'Regulators of G protein signaling' (RGS proteins) modulate the G proteincycle by enhancing the GTPase activity of Ga subunits. These changesaccelerate the kinetics of ion channel modulation by Gai/o-coupled receptors(GPCRs) such as the G protein-gated inward rectifier K+ (GIRK/Kir3) channel. Myexperiments indicate that a single cerebellar granule (CG) neuron, a cell type thatendogenously expresses GIRK channels is able to express a wide variety ofRGS proteins. I selected two of them, which are widely expressed andtranscriptionally regulated during pathophysiologic conditions, to compare theirfunctional properties. I originally described the differential modulatory effects oftwo RGS proteins, the RGS3 short isoform (RGS3s) and RGS4, on muscarinicm2 and serotonin 1A receptor-coupled Kir3.1/Kir3.2a channels expressed inChinese hamster ovary (CHO-K1) cells. Both RGS3s and RGS4 acceleratedGIRK activation and deactivation current kinetics in a similar way. However, onlyRGS3s si gnificantly decreased the maximal GIRK current (Imax) elicited by ACh(~45% inhibition) and significantly increased the EC50 for both GPCRs. Thehypothesis that emerged from this initial study was that the distinct RGS4 Nterminaldomain mediated a direct coupling of RGS4 to GPCR-GIRK channelsignaling complexes that was not shared by RGS3s. To test this hypothesis, Iepitope-tagged several GPCRs, the Kir3.1 subunit, RGS3s, RGS4, and severaldeletion mutants and chimeras for co-immunoprecipitation experiments. Using anepitope-tagged degradation resistant RGS4 mutant RGS4(C2V), I detected coprecipitationof different GPCR-GIRK channel complexes with RGS4 but notRGS3s.The functional impact of RGS4 coupling to the GPCR-Kir3 channelcomplex versus uncoupled RGS3s was not apparent in recordings from CHO-K1cells presumably due to a high degree of RGS collision-coupling. Controlledexpression in Xenopus oocytes revealed a 30-fold greater potency for RGS4 inthe accelerating GIRK channel gating kinetics. In summary, these findings demonstrate that one of the ways for the cellto achieve signaling pathway specificity may be through selective coupling of thedifferent GPCR-effector-RGS protein complexes.

The basis of developmental biology lies in the idea of when and how cells decide to divide or to differentiate. Previous studies have established several signaling pathways that determine cell fate decisions, including Notch, Wingless, Hedgehog, Bone morphogenetic protein, and Fibroblast growth factor. Signaling converges on transcriptional factors that regulate gene expression. In mouse embryonic stem cells, I explored how pluripotency and differentiation are regulated through opposing actions of beta-catenin-mediated canonical Wnt signaling, and the mechanisms underlying Sonic hedgehog signaling in generating progenitor cells in the ventral neural tube.

Endoplasmic reticulum (ER) stress has been implicated as a causative factor in the development of pancreatic beta-cell dysfunction and death resulting in type 2 diabetes. This thesis examined the role of ATF6beta in the ER stress response of beta-cells. Using an ATF6beta-specific antibody, expression of full-length ATF6beta was detected in various insulinoma cell lines and rodent islets and the induction of the active form (ATF6beta-p60) under ER stress conditions. Knock-down of ATF6beta in INS-1 832/13 cells did not affect mRNA induction of known ER stress response genes in response to tunicamycin-induced ER stress, however it increased the susceptibility of beta-cells to apoptosis. Conversely, overexpression of ATF6beta-p60 reduced the apoptotic phenotype. Microarray results suggest ATF6beta functions to induce expression of adaptive genes also regulated by ATF6alpha, but also several specific targets genes. These findings have increased our understanding of the role of ATF6beta in the ER stress response of beta-cells.

Endoplasmic reticulum (ER) stress has been implicated as a causative factor in the development of pancreatic beta-cell dysfunction and death resulting in type 2 diabetes. This thesis examined the role of ATF6beta in the ER stress response of beta-cells. Using an ATF6beta-specific antibody, expression of full-length ATF6beta was detected in various insulinoma cell lines and rodent islets and the induction of the active form (ATF6beta-p60) under ER stress conditions. Knock-down of ATF6beta in INS-1 832/13 cells did not affect mRNA induction of known ER stress response genes in response to tunicamycin-induced ER stress, however it increased the susceptibility of beta-cells to apoptosis. Conversely, overexpression of ATF6beta-p60 reduced the apoptotic phenotype. Microarray results suggest ATF6beta functions to induce expression of adaptive genes also regulated by ATF6alpha, but also several specific targets genes. These findings have increased our understanding of the role of ATF6beta in the ER stress response of beta-cells.

No description available.

Wolbachia are widely spread, maternally transmitted insect endosymbiotic intracellular bacteria. They have been implicated in the control of several insect transmitted diseases, including dengue, yellow fever, Zika and malaria. Effective pathogen suppression in the insect host is shown to be proportional to the intracellular levels of bacteria. Therefore, understanding the molecular mechanisms underlying Wolbachia accumulation within organisms is extremely important for future epidemic control and research. Using Drosophila as a model insect, our lab has previously observed Wolbachia tropism to stem cell niches. Current work has identified polar cells as an additional site of Wolbachia tropism and demonstrated that Wg/Wnt signaling is important for Wolbachia intracellular accumulation in these somatic cells. In this thesis, we first observed that the Wg/Wnt pathway protein Armadillo also controls Wolbachia levels in the germline cells, indicating the possibility of having a conserved molecular mechanism controlling Wolbachia. Using RNAi and small molecule inhibitors of Shaggy, another component of the canonical Wg/Wnt pathway, we demonstrate that the canonical Wg/Wnt signaling is essential for Wolbachia intracellular accumulation. Our investigation provides fundamental insights into the mechanisms of Wolbachia intracellular accumulation. Furthermore, it offers novel strategies to modulate Wolbachia in non-model insect species, including various disease transmitting Anopheles, Culex, and Aedes. These findings potentially will increase the effectiveness of a Wolbachia-based vector transmitted disease suppression. / 2017-02-28

Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2015-04-10T16:47:02Z No. of bitstreams: 1 Pablo Rafael Silveira Oliveira Genética....pdf: 12348951 bytes, checksum: 971e7af3b39a1bb56feeb26578855f45 (MD5) / Approved for entry into archive by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2015-04-10T16:47:18Z (GMT) No. of bitstreams: 1 Pablo Rafael Silveira Oliveira Genética....pdf: 12348951 bytes, checksum: 971e7af3b39a1bb56feeb26578855f45 (MD5) / Made available in DSpace on 2015-04-10T16:47:18Z (GMT). No. of bitstreams: 1 Pablo Rafael Silveira Oliveira Genética....pdf: 12348951 bytes, checksum: 971e7af3b39a1bb56feeb26578855f45 (MD5) Previous issue date: 2015 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / A leishmaniose cutânea (LC) é a forma clínica mais comum do complexo de doenças causadas por protozoários do gênero Leishmania. Interessantemente, alguns indivíduos infectados com espécies dermotrópicas do parasito não desenvolvem a LC, enquanto outros desenvolvem lesões crônicas. Os mecanismos envolvidos nesta variação permanecem amplamente desconhecidos, embora fatores genéticos do hospedeiro podem influenciar o risco de desenvolver a doença. No primeiro estudo apresentado nesta tese, foi mostrado que a sinalização IL-2/IL-2R desempenha um papel crucial na resposta imune contra espécies dermotrópicas de Leishmania. Os transcritos de vários genes da via de sinalização IL-2 são mais abundantes em úlceras cutâneas causadas por Leishmania braziliensis do que em amostras de pele normal de dadores não infectados. Um estudo de associação em famílias brasileiras (209 famílias nucleares) identificou dois polimorfismos no gene IL2RA associados à LC causada por L. braziliensis [rs10905669 (p = 3x10-4) e rs706778 (p = 3x10-4)]. Estes resultados foram replicados em uma segunda amostra brasileira (80 famílias nucleares) [rs10905669 (p = 0.08) e rs706778 (p = 0.04)] e em iranianos infectados com Leishmania tropica (coorte do tipo caso-controle composta por 236 indivíduos) [rs10905669 (p = 0.03) e rs706778 (p = 0.04)]. Uma metanálise dos três estudos confirmou que os alelos rs10905669 T (pcombinado = 6x10-7) e rs706778 T (pcombinado = 2x10-9) são fortemente associados a uma maior predisposição à LC. O alelo T do SNP rs706778 também foi associado a uma menor produção de IFN- por células mononucleares após a estimulação com extrato de Leishmania e com uma redução na ativação de células T regulatórias (Treg) FoxP3+ in vitro. Em conjunto, os dados apresentados no estudo 1 suportam a hipótese de que a via de sinalização IL-2 é implicada no desenvolvimento da LC, com possíveis consequências no controle da replicação do parasito e na imunopatologia associada à infecção. No segundo estudo desta tese, foi realizada uma análise de ligação genômica em famílias brasilieras expostas à L. braziliensis. Esta análise revelou um novo locus de suscetibilidade para a LC na região 10q21-q23 (LOD sugestivo = 2.39). Em toda esta região, os genes mais fortemente induzidos em lesões cutâneas (em relação aos controles) foram PRF1 (fold-change = 49.3) e SRGN (fold-change = 21.8). Interessantemente, ambos os genes codificam moléculas envolvidas nos mecanismos de citotoxicidade de células T CD8+ e de células natural killer. Por fim, dois polimorfismos na região do gene SRGN foram associados ao risco de LC em famílias brasileiras expostas à L. braziliensis [estudo primário (209 famílias): rs10998538 (p = 0.001) e rs12437 (p = 0.003); estudo de replicação (80 famílias): rs10998538 (p = 0.01) e rs12437 (p = 0.007)]. Por fim, os dados apresentados nesta tese apontam a serglicina (codificada pelo gene SRGN) e a via de sinalização IL-2 como alvos potenciais de novas estratégias de tratamento ou prevenção contra a LC em humanos. / Cutaneous leishmaniasis (CL) is the most common clinical form of leishmaniasis and can be caused by several dermotropic Leishmania species. Interestingly, some infected individuals do not develop cutaneous lesions, while others are severely affected. The basis of this variation remains largely unknown, although host genetic factors seem to influence disease risk. In the first study presented in this thesis, it was shown that IL-2 plays a crucial role in human immunity against dermotropic Leishmania species. It was observed that the transcripts of several genes of the IL-2 pathway were more abundant in skin ulcers caused by Leishmania braziliensis than in normal skin samples. A primary association study on Brazilians (754 individuals from 209 families) identified two polymorphisms in the IL2RA gene associated with CL caused by L. braziliensis [rs10905669 (p = 3x10-4) and rs706778 (p = 3x10-4)]. This result was confirmed in a second Brazilian sample (325 subjects from 80 nuclear families) [rs10905669 (p = 0.08) and rs706778 (p = 0.04)] and in Iranians infected with Leishmania tropica (236 individuals) [rs10905669 (p = 0.03) and rs706778 (p = 0.04)]. A meta-analysis confirmed that rs10905669 T allele (pcombined = 6x10-7) and rs706778 T allele (pcombined = 2x10-9) were strongly associated with increased susceptibility to CL. The T allele of rs706778 was also associated with lower IFN- production by peripheral blood mononuclear cells after Leishmania antigen stimulation and with reduced FoxP3+ Treg activation in vitro. Altogether, these data support the notion that the IL-2 signaling pathway is implicated in the development of cutaneous leishmaniasis and could be involved in the control of both parasite replication and infection-induced immunopathology. In the second study, a genome wide linkage (GWL) scan conducted in Brazilian multiplex families revealed a new susceptibility locus for CL on chromosome 10q21-q23 (suggestive LOD = 2.39). Interestingly, in this entire region, the most strongly induced transcripts were from PRF1 (fold change = 49.3) and SRGN (fold change = 21.8) genes, both encoding molecules involved in the cytotoxic mechanisms by a variety of cell types, including CD8+ T cells and natural killer cells. Finally, two polymorphisms in the SRGN region were associated with susceptibility to CL in Brazilian families exposed to L. braziliensis [Discovery study (209 families): rs10998538 (p = 0.001) and rs12437 (p = 0.003); Replication study (80 families): rs10998538 (p = 0.01) and rs12437 (p = 0.007)]. These data highlight the serglycin (encoded by the SRGN gene) and the IL-2 pathway as suitable targets for new strategies aimed to treat or prevent cutaneous leishmaniasis.

O meduloblastoma (MB) é o tumor cerebral maligno mais comum na infância. A formação/progressão desta neoplasia foi associada a alterações moleculares, que inclui a desregulação da via de sinalização Wingless (Wnt), responsável pelo desenvolvimento embrionário. Além disso, as proteínas da família Aurora-quinases (A, B e C) têm sido amplamente estudadas, uma vez que a Aurora A e B foram encontrados hiperexpressas em diversas neoplasias, como o MB. Estudos recentes mostraram que existe uma associação entre a Via Wnt e as Aurora-quinases. No entanto, poucos trabalhos foram realizados para confirmar essa associação. Ademais, não existem trabalhos que relatem os efeitos do AMG900, um pan-inibidor de aurora-quinases, em MB, dando enfoque na regulação da via Wnt. Assim, o objetivo deste trabalho foi avaliar a modulação da via Wnt pelo inibidor AMG900 nas linhagens celulares de meduloblastoma pediátrico. Foram realizados os ensaios de PCR convencional, sequenciamento, qRT-PCR, transfecção transiente, ensaio clonogênico, Western Blot e ciclo celular. As linhagens celulares UW402, UW473 e ONS-76 não apresentaram mutações no éxon 3 do gene CTNNB1 (?-catenina) e no éxon 15 do gene APC. Não foi observada uma expressão significativa de CTNNB1, confirmando que as linhagens não possuíam a via Wnt ativa. Com isso foi necessário a transfecção transiente com a ?- catenina. Após este ensaio, houve um aumento da expressão de CTNNB1, Ciclina D1 e CMyc nas três linhagens, o que não ocorreu com as Auroras A e B. No ensaio clonogênico foi observado uma redução do número de colônias nas linhagens UW473 e ONS-76. Observou-se um aumento da expressão proteica da ?-catenina, da Aurora A e B na UW473, o que ocorreu somente com a ?-catenina na linhagem ONS-76. Após o tratamento com o AMG900 ocorreu uma diminuição da expressão proteica de ?-catenina, da Aurora A e B em ambas as linhagens. A transfecção não alterou o percentil celular em G2/M na UW402 e UW473. Já na ONS-76 houve um aumento significativo em G2/M, e o AMG900 potencializou esse bloqueio apenas nessa linhagem. Os resultados sugerem que pode haver alguma relação entre a inibição das proteínas Aurora-quinases e a expressão de proteínas da via Wnt. / Medulloblastoma (MB) is the most common malignant brain tumor in childhood. Tumor formation/progression has been associated to molecular alterations that include dysregulation of signaling pathway Wingless (Wnt), responsible for embryonic development. In addition, cell cycle proteins Aurora-kinase (A, B and C) have been widely studied since Aurora A and B were found overexpressed in many cancers such as MB. Recent studies show that there is an association between Wnt pathway and Aurora kinase proteins. However, few studies have been conducted to confirm this association. Moreover, there are no studies reporting the effects of AMG900 in MB, by focusing on the regulation of the Wnt pathway. The aim of this study is to evaluate Wnt pathway modulation by Aurora kinases inhibitor AMG900 in pediatric medulloblastoma cell lines. Conventional PCR, sequencing, qRT-PCR, transient transfection, clonogenic assay, Western Blot and cell cycle assays were performed. UW402, UW473 and ONS-76 cell lines did not present mutations in exon 3 of CTNNB1 gene and exon 15 of APC gene. There was no significant expression of CTNNB1 and their target genes in these cell lines, confirming that they did not have Wnt pathway activated. Considering this, transient transfection was necessary. After this trial, there was an increase in expression of CTNNB1 gene and its target genes Cyclin D1 and C-Myc in the three cell lines, which was not observed in Aurora kinases. Furthermore, in the clonogenic assay, a reduction in the number of colonies in UW473 and ONS-76 cell lines was observed. It was also observed an increase in ?-catenin protein, Aurora A and B in UW473 cell line, but not in ONS-76 cell line. However, after treatment there was a decrease in protein expression of ?-catenin, Aurora A and B in both cells. Transfection did not change the cellular percentile in G2 / M in UW402 and UW473. In ONS-76 there was a significant increase in G2 / M, and the treatment with AMG900 potentiated this block only in this cell line. Results suggest that there may be some relation between the inhibition of Aurora kinase protein and protein expression in Wnt pathway.

O overreaching não funcional (NFOR) induzido por consecutivas sessões de treinamentos intensos intercaladas por períodos insuficientes de recuperação, está associado com inflamação e consequente prejuízo da via de sinalização insulínica em músculos esqueléticos de camundongos. Sabe-se que o miocárdio também é capaz de produzir tais proteínas inflamatórias associadas ao comprometimento da via hormonal e que alterações na atividade do receptor insulínico cardíaco levam à forçadas modificações na utilização dos substratos energéticos com prejuízos na mecanoenergética cardíaca predispondo o miocárdio à diversas injúrias. No entanto os efeitos do NFOR nas vias inflamatórias e insulínica cardíaca ainda não foram investigados. Assim, o presente estudo tem como objetivo avaliar os efeitos do NFOR no conteúdo de glicogênio cardíaco e ativação de proteínas relacionadas às vias insulínica e inflamatória. Os animais foram divididos em 6 grupos: Naive, Controle, Treinado, e os grupos submetidos ao protocolo de overtraining em declive (OTR/down), aclive (OTR/up) e sem inclinação (OTR). As especificidades das contrações musculares induziram diferentes adaptações cardíacas. Os grupos OTR e OTR/up não apresentaram sinais de inflamação além de superexpressarem a via insulínica, por outro lado, o grupo OTR/down apresentou inflamação cardíaca de baixo grau, contudo, sem queda no conteúdo de pIR. Todos os protocolos de overtraining induziram elevação no conteúdo de glicogênio cardíaco acompanhado de expressiva queda da pAMPK. Os resultados do presente trabalho nos trazem, portanto, a hipótese de que o tecido cardíaco apresente uma maior resistência à inflamação viabilizando dessa forma a melhora da resposta insulínica e acúmulo do glicogênio cardíaco a fim de fornecer a energia necessária ao extenuante exercício físico evitando a lipotoxicidade cardíaca. Por outro lado, a queda da AMPK consequente do excessivo acúmulo de glicogênio cardíaco pode predispor o miocárdio à diversas injúrias, sendo necessários mais estudos na área. / Non-functional overreaching (NFOR) induced by consecutive intense training sessions interspersed by insufficient periods of recovery is associated with inflammation and a consequent impairment of the insulin signaling pathway in skeletal muscle of mice. It is known that the myocardium is also capable of producing such inflammatory proteins associated with the impairment of the hormonal pathway and that changes in cardiac insulin receptor activity lead to forced modifications in the use of energetic substrates with losses in cardiac mecanoenergética predisposing the myocardium to various injuries. However, the effects of NFOR on inflammatory and cardiac insulin pathways have not been investigated yet. Thus, the present study aims to evaluate the effects of NFOR on cardiac glycogen content and activation of proteins related to insulin and inflammatory pathways. The animals were divided into 6 groups: Naïve, Control, Trained, and the groups submitted to the overtraining protocol in decline (OTR/down), uphill (OTR /up) and without inclination (OTR). The specificities of muscle contractions induced different cardiac adaptations. OTR and OTR/up groups showed no signs of inflammation and an over expressive of the insulin pathway; on the other hand, the OTR/down group presented low-grade cardiac inflammation, however, without any decrease in the pIR content. All overtraining protocols induced elevation in cardiac glycogen content accompanied by significant drop in pAMPK. The results of the present work hypothesize that the cardiac tissue presents a greater resistance to inflammation, thus enabling the improvement of the insulin response and the accumulation of cardiac glycogen in order to provide the necessary energy to the strenuous physical exercise avoiding cardiac lipotoxicity. On the other hand, the decrease in AMPK due to the excessive accumulation of cardiac glycogen may predispose the myocardium to several injuries, and further studies in the area are required.

Hippo signaling pathway represents organ size control mechanism constrained between all metazoans. Individual components of the Hippo signaling pathway were identified as key tumor-suppressors which phosphorylate and inhibit activity of several oncogenic factors and signaling pathways (such as YAP/TAZ, PI3K and mTOR). MST1 kinase is a part of central protein complex of the Hippo signaling pathway and its activation is involved in anti-cancer activity of several drugs. We have demonstrated activation of the MST1 kinase by natural compounds in leukemic cells followed by inhibition of proliferation and induction of apoptosis. Shikonin represents natural naphthoquinonic compound isolated from Lithospermum erythrorhizon which acts as inhibitor of glycolysis and mitochondrial respiratory chain in human cells. Shikonin induces fast activation of the MST1 protein in leukemic cells however mechanism of this activation remains unknown. Therefore, we tried to characterize posttranslational modifications of the MST1 kinase during shikonin treatment of leukemic cells. Firstly, we isolated MST1 kinase from control and shikonin-treated cells using immunoprecipitation. Then we characterized posttranslational modifications of the MST1 protein employing mass spectrometry. Using this approach we found out...