No description available.

Substantia nigra neurons produce dopamine in response to cholinergic stimuli that may involve receptor operated Ca²⁺ -entry that has been associated with the transient receptor potential (Trp) proteins. There were 6 Trp isoforms reported when I started this work. I set out to determine which isoforms of Trp mRNA were expressed in the substantia nigra using the whole brain for comparison. I initially used RT-PCR to determine the Trp mRNA expression. Subsequently, I used competitive RT-PCR for quantifying the major isoforms. Finally, I confirmed my results by Co-RT-PCR of the major isoforms. Trp3 and Trp6 were found to be the predominant forms expressed in the substantia nigra and whole brain, while the levels of Trps 1, 2, 4 and 5 were very low in both. Estimation of mRNA levels using competitive RT-PCR showed that the Trp6 mRNA levels in substantia nigra and the whole brain were similar while those for Trp3 were significantly lower in the substantia nigra than in the while brain. Thus substantia nigra differs from the whole brain in its Trp expression. Properties of Trps 3 and 6 are not fully known. Trp3 is regulated by IP₃-receptor activation but both Trp 3 and 6 can be activated by diacylglycerol. How this relates to the signal transduction events in substantia nigra remains to be determined. / Thesis / Master of Science (MS)

PEA3 is a member of the ETS family of genes. It is expressed in the adult mouse brain and epididymis. It is also expressed in the embryonal carcinoma P19 and F9 cell lines, where its expression is reduced following retinoic acid-induced differentiation. Sequencing of two human cDNA clones revealed the existence of alternatively-spliced PEA3 isoforms from the human PEA3 gene. Consequently there is a likelihood that such alternative splicing also occurs within the mouse PEA3 gene. If this is so, it would be of interest to determine the organization of the mouse PEA3 gene. This information will be necessary to explain any alternativelyspliced PEA3 isoforms that might be observed. To obtain this information, 21 kb of mouse genomic DNA containing the mouse PEA3 gene locus was isolated, subcloned and sequenced. This sequence data revealed that the mouse PEA3 messenger RNA (as present in several previously-characterized cDNAs) is encoded by 13 exons distributed over 14 kb of the mouse genome. To ensure that the complete PEA3 mRNA had been obtained and characterized, the 5' end of the PEA3 mRNA was isolated by the RACE protocol (Rapid Amplification of cDNA Ends). The results of this analysis indicated a transcription start site corresponding to the start of exon 1. The region immediately upstream of this likely initiation site contains numerous cognate sites for transcription factors which may play a role in controlling PEA3 transcription. / Thesis / Master of Science (MSc)

In eukaryotes, mRNA is in constant flux between an actively translating state and translationally repressed states. Specifically, mRNA degradation and repression factors compete with translation factors to direct mRNAs out of translation for storage or decay. This process often leads to formation of cytoplasmic aggregates. P-bodies are granules that contain mRNA and degradation factors, suggesting they are sites of mRNA decay or storage. Stress granules form in response to stress conditions and contain mRNAs and translation factors.P-bodies and stress granules consist of mRNPs of different compositions, believed to mature and transition between the states. It is proposed that mRNAs transition between the two granules. In the work described below, we use <italic>Saccharomyces cerevisiae</italic> to demonstrate that a decay factor, Dhh1 is capable of existing in both P-body and stress granule mRNPs. This suggests that a decay factor can be part of two different mRNP complexes. Additionally, we identify two novel components of the stress granule mRNPs, Pbp4 and Lsm12, and determine that they are not essential for stress granule formation. Lastly, we show that the stress granule mRNP factor, Pab1, is not absolutely required for stress granule formation.An important aspect of cytoplasmic mRNA regulation is mRNA quality control. One example of this is nonsense-mediated mRNA decay (NMD), whereby aberrant mRNAs containing premature termination codons are targeted for decay, and can be localized to P-bodies. Upf1-3 and the mRNA decapping complex, Dcp2/Dcp1 are essential for NMD, which requires Upf1 interaction with stalled ribosomal/mRNA complexes to target aberrant mRNA for decapping and degradation. How Dcp2/Dcp1 is recruited to aberrant mRNA is poorly understood.Here, we show by yeast two-hybrid assays that an interaction between Dcp2 and Upf1 is mediated by the decapping stimulator Edc3. Interestingly, Edc3 and Upf2 share overlapping binding sites on the Upf1 N-terminal domain. The decapping stimulator, Pat1, also interacts on the Upf1 N-terminus, but Edc3 and Pat1 are not essential for NMD. Surprisingly, the Upf1-Edc3 interaction does not promote or negatively regulate NMD. Thus, the Upf1-Edc3 and Upf1-Pat1 interactions likely regulate a subset of mRNA transcripts, or are essential for proper NMD under different environmental conditions.

Orientador: Cleslei Fernando Zanelli / Resumo: O fator de início de tradução 5A (eIF5A) é altamente conservado em arqueas e eucariotos e essencial para a viabilidade celular. eIF5A sofre uma modificação pós-traducional exclusiva e essencial para sua função, em que um resíduo específico de lisina é convertido em uma hipusina. Apesar eIF5A já ter sido relacionado com o início da tradução, uma quantidade crescente de estudos recentes têm estabelecido sua função na etapa de elongação da tradução, mais especificamente na elongação de sequências que são capazes de induzir um stalling (atraso ou parada) do ribossomo. Entretanto, existem ainda poucos trabalhos realizados com perfil proteômico na ausência de função de eIF5A, de maneira que atualmente pouco se sabe sobre as proteínas que têm sua tradução dependente de eIF5A. Desta forma, o presente projeto visa a busca de proteínas que têm sua tradução dependente de eIF5A através da comparação de perfil proteômico entre linhagens selvagens e mutantes de eIF5A em Saccharomyces cerevisiae. Para isto, utilizamos neste trabalho uma estratégia de perfil proteômico celular in vivo por fluorescência de GFP utilizando uma coleção de 4.156 linhagens, cada uma contendo uma ORF diferente em fusão com GFP no C-terminal, e uma proteína RFP (variante E2Crimson) constitutivamente produzida como normalizador, tanto no background selvagem (HYP2) como mutante para eIF5A (hyp2-3). Esta tese apresenta a análise dos dados de GFP/RFP e a validação desta análise utilizando-se western blot. Os resultados ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The translation factor 5A (eIF5A) is conserved and essential for cell viability. This is the only protein known to contain the amino acid residue hypusine, essential for eIF5A function, generated by a post-translational modification. Although it was initially suggested a function for eIF5A in the translation initiation, eIF5A has been demonstrated to have a role in translation elongation. More recent studies have established that eIF5A is necessary for the elongation of specific sequences, which are able to induce a ribosome stalling. Still, there are few studies with proteomic profile in the absence of eIF5A function and the proteins which syntheses are dependent on eIF5A are not well known. Thus, the present study aims to search for the proteins which syntheses are dependent on eIF5A by proteomic profile comparison between wild-type strains and eIF5A mutants in Saccharomyces cerevisiae. We present a proteomic profile for GFP fluorescence using a 4156 collection of strains, each one containing a different ORF fused to the C-terminal GFP and a protein RFP constitutively produced as normalizing, both in the wild and eIF5A mutant background. This thesis presents GFP / RFP data analysis and data validation using western blot. Our data using an in vivo proteome profile of the ORFs-GFP collection in a hyp2-3 mutant background demonstrating that yeast eIF5A shows several mitochondrial proteins downregulated in the eIF5A mutant. To confirm eIF5A involvement with mitochondrial functi... (Complete abstract click electronic access below) / Doutor

<p>The unique C-terminal domain (CTD) of RNA polymerase II (RNAPII), composed of tandem heptad repeats of the consensus sequence YSPTSPS, is subject to differential phosphorylation throughout the transcription cycle. Several RNA processing factors have been shown to bind the appropriately phosphorylated CTD, and this facilitates their localization to nascent pre-mRNA during transcription. In <italic>Saccharomyces cerevisiae</italic>, the mRNA export protein Yra1 (ALY/REF in metazoa) has been shown to cotranscriptionally associate with mRNA and is thought to deliver it to the nuclear pore complex for export to the cytoplasm. Based on a previous proteomics screen, I hypothesized that Yra1 is a <italic>bona fide</italic> phosphoCTD associated protein (PCAP) and that this interaction is responsible for the pattern of Yra1 cotranscriptional association observed <italic>in vivo</italic>. Using <italic>in vitro</italic> binding assays, I show that Yra1 directly binds the hyperphosphorylated form of the CTD characteristic of elongating RNAPII. Using truncations of Yra1, I determined that its phosphoCTD-interacting domain (PCID) resides in the segment comprising amino acids 18-184, which, interestingly, also contains the RNA Recognition Motif (RRM) (residues 77-184). Using UV crosslinking, I found that the RRM alone can bind RNA, although a larger protein segment, extending to the C-terminus (aa 77-226), displays stronger RNA binding activity. Even though the RRM is implicated in both RNA and CTD binding, certain RRM point mutations separate these two functions: thus, mutations that produce defects in RNA binding do not affect CTD binding. Both functions are important <italic>in vivo</italic>, in that RNA binding-defective or CTD binding-defective versions of Yra1 engender growth and mRNA export defects. I also report the construction and characterization of a useful new temperature sensitive <italic>YRA1</italic> allele (<italic>R107AF126A</italic>). Finally, using chromatin immunoprecipitation, I demonstrate that removing the N-terminal 76 amino acids of Yra1 (all of the PCID up to the RRM) results in a 10-fold decrease in Yra1 recruitment to genes during elongation. These results indicate that the PCTD is likely involved directly in cotranscriptional recruitment of Yra1 to active genes.</p> / Dissertation

Das Neuroblastom ist der häufigste extrakraniell gelegene solide Tumor der pädiatrischen Onkologie. Der Verlauf der Erkrankung geht von spontaner Regression oder Differenzierung bis hin zu tödlich verlaufenden Erkrankungen. Die Mortalität von Patienten mit Tumoren in fortgeschrittenen Stadien ist immer noch sehr hoch. Die aggressivsten Tumoren sind die, die eine Amplifikation des Protoonkogens MYCN aufweisen. Eine Untergruppe dieser MYCN amplifizierten Tumoren weist eine Coamplifikation von DDX1 auf. Die Prognose dieser Patienten ist besser als die mit allein MYCN amplifizierten Tumoren, wenn auch immer noch schlechter als die von Patienten ohne MYCN Amplifikation. Das DDX1-Protein ist eine putative RNA-Helikase. Über seine genaue Funktion ist noch nicht viel bekannt. Ziel dieser Arbeit war es, potentielle Ziel-mRNAs von DDX1 zu identifizieren, um einen besseren Einblick in die Funktionen von DDX1 und mögliche Wege der Beeinflussung von Tumorverhalten und Prognose zu erhalten. Hierzu wurden eine DDX1 amplifizierte und eine nicht amplifizierte Zelllinie in Kultur genommen und eine Immunopräzipitation mit Zelllysaten der beiden Zelllinien durchgeführt – jeweils mit einem spezifischen Antikörper gegen DDX1 und einem unspezifischen Kontrollantikörper. Die Identifizierung der an DDX1 gebundenen mRNAs erfolgte mittels Microarray. Validiert wurden einige der im Microarray identifizierten RNAs mittels RT-PCR. CDK1, ATM und p18 ließen sich als spezifische Ziel-mRNAs von DDX1 identifizieren.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-07-12T16:05:41Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação ADALUCIA DA SILVA PPGG 2016.pdf: 2174365 bytes, checksum: e3305d6246515bbc247cd29783f8b265 (MD5) / Made available in DSpace on 2017-07-12T16:05:41Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação ADALUCIA DA SILVA PPGG 2016.pdf: 2174365 bytes, checksum: e3305d6246515bbc247cd29783f8b265 (MD5) Previous issue date: 2016-03-07 / FACEPE / Os tripanossomatídeos são parasitas flagelados causadores de diversas doenças humanas e que apresentam algumas características moleculares bem distintas. Nestes organismos, o controle da sua expressão gênica é quase exclusivamente pós-transcricional e dados obtidos até o momento sugerem que a etapa de iniciação da tradução tem um papel importante neste controle. Durante a iniciação da tradução de eucariotos, o complexo trimérico eIF4F (formado pelas subunidades eIF4A, eIF4G e eIF4E) tem uma participação importante no reconhecimento do mRNA, facilitando o recrutamento ribossomal para iniciar a síntese proteica. Múltiplos homólogos das subunidades do complexo eIF4F foram identificados em tripanossomatídeos, mas não foi possível elucidar a função específica de cada um deles. Desta forma, este trabalho teve como objetivo o desenvolvimento de um ensaio in vivo para a avaliação do efeito da superexpressão desses homólogos de Trypanosoma brucei na tradução de um mRNA repórter, o qual codifica a proteína GFP (green fluorescent protein). Três linhagens repórter foram obtidas (4212, 4213 e 4235) e sete homólogos das subunidades do complexo eIF4F e um de PABP foram testados nestas linhagens. A análise da superexpressão foi feita através de ensaios de Western blot, seus perfis de crescimento foram avaliados por curvas de crescimento e a expressão de GFP foi avaliada através de citometria de fluxo. Os resultados apresentados mostram que as linhagens repórter 4213 e 4235 são viáveis para serem utilizadas na caracterização das proteínas envolvidas no controle da expressão gênica de tripanossomatídeos. Foi observado que as proteínas EIF4E1 e EIF4E2 provocam diminuição do crescimento, enquanto a superexpressão de EIF4E3, EIF4E4, EIF4E4W279A, EIF4G3, EIF4G4 e PABP1 não alteram o crescimento celular dos parasitas. Apesar da detecção de variações na expressão de GFP durante a superexpressão de alguns dos homólogos testados, não foi possível, contudo, confirmar que estas proteínas aumentam ou diminuem a tradução. Ensaios complementares ainda precisam ser feitos para confirmar a real função destes. / The trypanosomatids are flagellated parasites responsible for several human diseases and which display unique molecular characteristics. Control of gene expression in these organisms is almost exclusively post-transcriptional and the data generated so far suggest that the initiation stage of translation plays an important role in this control. During translation initiation in eukaryotes, the trimeric complex eIF4F (formed by the eIF4A eIF4G and eIF4E subunits) has a relevant role in mRNA recognition and facilitates ribosomal recruitment to start the protein synthesis. Multiples homologues for the eIF4F subunits have been identified in trypanosomes, but it has not been possible to elucidate their specific functions. Thus, this study aimed to develop an in vivo assay to evaluate the effect of the overexpression of these Trypanosoma brucei homologues during the translation of a reporter mRNA encoding for the green fluorescent protein (GFP). Three reporter strains were generated (4212, 4213 and 4235) in which seven homologues of eIF4F subunits and one of their PABP partner were overexpressed. Confirmation of overexpression was carried out by Western blot assays, growth profiles were evaluated by cell counting and GFP expression was assessed by flow cytometry. The results generated show that the reporter lines 4213 and 4235 are feasible for use in the characterization of proteins involved in the control of trypanosomatids gene expression. Overexpression of EIF4E1 and EIF4E2 was seen to induce a reduction in cell growth, while EIF4E3, EIF4E4, EIF4E4W279A, EIF4G3, EIF4G4 and PABP1 did not interfere with growh. Despite the detection of variations in GFP expression during overexpression of some of the homologues tested it was not possible to confirm if these proteins increase or decrease translation. Complementary assays still need to be done to confirm the true function of these factors.

Protein Prp22 is a DEAH box RNA helicase, which plays two distinct roles in pre-mRNA splicing: it participates in second transesterification step (ATP independent function) and it releases mature mRNA from the spliceosome (ATP dependent function). Prp45p, yeast ortholog of the human transcription co-regulator SNW/SKIP, is an essential splicing factor, it is included in spliceosome throughout the splicing reaction. Mutant prp45(1-169) genetically interacts with some alleles of NTC complex and second step splicing factors, one of them is also gene PRP22. Here we present, that mutants prp22(-158T) and prp22(-327A), which are synthetically lethal with prp45(1-169), express lower amount of Prp22p due to the mutation in upstream regulation region. Mutants prp22(-158T), prp22(300PPI) and prp22(-327A) affect splicing of pre-mRNA with mutation in 5'ss with respect to sequence of the second exon. N-terminal mutants prp22(∆301) and prp22(∆350) are synthetically lethal with prp45(1-169). Synthetic lethality is possibly caused by lower efficiency of Prp22 recruitment to the spliceosomes, which is no more viable for cells.

In my thesis, I focused on several underexplored areas of RNA splicing regulation. In the first part, I analyzed how chromatin and transcription regulatory elements change pre-mRNA splicing. In the second part, I studied why long non-coding RNAs (lncRNAs) are spliced less efficiently than protein-coding mRNAs. Finally, I was testing the importance of intron for the activating function of lncRNAs. It has been shown that chromatin and promoter identity modulate alternative splicing decisions. Here, I tested whether local chromatin and distant genomic elements that influence transcription can also modulate splicing. Using the chromatin modifying enzymes directly targeted to FOSL1 gene by TALE technology, I showed that changes in histone H3K9 methylation affect constitutive splicing. Furthermore, I provide evidence that deletion of transcription enhancer located several kilobases upstream of an alternative exons changes splicing pattern of the alternative exon. Many nascent lncRNAs undergo the same maturation steps as pre-mRNAs of protein- coding genes (PCGs), but they are often poorly spliced. To identify the underlying mechanisms for this phenomenon, we searched for putative splicing inhibitory sequences. Genome-wide analysis of intergenic lncRNAs (lincRNAs) revealed that, in general, they do not...