Liver progenitor cells (LPCs) respond to hepatic injury when hepatocyte division is impaired in chronic or severe injury. The LPCs are intimately surrounded by myofibroblasts, macrophages and laminin, thus constituting a potential progenitor cell niche. Laminin has been proposed to maintain LPCs in an undifferentiated state within the LPC niche. LPCs differentiate once they leave the laminin niche. However, mechanisms regulating this process have not been completely investigated. I hypothesized that cell membrane proteins which are implicated in intergin activation and mediation of cell adhesion to laminin such as galectin-3 and CD98 may be involved in this mechanism. Galectin-3 is a carbohydrate-binding protein which plays an important role in various cell functions, including cell growth, proliferation, adhesion, and differentiation. Galectin-3 has been reported to bind integrins and regulates β1 mediated adhesion to ECM. In addition, galectin-3 may also indirectly mediate β1 integrin activation by binding to and activating the heterodimeric transmembrane amino acid transporter CD98. However a role for galectin-3 in regulating LPC behavior has not been demonstrated. In this thesis, the mechanisms of galectin-3 mediating LPC proliferation and differentiation were investigated in an experimental model of LPC induction, the CDE diet, by using mutant mice lacking the gene encoding galectin-3. I have found galectin-3 is important for LPC induction and proliferation in vivo. In addition, galectin-3 is crucial for the LPC proliferation but is a negative regulator of LPC differentiation in vitro in a laminin dependent manner, suggesting that galectin-3 is required for LPC to maintain in an undifferentiated state on laminin. Moreover, the 2 extracellular binding activity of galectin-3 is important for LPC proliferation and adhesion to laminin. Furthermore, in the absence of galectin-3, LPCs down-regulate cyclin-D1 and the cyclin inhibitors p21 and p16 are elevated. Finally I suggest that integrin-β1 and CD98 are involved in regulating LPC proliferation. There is an increasing literature examining the role of LPC niche in regulating LPC behavior. My work suggests that galectin-3 is required for the expansion of LPCs in the injured adult liver. Galectin-3 enhances LPC adhesion to laminin. Galectin-3 is a crucial factor for LPCs to maintain in an undifferentiated state on laminin. My findings not only emphasize the requirement of LPCs to interact with their extracellular environment to expand but also propose that galectin-3 is a key signalling intermediary in the LPC niche, regulating homeostatic balance between proliferation and differentiation of LPCs, thus controlling regeneration.

Galectin-3, a unique member of the growing family of β-galactoside binding lectins, contains a single carbohydrate recognition domain and a glycine rich N-terminal domain through which it can form oligomers and functions to cross-link both carbohydrate and non-carbohydrate ligands. Galectin-3 is widely expressed in adult tissues, particularly on and secreted by activated macrophages and monocytes. Galectin-3 has been implicated in many facets of the inflammatory response including neutrophil and macrophage activation and function. In this thesis I have examined the role of galectin-3 during fibrosis, alternative activation of macrophages and pneumonia. Galectin-3 expression is upregulated in established human fibrotic liver disease and in a mouse model of liver fibrosis induced by carbon tetrachloride. Galectin-3 expression is temporally and spatially related to the induction and resolution of experimental hepatic fibrosis in this model. In addition, disruption of the galectin-3 gene markedly attenuates liver and kidney fibrosis, induced by unilateral ureteric obstruction, with reduced collagen deposition and myofibroblast activation. Results suggest that galectin-3 may promote fibrosis by stimulating myofibroblast activation by a transforming growth factor-β (TGF-β)-independent mechanism. Recent reports suggest that alternative macrophage activation is one of the key steps toward the progression of fibrosis. Disruption of the galectin-3 gene specifically restrains interleukin-4 (IL-4)/IL-13-induced alternative macrophage activation in vitro. My results suggest that the key mechanism required for activation of an alternative macrophage phenotype is an IL-4-stimulated galectin-3 feed back loop which directly activates CD98 causing sustained phosphatidylinositol 3-kinase (PI3-K) activation. The gram-positive Streptococcus pneumoniae (S. pn) is the leading cause of community acquired pneumonia worldwide, resulting in high mortality. Galectin-3-/- mice demonstrate a clearance defect of S. pn with increased septicaemia and a greater extent of lung damage compared to wild type mice. This phenotype is markedly reduced in pneumonia induced by the gram-negative Escherichia coli (E.coli). I have shown that presence of galectin-3 reduces the severity of pneumonia induced by S. pn and this is achieved through a number of processes: 1) Galectin-3 has bactericidal properties towards S. pn in vitro. 2) Galectin-3-/- macrophages show reduced production of nitrite following incubation with both S. pn and E. coli and hence a reduction in bacterial killing. 3) Galectin-3 activates neutrophils to produce reactive oxygen species which enhances the bactericidal activity of neutrophils. 4) Activation of neutrophils by galectin-3 augments phagocytosis of bacteria. 5) Finally, initial data suggests that galectin-3-/- neutrophils apoptose more readily than wild type neutrophils in vitro and galectin-3-/- macrophages phagocytose apoptotic neutrophils less efficiently compared to wild type. In vivo this would result in an accumulation of dying cells in the lung. The damage these apoptotic cells would have on the lung tissue may enable the bacteria to enter the blood stream resulting in sepsis. In summary, in response to chronic tissue injury, persistant upregulation of galectin-3 causes myofibroblast and alternative macrophage activation, thus enhancing collagen deposition and scarring. However during an acute S. pn infection, galectin-3 plays a benefitial role to aid the clearance of bacteria through a variety of processes. Therefore, galectin-3 plays a critical role in a variety of inflammatory disorders.

La galectine-3 (Gal-3), protéine de type lectine, de 29-35 kDa, étudiée comme marqueur d’aggressivité dans les gliomes, présente des caractéristiques biologiques importantes justifiant son étude dans le domaine du mélanome. En effet, la Gal-3 est une protéine qui peut se lier à la laminine, tout comme l’intégrine α6/β1 dont l’expression est réduite dans le mélanome. L’expression de cette intégrine peut d’ailleurs être modulée par la Gal-3 comme récemment montré dans des lignées cellulaires de cancer du sein (BT-549) et de glioblastome (U373). Le mélanome, véritable problème de santé publique qui est susceptible d’atteindre 1 individu sur 75 dans nos contrées, reste un tumeur mal comprise avec des évolutions parfois incertaines, et des traitements dont l’efficacité est limitée. Le diagnostic histologique du mélanome lui-même peut parfois représenter une difficulté pour le clinicien et l’expert pathologiste ou dermatopathologiste. La couleur (hyperpigmentation d’un lésion pigmentée), dont l’évaluation d’ailleurs reste subjective à défaut de standardisation, ne peut à elle seule signer la malignité d’une lésion pigmentée. Globalement l’évolution d’un patient est prédite par l’indice de Breslow qui traduit en mm l’épaisseur de la tumeur. Si cet indice dépasse 1mm, le risque métastatique augmente, justifiant la réalisation de bilans extensifs de suivi. Ceci dit, certains mélanomes épais peuvent ne pas présenter de caractéristiques d’aggressivité, alors que des mélanomes fins sont parfois mortels. L’identification de marqueurs moléculaires est donc impérative, tant pour développer des stratégies thérapeutiques ciblées, que pour affiner le diagnostic et le pronostic d’un patient. Après avoir mis en évidence par immunohistochimie une expression de Gal-3 par les mélanocytes, nous avons démontré une surexpression de cette protéine par les mélanocytes tumoraux. Nous avons démontré également sur des lésions primitives qu’à l’aggressivité mesurée selon l’indice de Breslow correspondait une diminution de cette surexpression. Cette observation a pu être confirmée par un modèle de greffe orthotopique chez la souris nude. Nous nous somme intéressés par la suite à la détection de la protéine dans le sérum, et nous avons constaté, un taux élevé de Gal-3 dans le sérum de patients en stade métastatique avancé, ce taux élevé pouvant s’expliquer tant par la charge tumorale que par la présence d’une inflammation, d’ailleurs bien connue chez le patient cancéreux en stade avancé. Le rôle antiapoptotique de la Gal-3 nous a alors amené à préciser la valeur prédictive et pronostique de cette protéine. L’hypothèse d’une potentielle action bénéfique sur la réponse immunitaire des patients atteints de mélanome qui ont été vaccinés a été rejetée. La Gal-3 sérique s’est révélée comme facteur de mauvais pronostic chez les patients métastatiques, et une analyse multivariée avec la définition d’une valeur « cut-off » de 10 ng/ml a permis de montrer une valeur pronostique indépendante, supérieure à la S100B et à la CRP.

The subventricular zone (SVZ) is an adult neurogenic niche that contains multipotent stem/progenitor cells that may be a viable target for remyelination in Multiple Sclerosis. In response to demyelination, SVZ progenitors are recruited into myelin lesions. Currently, the effect of inflammation on the endogenous brain stem cell compartment remains poorly characterised. Theiler's murine encephalomyelitis virus (TMEV) induces a demyelinating disease in susceptible SJL/J mice, due to persistence of the virus, which models the chronic progressive form of multiple sclerosis. In contrast, virus is rapidly cleared in TMEV resistant C57BL/6 mice. This viral clearance is critically dependent on infiltration of CD4⁺ and CD8⁺ T cells during the first 3-14 days after infection, through the blood vessels and meninges. This project aimed to characterise the impact of TMEV induced inflammation on SVZ homeostasis. In both strains of mice the most pronounced and consistent inflammation in the CNS was observed in periventricular regions and in particular, the SVZ, which showed targeted infection by the TMEV virus. However, the time course and kinetics for infiltration at 3,7 and 14 days post infection have very different profiles between resistant C57BL/6 and susceptible SJL mice. Using RT-PCR arrays and ELISA I have shown that these differences in T cell infiltration to the SVZ may be due to much higher chemokine and cytokine expression levels in B6 mice. TMEV infection decreases SVZ cell proliferation and results in a loss of neuroblast numbers. Galectin-3 (Gal-3) is a β-galactoside binding protein that is constitutively expressed specifically in the SVZ. Following TMEV infection Gal-3 levels are significantly upregulated in the SVZ, with higher expression in B6 mice compared to SJL mice. Primary SVZ astrocytes secrete extracellular Galectin-3 at much higher levels than cortical astrocytes. Galectin-3 is a pro-inflammatory mediator which upon secretion is able to activate immune and inflammatory signaling events and amplify pro-inflammatory cytokine production. Both SJL and B6 Gal-3^-/- KO mice have decreased expression of CCL2, CCL5 CXCL10 and CCL8 chemokines in the SVZ after TMEV infection. Deletion of Gal-3 prevents the loss of SVZ proliferation and in B6 mice decreases hematopoietic cell infiltration and enhances ectopic neuroblast emigration. These data implicate Galectin- 3 as a novel regulator of the SVZ inflammatory response and may provide a new target for regulating T cell CNS immigration in autoimmune disease.

Tumores são definidos como microambientes compostos não só pelas células malignas, mas também por células endoteliais, fibroblastos e leucócitos, que promovem o crescimento tumoral e a angiogênese. Galectina-3, uma proteína que se liga a b- galactosídeos, é abundantemente expressa por monócitos/macrófagos, dentre outros leucócitos. Inúmeras evidências sugerem que galectina-3 atua como uma molécula reguladora da resposta inflamatória. Tendo em vista que o infiltrado inflamatório pode promover a progressão de tumores, o objetivo do presente trabalho foi avaliar se galectina-3, expressa tanto pela célula tumoral como pelas células estromais, modula o crescimento de melanoma. Para tal, células de melanoma murino Tm1 foram transfectadas com o gene de galectina-3. Ambos clones celulares (galectina-3 positivos e negativos) foram injetados na intrafáscia ou no subcutâneo de camundongos (fêmeas) C57BL/6 selvagens e/ou nocautes para o gene de galectina-3 para análise da implantabilidade e crescimento tumoral. Com relação à implantabilidade, não foi observado diferenças no estabelecimento de uma massa tumoral proliferativa em animais selvagens inoculados com células Tm1 transfectadas ou não com o gene de galectina-3 em animais selvagens. Em relação a taxa de crescimento dos tumores, nenhum animal nocaute inoculado com células Tm1 galectina-3 positivas apresentou tumores de dimensões mensuráveis até o 11º dia pós-inóculo. Independente do nível de expressão de galectina- 3 pela célula tumoral, os tumores originados nos animais nocautes apresentavam menor massa em gramas comparados ao grupo selvagem, sugerindo que galectina-3 expressa pelas células estromais promove o crescimento tumoral. Ainda, os tumores originados nos animais nocautes e no grupo selvagem inoculado com células Tm1 galectina-3 positivas apresentavam menor extensão de área necrótica do que os animais selvagens inoculados com células Tm1 galectina-3 negativas. Interessantemente, os animais selvagens e nocautes inoculados com células Tm1 galectina-3 positivas apresentaram tumores com menor área vascular e menor número de estruturas vasculares funcionais quando comparados aos animais selvagens inoculados com células Tm1 galectina-3 negativas. A análise de expressão gênica nos tumores mostrou que os níveis relativos de RNAm de VEFG (fator de crescimento de endotélio vascular) foram menores nos animais inoculados com células Tm1 galectina-3 positivas em relação aos inoculados com células Tm1 galectina-3 negativas, indicando que galectina-3 expressa pelas células tumorais atua como uma molécula anti-angiogênica. Finalizando, o presente trabalho sugere que galectina-3 pode atuar como uma molécula pró- ou anti-tumoral, dependendo do tipo celular que a expressa no microambiente tumoral. / Tumors have been described as microenvironments composed not only by malignant cells, but also by endothelial cells, fibroblasts and leukocytes, which can promote tumor growth and angiogenesis. Galectin-3, a b-galactoside binding protein, is expressed by monocytes/macrophages and others leukocytes. In fact, several lines of evidence suggest that galectin-3 act as master regulators of the inflammatory response. Based on the fact that the inflammatory infiltrate can promote tumor progression, the proposal of this study was to evaluate if galectin-3, either from tumor or stromal cells could modulate melanoma growth. Tm1 murine melanoma cell line was transfected with the galectin-3 gene. Both clones (galectin-3 negative and positive) were injected in the foot pad or subcutaneous in female C57BL/6 wild-type (WT) and galectin-3 knock-out (KO) mice to tumor engraftment and growth analysis. There was no difference in the tumor engraftment between animas injected with Tm1 galectin-3 positive or negative cells. In addition, any knock-out mice injected with galectin-3 positive cells had measurable tumors up to day 11 post inoculation. Regardless the galectin-3 expression level in the melanoma cell, tumors from galectin-3 KO mice were smaller than those from WT animals, suggesting that galectin-3 expressed by stromal cells promotes tumor growth. Moreover, tumor necrotic area was smaller in KO mice and in wild-type animals injected with Tm1 galectin-3 positive cells compared to wild type animals injected with Tm1 galectin-3 negative cells. Interestingly, both vascular area and the number of functional vessels in animals injected with galectin-3 positive Tm1 cells were smaller in WT as well as in KO mice compared to the same animals injected with galectin-3 negative Tm1 cells. Gene expression analysis showed that VEGF (vascular endothelial growth factor) mRNA levels were smaller in wild type animals injected with Tm1 galectin-3 positive cells compared to those injected with Tm1 galectin-3 negative cells, indicating that galectin-3 expressed by tumor cells can act as an anti-angiogenic molecule. The present study suggests that galectin-3 can act either as a pro or antitumoral molecule, depending on which type of cell (tumoral or stromal) this lectin is expressed within tumor microenvironment.

Galectina-3, uma proteína que se liga a -galactosídeos, é expressa por neutrófilos e inúmeras evidências indicam que esta molécula atua como uma possível reguladora da resposta imune. Sabe-se que galectina-3 ao ligar com LPS pode levar a formação de oligômeros, que podem alterar o limiar de ativação de células da resposta imune inata. Apesar de existirem diversos estudos que mostram a influência de galectina-3 na resposta de neutrófilos frente a componentes bacterianos, os resultados são em sua maioria contraditórios e inconclusivos. Para elucidar a influência da galectina-3 na reposta imune inata a patógenos periodontais, o presente trabalho avaliou a atividade antimicrobiana in vitro de neutrófilos, isolados de camundongos selvagens (WT) ou geneticamente deficientes de galectina-3 (Gal-3KO), previamente estimulados com LPS de Aa e Pg. Os resultados não evidenciaram diferenças significativas no número de unidades formadoras de colônia (UFC) recuperadas das culturas de neutrófilos provenientes de animais deficientes de galectina-3 e do grupo controle (WT). Contudo, a estimulação de neutrófilos com LPS por 18 horas levou a redução no número de UFC recuperadas das culturas, quando comparado com as culturas estimuladas com LPS por apenas 3 horas. / Galectin-3, a protein that binds -galactosides, is expressed by neutrophils and numerous evidences indicate that this molecule acts as a possible regulator of the immune response. It is known that galectin-3 binding to LPS can lead to the formation of oligomers and thus changing the activation threshold of cells of the innate immune response. Although there are several studies that show the influence of galectin-3 in neutrophil response against bacterial components, the results are conflicting and inconclusive in their majority. To elucidate the influence of galectin-3 in the innate immune response to periodontal pathogens, the present study evaluated the in vitro antimicrobial activity of neutrophils, isolated from wild-type or galectin-3 deficient mice, previously stimulated with LPS of Aa and Pg. The results showed no significant differences in the number of colony forming units (CFU) recovered from cultured galectin-3 deficient neutrophils or control group. However, in a 18 hours time course of LPS stimulation, we observed reduction in the number of CFU, when compared to 3 hours of LPS stimulation.

Galectin-3 is a β-galactoside binding lectin expressed in tumour cells and macrophages and has been associated with increased malignancy in a variety of cancers. Previous work has shown that galectin-3 is an important regulator of macrophage function, promoting an alternative (M2) phenotype which potentiates chronic inflammation and fibrosis. Tumour associated macrophages (TAMs) adopt an M2 phenotype and are thought to promote tumour growth by down regulating T cell effector function and promoting angiogenesis. This project examines the hypothesis that host galectin-3 promotes lung cancer growth and spread. In order to test this hypothesis, Lewis Lung Carcinoma tumour growth and metastasis was investigated in strain matched mice either expressing or deficient in galectin-3. The Lewis Lung Carcinoma cell line (LLC1) is a spontaneous lung carcinoma line, derived from C57BL/6 mice, which readily forms tumours when transplanted. Furthermore, LLC1 cells were stably transfected with a Luciferase expressing vector in order to assist detection of tumour growth and metastasis in vivo. An orthotopic model of LLC1 growth suggested that galectin-3-/- animals do not support lung carcinoma growth and spread. This finding was confirmed by a subcutaneous model of cancer growth, where it was found that wild type animals display a higher proportion of macrophages expressing a prototypic M2 marker around tumour sites compared to galectin-3-/- animals. M2-promoting cytokine transcripts were also reduced in galectin-3-/- mice. Additionally, tumours of wild type mice were more invasive and presented more mature blood vessels compared to galectin-3-/- mice. To specifically address the role of recruited cells on tumour growth, metastasis and the inflammation profile around tumour sites, in relation to galectin-3 expression, bone marrow cells (BMCs) were transplanted from wild type to galectin-3-/- mice and vice versa. It was shown that galectin-3 positive BMCs restore the wild type phenotype of tumour growth in galectin-3-/- mice, while galectin-3 deficient BMCs impair tumour growth in wild type animals. Furthermore, macrophage ablation experiments demonstrated incapacity for tumour establishment in the absence of macrophages. A series of experiments investigating reported inhibition of galectin-3 by modified citrus pectin (MCP) via competitive inhibition did not provide conclusive results. MCP had no effect in vivo, but was able to inhibit LLC1 cell growth in vitro. Most importantly though, results were inconclusive as to whether galectin-3 binds MCP. Some ligand displacement was seen, but direct binding of the molecules could not be shown. In general, the results obtained demonstrate a strong pro-tumoural effect of galectin-3 on growth, tissue invasion and metastasis of LLC1 tumours via an increased proportion of Ym1-expressing macrophages around tumour sites. It was shown that macrophages are key cells for tumour initiation and that BMC phenotype in relation to galectin-3 expression determines the phenotype of tumour development in subcutaneous and orthotopic LLC1 models. Therefore, galectin-3 has a strong regulatory effect on tumour phenotype and could present a key target in the management of lung carcinomas.

Galectina-3, uma proteína que se liga a -galactosídeos, é expressa por neutrófilos e inúmeras evidências indicam que esta molécula atua como uma possível reguladora da resposta imune. Sabe-se que galectina-3 ao ligar com LPS pode levar a formação de oligômeros, que podem alterar o limiar de ativação de células da resposta imune inata. Apesar de existirem diversos estudos que mostram a influência de galectina-3 na resposta de neutrófilos frente a componentes bacterianos, os resultados são em sua maioria contraditórios e inconclusivos. Para elucidar a influência da galectina-3 na reposta imune inata a patógenos periodontais, o presente trabalho avaliou a atividade antimicrobiana in vitro de neutrófilos, isolados de camundongos selvagens (WT) ou geneticamente deficientes de galectina-3 (Gal-3KO), previamente estimulados com LPS de Aa e Pg. Os resultados não evidenciaram diferenças significativas no número de unidades formadoras de colônia (UFC) recuperadas das culturas de neutrófilos provenientes de animais deficientes de galectina-3 e do grupo controle (WT). Contudo, a estimulação de neutrófilos com LPS por 18 horas levou a redução no número de UFC recuperadas das culturas, quando comparado com as culturas estimuladas com LPS por apenas 3 horas. / Galectin-3, a protein that binds -galactosides, is expressed by neutrophils and numerous evidences indicate that this molecule acts as a possible regulator of the immune response. It is known that galectin-3 binding to LPS can lead to the formation of oligomers and thus changing the activation threshold of cells of the innate immune response. Although there are several studies that show the influence of galectin-3 in neutrophil response against bacterial components, the results are conflicting and inconclusive in their majority. To elucidate the influence of galectin-3 in the innate immune response to periodontal pathogens, the present study evaluated the in vitro antimicrobial activity of neutrophils, isolated from wild-type or galectin-3 deficient mice, previously stimulated with LPS of Aa and Pg. The results showed no significant differences in the number of colony forming units (CFU) recovered from cultured galectin-3 deficient neutrophils or control group. However, in a 18 hours time course of LPS stimulation, we observed reduction in the number of CFU, when compared to 3 hours of LPS stimulation.

Orientador: Paulo Pinto Joazeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-15T06:40:15Z (GMT). No. of bitstreams: 1 Nascimento_MariaAmaliaCavinato_M.pdf: 2973013 bytes, checksum: eef160eabbd2d1426a9f2e0795702488 (MD5) Previous issue date: 2009 / Resumo: É reconhecido que a sínfise púbica de algumas espécies de mamíferos, incluindo camundongos, passa por transformações estruturais durante a prenhez e no período pós-parto. Estas transformações incluem o surgimento de um ligamento interpúbico e o amolecimento deste tecido nos dois últimos dias antes do parto. Este ligamento permite a separação dos ossos púbicos, garantindo a passagem segura do feto pelo canal de parto. Após o parto ocorre a involução deste ligamento. Ambos os períodos de remodelação tecidual envolvem grandes modificações da matriz extracelular e de seus componentes, bem como um balanço entre proliferação e morte celular programada. A galectina-3, uma lectina animal com especificidade de ligação por ß-galactosídeos, é uma proteína amplamente distribuída entre diferentes tipos de células e tecidos, podendo ser encontrada dentro das células tanto no núcleo quanto no citoplasma, ou ainda na superfície celular ou no espaço extracelular. Através de interações específicas com diversos ligantes intra e extracelulares, a galectina-3 participa de numerosos processos fisiológicos e patológicos, como por exemplo, desenvolvimento, reações imunes, controle do ciclo celular, apoptose e metástase. Este estudo teve como objetivo localizar a expressão de galectina-3 nas populações celulares que compõem esta articulação durante o período de prenhez, a fim de investigar seu possível envolvimento nos processos de remodelação da sínfise. Foi observado que a galectina-3 está presente em todas as populações celulares que compõem a sínfise púbica e o ligamento interpúbico de todos os grupos estudados. Além disso, a galectina-3 é co-localizada com a a-actina de músculo liso em alguns tipos celulares. A quantificação da detecção de galectina-3 nos permitiu observar que ela é expressa em diferentes concentrações durante o período estudado. Esses resultados nos permitiram concluir que a galectina-3 parece estar envolvida na remodelação da sínfise púbica, através de sua participação na ativação de células semelhantes a fibroblastos, no ciclo celular, na diferenciação e nos processos de morte celular programada. / Abstract: It is recognized that the pubic symphysis of some mammal species, including mice, undergoes structural transformations during pregnancy and post-partum. These transformations include the emerging of an interpubic ligament and softening of this tissue in the two last days of pregnancy. This ligament allows the pelvic bones separation, warranting fetus self passage through the birth channel. After delivery this ligament involutes. Both periods of tissue remodeling involve changes in extracellular matrix and its components, as so a balance between cell proliferation and death. Galectin-3, an animal lectin with specificity for ß-galactosídes, is widely spread among different types of cells and tissues, thus being found inside the cells in the cytoplasm and in the nucleus, on cell surface or in the extracellular space. Through specific interactions with a variety of intra and extracellular ligands galectin-3 participates of numerous physiological and pathological processes, like for example, development, immune reactions, cell cycle control, apoptosis and metastasis. This research had the objective to localize galectin-3's expression in mouse pubic symphysis cells during pregnancy, and to investigate its involvement in the pubic remodeling process. It was observed that galectin-3 is present in all pubic cells populations of all of the studied groups. Besides that, galectin-3 is colocalized with a-smooth muscle actin in some cell types. Quantifying of galectin-3 detection revealed that this protein is expressed in different concentrations during the studied period. These results allowed us to conclude that galectin-3 seems to be involved in mouse pubic symphysis remodeling, probably working in the activation of fibroblast like cells, on cell cycle, on differentiation and in the processes of programmed cell death. / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural

Tumores são definidos como microambientes compostos não só pelas células malignas, mas também por células endoteliais, fibroblastos e leucócitos, que promovem o crescimento tumoral e a angiogênese. Galectina-3, uma proteína que se liga a b- galactosídeos, é abundantemente expressa por monócitos/macrófagos, dentre outros leucócitos. Inúmeras evidências sugerem que galectina-3 atua como uma molécula reguladora da resposta inflamatória. Tendo em vista que o infiltrado inflamatório pode promover a progressão de tumores, o objetivo do presente trabalho foi avaliar se galectina-3, expressa tanto pela célula tumoral como pelas células estromais, modula o crescimento de melanoma. Para tal, células de melanoma murino Tm1 foram transfectadas com o gene de galectina-3. Ambos clones celulares (galectina-3 positivos e negativos) foram injetados na intrafáscia ou no subcutâneo de camundongos (fêmeas) C57BL/6 selvagens e/ou nocautes para o gene de galectina-3 para análise da implantabilidade e crescimento tumoral. Com relação à implantabilidade, não foi observado diferenças no estabelecimento de uma massa tumoral proliferativa em animais selvagens inoculados com células Tm1 transfectadas ou não com o gene de galectina-3 em animais selvagens. Em relação a taxa de crescimento dos tumores, nenhum animal nocaute inoculado com células Tm1 galectina-3 positivas apresentou tumores de dimensões mensuráveis até o 11º dia pós-inóculo. Independente do nível de expressão de galectina- 3 pela célula tumoral, os tumores originados nos animais nocautes apresentavam menor massa em gramas comparados ao grupo selvagem, sugerindo que galectina-3 expressa pelas células estromais promove o crescimento tumoral. Ainda, os tumores originados nos animais nocautes e no grupo selvagem inoculado com células Tm1 galectina-3 positivas apresentavam menor extensão de área necrótica do que os animais selvagens inoculados com células Tm1 galectina-3 negativas. Interessantemente, os animais selvagens e nocautes inoculados com células Tm1 galectina-3 positivas apresentaram tumores com menor área vascular e menor número de estruturas vasculares funcionais quando comparados aos animais selvagens inoculados com células Tm1 galectina-3 negativas. A análise de expressão gênica nos tumores mostrou que os níveis relativos de RNAm de VEFG (fator de crescimento de endotélio vascular) foram menores nos animais inoculados com células Tm1 galectina-3 positivas em relação aos inoculados com células Tm1 galectina-3 negativas, indicando que galectina-3 expressa pelas células tumorais atua como uma molécula anti-angiogênica. Finalizando, o presente trabalho sugere que galectina-3 pode atuar como uma molécula pró- ou anti-tumoral, dependendo do tipo celular que a expressa no microambiente tumoral. / Tumors have been described as microenvironments composed not only by malignant cells, but also by endothelial cells, fibroblasts and leukocytes, which can promote tumor growth and angiogenesis. Galectin-3, a b-galactoside binding protein, is expressed by monocytes/macrophages and others leukocytes. In fact, several lines of evidence suggest that galectin-3 act as master regulators of the inflammatory response. Based on the fact that the inflammatory infiltrate can promote tumor progression, the proposal of this study was to evaluate if galectin-3, either from tumor or stromal cells could modulate melanoma growth. Tm1 murine melanoma cell line was transfected with the galectin-3 gene. Both clones (galectin-3 negative and positive) were injected in the foot pad or subcutaneous in female C57BL/6 wild-type (WT) and galectin-3 knock-out (KO) mice to tumor engraftment and growth analysis. There was no difference in the tumor engraftment between animas injected with Tm1 galectin-3 positive or negative cells. In addition, any knock-out mice injected with galectin-3 positive cells had measurable tumors up to day 11 post inoculation. Regardless the galectin-3 expression level in the melanoma cell, tumors from galectin-3 KO mice were smaller than those from WT animals, suggesting that galectin-3 expressed by stromal cells promotes tumor growth. Moreover, tumor necrotic area was smaller in KO mice and in wild-type animals injected with Tm1 galectin-3 positive cells compared to wild type animals injected with Tm1 galectin-3 negative cells. Interestingly, both vascular area and the number of functional vessels in animals injected with galectin-3 positive Tm1 cells were smaller in WT as well as in KO mice compared to the same animals injected with galectin-3 negative Tm1 cells. Gene expression analysis showed that VEGF (vascular endothelial growth factor) mRNA levels were smaller in wild type animals injected with Tm1 galectin-3 positive cells compared to those injected with Tm1 galectin-3 negative cells, indicating that galectin-3 expressed by tumor cells can act as an anti-angiogenic molecule. The present study suggests that galectin-3 can act either as a pro or antitumoral molecule, depending on which type of cell (tumoral or stromal) this lectin is expressed within tumor microenvironment.