The initial induction and subsequent patterning of the central nervous system (CNS) are both mediated by morphogenetic signals emanating from some transient cell populations referred to as signalling or organizing centres. Following induction of the CNS, global signals mediate the establishment of its gross mediolateral and anteroposterior axes at gastrulation and early neural plate stages. Subsequent to this, local signals refine these specifications. Local signalling centres usually lie at boundaries of the tissues they pattern. Also, they are rich sources of morphogens, and are capable of ectopically inducing cell fate changes in adjacent tissues when transplanted. The eminentia thalami (EmT) forms a boundary between the diencephalon and telencephalon during embryonic forebrain development. In amphibians and fishes, the EmT continues to be a prominent structure in the postnatal diencephalon though its role in these is still largely unknown. However, in mammals, it appears transient, being identifiable between embryonic days 11 (E11) and 17 (E17) in the mouse, but not discernible at other ages. Though its function is yet to be determined, available experimental evidence suggests that it might act as a signalling centre in forebrain patterning. Therefore, this study aimed at identifying in the EmT members of the Wnt, Fgf and Bmp families of morphogens implicated in patterning elsewhere, and their spatial and temporal patterns of expression; and also determining whether the EmT is able to induce ectopically cell fate changes in adjacent tissues when transplanted. To address the first aim, Reverse-transcription Polymerase Chain Reaction (RTPCR) and In Situ Hybridization were used to determine the spatial and temporal expression of some members of the Wnt, Fgf and Bmp signalling systems in the EmT in both wild-type mice and Pax6 (Sey/Sey) mutants. The results indicate nested expression of some Wnts, Fgfs and Bmps mRNA in the ventricular zone of the wildtype EmT till E14.5, after which they appear down-regulated. Also, Wnt7b and Wnt8b show the strongest expression at these ages and this may indicate a key role for these genes in the function of the EmT in mammals. In Sey/Sey mutants, the EmT was malformed as shown by the mis-expression of its markers. Additionally, the Wnt, Fgf and Bmp genes normally expressed in the wild-type EmT were either not expressed in the mutant or were mis-expressed. The second aim was addressed by transplanting the EmT into the ventral telencephalon, and using immunohistochemistry and in situ hybridization to analyse for the expression in the ventral telencephalon of Lef1, a transcriptional activator in the Wnt/β-catenin signalling pathway, which is not expressed here, as well as Foxg1, Mash1 and Islet1, three transcription factors normally expressed here. EmT explants induced ectopically Lef1 expression in the ventral telencephalon. Also, while the Lef1-expressing ventral telencephalic cells did express Foxg1, a telencephalic marker, they either did not express or sparsely expressed Mash1 and Islet1, which are specific markers of the ventral telencephalon. These results suggest that the EmT may possess some ability to induce cell fate changes in the ventral telencephalon. The role of Wnt/β-catenin signalling in the function of the EmT was also investigated by analysing Lef1, Foxg1 and Mash1 expression in the ventral telencephalon of cultured E13.5 brains in which Wnt signalling had been activated in the ventral telencephalon through small molecule inhibition of GSK3β, a member of the β- catenin destruction complex. Lef1 expression in the ventral telencephalon increased with an increased inhibition of GSK3β activity. Also, while Foxg1 was expressed normally in the ventral telencephalon irrespective of the level of GSK3β inhibition, there was a significant dose-dependent reduction in Mash1 expression here. These results show that up-regulation of Wnt signalling in the ventral telencephalon may result in cell fate changes here, and also suggest that ventral telencephalic cells are competent to respond to Wnt signalling at this stage of development.

Orientador: Aureo Tatsumi Yamada / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-13T00:51:13Z (GMT). No. of bitstreams: 1 Aires_MarluciaBastos_D.pdf: 2189429 bytes, checksum: 72ea45d01e8d2f7c191ae7c71d82c5f8 (MD5) Previous issue date: 2009 / Resumo: A implantação embrionária implica em alterações profundas do ambiente uterino, cujos eventos devem obedecer uma sincronia temporal e espacial com o estágio do desenvolvimento embrionário. Qualquer desequilíbrio nesta sincronia resulta em interrupção da gestação e o desconhecimento dos mecanismos que atuam nas interações materno-fetais inviabilizam as possíveis intervenções buscando controlar as causas que levam às perdas iniciais da gestação. Visando contribuir para a melhor compreensão da biologia da resposta uterina de bovinos, o presente trabalho utilizou úteros de bovinos (Bos spp) não gestantes (NG) e gestantes nos períodos correspondentes à implantação embrionária para a coleta de fragmentos das regiões carunculares (CAR) e intercarunculares (IC). Esses fragmentos foram processadas para embebição em parafina destinadas às análises histológicas e obtenção de RNA total para realização de RT-PCR semi-quantitativo dos morfógenos Bmp2, Wnt2, Wnt5a, Wnt7a, e de seus antagonistas Sostdc1, Noggin, Dkk1 e Sfrp2. Pela análise histológica do desenvolvimento da mucosa uterina da região CAR foram estabelecidos os critérios morfológicos das seqüências de alterações da histoarquitetura endometrial em resposta à implantação embrionária constituindo quatro grupos (P1-P4) definindo os períodos gestacionais correspondentes, quais sejam: P1 (20-26 dg) - adesão das células trofoblásticas na superfície apical das células epiteliais e/ou entremeadas no revestimento epitelial, P2 (28-33 dg) - presença de projeções digitiformes na superfície da região CAR e tecido epitelial uterino constantemente rompido em ambas as regiões CAR e IC, P3 (35-40 dg) - expansão das projeções da região CAR formando uma rede anastomosada, entremeada pelo córion e P4 (50-60dg) - consolidação do placentônio. A ruptura das células epiteliais observada em P2 demonstra a fragilidade da interação epitélio-córion neste período que pode estar diretamente relacionada com a alta freqüência de perdas gestacionais em bovinos particularmente durante a implantação embrionária. A reação imunocitoquímica para anti-PCNA demonstrou uma marcação crescente no epitélio (E) e estrato subepitelial (ES), particularmente nas projeções da CAR de P1 a P4 e em menor proporção no E e estrato compacto (EC) da IC, confirmando a intensa atividade proliferativa associada com a hipertrofia endometrial. As análises da expressão genica através de RT-PCR, demonstraram a presença dos transcritos de Bmp2, Sostdc1, Noggin, Wnt2, Wnt5a, Wnt7a, Sfrp2 e Dkk1, e pela hibridização in situ, confirmaram-se as expressões localizadas dos genes Bmp2, Wnt5a, Wnt7a, Dkk1, Sfrp2, além dos receptores Bmpr1a e Bmpr2 no E+ES da CAR e E+EC da IC no útero NG e gestantes de P1 a P4. A expressào de Bmp2 foi maior na CAR em relação a IC em P1 e P2 o que sugere uma participação importante na ativação da resposta da região CAR relacionada com a implantação embrionária, enquanto o Wnt5a parece não atuar neste período. A redução da expressão de Wnt2 em P1, indica uma regulação negativa na CAR e IC no inicio da implantação, enquanto que a menor expressão de Wnt7a na CAR em relação a IC sugere que este gene não está relacionado com as principais alterações observadas nessa região. A maior expressão de Dkk1 e Sfrp2 na CAR em relação à IC, sugere a participação na atividade celular da região CAR, porém não apresenta relação direta com a expressão dos genes Wnt analisados, assim como a ausência de Sostdc1 no endométrio e a menor expressão de Noggin demonstram não serem estes os antagonistas principais de BMP que atuam no endométrio bovino. A expressão de Wnt e Bmp em conjunto com seus antagonistas simultaneamente nas regiões CAR e IC atesta a dependência da ação múltipla e sinérgica/antagônica de vários fatores na modulação da resposta da mucosa uterina na implantação embrionária e durante o desenvolvimento da placentação sinepitéliocorial. / Abstract: The embryo implantation implies in deep changes of the uterine environment which events must be topologically and chronologically synchronized with embryo development stage. Any imbalance in this synchronization results in disruption of the gestation and the lack of knowledge regarding the mechanisms of maternal-fetal interaction make difficult any potential action intending to control the causes which induce early gestational loss. Aiming to contribute to a better understanding of the biology of bovine uterine response, the present work evaluated the caruncle (CAR) and intercaruncle (IC) regions collected from non-pregnant (NG) and pregnant bovine uteri (Bos spp) and processed for paraffin embedding and submitted to histological analysis, RNA isolation for RT-PCR of Bmp2, Wnt2, Wnt5a and Wnt7a morphogen genes and their antagonists Sostdc1, Noggin, Dkk1 and Sfrp2 gene expression. By histological analysis of CAR uterine mucosa development, the morphological criteria of the endometrial histoarchitecture changes sequences were established and adopted to compose four groups (P1- P4) with corresponding gestational stages: P1 (20-26 gd) - adhesion of throphoblast cells on the apical surface of epithelium cells and/or between them, P2 (28-33 gd) - villous-like projections on the CAR surface and areas of disrupted or absence of epithelial cells on both CAR and IC regions, P3 (35-40 gd) - expansion of villous-like projections resulting in an anastomosis mesh where chorion villi intrude, P4 (50-60 gd) - placentome consolidation. The constant disruption of epithelial cells seen in P2 evidenced the fragility of epithelium-chorion interaction that may be related to the high incidence of bovine pregnancy loss particularly during embryo implantation. The immunocytochemistry for PCNA demonstrated reactivity in epithelium (E) and subepithelium stratum (SS), particularly on CAR villous-like projections from P1-P4 and in a less frequent proportion in the epithelium (E) and compactum stratum (CS) from IC, demonstrating the intense proliferative activity associated with endometrial hypertrophy. The gene expression analysis by RT-PCR (Reverse Transcriptase Polymerase Chain Reaction) confirmed the transcripts for Bmp2, Sostdc1, Noggin, Wnt2, Wnt5a, Wnt7a, Sfrp2 and Dkk1, and by In situ hybridization the localized expression of Bmp2, Wnt5a, Wnt7a, Dkk1, Sfrp2, and also Bmpr1a and Bmpr2 receptors in E+SS and E+CS in NG and P1-P4 uteri. The Bmp2 expression was higher on CAR when compared to IC in P1 and P2 which suggest an important involvement on CAR response activation related to embryo implantation, whereas Wnt5a does not seem to participate at this period. The decreased expression of Wnt2 in P1 point out a negative regulation on CAR and IC in the beginning of implantation, while the lower expression of Wnt7a in CAR when compared to IC suggest that this is not the main gene related to changes of CAR in pregnancy. The highest expression of Dkk1 and Sfrp2 on CAR when compared to IC indicate their participation on the cellular activity on the CAR region, but it is not involved directly with the expression of Wnt genes analyzed, as well as the absence of Sostdc1 on the endometrium and the lowest expression of Noggin demonstrated that they are not the main BMP antagonists acting on bovine endometrium. The expression of Wnt and Bmp together with their antagonists simultaneously on CAR and IC regions attest the multiple and synergic/antagonic action of several factors on the modulation of uterine mucosa response during the embryo implantation and development of synepitheliochorial placentation. / Doutorado / Histologia / Doutor em Biologia Celular e Estrutural

Morphogens are secreted signalling molecules that are expressed in restricted groups of cells within the developing tissue. From there, they are secreted and travel throughout the target field and form concentration gradients. These concentration profiles endow receiving cells with positional information. A number of experiments in Drosophila demonstrated that the morphogen Decapentaplegic (Dpp) forms activity gradients by inducing the expression of several target genes above distinct concentration thresholds at different distances from the source. This way, Dpp contributes to developmental fates in the target field such as the Drosophila wing disc. Although the tissue distribution as well as the actual shape and size of the Dpp morphogen concentration gradient has been visualized, the cell biological mechanisms through which the morphogen forms and maintains a gradient are still a subject of debate. Two hypotheses as to the dominant mechanism of movement have been proposed that can account for Dpp spreading throughout the Drosophila wing imaginal target tissue: extracellular diffusion and planar transcytosis, i. e. endocytosis and resecretion of the ligand that is thereby transported through the cells. Here, I present data indicating that implications of a theoreticalanalysis of Dpp spreading, where Dpp transport through the target tissue is solely based on extracellular diffusion taking into account receptor binding and subsequent internalization, are inconsistent with experimental results. By performing Fluorescence Recovery After Photobleaching (FRAP) experiments, I demonstrate a key role of Dynamin-mediated endocytosis for Dpp gradient formation. In addition, I show that most of GFP-Dpp traffics through endocytic compartments at the receiving epithelial cells, probably recycled through apical recycling endosomes (ARE). Finally, a Dpp recycling assay based on subcellular photouncage of ligand is presented to address specifically the Dpp recycling event at the receiving cells.

Morphogens are secreted signalling molecules that are expressed in restricted groups of cells within the developing tissue. From there, they are secreted and travel throughout the target field and form concentration gradients. These concentration profiles endow receiving cells with positional information. A number of experiments in Drosophila demonstrated that the morphogen Decapentaplegic (Dpp) forms activity gradients by inducing the expression of several target genes above distinct concentration thresholds at different distances from the source. This way, Dpp contributes to developmental fates in the target field such as the Drosophila wing disc. Although the tissue distribution as well as the actual shape and size of the Dpp morphogen concentration gradient has been visualized, the cell biological mechanisms through which the morphogen forms and maintains a gradient are still a subject of debate. Two hypotheses as to the dominant mechanism of movement have been proposed that can account for Dpp spreading throughout the Drosophila wing imaginal target tissue: extracellular diffusion and planar transcytosis, i. e. endocytosis and resecretion of the ligand that is thereby transported through the cells. Here, I present data indicating that implications of a theoreticalanalysis of Dpp spreading, where Dpp transport through the target tissue is solely based on extracellular diffusion taking into account receptor binding and subsequent internalization, are inconsistent with experimental results. By performing Fluorescence Recovery After Photobleaching (FRAP) experiments, I demonstrate a key role of Dynamin-mediated endocytosis for Dpp gradient formation. In addition, I show that most of GFP-Dpp traffics through endocytic compartments at the receiving epithelial cells, probably recycled through apical recycling endosomes (ARE). Finally, a Dpp recycling assay based on subcellular photouncage of ligand is presented to address specifically the Dpp recycling event at the receiving cells.

Made available in DSpace on 2016-12-23T13:56:07Z (GMT). No. of bitstreams: 1 Dissertacao de Thiago de Almeida Pereira.pdf: 7083594 bytes, checksum: b087de1012807ea82b96d6e7ada7b3cc (MD5) Previous issue date: 2010-03-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Hedgehog (Hh) pathway activation promotes many processes that occur during fibrogenic liver repair. Whether the Hh pathway modulates the outcomes of virally-mediated liver injury has never been examined. Gene-profiling studies of human hepatocellular carcinomas (HCC) demonstrate Hh pathway activation in HCCs related to chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV). Because most HCC develop in cirrhotic livers, we hypothesized that Hh pathway activation occurs during fibrogenic repair of liver damage due to chronic viral hepatitis, and that Hh-responsive cells mediate disease progression and hepatocarcinogenesis in chronic viral hepatitis. Methods Immunohistochemistry and qRT-PCR analysis were used to analyze Hh pathway activation and identify Hhresponsive cell types in archival liver biopsies from 45 patients with chronic HBV or HCV with different stages of fibrosis (F0-4), some of which also presented HCC. Hh signaling was manipulated with cyclopamine in primary human hepatic stellate cells (HSC) and sinusoidal endothelial cells (SEC). Angiogenesis assay was used to investigate if the pathway plays a role in tube formation. SECs were incubated with recombinant Shh, conditioned media from HSC, cyclopamine, short hairpin RNA against smoothened or their respective controls and the length of vascular tubes were measured by morphometry. Hedgehog production was investigated in Huh7 cells infected with JFH-1 and in a rat hepatoma cell line that express the HBV X gene by qRT-PCR. Results We found increased hepatic expression of Hh ligands (Shh and Ihh) in all patients with chronic viral hepatitis (p<0.005), and demonstrated that infection with JFH-1 or ectopic expression of the HBV X gene stimulated cultured hepatocytes to produce Shh (p<0.005). The major cell populations that expanded during cirrhosis and HCC (i.e., liver myofibroblasts, activated endothelial cells, and progenitors expressing markers of tumor stem/initiating cells Krt7, CD133, Epcam and survivin) were Hh-responsive (Patched and Gli-2 positive) and higher levels of Hh pathway activity associated with cirrhosis and HCC (p<0.005). Inhibiting pathway activity in Hh-responsive target cells (HSC and SEC) reduced fibrogenesis (p<0.005 for &#945;SMA and p<0.05 for col1&#945;1 expression) and angiogenesis (p<0.05). Conclusions HBV/HCV infection increases hepatocyte production of Hh ligands in hepatocytes and expands types of Hh-responsive cells, including myofibroblasts and xiv sinusoidal endothelial cells that associate with fibrosis progression to cirrhosis and hepatocellular carcinoma. Moreover, hedgehog-responsive progenitors that are undergoing epithelial-to-mesenchymal transition accumulate during the progression of viral hepatitis and may play a role in the development or progression of hepatocellular carcinoma. In vitro inhibition of Hh-signaling in primary human hepatic stellate cells and sinusoidal endothelial cells suggest the possibility of using Hh inhibitors as potential tools to prevent cirrhosis and hepatocellular carcinoma in patients with chronic hepatitis B and C / Ativação da via do Hedgehog (Hh) promove vários processos que ocorrem durante o reparo fibrogênico hepático. O papel da via do Hh na lesão causada pela hepatite crônica B e C ainda não foi investigado. Estudos de expressão global em carcinomas hepatocelulares (CHC) demostraram a ativação da via do Hh em pacientes com CHC relacionados à infecção crônica com o vírus da hepatite B (VHB) ou vírus da hepatite C (VHC). Como a maioria dos CHCs desenvolve em fígados cirróticos, levantamos a hipótese de que a ativação da via do Hh ocorre durante o reparo fibrogênico relacionado à hepatite viral crônica B e C e que células Hh-reatoras poderiam orquestrar a progressão da doença e a hepatocarcinogênese na hepatite viral crônica. Métodos Immunohistoquímica e análise por PCR quantitativo em tempo real (qRTPCR) foram utilizados para investigar a ativação da via do Hh e identificar os tipos celulares que respondem aos ligantes dessa via em biópsias arquivadas de 45 pacientes com hepatite crônica B ou C, de diferentes graus de fibrose (F0-4), sendo que 7 também apresentavam CHC. A via do Hh foi manipulada com Ciclopamina em células estreladas hepáticas (HSC) e em células endoteliais sinusoidais hepáticas (SEC) primárias humanas. O ensaio da angiogênese foi usado para investigar o papel da via do Hh na formação de tubos. SECs foram incubadas com Shh recombinante, meio condicionado de HSC, ciclopamina, short hairpin RNA (shRNA) contra o Smoothened ou os seus controles respectivos e o comprimento dos tubos vasculares foram quantificados por morfometria. A produção de ligantes Hh foi investigada por qRT-PCR em células Huh7 infectadas com o virus JFH-1 e em uma linhagem de hepatoma de rato que expressa o gene da proteína X do VHB. Resultados Observamos um aumento dos níveis de expressão de ligantes Hh (Shh e Ihh) em todos os pacientes com hepatite crônica viral (p<0,005) e demonstramos que a infecção pelo vírus da hepatite C JFH-1 ou a expressão ectópica do gene X do VHB estimulam culturas de hepatoma a produzirem Shh (p<0,005). Os principais tipos celulares que proliferam durante a cirrose e CHC (miofibroblastos, células endoteliais ativadas e progenitores que expressam marcadores de células tronco/iniciadoras de tumor CD133, Krt7, EpCAM e survivina) são reatores aos ligantes Hh e os níveis mais altos de expressão de componentes da via do Hh (Shh, Ihh, Gli-2 e Ptch) estão associados xii com cirrose e CHC (p<0,005). Inibição da via do Hh em células reatoras (HSC e SEC) reduziu fibrogênese (p<0,005 para expressão de &#945;SMA e p<0,05 para expressão de col1&#945;1) e angiogênese (p<0,05). Conclusões A Infecção pelo VHB/VHC aumenta a produção de ligantes hedgehog em hepatócitos e expande o número de células estreladas hepáticas e células endoteliais sinusoidais primárias humanas reatoras a esses ligantes, em relação direta com a progressão da fibrose para a cirrose e o carcinoma hepatocelular. Também induz o acúmulo progressivo de células progenitoras reatoras a via do Hh e que estão em processo de transição epitélio mesenquimal, o que pode estar relacionado com o desenvolvimento ou a progressão do carcinoma hepatocelular. A inibição in vitro da ativação da via do Hedgehog em células estreladas e em células sinusoidais endoteliais hepáticas primárias humanas sugere a possibilidade de investigar inibidores dessa via como potenciais ferramentas para reduzir a progressão da fibrose hepática para cirrose e carcinoma hepatocelular nas hepatites crônicas produzidas pelos vírus B e C