respiratory rate), ECG (electrocardiogram), HR (pulse), SPO2 (saturation), body temperature and cough. Rule methods and machine learning were employed to automatically detect events. As a result, serious disorders of all the three patients were detected: cardiological and respiratory disorders that required extended diagnostics. Furthermore, average values of the selected parameters (RR, HR, SPO2) were calculated for every patient, including an indication of how often they exceeded the alarm thresholds. In conclusion, monitoring parameters in patients using telemedicine, especially in a time of limited access to the healthcare system, is a valuable clinical instrument. It enables medical professionals to recognize conditions which may endanger a patient's health or life. Telemedicine provides a reliable assessment of a patient's health status made over a distance, which can alleviate a patient's stress caused by long-COVID syndrome. Telemedicine allows identification of disorders and performing further diagnosis, which is possible owing to the implementation of advanced analysis. Telemedicine, however, requires flexibility and the engagement of a multidisciplinary team, who will respond to patients' problems on an ongoing basis.


Assuntos
COVID-19 , Telemedicina , COVID-19/complicações , COVID-19/diagnóstico , Humanos , Pandemias , SARS-CoV-2 , Telemedicina/métodos , Síndrome de COVID-19 Pós-Aguda
8.
Int J Mol Sci ; 20(19)2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31623386

RESUMO

This study aimed to examine the effect of follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), and growth hormone (GH) on Aquaporin 5 (AQP5) expression in granulosa (Gc) and theca cells (Tc) from medium (MF) and large (LF) ovarian follicles of pigs. The results showed that GH significantly decreased the expression of AQP5 in Gc from MF in relation to the control. In the Gc of large follicles, PRL stimulated the expression of AQP5. However, the increased expression of AQP5 in the Tc of LF was indicated by GH and PRL in relation to the control. A significantly higher expression of the AQP5 protein in the Gc from MF and LF was indicated by FSH and PRL. In co-cultures, an increased expression of AQP5 was observed in the Gc from LF incubated with LH, PRL, and GH. A significantly increased expression of AQP5 was also observed in co-cultures of Tc from all type of follicles incubated with LH, whereas PRL stimulated the expression of AQP5 in Tc from MF. Moreover, AQP5 protein expression increased in the co-culture isolated from MF and LF after treatment with FSH, LH, PRL, and GH. AQP5 immunoreactivity was observed in the cytoplasm, mainly in the perinuclear region and endosomes, as well as in the cell membranes of Gc and Tc from the LF and MF.


Assuntos
Aquaporina 5/genética , Regulação da Expressão Gênica de Plantas , Folículo Ovariano/metabolismo , Hormônios Hipofisários/metabolismo , Animais , Biomarcadores , Técnicas de Cocultura , Feminino , Hormônio Foliculoestimulante/metabolismo , Células da Granulosa/efeitos dos fármacos , Células da Granulosa/metabolismo , Hormônio do Crescimento/metabolismo , Hormônio Luteinizante/metabolismo , Folículo Ovariano/citologia , Folículo Ovariano/efeitos dos fármacos , Hormônios Hipofisários/farmacologia , Prolactina/metabolismo , Suínos , Células Tecais/efeitos dos fármacos , Células Tecais/metabolismo
9.
Pharmacoepidemiol Drug Saf ; 24(9): 971-9, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26175055

RESUMO

PURPOSE: Marketing authorization holders (MAHs) are expected to provide high-quality periodic safety update reports (PSURs) on their pharmaceutical products to health authorities (HAs). We present a novel instrument aiming at improving quality of PSURs based on standardized analysis of PSUR assessment reports (ARs) received from the European Union HAs across products and therapeutic areas. METHODS: All HA comments were classified into one of three categories: "Request for regulatory actions," "Request for medical and scientific information," or "Data deficiencies." The comments were graded according to their impact on patients' safety, the drug's benefit-risk profile, and the MAH's pharmacovigilance system. RESULTS: A total of 476 comments were identified through the analysis of 63 PSUR HA ARs received in 2013 and 2014; 47 (10%) were classified as "Requests for regulatory actions," 309 (65%) as "Requests for medical and scientific information," and 118 (25%) comments were related to "Data deficiencies." The most frequent comments were requests for labeling changes (35 HA comments in 19 ARs). The aggregate analysis revealed commonly raised issues and prompted changes of the MAH's procedures related to the preparation of PSURs. CONCLUSION: The authors believe that this novel instrument based on the evaluation of PSUR HA ARs serves as a valuable mechanism to enhance the quality of PSURs and decisions about optimization of the use of the products and, therefore, contributes to improve further the MAH's pharmacovigilance system and patient safety.


Assuntos
Sistemas de Notificação de Reações Adversas a Medicamentos/normas , Segurança do Paciente/normas , Preparações Farmacêuticas/normas , Relatório de Pesquisa/normas , Estatística como Assunto/métodos , Sistemas de Notificação de Reações Adversas a Medicamentos/estatística & dados numéricos , União Europeia , Humanos , Segurança do Paciente/estatística & dados numéricos , Farmacovigilância , Projetos Piloto
10.
PLoS One ; 10(7): e0132127, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26226348

RESUMO

BACKGROUND: MiRNAs and other small noncoding RNAs (sncRNAs) are key players in post-transcriptional gene regulation. HIV-1 derived small noncoding RNAs (sncRNAs) have been described in HIV-1 infected cells, but their biological functions still remain to be elucidated. Here, we approached the question whether viral sncRNAs may play a role in the RNA interference (RNAi) pathway or whether viral mRNAs are targeted by cellular miRNAs in human monocyte derived macrophages (MDM). METHODS: The incorporation of viral sncRNAs and/or their target RNAs into RNA-induced silencing complex was investigated using photoactivatable ribonucleoside-induced cross-linking and immunoprecipitation (PAR-CLIP) as well as high-throughput sequencing of RNA isolated by cross-linking immunoprecipitation (HITS-CLIP), which capture Argonaute2-bound miRNAs and their target RNAs. HIV-1 infected monocyte-derived macrophages (MDM) were chosen as target cells, as they have previously been shown to express HIV-1 sncRNAs. In addition, we applied small RNA deep sequencing to study differential cellular miRNA expression in HIV-1 infected versus non-infected MDMs. RESULTS AND CONCLUSION: PAR-CLIP and HITS-CLIP data demonstrated the absence of HIV-1 RNAs in Ago2-RISC, although the presence of a multitude of HIV-1 sncRNAs in HIV-1 infected MDMs was confirmed by small RNA sequencing. Small RNA sequencing revealed that 1.4% of all sncRNAs were of HIV-1 origin. However, neither HIV-1 derived sncRNAs nor putative HIV-1 target sequences incorporated into Ago2-RISC were identified suggesting that HIV-1 sncRNAs are not involved in the canonical RNAi pathway nor is HIV-1 targeted by this pathway in HIV-1 infected macrophages.


Assuntos
Proteínas Argonautas/genética , HIV-1/genética , Macrófagos/imunologia , Interferência de RNA , RNA Viral/genética , Sequência de Bases , Linhagem Celular , Regulação da Expressão Gênica , Células HEK293 , Humanos , MicroRNAs/genética , Alinhamento de Sequência , Análise de Sequência de RNA
11.
Genome Res ; 24(6): 906-19, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24668909

RESUMO

Gene expression is regulated in a context-dependent, cell-type-specific manner. Condition-specific transcription is dependent on the presence of transcription factors (TFs) that can activate or inhibit its target genes (global context). Additional factors, such as chromatin structure, histone, or DNA modifications, also influence the activity of individual target genes (individual context). The role of the global and individual context for post-transcriptional regulation has not systematically been investigated on a large scale and is poorly understood. Here we show that global and individual context dependency is a pervasive feature of microRNA-mediated regulation. Our comprehensive and highly consistent data set from several high-throughput technologies (PAR-CLIP, RIP-chip, 4sU-tagging, and SILAC) provides strong evidence that context-dependent microRNA target sites (CDTS) are as frequent and functionally relevant as constitutive target sites (CTS). Furthermore, we found the global context to be insufficient to explain the CDTS, and that flanking sequence motifs provide individual context that is an equally important factor. Our results demonstrate that, similar to TF-mediated regulation, global and individual context dependency are prevalent in microRNA-mediated gene regulation, implying a much more complex post-transcriptional regulatory network than is currently known. The necessary tools to unravel post-transcriptional regulations and mechanisms need to be much more involved, and much more data will be needed for particular cell types and cellular conditions in order to understand microRNA-mediated regulation and the context-dependent post-transcriptional regulatory network.


Assuntos
Inativação Gênica , Genoma Humano , MicroRNAs/genética , Linhagem Celular Tumoral , Sequência Conservada , Redes Reguladoras de Genes , Humanos , MicroRNAs/metabolismo , Motivos de Nucleotídeos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
12.
Mol Syst Biol ; 9: 711, 2013 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-24301800

RESUMO

MiRNAs are post-transcriptional regulators that contribute to the establishment and maintenance of gene expression patterns. Although their biogenesis and decay appear to be under complex control, the implications of miRNA expression dynamics for the processes that they regulate are not well understood. We derived a mathematical model of miRNA-mediated gene regulation, inferred its parameters from experimental data sets, and found that the model describes well time-dependent changes in mRNA, protein and ribosome density levels measured upon miRNA transfection and induction. The inferred parameters indicate that the timescale of miRNA-dependent regulation is slower than initially thought. Delays in miRNA loading into Argonaute proteins and the slow decay of proteins relative to mRNAs can explain the typically small changes in protein levels observed upon miRNA transfection. For miRNAs to regulate protein expression on the timescale of a day, as miRNAs involved in cell-cycle regulation do, accelerated miRNA turnover is necessary.


Assuntos
Regulação da Expressão Gênica , MicroRNAs , Modelos Genéticos , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Simulação por Computador , Regulação da Expressão Gênica/genética , Regulação da Expressão Gênica/fisiologia , Células HEK293 , Humanos , Cinética , MicroRNAs/genética , MicroRNAs/fisiologia , Reprodutibilidade dos Testes
13.
Genome Biol ; 14(7): R79, 2013 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-23895117

RESUMO

PARma is a complete data analysis software for AGO-PAR-CLIP experiments to identify target sites of microRNAs as well as the microRNA binding to these sites. It integrates specific characteristics of the experiments into a generative model. The model and a novel pattern discovery tool are iteratively applied to data to estimate seed activity probabilities, cluster confidence scores and to assign the most probable microRNA. Based on differential PAR-CLIP analysis and comparison to RIP-Chip data, we show that PARma is more accurate than existing approaches. PARma is available from http://www.bio.ifi.lmu.de/PARma.


Assuntos
Proteínas Argonautas/metabolismo , Imunoprecipitação , MicroRNAs/genética , Ribonucleosídeos/metabolismo , Software , Algoritmos , Linfócitos B , Análise por Conglomerados , Humanos , Modelos Genéticos , Reprodutibilidade dos Testes
14.
RNA ; 19(9): 1238-52, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23882114

RESUMO

Dicer is a key player in microRNA (miRNA) and RNA interference (RNAi) pathways, processing miRNA precursors and double-stranded RNA into ∼21-nt-long products ultimately triggering sequence-dependent gene silencing. Although processing of substrates in vertebrate cells occurs in the cytoplasm, there is growing evidence suggesting Dicer is also present and functional in the nucleus. To address this possibility, we searched for a nuclear localization signal (NLS) in human Dicer and identified its C-terminal double-stranded RNA binding domain (dsRBD) as harboring NLS activity. We show that the dsRBD-NLS can mediate nuclear import of a reporter protein via interaction with importins ß, 7, and 8. In the context of full-length Dicer, the dsRBD-NLS is masked. However, duplication of the dsRBD localizes the full-length protein to the nucleus. Furthermore, deletion of the N-terminal helicase domain results in partial accumulation of Dicer in the nucleus upon leptomycin B treatment, indicating that CRM1 contributes to nuclear export of Dicer. Finally, we demonstrate that human Dicer has the ability to shuttle between the nucleus and the cytoplasm. We conclude that Dicer is a shuttling protein whose steady-state localization is cytoplasmic.


Assuntos
RNA Helicases DEAD-box/química , Sinais de Localização Nuclear/metabolismo , RNA de Cadeia Dupla/química , RNA de Cadeia Dupla/metabolismo , Ribonuclease III/química , Transporte Ativo do Núcleo Celular , Sítios de Ligação , Núcleo Celular/metabolismo , Células Cultivadas , Citoplasma/metabolismo , RNA Helicases DEAD-box/metabolismo , Humanos , Sinais de Localização Nuclear/química , Transporte Proteico , Ribonuclease III/metabolismo , Transfecção
15.
Genome Biol ; 13(11): 179, 2012 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-23194401

RESUMO

Processing of pre-miRNAs by Dicer is regulated by its dsRNA-binding protein partner, and leads to the generation of alternative miRNA forms with distinct target sets.


Assuntos
RNA Helicases DEAD-box/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , RNA Helicases/metabolismo , Proteínas de Ligação a RNA/metabolismo , Ribonuclease III/metabolismo , Animais , Feminino , Humanos , Masculino
16.
Methods ; 58(2): 106-12, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23022257

RESUMO

microRNAs are important regulators of gene expression that guide translational repression and degradation of target mRNAs. Only relatively few miRNA targets have been characterized, and computational prediction is hampered by the relatively small number of nucleotides that seem to be involved in target recognition. Argonaute (Ago) crosslinking and immunoprecipitation (CLIP) in combination with next-generation sequencing proved to be a successful method for identifying targets of endogenous cellular miRNAs on a transcriptome-wide scale. Here we review various approaches to Ago CLIP, describe in detail the PAR-CLIP method and provide an outline of the necessary computational analysis for identification of in vivo miRNA binding sites.


Assuntos
Proteínas Argonautas , MicroRNAs , Estabilidade de RNA , RNA Mensageiro , Animais , Proteínas Argonautas/química , Proteínas Argonautas/genética , Sítios de Ligação , Biologia Computacional/métodos , Regulação da Expressão Gênica , Genoma , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , MicroRNAs/química , MicroRNAs/genética , MicroRNAs/isolamento & purificação , RNA Mensageiro/química , RNA Mensageiro/genética , RNA Mensageiro/isolamento & purificação
17.
Nat Methods ; 8(7): 559-64, 2011 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-21572407

RESUMO

Cross-linking and immunoprecipitation (CLIP) is increasingly used to map transcriptome-wide binding sites of RNA-binding proteins. We developed a method for CLIP data analysis, and applied it to compare CLIP with photoactivatable ribonucleoside-enhanced CLIP (PAR-CLIP) and to uncover how differences in cross-linking and ribonuclease digestion affect the identified sites. We found only small differences in accuracies of these methods in identifying binding sites of HuR, which binds low-complexity sequences, and Argonaute 2, which has a complex binding specificity. We found that cross-link-induced mutations led to single-nucleotide resolution for both PAR-CLIP and CLIP. Our results confirm the expectation from original CLIP publications that RNA-binding proteins do not protect their binding sites sufficiently under the denaturing conditions used during the CLIP procedure, and we show that extensive digestion with sequence-specific RNases strongly biases the recovered binding sites. This bias can be substantially reduced by milder nuclease digestion conditions.


Assuntos
Reagentes de Ligações Cruzadas/química , Imunoprecipitação/métodos , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo , Sítios de Ligação , Proteínas de Ligação a RNA/análise
18.
BMC Genomics ; 12: 46, 2011 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-21247452

RESUMO

BACKGROUND: The piRNA pathway operates in animal germ lines to ensure genome integrity through retrotransposon silencing. The Piwi protein-associated small RNAs (piRNAs) guide Piwi proteins to retrotransposon transcripts, which are degraded and thereby post-transcriptionally silenced through a ping-pong amplification process. Cleavage of the retrotransposon transcript defines at the same time the 5' end of a secondary piRNA that will in turn guide a Piwi protein to a primary piRNA precursor, thereby amplifying primary piRNAs. Although several studies provided evidence that this mechanism is conserved among metazoa, how the process is initiated and what enzymatic activities are responsible for generating the primary and secondary piRNAs are not entirely clear. RESULTS: Here we analyzed small RNAs from three mammalian species, seeking to gain further insight into the mechanisms responsible for the piRNA amplification loop. We found that in all these species piRNA-directed targeting is accompanied by the generation of short sequences that have a very precisely defined length, 19 nucleotides, and a specific spatial relationship with the guide piRNAs. CONCLUSIONS: This suggests that the processing of the 5' product of piRNA-guided cleavage occurs while the piRNA target is engaged by the Piwi protein. Although they are not stabilized through methylation of their 3' ends, the 19-mers are abundant not only in testes lysates but also in immunoprecipitates of Miwi and Mili proteins. They will enable more accurate identification of piRNA loci in deep sequencing data sets.


Assuntos
RNA Interferente Pequeno/genética , Animais , Masculino , Camundongos , Ornitorrinco/genética , Ratos , Retroelementos/genética
19.
Genome Res ; 19(11): 2009-20, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19767416

RESUMO

How miRNAs recognize their target sites is a puzzle that many experimental and computational studies aimed to solve. Several features, such as perfect pairing of the miRNA seed, additional pairing in the 3' region of the miRNA, relative position in the 3' UTR, and the A/U content of the environment of the putative site, have been found to be relevant. Here we have used a large number of previously published data sets to assess the power that various sequence and structure features have in distinguishing between putative sites that do and those that do not appear to be functional. We found that although different data sets give widely different answers when it comes to ranking the relative importance of these features, the sites inferred from most transcriptomics experiments, as well as from comparative genomics, appear similar at this level. This suggests that miRNA target sites have been selected in evolution on their ability to trigger mRNA degradation. To understand at what step in the miRNA-induced response individual features play a role, we transfected human HEK293 cells with miRNAs and analyzed the association of Argonaute/EIF2C-miRNA complexes with target mRNAs and the degradation of these messages. We found that structural features of the target site are only important for Argonaute/EIF2C binding, while sequence features such as the A/U content of the 3' UTR are important for mRNA degradation.


Assuntos
Fatores de Iniciação em Eucariotos/genética , Perfilação da Expressão Gênica , MicroRNAs/metabolismo , RNA Mensageiro/metabolismo , Regiões 3' não Traduzidas/genética , Proteínas Argonautas , Sítios de Ligação/genética , Linhagem Celular , Análise por Conglomerados , Bases de Dados Genéticas , Humanos , MicroRNAs/química , MicroRNAs/genética , Conformação de Ácido Nucleico , RNA Mensageiro/química , RNA Mensageiro/genética , Transcrição Gênica , Transfecção
20.
PLoS One ; 3(9): e3164, 2008 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-18776931

RESUMO

Genome-wide identification of mRNAs regulated by RNA-binding proteins is crucial to uncover post-transcriptional gene regulatory systems. The conserved PUF family RNA-binding proteins repress gene expression post-transcriptionally by binding to sequence elements in 3'-UTRs of mRNAs. Despite their well-studied implications for development and neurogenesis in metazoa, the mammalian PUF family members are only poorly characterized and mRNA targets are largely unknown. We have systematically identified the mRNAs associated with the two human PUF proteins, PUM1 and PUM2, by the recovery of endogenously formed ribonucleoprotein complexes and the analysis of associated RNAs with DNA microarrays. A largely overlapping set comprised of hundreds of mRNAs were reproducibly associated with the paralogous PUM proteins, many of them encoding functionally related proteins. A characteristic PUF-binding motif was highly enriched among PUM bound messages and validated with RNA pull-down experiments. Moreover, PUF motifs as well as surrounding sequences exhibit higher conservation in PUM bound messages as opposed to transcripts that were not found to be associated, suggesting that PUM function may be modulated by other factors that bind conserved elements. Strikingly, we found that PUF motifs are enriched around predicted miRNA binding sites and that high-confidence miRNA binding sites are significantly enriched in the 3'-UTRs of experimentally determined PUM1 and PUM2 targets, strongly suggesting an interaction of human PUM proteins with the miRNA regulatory system. Our work suggests extensive connections between the RBP and miRNA post-transcriptional regulatory systems and provides a framework for deciphering the molecular mechanism by which PUF proteins regulate their target mRNAs.


Assuntos
Regulação da Expressão Gênica , MicroRNAs , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/química , Motivos de Aminoácidos , Animais , Sítios de Ligação , Primers do DNA/química , Drosophila melanogaster/metabolismo , Células HeLa , Humanos , Família Multigênica , Ligação Proteica , Proteínas de Ligação a RNA/metabolismo
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