A montagem e desmontagem das adesões focais (AF) desempenham um papel fundamental em diversos processos celulares, incluindo migração celular e sobrevivência. Resultados prévios do nosso laboratório mostram que fibroblastos nulos ou silenciados para miosina-Va sofrem um atraso na desmontagem das adesões, sugerindo um papel para a miosinaVa neste processo. Neste trabalho, visamos analisar a dinâmica de montagem das AF em fibroblastos murinos imortalizados NIH3T3, utilizando sondas fluorescentes para visualização de componentes de adesão focal. A formação das AF foi analisada após estímulo por soro de células quiescentes, o que leva a intensa polimerização de actina, reorganização do citoesqueleto e montagem das AF. A cinética de montagem das AF foi observada em ensaios ao longo do tempo, de células fixadas em 0, 5, 15, 30, 120 minutos após estímulo, e marcadas para miosina-Va fosforilada (p-miosina-Va, S1650), FAK fosforilada (p-FAK, Y397), vinculina, dinamina-2, integrina-?1, faloidina, Ki67 e DAPI. Os nossos resultados mostraram um aumento de fluorescência de p-miosina-Va por todo o citoplasma após a estímulo com soro, e revelaram que a p-miosina-Va co-localiza com pFAK nas AF logo após o estímulo, essa localização da p-miosina-Va nas AF diminui ao passar do tempo e retorna após 120 minutos. Isto é consistente com os resultados anteriores de um papel da miosina-Va na dinâmica das AF. Também é possível perceber uma maior concentração de p-miosina-Va e dinamina-2 na região perinuclear, 5 minutos após estímulo, e o espalhamento de ambas as proteínas pelo citoplasma com o passar do tempo. Demonstramos, por Western blotting, que o estímulo por soro não causa alteração na quantidade total de miosina-Va em nenhum dos tempos analisados em relação à condição de quiescência, mas induz, após 5 e 15 minutos, um aumento apreciável de p-miosina-Va, que sofre queda e variações nos tempos posteriores. Para nosso conhecimento, esta é a primeira demonstração de que a fosforilação da miosina-Va aumenta em resposta ao soro e estamos investigando se este evento está ligado à dinâmica das adesões focais em fibroblastos / The assembly and disassembly of focal adhesions (FA) play a critical role in several cellular process, including cell migration and survival. Previous work from our laboratory showed that fibroblasts without myosin-Va show a delay in focal adhesion disassembly, suggesting a role for myosin-Va in this process. In this work, we aim at imaging the dynamics of focal adhesion disassembly and reassembly in cells, with fluorescent probes for visualization of focal adhesion components. Here, we used murine NIH3T3 fibroblasts to analyze FA formation after serum stimulation of quiescent cells, which leads to intense polymerization of actin and reorganization of the cytoskeleton and FA assembly. The kinetics of FA assembly was observed in a time-course assay of cells fixed at 0, 5, 15, 30 and 120 min after serum stimulation, and stained for phosphorylated myosin-Va (p-myosin-Va, S1650), phosphorylated FAK (p-FAK, Y397), vinculin, phalloidin and DAPI. Our results showed an increase of pmyosin-Va staining throughout the cytoplasm upon serum stimulation, and revealed that pmyosin-Va does not colocalize with FAK in FA at early time points. However, colocalization is observed after 30 to 120 min. This is consistent with previous results of a role for myosin-Va in FA disassembly. It is also possible to observe a higher concentration of p-myosin-Va and dynamin-2 in the perinuclear region 5 minutes after stimulation, and the spreading of both proteins in the cytoplasm over time. We demonstrate by Western blotting that serum stimulation does not cause change in total amount of myosin-Va, in any of the times analyzed in relation to the quiescent condition, but induces, after 5 and 15 minutes, an appreciable increase of pmyosin-Va suffering drop and variations in the later times. To our knowledge, this is the first demonstration that phosphorylation of myosin-Va increases in response to serum and we are investigating whether this event is connected to the dynamics of focal adhesions in fibroblasts

A miosina Va é uma proteína motora envolvida no transporte e posicionamento de vesículas, organelas e mRNA. Além disso, postulou-se que a miosina-Va atua no seqüestro do fator pró-apoptótico, Bmf, no citoesqueleto de actina. Pesquisas realizadas em nosso laboratório demonstraram que um fragmento da miosina Va (MVaf), que corresponde ao sítio ligante de DLC2-Bmf, é capaz de induzir intensa apoptose em células de melanoma e de carcinoma in vitro. O presente trabalho teve por objetivo principal avaliar o potencial do MVaf como agente antitumoral, através de abordagens de terapia gênica em modelo animal. Foram geradas linhagens estabilizadas e com expressão controlada pelo sistema Tet-ON onde a expressão de EGFP ou EGFP-MVaf é induzida com a adição de doxiciclina. Essas linhagens foram testadas quanto à porcentagem de morte por apoptose e ativação de caspases. Tumores foram induzidos em camundongos C57BL/6 por inoculação subcutânea de células tumorigênicas positivas ou não para a expressão de EGFP-MVaf. Também foram utilizadas linhagens de fibroblasto embrionário murino selvagem (MEFs WT) e nocautes para os fatores Bim/Bmf e Bax/Bak (MEFsBim-/-,Bmf-/-; MEFsBax-/-,Bak-/-) para estudos do mecanismo de ação do fragmento da miosina Va. Observou-se que a adição de butirato de sódio potencializa a expressão de EGFP-MVaf e, conseqüentemente, o efeito pró-apoptótico desse fragmento e que essas células são mais sensíveis aos quimioterápicos etoposídeo e taxol, apresentando maior susceptibilidade à apoptose. Verificou-se que a expressão de EGFP-MVaf em células de tumores de melanoma induzidos em camundongos C57BL/6J dificulta o crescimento desses tumores. Quanto ao estudo com MEFs, observou-se que células nocautes para os fatores pró-apoptóticos Bim/Bmf e Bax/Bak são menos susceptíveis à morte induzida pelo fragmento da miosina Va. Indução da expressão de MVaf desencadeia a liberação da proteína proapoptótica Smac (fusionada ao repórter fluorescente Cherry) do espaço intermembranas da mitocôndria para o citoplasma sugerindo que a morte apoptótica induzida por MVaf requer a permeabilização da membrana mitocondrial externa (MOMP). Concluindo, os dados apresentados aqui nos permitem propor o MVaf como uma molécula promissora para o desenvolvimento de novas abordagens terapêuticas contra o câncer. / Myosin Va is a motor protein involved in the transport and positioning of vesicles, organelles and mRNA. Additionally, myosin-Va has been implicated in the sequestering of a proapoptotic factor, Bmf, to the actin cytoskeleton. Research in our laboratory demonstrated that a fragment of myosin Va (MVaf), which corresponds to the binding site of DLC2-Bmf, is capable to induce intense apoptosis in melanoma and carcinoma cells in vitro. Here, our goal was to assess the potential of MVaf as antitumor agent, through gene therapy approaches in animal models. We generated Tet-ON controlled B16-F10 melanoma cells whose expression of EGFP or EGFP-MVaf is induced with the addition of doxycycline. These cells were tested for apoptotic death and activation of caspases, and were used to induce tumors in C57BL/6J mice by subcutaneous inoculation. We also used cell lines of murine embryonic fibroblasts, wild-type (MEFs WT) and knockouts for the proapoptotic proteins Bim/Bmf or Bax/Bak (MEFsBim-/-,Bmf-/-, MEFsBax-/-,Bak-/-), to study the mechanism by which MVaf induces apoptosis. We observed that addition of sodium butyrate to the cultures enhances the EGFP-MVaf expression and, consequently, the pro-apoptotic effect of this fragment. Treated cells were more sensitive to the chemotherapeutic drugs etoposide and taxol, showing a higher susceptibility to apoptosis. Moreover, in vivo induction of EGFP-MVaf expression retards growth of B16-F10 melanoma tumors in mouse model. As for the study with MEFs, we observed that cells knockout for the proapoptotic factors Bim/Bmf or Bax/Bak are less susceptible to death induced by MVaf than wild-type MEFs. Accordingly, we showed that MVaf expression triggers release of the proapoptotic protein Smac (tagged with the fluorescent protein Cherry) supporting the involvement of the mitochondrial outer membrane permeabilization (MOMP) in the MVaf-induced apoptotic death response. In conclusion, these data lead us to propose MVaf as a promising molecule for the development of new therapeutic approaches against cancer.

L’hypertension artérielle pulmonaire (HTAP) est définie par une pression artérielle moyenne >25 mmHg associée à une pression capillaire ≤ 15 mmHg. L’augmentation des résistances artérielles pulmonaires dans l’HTAP est associée à des phénomènes de vasoconstriction, de remodelage pariétal et de thrombose au niveau des artères pulmonaires de petit calibre. Plusieurs données expérimentales montrent que l’hypoxie est susceptible d’induire ces mêmes changements au niveau du lit artériel pulmonaire. De plus, d’après les petites cohortes étudiées dans la littérature, une hypoxémie nocturne (HN) serait fréquente dans l’HTAP pouvant se rencontrer chez presque 77% des malades. Les mécanismes de cette HN sont mal élucidés, en rapport avec une respiration périodique de type Cheyne Stokes (CS) pour certains auteurs, ou avec des apnées-hypopnées obstructives (AHO) du sommeil pour d’autres.Nous avons voulu ainsi explorer le sommeil des malades porteurs d’HTAP à la recherche de ces anomalies du sommeil et dans le but de déterminer leur prévalence et leurs mécanismes physiopathologiques. Quarante six malades hospitalisés dans le service de pneumologie de l’Hôpital Antoine Béclère, centre de référence national pour l’HTAP, ont bénéficié d’une nuit de polysomnographie (CIDELEC) avec une mesure de la capnographie transcutanée (TOSCA). Il s’agissait d’une population homogène comprenant 29 malades porteurs d’une HTAP idiopathique (HTAPI) et de 17 malades porteurs d’un coeur pulmonaire chronique postembolique (CPCPE), n’ayant pas d’anomalies fonctionnelles respiratoires sévères (VEMS etCPT ≥ 60 % de la théorique), ni d’obésité sévère (IMC < 35 Kg/m²), et stables depuis au moins 3mois, sous traitement spécifique optimal pour l’HTAP. Ces malades étaient pour la plupart en classe fonctionnelle II de la NYHA, parcouraient > 400m au test de marche de 6 minutes, etavaient un index cardiaque moyen mesuré sur le cathétérisme cardiaque droit dans les normes(3,2 ± 0,6 L/min/m²).La majorité (38/46 soit 82,6%) avaient une HN définie par un temps de sommeil passé avec uneSpO2 < 90%, > 60min et/ou un index de désaturation ≥ 20/h. Ces patients passaient 48.9 ± 35.9%de leur temps de sommeil avec une SpO2 < 90%. Le mécanisme le plus fréquemment rencontré(76% des malades désaturateurs) correspond à une hétérogénéité ventilation/perfusion (VA/Q)isolée ou associée à des AHO du sommeil. La prévalence des apnées-hypopnées (AH) était très élevée avec un index d’apnées-hypopnées (IAH) ≥ 5/h chez 89% des malades et un IAH moyende 24.9 ± 22.1/ h. La majorité de ces évènements était d’origine obstructive, seulement 4malades présentaient des AH de mécanisme central dont 3 avaient une respiration périodique de type CS. Un seul cas d’hypoventilation alvéolaire nocturne associé à un IAH obstructif modéré a été identifié, avec une désaturation nocturne prolongée concomitante d’une majoration significative de la capnie transcutanée de plus que 30 mmHg. Aucun facteur clinique ni hémodynamique n’a pu être identifié comme prédictif de la survenue de l’HN malgré certaines corrélations notées entre les paramètres de désaturation nocturne et la PaO2 diurne d’une part, et l’obstruction des petites voies aériennes d’autre part.Nous avons pu conclure que l’HN est fréquente dans l’HTAPI et dans le CPCPE, en rapport avec un déséquilibre VA/Q et/ou des AHO du sommeil. Reste à préciser dans des études ultérieures si la correction de cette HN aura des effets bénéfiques pour les patients en termes d’amélioration fonctionnelle, hémodynamique ou de réponse au traitement. / Precapillary pulmonary hypertension (PH) is defined by a mean pulmonary pressure > 25 mmHg associated with a normal wedge pressure (≤ 15 mmHg). Increase in vascular resistances in PH is due to vasoconstriction, vascular wall remodelling and thromboses of small pulmonary arterioles. Hypoxia is known to cause similar changes in pulmonary vasculature. Although some cohorts studies have shown that nocturnal hypoxemia (NH) is frequent in PH, accounting for up to 77% of cases, the mechanisms of this NH were not well established, being associated to periodic respiration like the Cheyne Stokes respiration (CS) by some authors, and to obstructive apneas-hypopneas (OAH) by others.The aim of our study was to search for sleep-related breathing disorders in PH, to determine their prevalence and their mechanisms. Fourty six patients hospitalized in the pulmonary department of Antoine Béclère Hospital, which is the national referral center for PH in France, underwent a one night polysomnography (CIDELEC) with a transcutaneous capnography (TOSCA). Our population was homogeneous with 29 patients having idiopathic pulmonary arterial hypertension (IPAH) and 17 patients having chronic thrombo-embolic PH (CTEPH). Patients had no severe functional limitation (FEV1 and TLC ≥ 60 % of predicted), nor severe obesity (BMI < 35 Kg/m²), and they were in a steady state with optimal PH treatment for at least three months. The majority of patients were in NYHA functional class II, had a 6 minutes walking distance > 400m and a mean cardiac index measured on right heart catheterization within normal ranges (3,2 ± 0,6 L/min/m²).Thirty eight out of the 46 patients (82,6%) had a NH as defined by a sleeping time spent with a SpO2 < 90%, > 60min and/or an oxygen desaturation index ≥ 20/h. These patients spent 48.9 ± 35.9% of their sleeping time with a SpO2 < 90%. The most frequent mechanism underlying theses abnormalities (76% of desaturators patients) was due to ventilation/perfusion (VA/Q) heterogeneity, isolated or associated to OAH. Apneas-hypopneas (AH) were frequent in PH patients with an AH index (AHI) ≥ 5/h in 89% of cases, and a mean AHI of 24.9 ± 22.1/ h. Most of these respiratory events were obstructive, only four patients had central AH with a CS pattern in 3 out them. A single case of alveolar hypoventilation associated with a moderate AHI was identified and was caracterized by a sustained nocturnal desaturation associated with a significant increase in transcutaneous CO2 pressure ( > 30 mmHg). No clinical nor hemodynamic factor was found to be predicting for NH, although minor correlations were found between nocturnal desaturation parameters and PaO2, and nocturnal desaturation parameters and small airways obstruction.We conclude that NH is frequent in IPAH and CTEPH, due to VA/Q mismatch and/or OAH. Future studies are needed to determine the impact of the correction of this NH on PH patients regarding their NYHA functionnal class, their hemodynamic parameters and their responsiveness to PH specific treatment.

A miosina Va é uma proteína motora envolvida no transporte e posicionamento de vesículas, organelas e mRNA. Além disso, postulou-se que a miosina-Va atua no seqüestro do fator pró-apoptótico, Bmf, no citoesqueleto de actina. Pesquisas realizadas em nosso laboratório demonstraram que um fragmento da miosina Va (MVaf), que corresponde ao sítio ligante de DLC2-Bmf, é capaz de induzir intensa apoptose em células de melanoma e de carcinoma in vitro. O presente trabalho teve por objetivo principal avaliar o potencial do MVaf como agente antitumoral, através de abordagens de terapia gênica em modelo animal. Foram geradas linhagens estabilizadas e com expressão controlada pelo sistema Tet-ON onde a expressão de EGFP ou EGFP-MVaf é induzida com a adição de doxiciclina. Essas linhagens foram testadas quanto à porcentagem de morte por apoptose e ativação de caspases. Tumores foram induzidos em camundongos C57BL/6 por inoculação subcutânea de células tumorigênicas positivas ou não para a expressão de EGFP-MVaf. Também foram utilizadas linhagens de fibroblasto embrionário murino selvagem (MEFs WT) e nocautes para os fatores Bim/Bmf e Bax/Bak (MEFsBim-/-,Bmf-/-; MEFsBax-/-,Bak-/-) para estudos do mecanismo de ação do fragmento da miosina Va. Observou-se que a adição de butirato de sódio potencializa a expressão de EGFP-MVaf e, conseqüentemente, o efeito pró-apoptótico desse fragmento e que essas células são mais sensíveis aos quimioterápicos etoposídeo e taxol, apresentando maior susceptibilidade à apoptose. Verificou-se que a expressão de EGFP-MVaf em células de tumores de melanoma induzidos em camundongos C57BL/6J dificulta o crescimento desses tumores. Quanto ao estudo com MEFs, observou-se que células nocautes para os fatores pró-apoptóticos Bim/Bmf e Bax/Bak são menos susceptíveis à morte induzida pelo fragmento da miosina Va. Indução da expressão de MVaf desencadeia a liberação da proteína proapoptótica Smac (fusionada ao repórter fluorescente Cherry) do espaço intermembranas da mitocôndria para o citoplasma sugerindo que a morte apoptótica induzida por MVaf requer a permeabilização da membrana mitocondrial externa (MOMP). Concluindo, os dados apresentados aqui nos permitem propor o MVaf como uma molécula promissora para o desenvolvimento de novas abordagens terapêuticas contra o câncer. / Myosin Va is a motor protein involved in the transport and positioning of vesicles, organelles and mRNA. Additionally, myosin-Va has been implicated in the sequestering of a proapoptotic factor, Bmf, to the actin cytoskeleton. Research in our laboratory demonstrated that a fragment of myosin Va (MVaf), which corresponds to the binding site of DLC2-Bmf, is capable to induce intense apoptosis in melanoma and carcinoma cells in vitro. Here, our goal was to assess the potential of MVaf as antitumor agent, through gene therapy approaches in animal models. We generated Tet-ON controlled B16-F10 melanoma cells whose expression of EGFP or EGFP-MVaf is induced with the addition of doxycycline. These cells were tested for apoptotic death and activation of caspases, and were used to induce tumors in C57BL/6J mice by subcutaneous inoculation. We also used cell lines of murine embryonic fibroblasts, wild-type (MEFs WT) and knockouts for the proapoptotic proteins Bim/Bmf or Bax/Bak (MEFsBim-/-,Bmf-/-, MEFsBax-/-,Bak-/-), to study the mechanism by which MVaf induces apoptosis. We observed that addition of sodium butyrate to the cultures enhances the EGFP-MVaf expression and, consequently, the pro-apoptotic effect of this fragment. Treated cells were more sensitive to the chemotherapeutic drugs etoposide and taxol, showing a higher susceptibility to apoptosis. Moreover, in vivo induction of EGFP-MVaf expression retards growth of B16-F10 melanoma tumors in mouse model. As for the study with MEFs, we observed that cells knockout for the proapoptotic factors Bim/Bmf or Bax/Bak are less susceptible to death induced by MVaf than wild-type MEFs. Accordingly, we showed that MVaf expression triggers release of the proapoptotic protein Smac (tagged with the fluorescent protein Cherry) supporting the involvement of the mitochondrial outer membrane permeabilization (MOMP) in the MVaf-induced apoptotic death response. In conclusion, these data lead us to propose MVaf as a promising molecule for the development of new therapeutic approaches against cancer.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 85 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 62-69).

Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains ix, 199 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 142-172).

Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xxxvii, 556 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 505-530).

Thesis (M.S.)--Northwest Missouri State University, 2006. / The full text of the thesis is included in the pdf file. Title from title screen of full text.pdf file (viewed on January 25, 2008) Includes bibliographical references.

Thesis (Ph.D.)--Bowling Green State University, 2007. / Document formatted into pages; contains x, 268 p. : ill. Includes bibliographical references.

Report (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Abstract. Includes bibliographical references (leaves 173-175). Also available via the Internet.