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Ferret CFTR processing and functionFisher, John T. 01 December 2012 (has links)
The most common cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation is δF508 and this causes cystic fibrosis (CF). Animal models that recapitulate the human disease phenotype are critical to understanding pathophysiologic mechanisms in CF and developing therapies. New CF models in the pig and ferret have been generated that develop lung, pancreatic, liver, and intestinal pathologies that reflect disease in CF patients. Species-specific biology in the processing of CFTR has demonstrated that pig and mouse δF508-CFTR proteins are more effectively processed to the apical membrane of airway epithelia than human δF508-CFTR. The processing behavior of ferret wild-type (WT) and δF508-CFTR proteins remain unknown and such information is important to predicting the utility of a δF508-CFTR ferret. To this end, we sought to compare processing, membrane stability, and function of human and ferret WT- and δF508-CFTR proteins in a heterologous expression system using HT1080, HEK293T, BHK21, and Cos7 cells, as well as human and ferret CF polarized airway epithelia. Analysis of the protein processing and stability by metabolic pulse-chase and surface On-Cell Western blots revealed that WT-fCFTR half-life and membrane stability were increased relative to WT-hCFTR. Furthermore, in BHK21, Cos7, and CuFi cells, human and ferret δF508-CFTR processing was negligible, while low levels of processing of δF508-fCFTR could be seen in HT1080 and HEK293T cells. Only the WT-fCFTR, but not δF508-fCFTR, produced functional cAMP-inducible chloride currents in both CF human and ferret airway epithelia. Further elucidation of the mechanism responsible for elevated fCFTR protein stability may lead to new therapeutic approaches to augment CFTR function. These findings also suggest that generation of a ferret CFTRδF508/δF508 animal model may be useful.
Furthermore, in the CFTR and CFTR+/+ ferret model we have characterized abnormalities in the bioelectric properties of the trachea, stomach, intestine and gallbladder of newborn CF ferrets. Short circuit current (ISC) analysis of CF and WT tracheas revealed the following similarities and differences: 1) amiloride sensitive sodium currents were similar between genotypes, 2) responses to 4,4'-diisothiocyano-2,2'-stilbene disulphonic acid (DIDS) were ~4-fold greater in CF animals, suggesting elevated baseline chloride transport through non-CFTR channels, and 3) as expected, there was a lack of IBMX/forskolin-stimulated and GlyH-101-inhibited currents in CF animals due to the lack of CFTR. CFTR mRNA and protein was present throughout all levels of the WT ferret and IBMX/forskolin-inducible ISC was only observed in WT animals. Interestingly, IBMX/forskolin-inducible intestinal ISC in WT animals was not inhibited by the CFTR inhibitor GlyH-101 or bumetanide. The luminal pH of the CF ferret stomach was significantly decreased relative to the controls, while both genotypes maintained near neutral pH along the length of the intestine. The WT stomach and gallbladder exhibited significantly enhanced IBMX/forskolin ISC responses and inhibition by GlyH-101 relative to CF samples. These findings demonstrate that multiple organs affected by disease in the CF ferret have bioelectric abnormalities consistent with the lack of cAMP-mediated chloride transport.
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Avaliação da insuficiência pancreática pelo teste elastase-1 fecal em pacientes pediátricos com fibrose cística portadores da mutação DF508Gonzales, Andréa Cristina Silva January 2010 (has links)
Introdução e objetivo: Elastase-1 fecal (EL-1) é um teste não invasivo que serve para avaliar a função pancreática exócrina. Neste estudo, buscou-se avaliar e quantificar a concentração da EL-1 fecal em pacientes com Fibrose Cística (FC), portadores da mutação ΔF508, e padronizar o teste Elastase monoclonal para a população estudada. Métodos: Estudo transversal prospectivo, com pacientes portadores de FC. Foram coletadas amostras de fezes para a quantificação da concentração da EL-1fecal pelo teste ELISA. A avaliação antropométrica baseou-se no percentil de IMC para crianças de 2 a 18 anos e percentil de P/E para crianças menores de 2 anos. Foi feita uma revisão nos prontuários dos pacientes para identificar a mutação da FC e coletar informações a respeito da dose da enzima administrada. Os desfechos analisados foram a insuficiência pancreática exócrina (IP) e sua intensidade, definida pela atividade da EL-1 fecal < 200μg/g. Resultados: Cinquenta e um pacientes com idade entre 4 meses e 17 anos participaram do estudo, divididos em 3 grupos: 17 homozigotos, 17 heterozigotos e 17 não ΔF508. A média de idade foi de 9,11 anos (± 4,74) e 62,8% eram do sexo masculino. As enzimas pancreáticas foram utilizadas em 46 pacientes (90,2%). Pacientes com o teste da EL-1 fecal com valores abaixo de 100μg/g representaram um total de 80,4% (n=41), sendo 17 homozigotos (41,5%), 14 heterozigotos (34,1%) e 10 com ausência de ΔF508 (24,4%). Houve associação estatisticamente significativa entre os homozigotos e a concentração da EL-1 fecal < 100μg/g. Todos os pacientes considerados IP pelo teste da EL-1 fecal faziam terapia de reposição enzimática (41 - 100%). Dez pacientes (19,6%) estavam com concentração da EL-1 fecal >200μg/g e, desses, 5 utilizavam enzimas pancreáticas. Onze pacientes (21,6%) apresentaram-se desnutridos, 10 (19,6%) em risco nutricional e 30 (58,8%) eutróficos. Não houve relação estatisticamente significativa entre estado nutricional, mutações e IP. Conclusões: A atividade de EL-1 fecal < 100 μg/g, indicativa de IP grave pelo teste, foi observada em 17/17 (100%) pacientes homozigotos para a mutação ΔF508 e em 14/17 (82,3%) heterozigotos para a mesma mutação. Não houve relação entre os valores de EL-1 fecal e o estado nutricional, avaliados pelo percentil do P/E para < 2 anos e percentil do IMC para >de 2 anos. O teste EL-1 fecal é de fácil execução e pode ser feito com uma pequena amostra de fezes; neste estudo, revelou-se útil na avaliação pancreática dos pacientes com FC. / Introduction and Objective: The fecal Elastase-1 (EL-1) is a noninvasive test used to assess exocrine pancreatic function. This study aims to assess and quantify the concentration of fecal Elastase -1 in patients with cystic fibrosis ΔF508 mutation carriers and to standardize the testing Elastase monoclonal test in our study group. Methods: Cross-sectional study with patients diagnosed with Cystic Fibrosis, being treated by the Hospital de Clínicas de Porto Alegre. Feces were collected for the quantification of Elastase concentration by ELISA. Nutritional assessment was calculated by percentile of BMI for children aged 2 to 18 years and percentile P / E for children under 2 years. Patient charts were reviewed to identify the cystic fibrosis mutation and to collect information about the dose of enzyme administered. The results analyzed were the exocrine pancreatic insufficiency and its intensity, defined by the activity of fecal EL-1 <200μg/g. Results: Fifty-one patients with ages ranging from 4 months to 17 years participated in the study and were divided into 3 groups: 17 homozygotes, 17 heterozygotes and 17 non ΔF508. The average age was 9.11 years (± 4.74) and 62.8% were male. The pancreatic enzymes were used in 46 (90.2%) patients. Patients with Elastase test with values below 100μg/g represented a total of 80.4% (n = 41) and 17 (41.5%) homozygous, 14 heterozygous (34.1%) and 10 with no ΔF508 (24.4%). There was a statistically significant association between the homozygous and the concentration of fecal EL-1 <100μg/g. All patients identified as PI by the EL-1 fecal test were in enzyme replacement therapy 41 (100%). Ten patients (19.6%) had a concentration of EL-1 fecal >200 μg / g, and 5 of pancreatic enzymes used. Eleven (21.6%) patients were malnourished, 10 (19.6%) were at nutritional risk and for 30 (58.8%) the nutritional status was normal. There was no significant relationship between nutritional status, mutations and pancreatic insufficiency. Conclusion: The activity of EL Fecal -1 <100 μg/g indicative of severe PI by the test, was observed in 17/17 (100%) patients homozygous for the mutation ΔF508 and 14/17 (82.3%) heterozygous for the same mutation. There was no association between the levels of fecal EL-1 and nutritional status assessed by the percentile of the P/E < 2 years and BMI percentile for >2 years. The fecal Elastase-1 test can be easily performed with a small stool sample and proved useful in the pancreatic evaluation of patients with cystic fibrosis.
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Avaliação da insuficiência pancreática pelo teste elastase-1 fecal em pacientes pediátricos com fibrose cística portadores da mutação DF508Gonzales, Andréa Cristina Silva January 2010 (has links)
Introdução e objetivo: Elastase-1 fecal (EL-1) é um teste não invasivo que serve para avaliar a função pancreática exócrina. Neste estudo, buscou-se avaliar e quantificar a concentração da EL-1 fecal em pacientes com Fibrose Cística (FC), portadores da mutação ΔF508, e padronizar o teste Elastase monoclonal para a população estudada. Métodos: Estudo transversal prospectivo, com pacientes portadores de FC. Foram coletadas amostras de fezes para a quantificação da concentração da EL-1fecal pelo teste ELISA. A avaliação antropométrica baseou-se no percentil de IMC para crianças de 2 a 18 anos e percentil de P/E para crianças menores de 2 anos. Foi feita uma revisão nos prontuários dos pacientes para identificar a mutação da FC e coletar informações a respeito da dose da enzima administrada. Os desfechos analisados foram a insuficiência pancreática exócrina (IP) e sua intensidade, definida pela atividade da EL-1 fecal < 200μg/g. Resultados: Cinquenta e um pacientes com idade entre 4 meses e 17 anos participaram do estudo, divididos em 3 grupos: 17 homozigotos, 17 heterozigotos e 17 não ΔF508. A média de idade foi de 9,11 anos (± 4,74) e 62,8% eram do sexo masculino. As enzimas pancreáticas foram utilizadas em 46 pacientes (90,2%). Pacientes com o teste da EL-1 fecal com valores abaixo de 100μg/g representaram um total de 80,4% (n=41), sendo 17 homozigotos (41,5%), 14 heterozigotos (34,1%) e 10 com ausência de ΔF508 (24,4%). Houve associação estatisticamente significativa entre os homozigotos e a concentração da EL-1 fecal < 100μg/g. Todos os pacientes considerados IP pelo teste da EL-1 fecal faziam terapia de reposição enzimática (41 - 100%). Dez pacientes (19,6%) estavam com concentração da EL-1 fecal >200μg/g e, desses, 5 utilizavam enzimas pancreáticas. Onze pacientes (21,6%) apresentaram-se desnutridos, 10 (19,6%) em risco nutricional e 30 (58,8%) eutróficos. Não houve relação estatisticamente significativa entre estado nutricional, mutações e IP. Conclusões: A atividade de EL-1 fecal < 100 μg/g, indicativa de IP grave pelo teste, foi observada em 17/17 (100%) pacientes homozigotos para a mutação ΔF508 e em 14/17 (82,3%) heterozigotos para a mesma mutação. Não houve relação entre os valores de EL-1 fecal e o estado nutricional, avaliados pelo percentil do P/E para < 2 anos e percentil do IMC para >de 2 anos. O teste EL-1 fecal é de fácil execução e pode ser feito com uma pequena amostra de fezes; neste estudo, revelou-se útil na avaliação pancreática dos pacientes com FC. / Introduction and Objective: The fecal Elastase-1 (EL-1) is a noninvasive test used to assess exocrine pancreatic function. This study aims to assess and quantify the concentration of fecal Elastase -1 in patients with cystic fibrosis ΔF508 mutation carriers and to standardize the testing Elastase monoclonal test in our study group. Methods: Cross-sectional study with patients diagnosed with Cystic Fibrosis, being treated by the Hospital de Clínicas de Porto Alegre. Feces were collected for the quantification of Elastase concentration by ELISA. Nutritional assessment was calculated by percentile of BMI for children aged 2 to 18 years and percentile P / E for children under 2 years. Patient charts were reviewed to identify the cystic fibrosis mutation and to collect information about the dose of enzyme administered. The results analyzed were the exocrine pancreatic insufficiency and its intensity, defined by the activity of fecal EL-1 <200μg/g. Results: Fifty-one patients with ages ranging from 4 months to 17 years participated in the study and were divided into 3 groups: 17 homozygotes, 17 heterozygotes and 17 non ΔF508. The average age was 9.11 years (± 4.74) and 62.8% were male. The pancreatic enzymes were used in 46 (90.2%) patients. Patients with Elastase test with values below 100μg/g represented a total of 80.4% (n = 41) and 17 (41.5%) homozygous, 14 heterozygous (34.1%) and 10 with no ΔF508 (24.4%). There was a statistically significant association between the homozygous and the concentration of fecal EL-1 <100μg/g. All patients identified as PI by the EL-1 fecal test were in enzyme replacement therapy 41 (100%). Ten patients (19.6%) had a concentration of EL-1 fecal >200 μg / g, and 5 of pancreatic enzymes used. Eleven (21.6%) patients were malnourished, 10 (19.6%) were at nutritional risk and for 30 (58.8%) the nutritional status was normal. There was no significant relationship between nutritional status, mutations and pancreatic insufficiency. Conclusion: The activity of EL Fecal -1 <100 μg/g indicative of severe PI by the test, was observed in 17/17 (100%) patients homozygous for the mutation ΔF508 and 14/17 (82.3%) heterozygous for the same mutation. There was no association between the levels of fecal EL-1 and nutritional status assessed by the percentile of the P/E < 2 years and BMI percentile for >2 years. The fecal Elastase-1 test can be easily performed with a small stool sample and proved useful in the pancreatic evaluation of patients with cystic fibrosis.
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Avaliação da insuficiência pancreática pelo teste elastase-1 fecal em pacientes pediátricos com fibrose cística portadores da mutação DF508Gonzales, Andréa Cristina Silva January 2010 (has links)
Introdução e objetivo: Elastase-1 fecal (EL-1) é um teste não invasivo que serve para avaliar a função pancreática exócrina. Neste estudo, buscou-se avaliar e quantificar a concentração da EL-1 fecal em pacientes com Fibrose Cística (FC), portadores da mutação ΔF508, e padronizar o teste Elastase monoclonal para a população estudada. Métodos: Estudo transversal prospectivo, com pacientes portadores de FC. Foram coletadas amostras de fezes para a quantificação da concentração da EL-1fecal pelo teste ELISA. A avaliação antropométrica baseou-se no percentil de IMC para crianças de 2 a 18 anos e percentil de P/E para crianças menores de 2 anos. Foi feita uma revisão nos prontuários dos pacientes para identificar a mutação da FC e coletar informações a respeito da dose da enzima administrada. Os desfechos analisados foram a insuficiência pancreática exócrina (IP) e sua intensidade, definida pela atividade da EL-1 fecal < 200μg/g. Resultados: Cinquenta e um pacientes com idade entre 4 meses e 17 anos participaram do estudo, divididos em 3 grupos: 17 homozigotos, 17 heterozigotos e 17 não ΔF508. A média de idade foi de 9,11 anos (± 4,74) e 62,8% eram do sexo masculino. As enzimas pancreáticas foram utilizadas em 46 pacientes (90,2%). Pacientes com o teste da EL-1 fecal com valores abaixo de 100μg/g representaram um total de 80,4% (n=41), sendo 17 homozigotos (41,5%), 14 heterozigotos (34,1%) e 10 com ausência de ΔF508 (24,4%). Houve associação estatisticamente significativa entre os homozigotos e a concentração da EL-1 fecal < 100μg/g. Todos os pacientes considerados IP pelo teste da EL-1 fecal faziam terapia de reposição enzimática (41 - 100%). Dez pacientes (19,6%) estavam com concentração da EL-1 fecal >200μg/g e, desses, 5 utilizavam enzimas pancreáticas. Onze pacientes (21,6%) apresentaram-se desnutridos, 10 (19,6%) em risco nutricional e 30 (58,8%) eutróficos. Não houve relação estatisticamente significativa entre estado nutricional, mutações e IP. Conclusões: A atividade de EL-1 fecal < 100 μg/g, indicativa de IP grave pelo teste, foi observada em 17/17 (100%) pacientes homozigotos para a mutação ΔF508 e em 14/17 (82,3%) heterozigotos para a mesma mutação. Não houve relação entre os valores de EL-1 fecal e o estado nutricional, avaliados pelo percentil do P/E para < 2 anos e percentil do IMC para >de 2 anos. O teste EL-1 fecal é de fácil execução e pode ser feito com uma pequena amostra de fezes; neste estudo, revelou-se útil na avaliação pancreática dos pacientes com FC. / Introduction and Objective: The fecal Elastase-1 (EL-1) is a noninvasive test used to assess exocrine pancreatic function. This study aims to assess and quantify the concentration of fecal Elastase -1 in patients with cystic fibrosis ΔF508 mutation carriers and to standardize the testing Elastase monoclonal test in our study group. Methods: Cross-sectional study with patients diagnosed with Cystic Fibrosis, being treated by the Hospital de Clínicas de Porto Alegre. Feces were collected for the quantification of Elastase concentration by ELISA. Nutritional assessment was calculated by percentile of BMI for children aged 2 to 18 years and percentile P / E for children under 2 years. Patient charts were reviewed to identify the cystic fibrosis mutation and to collect information about the dose of enzyme administered. The results analyzed were the exocrine pancreatic insufficiency and its intensity, defined by the activity of fecal EL-1 <200μg/g. Results: Fifty-one patients with ages ranging from 4 months to 17 years participated in the study and were divided into 3 groups: 17 homozygotes, 17 heterozygotes and 17 non ΔF508. The average age was 9.11 years (± 4.74) and 62.8% were male. The pancreatic enzymes were used in 46 (90.2%) patients. Patients with Elastase test with values below 100μg/g represented a total of 80.4% (n = 41) and 17 (41.5%) homozygous, 14 heterozygous (34.1%) and 10 with no ΔF508 (24.4%). There was a statistically significant association between the homozygous and the concentration of fecal EL-1 <100μg/g. All patients identified as PI by the EL-1 fecal test were in enzyme replacement therapy 41 (100%). Ten patients (19.6%) had a concentration of EL-1 fecal >200 μg / g, and 5 of pancreatic enzymes used. Eleven (21.6%) patients were malnourished, 10 (19.6%) were at nutritional risk and for 30 (58.8%) the nutritional status was normal. There was no significant relationship between nutritional status, mutations and pancreatic insufficiency. Conclusion: The activity of EL Fecal -1 <100 μg/g indicative of severe PI by the test, was observed in 17/17 (100%) patients homozygous for the mutation ΔF508 and 14/17 (82.3%) heterozygous for the same mutation. There was no association between the levels of fecal EL-1 and nutritional status assessed by the percentile of the P/E < 2 years and BMI percentile for >2 years. The fecal Elastase-1 test can be easily performed with a small stool sample and proved useful in the pancreatic evaluation of patients with cystic fibrosis.
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Approches transcriptomiques dans l’étude de la fibrose kystiqueVoisin, Gregory 03 1900 (has links)
Les avancées en biotechnologie ont permis l’identification d’un grand nombre
de mécanismes moléculaires, soulignant également la complexité de la
régulation génique. Néanmoins, avoir une vision globale de l’homéostasie
cellulaire, nous est pour l’instant inaccessible et nous ne sommes en mesure
que d’en avoir qu’une vue fractionnée. Étant donné l’avancement des
connaissances des dysfonctionnements moléculaires observés dans les
maladies génétiques telles que la fibrose kystique, il est encore difficile de
produire des thérapies efficaces.
La fibrose kystique est causée par la mutation de gène CFTR (cystic fibrosis
transmembrane conductance regulator), qui code pour un canal chlorique
transmembranaire. La mutation la plus fréquente (ΔF508) induit un repliement
incorrect de la protéine et sa rétention dans le réticulum endoplasmique.
L’absence de CFTR fonctionnel à la membrane a un impact sur l’homéostasie
ionique et sur l’hydratation de la muqueuse respiratoire. Ceci a pour
conséquence un défaut dans la clairance mucocilliaire, induisant infection
chronique et inflammation excessive, deux facteurs fondamentaux de la
physiopathologie.
L’inflammation joue un rôle très important dans l’évolution de la maladie et
malgré le nombre important d’études sur le sujet, la régulation du processus
inflammatoire est encore très mal comprise et la place qu’y occupe le CFTR
n’est pas établie.
Toutefois, plusieurs autres facteurs, tels que le stress oxydatif participent à la
physiopathologie de la maladie, et considérer leurs impacts est important pour
permettre une vision globale des acteurs impliqués.
Dans notre étude, nous exploitons la technologie des puces à ADN, pour
évaluer l’état transcriptionnel d’une cellule épithéliale pulmonaire humaine
fibro-kystique.
Dans un premier temps, l’analyse de notre expérience identifie 128 gènes
inflammatoires sur-exprimés dans les cellules FK par rapport aux cellules non
FK où apparaissent plusieurs familles de gènes inflammatoires comme les
cytokines ou les calgranulines. L’analyse de la littérature et des annotations
suggèrent que la modulation de ces transcripts dépend de la cascade de NF-κB
et/ou des voies de signalisation associées aux interférons (IFN). En outre, leurs
modulations pourraient être associées à des modifications épigénétiques de
leurs loci chromosomiques.
Dans un second temps, nous étudions l’activité transcriptionnelle d’une cellule
épithéliale pulmonaire humaine FK en présence de DMNQ, une molécule
cytotoxique. Notre but est d’identifier les processus biologiques perturbés par la
mutation du gène CFTR en présence du stress oxydatif.
Fondé sur une analyse canonique de redondance, nous identifions 60 gènes
associés à la mort cellulaire et leur variance, observée dans notre expérience,
s’explique par un effet conjoint de la mutation et du stress oxydatif. La mesure
de l’activité des caspases 3/7, des effecteurs de l’apoptose (la mort cellulaire
programmée), montre que les cellules porteuses de la mutation ΔF508, dans
des conditions de stress oxydatif, seraient moins apoptotiques que les cellules
saines. Nos données transcriptomiques suggèrent que la sous-activité de la
cascade des MAPK et la sur-expression des gènes anti-apoptotiques pourraient
être impliquées dans le déséquilibre de la balance apoptotique. / Biotechnical advances have allowed a large number of molecular mechanisms
to be identified, and have also underlined the complexity of gene regulation.
Nonetheless, we still only have a partial understanding of cellular homeostasis.
Even with our current knowledge, molecular dysfunctionality observed in genetic
illnesses such as cystic fibrosis remain largely misunderstood, prohibiting us
from developing efficient treatments. Cystic fibrosis is caused by a mutation of
the CFTR (cystic fibrosis transmembrane conductance regulator) gene which
codes for a chloric transmembrane channel. The most frequent mutation
(ΔF508) causes the unfolding of the protein and its retention in the endoplasmic
reticulum. This absence of a functional CFTR to the membrane has an impact
on the ionic homeostasis and the hydration of the respiratory mucus.
Consequently, the mucociliary clearance is disrupted, which leads to chronic
infection and excessive inflammation - two fundamental factors of CF’s
physiopathology.
Inflammation plays a key role in the evolution of the illness and despite many
studies on this subject, the regulation of the inflammatory process remains a
mystery and CFTR’s role is not well established. Additionally, since the
physiopathology cannot be explained by mutation alone, several authors
suggest the importance of other factors (genetic and/or environmental) which
are factors in the clinical picture of the illness.
In our study, we use microarray technology to evaluate the transcriptional state
of an epithelial lung cell issued from a human with cystic fibrosis. Initially, our
analysis identifies 128 inflammatory genes which are over-expressed in the
cystic fibrosis cells versus non-cystic fibrosis cells, showing several
inflammatory gene families such as cytokines or calgranulins. An analysis of the
publications and annotations of these transcripts suggests that their
modulations depend upon the cascade of NF-κB and/or signalling pathways associated with interferons (IFN). In other words, their modulations could be
associated with epigenetic modifications of their chromosomal loci. Secondly,
we study the transcriptional activity of an epithelial lung cell issued from a
human with cystic fibrosis in the presence of DMNQ, a cytotoxic molecule. Our
goal is to identify the biological processus which are disturbed by the mutation
of the CFTR gene in the presence of oxidative stress.
Based on a canonical redundancy analysis, we identify 60 genes associated
with cell death and their modulation in our study explained by the combined
effect of mutation and oxidative stress. By measuring the activity of caspase
3/7, an effector of apoptosis (programmed cell death), we see that the cells
containing the mutation ΔF508 could present a problem with apoptosis. Our
transcriptomic data suggest that decreased activity of the MAPK cascade and
over-expression of anti-apoptotic genes would be a factor in apoptotic
imbalance.
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Approches transcriptomiques dans l’étude de la fibrose kystiqueVoisin, Gregory 03 1900 (has links)
Les avancées en biotechnologie ont permis l’identification d’un grand nombre
de mécanismes moléculaires, soulignant également la complexité de la
régulation génique. Néanmoins, avoir une vision globale de l’homéostasie
cellulaire, nous est pour l’instant inaccessible et nous ne sommes en mesure
que d’en avoir qu’une vue fractionnée. Étant donné l’avancement des
connaissances des dysfonctionnements moléculaires observés dans les
maladies génétiques telles que la fibrose kystique, il est encore difficile de
produire des thérapies efficaces.
La fibrose kystique est causée par la mutation de gène CFTR (cystic fibrosis
transmembrane conductance regulator), qui code pour un canal chlorique
transmembranaire. La mutation la plus fréquente (ΔF508) induit un repliement
incorrect de la protéine et sa rétention dans le réticulum endoplasmique.
L’absence de CFTR fonctionnel à la membrane a un impact sur l’homéostasie
ionique et sur l’hydratation de la muqueuse respiratoire. Ceci a pour
conséquence un défaut dans la clairance mucocilliaire, induisant infection
chronique et inflammation excessive, deux facteurs fondamentaux de la
physiopathologie.
L’inflammation joue un rôle très important dans l’évolution de la maladie et
malgré le nombre important d’études sur le sujet, la régulation du processus
inflammatoire est encore très mal comprise et la place qu’y occupe le CFTR
n’est pas établie.
Toutefois, plusieurs autres facteurs, tels que le stress oxydatif participent à la
physiopathologie de la maladie, et considérer leurs impacts est important pour
permettre une vision globale des acteurs impliqués.
Dans notre étude, nous exploitons la technologie des puces à ADN, pour
évaluer l’état transcriptionnel d’une cellule épithéliale pulmonaire humaine
fibro-kystique.
Dans un premier temps, l’analyse de notre expérience identifie 128 gènes
inflammatoires sur-exprimés dans les cellules FK par rapport aux cellules non
FK où apparaissent plusieurs familles de gènes inflammatoires comme les
cytokines ou les calgranulines. L’analyse de la littérature et des annotations
suggèrent que la modulation de ces transcripts dépend de la cascade de NF-κB
et/ou des voies de signalisation associées aux interférons (IFN). En outre, leurs
modulations pourraient être associées à des modifications épigénétiques de
leurs loci chromosomiques.
Dans un second temps, nous étudions l’activité transcriptionnelle d’une cellule
épithéliale pulmonaire humaine FK en présence de DMNQ, une molécule
cytotoxique. Notre but est d’identifier les processus biologiques perturbés par la
mutation du gène CFTR en présence du stress oxydatif.
Fondé sur une analyse canonique de redondance, nous identifions 60 gènes
associés à la mort cellulaire et leur variance, observée dans notre expérience,
s’explique par un effet conjoint de la mutation et du stress oxydatif. La mesure
de l’activité des caspases 3/7, des effecteurs de l’apoptose (la mort cellulaire
programmée), montre que les cellules porteuses de la mutation ΔF508, dans
des conditions de stress oxydatif, seraient moins apoptotiques que les cellules
saines. Nos données transcriptomiques suggèrent que la sous-activité de la
cascade des MAPK et la sur-expression des gènes anti-apoptotiques pourraient
être impliquées dans le déséquilibre de la balance apoptotique. / Biotechnical advances have allowed a large number of molecular mechanisms
to be identified, and have also underlined the complexity of gene regulation.
Nonetheless, we still only have a partial understanding of cellular homeostasis.
Even with our current knowledge, molecular dysfunctionality observed in genetic
illnesses such as cystic fibrosis remain largely misunderstood, prohibiting us
from developing efficient treatments. Cystic fibrosis is caused by a mutation of
the CFTR (cystic fibrosis transmembrane conductance regulator) gene which
codes for a chloric transmembrane channel. The most frequent mutation
(ΔF508) causes the unfolding of the protein and its retention in the endoplasmic
reticulum. This absence of a functional CFTR to the membrane has an impact
on the ionic homeostasis and the hydration of the respiratory mucus.
Consequently, the mucociliary clearance is disrupted, which leads to chronic
infection and excessive inflammation - two fundamental factors of CF’s
physiopathology.
Inflammation plays a key role in the evolution of the illness and despite many
studies on this subject, the regulation of the inflammatory process remains a
mystery and CFTR’s role is not well established. Additionally, since the
physiopathology cannot be explained by mutation alone, several authors
suggest the importance of other factors (genetic and/or environmental) which
are factors in the clinical picture of the illness.
In our study, we use microarray technology to evaluate the transcriptional state
of an epithelial lung cell issued from a human with cystic fibrosis. Initially, our
analysis identifies 128 inflammatory genes which are over-expressed in the
cystic fibrosis cells versus non-cystic fibrosis cells, showing several
inflammatory gene families such as cytokines or calgranulins. An analysis of the
publications and annotations of these transcripts suggests that their
modulations depend upon the cascade of NF-κB and/or signalling pathways associated with interferons (IFN). In other words, their modulations could be
associated with epigenetic modifications of their chromosomal loci. Secondly,
we study the transcriptional activity of an epithelial lung cell issued from a
human with cystic fibrosis in the presence of DMNQ, a cytotoxic molecule. Our
goal is to identify the biological processus which are disturbed by the mutation
of the CFTR gene in the presence of oxidative stress.
Based on a canonical redundancy analysis, we identify 60 genes associated
with cell death and their modulation in our study explained by the combined
effect of mutation and oxidative stress. By measuring the activity of caspase
3/7, an effector of apoptosis (programmed cell death), we see that the cells
containing the mutation ΔF508 could present a problem with apoptosis. Our
transcriptomic data suggest that decreased activity of the MAPK cascade and
over-expression of anti-apoptotic genes would be a factor in apoptotic
imbalance.
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