Dans mon projet de doctorat, j’ai étudié des fonctions primordiales de l’épithélium respiratoire telles que la régulation du transport ionique, la clairance liquidienne et la réparation épithéliale. J’ai particulièrement mis l’emphase sur le rôle des canaux potassiques qui interviennent dans ces trois fonctions de l’épithélium respiratoire. J’ai tout d’abord prouvé que la modulation des canaux potassiques régulait l’activité du promoteur de αENaC, en partie via la voie de signalisation ERK1/2, dans des cellules alvéolaires. Cette régulation entraîne une variation de l’expression génique et protéique du canal ENaC. Physiologiquement, il en résulte une augmentation du phénomène de clairance liquidienne suite à l’activation des canaux K+, tandis que l’inhibition de ces canaux la diminue sévèrement. J’ai aussi pu démontrer que l’absence de canal KvLQT1 entraînait une diminution du courant (ENaC) sensible à l’amiloride, dans les cellules de trachée en culture primaire, isolées de souris KO pour kcnq1. Dans la seconde partie de mon étude, j’ai évalué l’impact de l’hyperglycémie sur la capacité de transport ionique et de réparation de cellules épithéliales bronchiques saines ou Fibrose Kystique. Mes résultats montrent que l’hyperglycémie diminue le transport transépithélial de chlore et le transport basolatéral de potassium. Des études préalables du laboratoire ayant montré que les canaux K+ et Cl- contrôlent les processus de réparation, j’ai donc évalué si ceux-ci étaient modifiés par l’hyperglycémie. Et en effet, l’hyperglycémie ralentit la vitesse de réparation des cellules issues des voies aériennes (CFBE-wt et CFBE-ΔF508). J’ai donc démontré que le transport de potassium intervenait dans des fonctions clés de l’épithélium respiratoire, comme dans la régulation génique de canaux ioniques, le contrôle de la clairance liquidienne alvéolaire, et que l’hyperglycémie diminuait le transport ionique (K+ et Cl-) et la réparation épithéliale. / During my Ph.D. training, I studied 3 important functions of respiratory epithelium : regulation of ion transport, liquid clearance and epithelial repair. I focused on potassium channels, because they control these three respiratory epithelial functions. First, I proved that αENaC promoter activity was regulated following K+ channel modulation, in alveolar cells. This regulation of αENaC promoter which might be through a modification of ERK1/2 phosphorylation, was followed by ENaC mRNA and protein expression regulation. I then showed that activation of KvLQT1 and KATP channels increased alveolar liquid clearance, whereas inhibition of these K+ channels decreased the alveolar clearance. I showed that the absence of KvLQT1 channel inhibited the amiloride-sensitive current (ENaC), in tracheal epithelial cells isolated from KvLQT1-KO mice. In the second part of my Ph.D. project, I studied the impact of hyperglycemia on Cystic Fibrosis (CF) and non-CF epithelial cells. I first observed that K+ and Cl- currents were reduced by hyperglycemia. Because we have previously shown that wound-healing process was dependant on K+ and Cl- channels, I then evaluated the impact of hyperglycemia on wound-healing. As expected, hyperglycemia slowed the repair rate of non-CF (CFBE-wt) and CF (CFBE-ΔF508) cell monolayers.

A Fibrose Cística (FC) é a doença autossômica recessiva mais freqüente em caucasianos e está associada, em seu amplo espectro de apresentação clínica, a mais de 1500 mutações no gene CFTR (Cystic Fibrosis Transmembrane conductance regulator). O papel de CFTR é especialmente relevante no desenvolvimento da porção reprodutiva dos ductos mesonéfricos. Em 98% dos pacientes masculinos portadores da FC, mutações em CFTR são responsáveis pela ausência bilateral congênita dos ductos deferentes (CBAVD), associada à anomalias variáveis das vesículas seminais, ductos ejaculatórios e da porção distal dos epidídimos. A ausência uni ou bilateral congênita dos ductos deferentes (CAVD), na ausência de outros sinais clínicos de FC, é conhecida causa de infertilidade masculina, presente em 1%-2% de todos os homens inférteis, e em cerca de 10% dos azoospérmicos. A reprodução assistida utilizando a injeção intracitoplasmática de espermatozóides (ICSI) obtidos preferencialmente por aspiração microcirurgica de espermatozóides do epidídimo (MESA) permite a paternidade biológica a esses pacientes. Em função da alta morbi-mortalidade da FC e da alta freqüência de portadores assintomáticos, estimada em 1:25, é recomendável que seja realizado teste para identificação de mutações em CFTR em todos os pacientes com CAVD antes de serem submetidos à ICSI. Em populações de etnia homogênea, a mutação F508 é identificada em 90% dos pacientes com FC e em 70% a 85% dos pacientes com CAVD. No Brasil, onde diferenças étnicas refletem a heterogeneidade genética, a freqüência da mutação F508 varia entre 23% e 50% em paciente com FC indicando que outras mutações devam estar envolvidas. Este dado levou ao estudo completo do gene CFTR de 20 homens inférteis com CAVD visando a identificação das mutações mais prevalentes em nossa população. Foram identificadas mutações em 17 pacientes (85%): três DF508 representando 15% (3/20), uma G542X, uma 875+1G>A e 4 mutações ainda não descritas na literatura, a S753R, G149W identificada em dois irmãos, V580F e a 712-1G>T. A variação no trato polipirimidínico em IVS8 (alelo 5T), seja como segunda mutação ou presente em homozigose, está diretamente relacionada com a CAVD, com freqüências em população caucasiana masculina infértil variando entre 21% e 30%. No presente estudo, 15 (15/20=75%) pacientes apresentaram o alelo a variante alélica 5T sendo que em 8 pacientes essa variante alélica foi identificada em heterozigose composta com outra mutação. Anomalias renais foram identificadas em 6 pacientes, todos com CBAVD. O presente estudo pode correlacionar o fenótipo da CAVD a alterações no genótipo de CFTR em 100% dos pacientes investigados / Cystic Fibrosis (CF) is the most common autosomal recessive disorder in caucasians and is associated, in an wide variety of different clinical manifestatons. More than 1500 mutations in the CFTR gene (Cystic Fibrosis regulator Transmembrane conductance) have been described and an even growing number of mutations are being currently studied worldwide. The role of CFTR gene is especially important in reproductive tissues of the mesonephric tract sensitive to the expression of the CFTR gene. The great majority of infertile males with CF (98%) have clinical manifestations and mutations in CFTR are responsible for the congenital bilateral absence of the vas deferens (CBAVD), associated to the abnormalities of the seminal vesicles, ejaculatory ducts and/or the distal portion of the epididymis. The congenital absence, uni or bilateral, of the vas deferens (CAVD), in the absence of other clinical signals of CF is a known cause of male infertility present in 1%-2% of all men investigated and in about 10% of men with obstructive azoospermia. Serious considerations should be drawn about the lack of proper diagnosis of infetile males with CFTR that seek reproductive clinics for assisted reproductive techniques (ARTs), as well as the lack of proper consideratins of the existance of this disease as a potential cause of male infetility among male are takers, like urologistas, andrologistas and gynecologists that rush for the misuse of ARTs. The introduction of Intracytoplasmic Sperm Injection (ICSI), has given new reproductive potetntial for these couples, but again as in the majority of cases it is obstructive azoospermia, couples should be advised about proper microsurgical sperm retrieval, preferentialy microsurgical epydidymal sperm aspiration (MESA). As a consequence of the potential high mortality rate of the CF descendents and the high frequency of carriers, estimated in 1:25,it is highly recommended that tests for correct identification of mutations in CFTR gene are carried out for all patients with CAVD before considered being submitted to ICSI. In populations of homogeneous ethnic origin, the mutation F508 is identified in 90% of the patients with CF and between 70% and 85% of the patients with CAVD. In Brazil, where ethnic differences reflect the genetic heterogeneity, the frequency of the mutation in F508 varies between 23% and 50%, indicating that other mutations must have a role. Our data looked carefully in the CFTR gene of 20 infertile men with CAVD aiming at the identification of the most prevalent mutations in our population. Mutations had been identified in 17 patients (85%): three DF508 representing 15% (3/20), one G542X, one 875+1G>A and 4 mutations not yet described in literature, S753R, G149W identified in two brothers, V580F and 712-1G>T. In the literature the allelic variant in IVS8 (allele 5T), either as a second mutation or in homozygosis, is directly related with the CAVD, with reported frequencies in the infertile caucasian male population varying between 21% and 30%. In the present study, 15 (15/20=75%) patients presented the CFTR mutation in the IVS8/5T: eight of them in heterozygosis composed with another mutation. Regarding genitourinary tract malformations, kidney anomalies were identified in 6 patients, all with CBAVD. In the present study we could correlationate the phenotype of the CAVD with the genotype alterations of CFTR gene in 100% of the investigated patients

A Fibrose Cística (FC) é a doença autossômica recessiva mais freqüente em caucasianos e está associada, em seu amplo espectro de apresentação clínica, a mais de 1500 mutações no gene CFTR (Cystic Fibrosis Transmembrane conductance regulator). O papel de CFTR é especialmente relevante no desenvolvimento da porção reprodutiva dos ductos mesonéfricos. Em 98% dos pacientes masculinos portadores da FC, mutações em CFTR são responsáveis pela ausência bilateral congênita dos ductos deferentes (CBAVD), associada à anomalias variáveis das vesículas seminais, ductos ejaculatórios e da porção distal dos epidídimos. A ausência uni ou bilateral congênita dos ductos deferentes (CAVD), na ausência de outros sinais clínicos de FC, é conhecida causa de infertilidade masculina, presente em 1%-2% de todos os homens inférteis, e em cerca de 10% dos azoospérmicos. A reprodução assistida utilizando a injeção intracitoplasmática de espermatozóides (ICSI) obtidos preferencialmente por aspiração microcirurgica de espermatozóides do epidídimo (MESA) permite a paternidade biológica a esses pacientes. Em função da alta morbi-mortalidade da FC e da alta freqüência de portadores assintomáticos, estimada em 1:25, é recomendável que seja realizado teste para identificação de mutações em CFTR em todos os pacientes com CAVD antes de serem submetidos à ICSI. Em populações de etnia homogênea, a mutação F508 é identificada em 90% dos pacientes com FC e em 70% a 85% dos pacientes com CAVD. No Brasil, onde diferenças étnicas refletem a heterogeneidade genética, a freqüência da mutação F508 varia entre 23% e 50% em paciente com FC indicando que outras mutações devam estar envolvidas. Este dado levou ao estudo completo do gene CFTR de 20 homens inférteis com CAVD visando a identificação das mutações mais prevalentes em nossa população. Foram identificadas mutações em 17 pacientes (85%): três DF508 representando 15% (3/20), uma G542X, uma 875+1G>A e 4 mutações ainda não descritas na literatura, a S753R, G149W identificada em dois irmãos, V580F e a 712-1G>T. A variação no trato polipirimidínico em IVS8 (alelo 5T), seja como segunda mutação ou presente em homozigose, está diretamente relacionada com a CAVD, com freqüências em população caucasiana masculina infértil variando entre 21% e 30%. No presente estudo, 15 (15/20=75%) pacientes apresentaram o alelo a variante alélica 5T sendo que em 8 pacientes essa variante alélica foi identificada em heterozigose composta com outra mutação. Anomalias renais foram identificadas em 6 pacientes, todos com CBAVD. O presente estudo pode correlacionar o fenótipo da CAVD a alterações no genótipo de CFTR em 100% dos pacientes investigados / Cystic Fibrosis (CF) is the most common autosomal recessive disorder in caucasians and is associated, in an wide variety of different clinical manifestatons. More than 1500 mutations in the CFTR gene (Cystic Fibrosis regulator Transmembrane conductance) have been described and an even growing number of mutations are being currently studied worldwide. The role of CFTR gene is especially important in reproductive tissues of the mesonephric tract sensitive to the expression of the CFTR gene. The great majority of infertile males with CF (98%) have clinical manifestations and mutations in CFTR are responsible for the congenital bilateral absence of the vas deferens (CBAVD), associated to the abnormalities of the seminal vesicles, ejaculatory ducts and/or the distal portion of the epididymis. The congenital absence, uni or bilateral, of the vas deferens (CAVD), in the absence of other clinical signals of CF is a known cause of male infertility present in 1%-2% of all men investigated and in about 10% of men with obstructive azoospermia. Serious considerations should be drawn about the lack of proper diagnosis of infetile males with CFTR that seek reproductive clinics for assisted reproductive techniques (ARTs), as well as the lack of proper consideratins of the existance of this disease as a potential cause of male infetility among male are takers, like urologistas, andrologistas and gynecologists that rush for the misuse of ARTs. The introduction of Intracytoplasmic Sperm Injection (ICSI), has given new reproductive potetntial for these couples, but again as in the majority of cases it is obstructive azoospermia, couples should be advised about proper microsurgical sperm retrieval, preferentialy microsurgical epydidymal sperm aspiration (MESA). As a consequence of the potential high mortality rate of the CF descendents and the high frequency of carriers, estimated in 1:25,it is highly recommended that tests for correct identification of mutations in CFTR gene are carried out for all patients with CAVD before considered being submitted to ICSI. In populations of homogeneous ethnic origin, the mutation F508 is identified in 90% of the patients with CF and between 70% and 85% of the patients with CAVD. In Brazil, where ethnic differences reflect the genetic heterogeneity, the frequency of the mutation in F508 varies between 23% and 50%, indicating that other mutations must have a role. Our data looked carefully in the CFTR gene of 20 infertile men with CAVD aiming at the identification of the most prevalent mutations in our population. Mutations had been identified in 17 patients (85%): three DF508 representing 15% (3/20), one G542X, one 875+1G>A and 4 mutations not yet described in literature, S753R, G149W identified in two brothers, V580F and 712-1G>T. In the literature the allelic variant in IVS8 (allele 5T), either as a second mutation or in homozygosis, is directly related with the CAVD, with reported frequencies in the infertile caucasian male population varying between 21% and 30%. In the present study, 15 (15/20=75%) patients presented the CFTR mutation in the IVS8/5T: eight of them in heterozygosis composed with another mutation. Regarding genitourinary tract malformations, kidney anomalies were identified in 6 patients, all with CBAVD. In the present study we could correlationate the phenotype of the CAVD with the genotype alterations of CFTR gene in 100% of the investigated patients

Dans un contexte où les iminosucres multivalents représentent, en tant qu’inhibiteurs puissants de glycosidases, des structures privilégiées pour le développement de nouveaux agents thérapeutiques, nous nous sommes intéressés à ce type de composés pour le traitement de deux maladies génétiques rares. Le premier axe de recherche a consisté à synthétiser des iminosucres di- à tétravalents en série 1-désoxymannojirimycine dans le but d’inhiber l’α1,2-mannosidase I du réticulum endoplasmique qui est impliquée dans la destruction de la protéine delF508-CFTR chez les malades atteints de la mucoviscidose. Un effet multivalent fort sur la correction de cette protéine mutée a alors été mis en évidence avec un composé trivalent basé sur le pentaérythritol. Efficace à des concentrations submicromolaires, ce dernier s’est montré 140 fois plus efficace que le modèle monovalent correspondant. Le second axe de recherche a consisté à identifier de nouveaux chaperons pharmacologiques de la β-glucocérébrosidase, l’enzyme lysosomale impliquée dans la maladie de Gaucher. Pour cela, nous avons préparé une série d’iminosucres hétérodivalents conçus pour cibler simultanément le site actif et un site secondaire de cette enzyme. Même si cet objectif n’a pas encore été atteint, nous avons malgré tout mis en évidence des chaperons monovalents capables de quasiment quadrupler l’activité de la β-glucocérébrosidase portant la mutation G202R. En marge de ces deux axes principaux, une sonde mécanistique basée sur un C-glycoside multivalent a également été développée dans le but de préciser les mécanismes à l’origine des effets multivalents puissants observés pour l’inhibition des glycosidases. / Because multivalent iminosugars represent, as potent glycosidase inhibitors, privileged structures for the design of novel drugs, we took a particular interest in this class of compounds for the treatment of two rare genetic diseases. The first research topic was dedicated to the synthesis of di- to tetravalent iminosugars in the 1-deoxymannojirimycin series in order to inhibit the endoplasmic reticulum α1,2-mannosidase I involved in the destruction of delF508-CFTR, the mutant protein responsible of cystic fibrosis. A strong multivalent effect for restoring its activity in cells was reported with a trivalent analogue based on pentaerythritol. This submicromolar corrector was found to be 140-fold more potent than the corresponding monovalent model. The second research topic focused on the identification of novel pharmacological chaperones of the β-glucocerebrosidase, the lysosomal enzyme involved in Gaucher’s disease. For this purpose, we developed a series of heterodivalent iminosugars designed to both bind to the active site and a secondary site of the enzyme. This goal could not be reached yet, nevertheless we identified monovalent chaperones which were able to fourfold increase β-glucocerebrosidase activity in G202R cell lines. Next to these main research topics, a mechanistic probe based on a multivalent C-glycoside was also developed to investigate the multivalent effect of iminosugar clusters in glycosidase inhibition.

[pt] Por ser uma doença genética, resultado de uma mutação em um gene específico, que gera proteínas (CFTR) defeituosas, a Fibrose Cística é uma patologia difícil de ser tratada. Os custos para os tratamentos atualmente disponíveis são altos, sem os quais, porém, a gravidade da doença tende a crescer ainda mais. Por esse motivo, novos tratamentos farmacológicos vêm surgindo, como o Trikafta (marca registrada), uma combinação tripla de fármacos com ação sinérgica (elexacaftor, ivacaftor e tezacaftor). Porém, esse medicamento ainda não é disponível no Brasil e o acesso aos tratamentos, em geral, são onerosos. Sendo assim, este trabalho visa a síntese de compostos 1,2,3-triazóis, com possível atividade biológica frente a proteína CFTR, sugerida por ancoragem molecular. Este trabalho também visa selecionar as melhores moléculas quanto aos perfis farmacocinéticos e toxicológicos, avaliados por ferramentas computacionais como swissADME e VirtualToxLab, respectivamente. Dessa forma, a estratégia sintética para a obtenção dos compostos consiste em duas etapas sintéticas. A primeira, envolve a síntese da enaminona – (E)-3-(dimetilamino)acrilaldeido (3a-d) – por organocatálise, a partir de L-prolina e DMA-DMF (1,1-dimetoxi-N,N-dimetillmetanamina) (1). A segunda etapa inclui a reação de cicloadição 1,3-dipolar onpot entre as azidas (5a-h) e as enaminonas previamente obtidas. Assim, foi possível obter 1,2,3-triazóis 1,4-substituídos (6a-k), com rendimentos de 5 a 96 por cento. Dentre eles, a molécula 6k, N-(2-(1-(4-metoxifenil)-1H-1,2,3-triazol-4-carbonil)fenil)acetamida), destacou-se quanto aos perfis toxicológicos e também pelos resultados observados nos estudos de ancoragem molecular. Os espectros de RMN de 1H e 13C RMN confirmaram a obtenção das estruturas. / [en] Because it is a genetic disease, the result of a mutation in a specific gene, which generates defective proteins (CFTR), Cystic Fibrosis is a pathology that is difficult to be treated. The costs for currently available treatments are high, without which, however, the severity of the disease tends to increase even more. For this reason, new pharmacological treatments are emerging, such as Trikafta (trademark), a triple combination of drugs with synergistic action (elexacaftor, ivacaftor and tezacaftor). However, this drug is not yet available in Brazil and access to treatments, in general, is expensive. Therefore, this work aims at the synthesis of 1,2,3-triazole compounds, with possible biological activity against the CFTR protein, proposed by molecular anchoring. This work also aims to select the best molecules in terms of pharmacokinetic and toxicological profiles, evaluated by computational tools such as swissADME and VirtualToxpot, respectively. Thus, the synthetic strategy for obtaining the compounds consists of two synthetic steps. The first involves the synthesis of enaminone - (E)-3-(dimethylamino) acrylaldehyde (3a-d) - by organocatalysis, starting from L- proline and DMA-DMF (1,1-dimethoxy-N, N-dimethylmethanamine) (1). The second stage includes the 1,3-dipolar onpot cycloaddition reaction between the azides (5a-h) and the previously obtained enaminones. Thus, it was possible to obtain 1,4-substituted 1,2,3-triazoles (6a-k), with yields of 5 to 96 percent. Among them, the molecule 6k, N- (2- (1- (4-methoxyphenyl) -1H-1,2,3-triazol-4-carbonyl) phenyl) acetamide), stood out in terms of toxicological profiles and also by results observed in molecular anchorage studies. The 1H and 13C NMR NMR spectra confirmed the structures obtained.

No description available.

<p>S-nitrosogluthatione is an endogenous substance, present at decreased levels in the lungs of CF patients and was recently found to induce mature CFTR in airway epithelial CF cell lines. We show that S-nitrosoglutathione in physiological concentrations increases the presence of ΔF508 CFTR in the cell membrane and induces cAMP dependent chloride transport in cystic fibrosis airway epithelial cells. The properties of S-nitrosoglutathione include other potential benefits for the CF patient and make this agent an interesting candidate for pharmacological treatment of CF that needs to be further evaluated.</p><p>Genistein was found to increase the chloride efflux in both normal and ΔF508 cells without stimulation of cAMP elevating agents and without prior treatment with phenylbutyrate. Genistein, in concentrations close to those that can be detected in plasma after a high soy diet, could induce chloride efflux in cells with the ΔF508 CFTR mutation and its possible use in the treatment of CF should therefore be further investigated.</p><p>Studies on nasal epithelial cells from CF patients showed cAMP dependent chloride efflux in some of the patients with severe genotypes. This may complicate <i>in vitro</i> evaluation of clinical treatment of these patients. The presence of cAMP dependent chloride transport did not necessarily lead to a milder phenotype. Other factors than CFTR may influence the clinical development of the disease.</p><p>Cystic fibrosis (CF) is the most common monogenetic disease among Caucasians. A defective cAMP regulated chloride channel (cystic fibrosis transmembrane conductance regulator, CFTR) in epithelial cells leads to viscous mucus, bacterial infections, inflammation and tissue damage in the lungs that cause death in 95% of the cystic fibrosis patients. There is no cure for the disease although existing treatment has dramatically prolonged the life expectancy. The aim of this thesis was to study pharmacological agents for their ability to restore the cellular deficiency in CF airway epithelial cells. X-ray microanalysis, MQAE fluorescence and immunocytochemistry were used to evaluate the effects.</p>

S-nitrosogluthatione is an endogenous substance, present at decreased levels in the lungs of CF patients and was recently found to induce mature CFTR in airway epithelial CF cell lines. We show that S-nitrosoglutathione in physiological concentrations increases the presence of ΔF508 CFTR in the cell membrane and induces cAMP dependent chloride transport in cystic fibrosis airway epithelial cells. The properties of S-nitrosoglutathione include other potential benefits for the CF patient and make this agent an interesting candidate for pharmacological treatment of CF that needs to be further evaluated. Genistein was found to increase the chloride efflux in both normal and ΔF508 cells without stimulation of cAMP elevating agents and without prior treatment with phenylbutyrate. Genistein, in concentrations close to those that can be detected in plasma after a high soy diet, could induce chloride efflux in cells with the ΔF508 CFTR mutation and its possible use in the treatment of CF should therefore be further investigated. Studies on nasal epithelial cells from CF patients showed cAMP dependent chloride efflux in some of the patients with severe genotypes. This may complicate in vitro evaluation of clinical treatment of these patients. The presence of cAMP dependent chloride transport did not necessarily lead to a milder phenotype. Other factors than CFTR may influence the clinical development of the disease. Cystic fibrosis (CF) is the most common monogenetic disease among Caucasians. A defective cAMP regulated chloride channel (cystic fibrosis transmembrane conductance regulator, CFTR) in epithelial cells leads to viscous mucus, bacterial infections, inflammation and tissue damage in the lungs that cause death in 95% of the cystic fibrosis patients. There is no cure for the disease although existing treatment has dramatically prolonged the life expectancy. The aim of this thesis was to study pharmacological agents for their ability to restore the cellular deficiency in CF airway epithelial cells. X-ray microanalysis, MQAE fluorescence and immunocytochemistry were used to evaluate the effects.

Cystic fibrosis (CF) is one of the most common fatal inherited diseases, most prevalent among Caucasians. CF is caused by a mutation in the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR), which helps to create sweat, digestive juices, and airway surface liquid (ASL). The airways are covered with a thin layer of fluid, the airway surface liquid, in which the cilia bathe. Defective or absent CFTR leads to a defective water and ion transport in the epithelial cells, which results in viscous mucus, defective ciliary clearance, bacterial inflammation and tissue damage. The volume and composition of ASL are important in the pathogenesis of cystic fibrosis and it is therefore relevant to determine its composition. However, there are a number of difficulties in determining the ionic composition of the ASL due to its small volume. Literature data vary from very hypotonic to markedly hypertonic. These controversial data inspired the development of a simple method for determining the elemental composition of the ASL in different animal species and humans. Two techniques were developed to determine the composition of ASL, from which indirect information on chloride transport in airway epithelium can be obtained. In the first method, tissue is removed from the animals under anesthesia, frozen and analyzed in the frozen-hydrated state. In the second method, the ASL is collected with small dextran (Sephadex) beads; the dried beads are then analyzed by X-ray microanalysis. The Sephadex-bead method appears more accurate compared to the frozen-hydrated samples. Both methods were applied to collect tracheal and/or nasal fluid in pigs, normal and transgenic cystic fibrosis mice, the fluid covering the apical surface of normal bronchial cells (16HBE14o-) and a cystic fibrosis human bronchial cell line (CFBE41o-), and finally nasal fluid in healthy and diseased subjects. The ionic composition of the ASL was isotonic both in pigs and healthy human subjects. CF patients had much higher levels of Na and Cl ions than healthy subjects. The ASL under control conditions was hypotonic in mice and cell cultures, whereas the concentrations of Na and Cl ions in the species with the ΔF508 mutation or absent CFTR were significantly higher than in the corresponding controls. It was also demonstrated that the ionic composition of the ASL can be influenced by pharmacological treatment. The study confirms earlier findings that CFTR also is involved in bicarbonate transport. Mist tent therapy has been tested in the study of a treatment for CF patients, in order to hydrate the viscous mucus. But the effect of mist tent therapy on ion concentrations in the ASL appeared to be short-lived, although no patients became chronically colonized with pseudomonads while on nocturnal mist tent therapy.

En este trabajo de tesis doctoral se caracteriza funcional y molecularmente el canal TRPV4 en varios modelos de células epiteliales respiratorias mostrando por primera vez la participación de este canal en la función osmoreguladora a nivel celular así como la identificación de nuevas variantes del canal. Se demuestra que la entrada de Ca2+ en respuesta a un hinchamiento hipotónico se produce a través del canal TRPV4 y es necesaria para una eficiente recuperación del volumen o RVD. Por su parte, las células epiteliales respiratorias con fenotipo de fibrosis quística no son capaces de reducir su volumen en un medio hipotónico a causa de una regulación defectuosa del canal, indicando, al mismo tiempo, que la regulación del TRPV4 por el estímulo hipotónico es dependiente de la CFTR.La caracterización de las variantes del canal TRPV4 demuestra que los dominios de ANK son determinantes moleculares claves en el proceso de oligomerización del canal. Al mismo tiempo este trabajo describe nuevos aspectos relacionados con la biogénesis del TRPV4 hasta ahora desconocidos: la oligomerización del canal tiene lugar en el RE, orgánulo donde es N-glicosilado de forma simple antes de ser transportado hacia el Golgi donde sus N-glicanos son madurados. / This thesis characterizes molecularly and funcionally the TRPV4 channel in various models of airway epithelial cells showing, for the first time, the involvement of this channel in an osmoregulatory cellular function as well as the isolation of new splice variants of this channel. It is demonstrated that the TRPV4 channel is the molecular Ca2+ pathway activated by hypotonic estimulus needed to trigger the RVD response. Furthermore, the cystic fibrosis airway epithelial cells showed an impaired RVD due to the misregulation of the TRPV4 channel, indicating that the regulation by the hypotonic stimulus is CFTR-dependent.The characterization of the new variants demonstrated that the ANK domains are key structural determinants in the oligomerization process of the TRPV4. This work also describes new aspects related to the biogenesis of this channel: oligomerization is achieved in the ER, where the TRPV4 is N-glycosilated and then transported to the Golgi where the glycans are matured.