RESUMO
Eating disorders among children and youth are a serious social problem. The time of development is the starting point in shaping eating patterns. Proper nutrition provides the basis for psychophysical development. A knowledgeable pediatrician can improve society's health by engaging parents and, later, the child or youth. We offer knowledge on the nutrition basics and the commonly available tools to assess the nutritional status. We will discuss the characteristics of eating and body mass disorders in developing children. We will provide information on the warning signals of eating and body mass disorders and recommend prophylaxis. The reader will be familiarized with the motivational dialogue as an effective control tool for the discussed health issues.
RESUMO
Initiation of influenza A virus (IAV) transcription depends on RNA primers derived from host RNAs. During this process, some primers are elongated by a few nucleotides, realigned on the viral RNA templates (vRNA), and then used to initiate another round of transcription. Here, we used information on the host primers used by four IAV strains and four mini-replicons to investigate the characteristics of primer undergoing priming and realignment. We report that primers are biased towards this mechanism on the basis of length and RNA duplex stability with the vRNA templates. Priming and realignment results in primers three nucleotides longer, ending in a nucleotide sequence able to base pair with the 3' end of the vRNA template. By acting on primers based on length and sequence compatibility with the 3' end of the vRNA, priming and realignment rescues suboptimal primers, converting them into ones that can efficiently initiate transcription.
Assuntos
Regulação Viral da Expressão Gênica , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H3N2/genética , RNA Viral/genética , RNA Polimerase Dependente de RNA/genética , Transcrição Gênica , Proteínas Virais/genética , Células A549 , Pareamento de Bases , Sequência de Bases , Expressão Gênica , Biblioteca Gênica , Interações Hospedeiro-Patógeno/genética , Humanos , Vírus da Influenza A Subtipo H1N1/química , Vírus da Influenza A Subtipo H1N1/metabolismo , Vírus da Influenza A Subtipo H3N2/metabolismo , Plasmídeos/química , Plasmídeos/metabolismo , RNA/genética , RNA/metabolismo , RNA Viral/metabolismo , RNA Polimerase Dependente de RNA/metabolismo , Transfecção , Proteínas Virais/metabolismoRESUMO
The influenza A virus (IAV) genome consists of eight single-stranded RNA segments. Each segment is associated with a protein complex, with the 3' and 5' ends bound to the RNA-dependent RNA polymerase (RdRp) and the remainder associated with the viral nucleoprotein. During transcription of viral mRNA, this ribonucleoprotein complex steals short, 5'-capped transcripts produced by the cellular DNA dependent RNA polymerase II (RNAPII) and uses them to prime transcription of viral mRNA. Here, we review the current knowledge on the process of IAV cap-snatching and suggest a requirement for RNAPII promoter-proximal pausing for efficient IAV mRNA transcription.
Assuntos
Vírus da Influenza A/fisiologia , Capuzes de RNA , RNA Polimerase II/metabolismo , RNA Mensageiro/metabolismo , RNA Viral/metabolismo , Proteínas de Ligação a RNA/metabolismo , Transcrição Gênica , Proteínas do Core Viral/metabolismo , Proteínas do Nucleocapsídeo , Ligação Proteica , Replicação ViralRESUMO
The influenza A virus RNA polymerase cleaves the 5' ends of host RNAs and uses these RNA fragments as primers for viral mRNA synthesis. We performed deep sequencing of the 5' host-derived ends of the eight viral mRNAs of influenza A/Puerto Rico/8/1934 (H1N1) virus in infected A549 cells, and compared the population to those of A/Hong Kong/1/1968 (H3N2) and A/WSN/1933 (H1N1). In the three strains, the viral RNAs target different populations of host RNAs. Host RNAs are cap-snatched based on their abundance, and we found that RNAs encoding proteins involved in metabolism are overrepresented in the cap-snatched populations. Because this overrepresentation could be a reflection of the host response early after infection, and thus of the increased availability of these transcripts, our results suggest that host RNAs are cap-snatched mainly based on their abundance without preferential targeting.
Assuntos
Células Epiteliais/virologia , Interações Hospedeiro-Patógeno , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H3N2/genética , Capuzes de RNA/genética , Capuzes de RNA/metabolismo , Replicação Viral , Linhagem Celular , Variação Genética , Humanos , Análise de Sequência de DNARESUMO
The influenza A virus RNA polymerase cleaves the 5' end of host pre-mRNAs and uses the capped RNA fragments as primers for viral mRNA synthesis. We performed deep sequencing of the 5' ends of viral mRNAs from all genome segments transcribed in both human (A549) and mouse (M-1) cells infected with the influenza A/HongKong/1/1968 (H3N2) virus. In addition to information on RNA motifs present, our results indicate that the host primers are divergent between the viral transcripts. We observed differences in length distributions, nucleotide motifs and the identity of the host primers between the viral mRNAs. Mapping the reads to known transcription start sites indicates that the virus targets the most abundant host mRNAs, which is likely caused by the higher expression of these genes. Our findings suggest negligible competition amongst RdRp:vRNA complexes for individual host mRNA templates during cap-snatching and provide a better understanding of the molecular mechanism governing the first step of transcription of this influenza strain.
Assuntos
Vírus da Influenza A Subtipo H3N2/genética , Transcrição Gênica , Regiões 5' não Traduzidas , Animais , Sequência de Bases , Linhagem Celular Tumoral , Mapeamento Cromossômico , Sequência Consenso , Primers do DNA/genética , Regulação Viral da Expressão Gênica , Ontologia Genética , Genes Virais , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Camundongos , Dados de Sequência Molecular , RNA Mensageiro/genética , RNA Viral/genética , Análise de Sequência de DNA , Sítio de Iniciação de TranscriçãoRESUMO
The hepatitis delta virus (HDV) is a small (~1700 nucleotides) RNA pathogen which encodes only one open reading frame. Consequently, HDV is dependent on host proteins to replicate its RNA genome. Recently, we reported that ASF/SF2 binds directly and specifically to an HDV-derived RNA fragment which has RNA polymerase II promoter activity. Here, we localized the binding site of ASF/SF2 on the HDV RNA fragment by performing binding experiments using purified recombinant ASF/SF2 combined with deletion analysis and site-directed mutagenesis. In addition, we investigated the requirement of ASF/SF2 for HDV RNA replication using RNAi-mediated knock-down of ASF/SF2 in 293 cells replicating HDV RNA. Overall, our results indicate that ASF/SF2 binds to a purine-rich region distant from both the previously published initiation site of HDV mRNA transcription and binding site of RNAP II, and suggest that this protein is not involved in HDV replication in the cellular system used.
Assuntos
Vírus Delta da Hepatite/genética , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , RNA/genética , Sítios de Ligação , Genoma Viral , Células HEK293 , Vírus Delta da Hepatite/crescimento & desenvolvimento , Vírus Delta da Hepatite/patogenicidade , Humanos , Regiões Promotoras Genéticas , Ligação Proteica , RNA Polimerase II/genética , Fatores de Processamento de Serina-Arginina , Replicação Viral/genéticaRESUMO
Because of its extremely limited coding capacity, the hepatitis delta virus (HDV) takes over cellular machineries for its replication and propagation. Despite the functional importance of host factors in both HDV biology and pathogenicity, little is known about proteins that associate with its RNA genome. Here, we report the identification of several host proteins interacting with an RNA corresponding to the right terminal stem-loop domain of HDV genomic RNA, using mass spectrometry on a UV crosslinked ribonucleoprotein complex, RNA affinity chromatography, and screening of a library of purified RNA-binding proteins. Co-immunoprecipitation was used to confirm the interactions of eEF1A1, p54(nrb), hnRNP-L, GAPDH and ASF/SF2 with the right terminal stem-loop domain of HDV genomic RNA in vitro, and with both polarities of HDV RNA within HeLa cells. Our discovery that HDV RNA associates with RNA-processing pathways and translation machinery during its replication provides new insights into HDV biology and its pathogenicity.