Avanços na identificação e caracterização de diferentes populações de célulastronco tem melhorado as perspectivas do seu uso clínico. A maioria dos estudos obtêm as células-tronco com base na expressão de marcadores de superfície celular e testa as suas propriedades por meio de ensaios funcionais in vitro e in vivo. Na presente pesquisa foram isoladas diferentes populações de células epiteliais com base na expressão de dois marcadores de células-tronco epiteliais descritos pela literatura, o receptor de neurotrofina p75 (p75NTR) e o receptor de transferrina 1 (CD71). Uma vez isso feito, foi avaliado a co-expressão de outros marcadores de células-tronco epiteliais, como as integrinas 6 e 1, e realizado ensaios de eficiência de formação de colônias, potencial de crescimento celular, capacidade de reconstrução epitelial in vitro, análise da resposta ao trauma e avaliação da capacidade de auto renovação. Os resultados mostram que as células p75NTR+ tem um desempenho funcional melhor do que as p75NTR- na maioria dos ensaios funcionais realizados, exceto pela capacidade de responder ao trauma e de se autorenovar. Ademais, comprovou-se que células p75NTR+ expressam em maior proporção as integrinas 6 e 1 e que o isolamento de células por dupla marcação (p75NTR+CD71-) possibilita a obtenção de uma população de células epiteliais ainda mais enriquecida com estes marcadores. No entanto, foi observado também que independentemente da população celular estudada e do tempo em cultivo, as populações de células epiteliais alteraram drasticamente o seu fenótipo quando de tal forma que as populações celulares inicialmente positivas se tornaram majoritariamente negativas e que as populações celulares inicialmente negativas passaram a ter células positivas em seu meio. / Recent advances in cell sorting and characterization technics of stem cells have provided new insights and perspectives for clinical applications of this particular cell population. Most of the studies isolat stem cells based on the expression of cell surface markers and evaluate their stem cells-like proprieties by performing in vitro and in vivo assays. Here we isolated different populations of keratinocytes based on the expression of the epithelial stem cell markers neurotrophin receptor p75 (p75NTR) and transferrin receptor 1 (CD71). The co-expression of other epithelial stem markers such as integrins 6 and 1 was also assessed and in vitro functional assays such as colony-forming efficiency; long-term growth potential, in vitro epithelial reconstruction-capacity and response to damage and self-renew capacity. Our results showed that p75NTR+ve cells have better functional proprieties in most of the assays however they did not respond to damage nether presented self-renew capacity. Additionally, p75NTR-ve cells express higher percentage of other epithelial stem cell markers such as integrins 6 and 1 when compared to p75NTR-ve cells and the double staining (p75NTR+veCD71-ve) contributes to isolate a more enriched cell population based on the expression of the integrins. Nevertheless, independently of the cell population or of the amount of time in culture, cells have changed dramatically their phenotype in a way that the cell population initially p75NTR+ve lost the expression of the p75NTR and the negative population have gained it.

O patótipo de Escherichia coli diarreiogênica denominado E. coli enteroagregativa (EAEC) é caracterizado pela expressão do padrão de adesão agregativo (AA) em células epiteliais cultivadas. Amostras de EAEC são classificadas como típicas ou atípicas, dependendo da presença ou não do gene aggR, respectivamente. O padrão AA no teste de adesão em células epiteliais é o diagnóstico padrão para a classificação de EAEC. Técnicas moleculares, como a PCR multiplex, são alternativas a esse teste. No presente estudo foi desenvolvida uma PCR multiplex para o diagnóstico molecular de EAEC típica e atípica, baseada na detecção dos genes aatA, aggR, aaiA e aaiG. A partir de colônias isoladas de E. coli de origem fecal o teste apresentou sensibilidade de 94,8%, especificidade de 94,7%, valor preditivo de teste positivo de 74,3% e valor preditivo de teste negativo de 99,1%. O teste desenvolvido mostrou-se uma alternativa diagnóstica sensível e específica para EAEC e permite um acréscimo significativo na detecção de EAEC atípica. / The diarrheagenic Escherichia coli pathotype known as enteroaggregative E. coli (EAEC) is characterized by the expression of the aggregative adherence pattern (AA) on cultured epithelial cells. EAEC strains are classified as typical or atypical, depending on the presence or absence of the aggR gene, respectively. The AA pattern in the adherence assay with epithelial cells is the gold standard diagnostic for EAEC. Molecular techniques, such as multiplex PCR, are alternatives to this test. In the present study we developed a multiplex PCR for the molecular diagnostic of typical and atypical EAEC, based on the detection of aatA, aggR, aaiA and aaiG genes. The test presented 96.5% of sensitivity, 94.8% of specificity, 74.3% of positive predictive value and 99.1% of negative predictive value, when tested in isolated colonies of E. coli from feces. The test developed is a sensitive and specific diagnostic alternative for EAEC and allows a significant increase in atypical EAEC detection.

Le syndrome sec de Gougerot Sjögren (SGS) est une maladie auto-immune chronique qui présente des dommages progressifs et irréversibles des glandes exocrines lacrymales et salivaires. Cette pathologie affecte entre 0.1 et 3 % de la population et est plus commune chez les femmes avec un ratio de 9 femmes pour 1 homme. Dans la glande salivaire, une infiltration lymphocytaire est observée et est associée avec la destruction de l'épithélium sécrétoire, qui joue un rôle central dans l'initiation et le développement du SGS. Le processus physiopathologique est loin d’être compris et semble dépendant de phénomènes épigénétiques. En effet, des perturbations importantes de la méthylation de l'ADN sont observées dans les cellules épithéliales en lien avec le niveau d’infiltration lymphocytaire des glandes salivaires.L'objectif de ce travail est de mieux comprendre les changements épigénétiques au cours du SGS et en particulier les défauts de méthylation/déméthylation de l’ADN observés dans les Cellules Epithéliales de Glandes Salivaires (SGEC) et leurs rôles dans le développement de la pathologie.Dans ce but, Une étude globale de la méthylation de l'ADN a été réalisée après culture cellulaire destinée à isoler les SGEC de patients SGS. La puce « human methylation 450k » d’Illumina utilisée couvre plus de 485 000 sites CpG du génome. Des analysesbioinformatiques nous ont permis d'obtenir un panel de gènes différentiellement méthylés. Nous avons ainsi mis en évidence l’importance de la voie calcique (déméthylée, connue pour avoir un impact sur la salivation) et de la voie WNT (hyperméthylée). De plus nous avons pu identifier une régulation interféron et montrer l’importance d’un changement du type d'interféron (I à II) lors de l’évolution vers un lymphome de type MALT. En outre, nous montrons qu’il existe une inter-relation forte entre les processus épigénétiques et les facteurs génétiques associés au SGS. Enfin la dernière partie de ce travail met en lumière l’implication d’un environnement inflammatoire dans le contrôle du processus de méthylation/déméthylation de l’ADN dans les cellules épithéliales.Ainsi, les altérations du méthylome des SGECs pourraient contribuer à la pathophysiologie du SGS et à son évolution en un lymphome du MALT, ceci en lien avec son environnement inflammatoire. / Sjögren Syndrome (SjS) is a chronic autoimmune disease characterized by a progressive and irreversible damage of exocrine glands, particularly salivary and lacrymal glands. This pathology affects between 0.1 and 3% of the population and is more common in women with a ratio of 9 women for 1 man. In salivary glands, a lymphocytic infiltration is observed and associated with the destruction of the secretory epithelium, which plays a central role in initiation and development of the SjS. The process remains incompletely clarified and contains a strong epigenetic component. Indeed, important disturbances of the process of DNA methylation are observed in epithelial cells and they are linked with the level of lymphocyte infiltration in salivary glands.The objective of this work is to better understand epigenetic changes during the SjS and in particular the DNA methylation/demethylation defects observed in Salivary Gland Epithelial Cells Epithelial (SGEC) and their roles in the pathology development.For that purpose, a global study of DNA methylation was done on 12 patients SGECs with the Infinium HumanMethylation450 BeadChip (Illumina). The 450k HM allows to cover more than 485,000 CpG sites on the whole genome. Bioinformatic analysis allowed us to obtain genes panels which are differentially methylated during this pathological phenomenon. In an interesting way, we identified the potential involvement of the calcic (hypomethylated, known to impact salivation) and WNT pathways (hypermethylated). Besides we were able to identify interferon regulation and the shift from interferon type I to type II with mucosa associated lymphoid tissue (MALT) lymphoma evolution. Furthermore, the simultaneous genomic–epigenomic analysis revealed significant associations between SjS-associated genetic risk factors and epigenetic modifications. Finally, the last part of this work highlights inflammatory environment involvement to control DNA methylation/demethylation in salivary gland epithelial cells.Altogether, alterations of DNA methylation in SGEC may contribute to SjS pathophysiology and evolution to MALT and this in link with the inflammatory environment.

Antimicrobial peptides (AMPs) are small proteins produced by epithelial surfaces, which have broad-spectrum antimicrobial and immunomodulatory activities. In the lung, skin and alimentary tract AMPs are known to be important in infectious and inflammatory conditions. Far less is known regarding the role of AMPs within the female reproductive tract, but as infection and inflammation are causes of preterm labour, AMPs may have a key function in maintain and protecting pregnancy. The major groups of human AMPs include the human beta defensins (HBDs), two antileukoproteinases (secretory leukocyte protease inhibitor (SLPI) and Trappin-2/Elafin), and the human cathelicidin hCAP18/LL-37, with several studies identifying their presence at sites throughout the reproductive tract. The cervix in pregnancy is positioned between the upper genital tract containing the developing fetus and the lower tract where infections usually arise. I hypothesise that AMPs are fundamental to mucosal immune defence of the cervix in pregnancy, preventing ascending infection and excessive inflammation that can cause preterm labour. This thesis focused on the human cathelicidin hCAP18/LL-37 and its role within the cervix and vagina. The aims of this thesis were to; investigate the inflammatory effects of LL-37 from cervical and vaginal derived epithelial cells and determine the pathways and receptors in which LL-37 may elicit its effects and how production may be regulated; investigate the role of CRAMP in a mouse model of preterm birth; and determine the production of AMPs by the pregnant cervix whilst investigating the relationship between AMP concentrations in cervicovaginal secretions and preterm labour. The inflammatory effect of LL-37 was investigated using cell lines derived from endocervical, ectocervical and vaginal epithelium. The study of these cell lines suggests divergent responses of cervical and vaginal epithelial cells. LL-37 mediated induction of IL-8 and IL-6 production from endocervical epithelial cells was observed in a dose-dependent and time-dependent manner, whilst ectocervical and vaginal cells also respond to treatment with LL-37 through IL-8 and IL-6 production. To determine a possible mechanism of action of LL-37 on IL-8 and IL-6 in the three cell lines, inhibitors against MAPK cascades, ERK, p38 MAPK and JNK, and known LL-37 receptors were investigated. In endocervical cells LL-37 mediated IL-8 occurs via activation of unidentified GPCRs, whilst in ectocervical cells this effect on IL‐8 and IL-6 is via the activation of ERK and p38 MAPK cascades. The mechanism by which LL-37 induces IL-8 secretion in vaginal epithelial cells remains unknown. Expression of LL-37 was shown to be mediated by vitamin D3 in vitro in cervical and vaginal epithelial cells. However when this relationship was investigated in vivo, using matched serum and cervicovaginal secretions from woman at early pregnancy, no correlation was observed between circulating vitamin D and cervicovaginal or circulating hCAP18/LL-37. However, the majority of women in this study reported with insufficient levels of vitamin D, which may effect the relationship observed with hCAP18/LL-37. Using a mouse model of LPS-induced preterm labour, to mimic the presence of intrauterine infection bacterial infection, I aimed to characterise the role of CRAMP, the mouse orthologue of hCAP18/LL-37, in the lower inflammatory and immune response that results in preterm labour. Wild type C57Bl/6J mice receiving an intrauterine injection of LPS deliver prematurely, within 24 hours of injection. However mice deficient in CRAMP (Camp -/-) receiving an intrauterine injection of LPS deliver significantly later and have a non-significant increase in pup survival compared to wild type C57Bl/6J mice. Cervical tissue collected post partum showed no difference in inflammatory markers between wild type C57Bl/6J and Camp -/- mice, however there was increased expression of the neutrophil chemoattractant marker, Cxcl5, and the neutrophil marker, Ngp in Camp -/- mice. In the lower genital tract, levels of antimicrobial peptides were determined in samples of cervicovaginal secretions collected from pregnant women. AMPs, hCAP18/LL-37, HBD-2 and SLPI were found in cervicovaginal secretions, and levels of hCAP18/LL-37 were increased in women with the common vaginal infection bacterial vaginosis. However no relationship was identified between the concentration of AMPs and preterm birth in this study. This work has shown that the lower genital tract, where infections that are associated with preterm labour originate, expresses the human cathelicidin hCAP18/LL-37. It may play an important role in modulating the immune response to invading infection associated with preterm labour. Further investigation of these responses may increase understanding of the physiology and pathophysiology of labour, and lead to strategies for the prevention of premature delivery.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Estreptococos do grupo B (EGB) comumente colonizam adultos saudáveis, sem sintomas, mas sob certas circunstâncias possui a capacidade de invadir tecidos do hospedeiro, evadir da detecção imunológica e causar doenças invasivas graves. Por conseguinte, os EGB continuam sendo uma das principais causas de mortalidade neonatal, pneumonia, sepse e meningite. Contudo, a patogênese desta infecção ainda está pouco elucidada. O sorotipo V é freqüentemente associado à doença invasiva em mulheres adultas não gestantes e o segundo mais prevalente em mulheres grávidas. O principal objetivo deste trabalho foi estudar a aderência, invasão e persistência intracelular de amostras pertencentes ao sorotipo V (88641-vagina/portador e 90186-sangue/paciente) usando as células epiteliais respiratórias A549. As amostras de EGB demonstraram capacidade de aderir e invadir as células epiteliais A549, mas somente a amostra 90186-sangue apresentou maior invasão quando comparada com a de vagina (P <0.001). Ambas as amostras demonstraram persistência intracelular sem replicação no interior das células A549. Apenas o isolado 90186-sangue sobreviveu dentro das células epiteliais até 24h de incubação (P <0,05). A fusão dos lisossomas das células epiteliais com vacúolos contendo bactérias foi observada em células A549 tratadas com Lyso Tracker Grenn DND-26 para todas as amostras testadas. Nossos dados indicam pela primeira vez que as amostras viáveis do sorotipo V permanecem dentro de vacúolos ácidos epiteliais. Curiosamente, a amostra 90186- sangue induziu vacuolização celular e a amostra 88641-vagina promoveu a morte celular após 7h de incubação. Finalmente, nossos resultados aumentam o nosso conhecimento sobre eventos celulares da fagocitose e da patogênese das doenças invasivas promovidas pelos EGB. / Group B Streptococcus (GBS) commonly colonizes healthy asymptomatic adults, yetunder certain circumstances displays the ability to invade host tissues, evade the immune system and cause serious invasive disease. Consequently, GBS remains the major cause of neonatal pneumonia, sepsis and meningitis. However, the pathogenesis of this infection is poorly understood. The serotype V is frequently associated with invasive diseases in non-pregnant adults and the second most prevalent in pregnant women. The aim of this work was to study the adherence; invasion and persistence intracellular of the GBS serotype V (88641-vagina/carriers and 90186-blood/patient) in epithelial cells A549. All GBS strains showed ability to adhere and invade the epithelial A549 cells, but GBS 90186-blood was more invasive than the vagina isolate (P<0,001). Both strains persisted intracellular, but without replicating into the A549 cells. Only 90186-blood strain survived within epithelial cells even after a 24h incubation (P<0,05). Fusion of epithelial lysosomes with bacteria containing phagocytic vacuoles was observed in A549 cells treated with Lysotracker Grenn DND-26 for all strains tested. Our data indicate for the first time that viable strains of serotype V remain within acidic epithelial vacuoles. Interestingly, the 90186-blood strain induced cellular vacuolization and 88641-vagina strain caused cell death after 7h incubation. Lastly, our results increase our knowledge about cellular events of phagocytosis and pathogeneses of GBS diseases.

Avanços na identificação e caracterização de diferentes populações de célulastronco tem melhorado as perspectivas do seu uso clínico. A maioria dos estudos obtêm as células-tronco com base na expressão de marcadores de superfície celular e testa as suas propriedades por meio de ensaios funcionais in vitro e in vivo. Na presente pesquisa foram isoladas diferentes populações de células epiteliais com base na expressão de dois marcadores de células-tronco epiteliais descritos pela literatura, o receptor de neurotrofina p75 (p75NTR) e o receptor de transferrina 1 (CD71). Uma vez isso feito, foi avaliado a co-expressão de outros marcadores de células-tronco epiteliais, como as integrinas 6 e 1, e realizado ensaios de eficiência de formação de colônias, potencial de crescimento celular, capacidade de reconstrução epitelial in vitro, análise da resposta ao trauma e avaliação da capacidade de auto renovação. Os resultados mostram que as células p75NTR+ tem um desempenho funcional melhor do que as p75NTR- na maioria dos ensaios funcionais realizados, exceto pela capacidade de responder ao trauma e de se autorenovar. Ademais, comprovou-se que células p75NTR+ expressam em maior proporção as integrinas 6 e 1 e que o isolamento de células por dupla marcação (p75NTR+CD71-) possibilita a obtenção de uma população de células epiteliais ainda mais enriquecida com estes marcadores. No entanto, foi observado também que independentemente da população celular estudada e do tempo em cultivo, as populações de células epiteliais alteraram drasticamente o seu fenótipo quando de tal forma que as populações celulares inicialmente positivas se tornaram majoritariamente negativas e que as populações celulares inicialmente negativas passaram a ter células positivas em seu meio. / Recent advances in cell sorting and characterization technics of stem cells have provided new insights and perspectives for clinical applications of this particular cell population. Most of the studies isolat stem cells based on the expression of cell surface markers and evaluate their stem cells-like proprieties by performing in vitro and in vivo assays. Here we isolated different populations of keratinocytes based on the expression of the epithelial stem cell markers neurotrophin receptor p75 (p75NTR) and transferrin receptor 1 (CD71). The co-expression of other epithelial stem markers such as integrins 6 and 1 was also assessed and in vitro functional assays such as colony-forming efficiency; long-term growth potential, in vitro epithelial reconstruction-capacity and response to damage and self-renew capacity. Our results showed that p75NTR+ve cells have better functional proprieties in most of the assays however they did not respond to damage nether presented self-renew capacity. Additionally, p75NTR-ve cells express higher percentage of other epithelial stem cell markers such as integrins 6 and 1 when compared to p75NTR-ve cells and the double staining (p75NTR+veCD71-ve) contributes to isolate a more enriched cell population based on the expression of the integrins. Nevertheless, independently of the cell population or of the amount of time in culture, cells have changed dramatically their phenotype in a way that the cell population initially p75NTR+ve lost the expression of the p75NTR and the negative population have gained it.

O leite materno constitui uma rica fonte de nutrientes e peptídeos. O desmame precoce (DP) induz o aumento da proliferação e da diferenciação celular, e pode ser uma condição estressante capaz de elevar a corticosterona (CORT). Neste estudo, investigamos a interação entre padrão alimentar, CORT, TGF<font face=\"Symbol\">a e TGF<font face=\"Symbol\">b na regulação da proliferação celular na mucosa gástrica de ratos em desenvolvimento pós-natal. Utilizamos ratos Wistar em DP a partir do 15ºd, e observamos o aumento de CORT aos 16, 17 e 18d (p<0,05). No 17ºd, encontramos nível alto de TGF<font face=\"Symbol\">a e baixo de TGF<font face=\"Symbol\">b1 na mucosa gástrica (p<0,05). Para avaliarmos a ação da CORT, usamos o RU486, que ao reduzir a ação hormonal, estimulou a proliferação celular nos animais amamentados e DP (p<0,05), sem alterar os níveis de TGF<font face=\"Symbol\">a e TGF<font face=\"Symbol\">b. A sinalização para esses fatores foi estudada, e RU486 reduziu a ativação de ERK1/2 (p<0,05) no DP. Concluímos que a corticosterona circulante possui efeito antiproliferativo sobre a mucosa gástrica de ratos, e sua ação parece direta sem depender da regulação dos níveis de TGF<font face=\"Symbol\">a e TGF<font face=\"Symbol\">b. / Milk is a source of nutrients and active peptides. Early weaning (EW) leads to the increase of cell proliferation and differentiation, and can characterize a stressful condition to induce corticosterone (CORT). In the current study we investigated the interaction among dietary pattern, CORT, TGF<font face=\"Symbol\">a and TGF<font face=\"Symbol\">b on the regulation of cell proliferation in gastric mucosa of developing rats. We used Wistar rats submitted to EW on the 15thd, and we observed higher CORT levels throughout EW (p<0.05). At 17d, we also found higher TGF<font face=\"Symbol\">a and lower TGF<font face=\"Symbol\">b1 in the gastric mucosa (p<0.05). To evaluate CORT action, we used RU486 which antagonized the hormone and increased cell proliferation in both suckling and EW pups (p<0.05), without changing TGF<font face=\"Symbol\">a and TGF<font face=\"Symbol\">b1 levels. The signaling pathways triggered by these factors were studied and RU486 reduced ERK1/2 phosphorylation (p<0.05) in EW. We conclude that CORT is repressive for cell proliferation in the rat gastric mucosa, and its action seems to be direct, i.e. independent of TGF<font face=\"Symbol\">a and TGF<font face=\"Symbol\">b regulation.

<p>Basement membranes are thin extracellular sheets that surround muscle, fat and peripheral nerve cells and underlay epithelial and endothelial cells. Laminins are one of the main protein families of these matrices. Integrins and dystroglycan are receptors for laminins, connecting cells to basement membranes. Each laminin consists of three different chains, (α, β, γ). Laminin-1 (α1β1γ1) was the first laminin to be found and is the most frequently studied. Despite this, it was unclear where its α1 chain was expressed. A restricted distribution of the α1 chain in the adult epithelial basement membranes was demonstrated in the present study. In contrast, dystroglycan was found to have a much broader distribution. Dystroglycan is an important receptor for α2-laminins in muscle, but binds also α1-laminins. The more ubiquitous α5-laminins were also shown to bind dystroglycan, but with distinctly lower affinity than α1- and α2- laminins. </p><p>The biological roles of different laminin isoforms have been investigated. Differences were found in the capacity of various tested laminins to promote epithelial cell adhesion. The α5-laminins were potent adhesive substrates, a property shown to be dependent on α3 and α6 integrins. Each receptor alone could promote efficient epithelial cell adhesion to α5-laminins. Yet, only α6 integrin and in particular the α6A cytoplasmic splice variant could be linked to laminin-mediated activation of a mitogen-activated protein kinase (MAP kinase) pathway. Attachment to either α1- or α5-laminins activated extracellular-signal regulated kinase (ERK) in cells expressing the integrin α6A variant, but not in cells expressing α6B. A new role for dystroglycan as a suppressor of this activation was demonstrated. Dystroglycan antibodies, or recombinant fragments with high affinity for dystroglycan, decreased ERK activation induced by integrin α6 antibodies. Integrin αvβ3 was identified as a novel co-receptor for α5-laminin trimers. Cell attachment to α5-laminins was found to facilitate growth factor induced cell proliferation. This proliferation could be blocked by antibodies against integrin αvβ3 or by an inhibitor of the MEK/ERK pathway. Therefore, integrin αvβ3 binding to α5-laminins could be of biological significance.</p>

<p>Epithelial cell polarisation is a prerequisite for the branching morphogenesis in several organs. Differential screening techniques were used to identify genes, which are upregulated during induction of epithelium in early kidney development. This investigation revealed two separate genes, Nuclear localising protein 1 (Nulp1), a previously undescribed gene with sequence characteristics of the basic helix-loop-helix transcription factor family, and glycoprotein 210 (gp210, POM210), an integral membrane protein constituent of the nuclear pore complex (NPC). Of these, gp210 was found to be upreglated during conversion of mesenchyme to epithelium. </p><p>The nuclear envelope, which demarcates the nuclear region in the eukaryotic cell, consists of an inner and an outer membrane that are fused at the locations for NPCs. These large macromolecular assemblages are tube like structures connecting the cytoplasmic and nuclear compartments of the cell. NPCs serve as the only conduits for exchange of molecular information between these cellular rooms. Electron microscopy techniques have revealed detailed information about the NPC architecture. A number of proteins (nucleoporins) have been characterised and embodied as components of the NPC structure. Active, energy dependent nucleocytoplasmic transport of RNAs and proteins is mediated by a group of soluble receptor proteins, collectively termed karyopherins. </p><p>Gp210 has been suggested to be important for nuclear pore formation. Nevertheless, our analyses showed a limited expression pattern of gp210, with its mRNA and protein largely confined to epithelial cells in the mouse embryo. Furthermore, in several cell lines, gp210 was undetectable. The expression pattern of gp210 was not synchronised with some other nucleoporins, indicating NPC heterogeneity. Characterisation of the structure of the human gp210 gene, including its promoter region, gave insight about possible cell-type specific gene regulatory mechanisms. </p><p>Regulation of molecular traffic between the nucleus and the cytoplasm leads to transcriptional control. Cell specific configuration of the NPC structure, due to diffential expression of gp210, could be involved in this control. Gp210 could be of importance for the development of epithelial cell polarisation.</p>

Basement membranes are thin extracellular sheets that surround muscle, fat and peripheral nerve cells and underlay epithelial and endothelial cells. Laminins are one of the main protein families of these matrices. Integrins and dystroglycan are receptors for laminins, connecting cells to basement membranes. Each laminin consists of three different chains, (α, β, γ). Laminin-1 (α1β1γ1) was the first laminin to be found and is the most frequently studied. Despite this, it was unclear where its α1 chain was expressed. A restricted distribution of the α1 chain in the adult epithelial basement membranes was demonstrated in the present study. In contrast, dystroglycan was found to have a much broader distribution. Dystroglycan is an important receptor for α2-laminins in muscle, but binds also α1-laminins. The more ubiquitous α5-laminins were also shown to bind dystroglycan, but with distinctly lower affinity than α1- and α2- laminins. The biological roles of different laminin isoforms have been investigated. Differences were found in the capacity of various tested laminins to promote epithelial cell adhesion. The α5-laminins were potent adhesive substrates, a property shown to be dependent on α3 and α6 integrins. Each receptor alone could promote efficient epithelial cell adhesion to α5-laminins. Yet, only α6 integrin and in particular the α6A cytoplasmic splice variant could be linked to laminin-mediated activation of a mitogen-activated protein kinase (MAP kinase) pathway. Attachment to either α1- or α5-laminins activated extracellular-signal regulated kinase (ERK) in cells expressing the integrin α6A variant, but not in cells expressing α6B. A new role for dystroglycan as a suppressor of this activation was demonstrated. Dystroglycan antibodies, or recombinant fragments with high affinity for dystroglycan, decreased ERK activation induced by integrin α6 antibodies. Integrin αvβ3 was identified as a novel co-receptor for α5-laminin trimers. Cell attachment to α5-laminins was found to facilitate growth factor induced cell proliferation. This proliferation could be blocked by antibodies against integrin αvβ3 or by an inhibitor of the MEK/ERK pathway. Therefore, integrin αvβ3 binding to α5-laminins could be of biological significance.