ENGLISH ABSTRACT: This research study examines the beliefs related to HIV/AIDS risks and the perceived effectiveness of preventative measures among men who have sex with men (MSM) in the Philippines. Using a questionnaire developed using the Health Belief Model (HBM), this study endeavors to understand beliefs and thus improve counseling guidelines for MSM who continue to engage in risky sexual behaviors following VCT and a negative HIV test. The impact of HIV/AIDS on the Philippines is beginning to increase, affecting men and their partners. The rapid growth of HIV/AIDS among Filipino MSM indicates that more attention must be paid to the barriers and benefits of condom use within this high-risk population. A background of the presence and prevalence of HIV/AIDS is presented. This study aims to answer the question of why MSM choose to have unprotected sex despite the risk of HIV/AIDS. Multiple barriers to condom use are identified, including the availability of condoms, partner resistance, and reduced pleasure. The impacts of culture and society, the media, role models, social networking, drug use, and riskseeking behavior on safer sex are assessed. Currently, supplying condoms and providing voluntary testing and counseling is the primary mode of preventing the spread of HIV/AIDS, but this study sheds light on the critical issues of condom availability, perceived benefits and barriers to condom use, and the disconnect between belief and behavior regarding HIV/AIDS and unprotected sex among MSM in the Philippines. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie is ‗n ondersoek na die gelowe (beliefs) teenoor MIV/Vigs van mans wat seks het met mans. Die studie poog verder om ondersoek in te stel na moontlike voorkomende maatreëls wat ingestel kan word om die pandemie te bekamp. Vir die doel van hierdie studie is ‗n vraelys ontwikkel , deur gebruik te maak van die Health Belief Model, met die doel om ‗n beter begrip te kry van die redes vir risikogedrag onder mans wat seks het met mans in die Fillipyne. Die voorkoms van MIV/Vigs by mans wat seks het met mans is steeds aan die toeneem in die Fillipyne en dringende maatreëls is nodig om die groei van die pandemie te beperk. Die studie gee ‗n agtergrond tot MIV/Vigs in die Fillipyne. Die ondersoek gaan dan voort om te probeer bepaal waarom risikogroepe steeds voortgaan om aan onbeskermende seksuele aktiwiteite deel te neem. Resultate van die studie toon aan dat daar verskeie faktore is wat die gebruik van kondome ontmoedig in die risikogroep wat in hierdie studie aangespreek word. Kondome is nie altyd beskikbaar nie; seksuele vennote wil nie kondome gebruik nie en die vermindering in seksuele plesier word as redes aangevoer. Hierdie studie maak ‗n betekenisvolle bydrae tot die kennisbasis van die gelowe en houdings van mans wat seks het met mans ( en dan MIV-positief raak) en sal na alle waarskynlikheid betekenisvol bydra tot die meer suksesvolle bestuur van hierdie risikogroep in die Fillipyne.

Orientadores: Ricardo Della Coletta / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-08T10:13:56Z (GMT). No. of bitstreams: 1 Kellermann_MicheleGassen_M.pdf: 7081886 bytes, checksum: a59559c13daf66177d18ab7cb24bfbcf (MD5) Previous issue date: 2007 / Resumo: Miofibroblastos são caracterizados pela expressão de niveis elevados de fatores de crescimento, proteases e proteinas da matriz extracelular, que podem influenciar a progressão tumoral. Recentes estudos encontraram miofibroblastos no estroma de varios tipos de canceres humanos, incluindo os de mama, rim, figado, bexiga, colon e prostata, sendo a presença dos miofibroblastos frequentemente associada a um pior prognostico. Os objetivos deste estudo foram avaliar a presença dos miofibroblastos em amostras de mucosa oral normal, leucoplasias com o diagnostico histologico de displasia e 2 grupos de carcinomas espinocelulares (CEC) orais e correlacionar a presença destas celulas com as caracteristicas cronico-patologicas dos tumores. O primeiro grupo foi formado por leses exclusivamente de língua, enquanto que o segundo grupo foi composto por 38 CECs de várias localizações da cavidade oral. Adicionalmente, nós determinamos in vitro o efeito dos produtos da síntese das células de CEC oral sobre a transdiferenciação dos fibroblastos em miofibroblastos, bem como o efeito dos produtos de síntese dos miofibroblastos sobre a proliferação celular e atividade das metaloproteinases de matriz (MMP) nas linhagens celulares de CEC oral. A análise imunohistoquímica revelou a ausência dos miofibroblastos em amostras de mucosa oral normal e em lesões leucoplásicas com o diagnóstico histológico de displasia. Em contraste, miofibroblastos foram encontrados no estroma e/ou fronte invasivo de aproximadamente 60% das amostras de CEC oral. No primeiro grupo, a presença abundante dos miofibroblastos no estroma ou fronte invasivo do tumor correlacionou significantemente com o estádio clínico N, invasão linfática e vascular, presença de metástases histologicamente confirmadas em linfonodos e infiltração extra-capsular de metástases linfonodais. Presença abundante dos miofibroblastos foi também correlacionada com uma menor sobrevida global dos pacientes e com um maior potencial proliferativo das células tumorais. No segundo grupo de CECs orais, a presença abundante dos miofibroblastos correlacionou significantemente com o estádio clínico N, presença de células tumorais nas margens da peça cirúrgica e recorrência regional. Utilizando 4 linhagens celulares de CEC oral e 3 linhagens de fibroblastos de mucosa oral normal, nós demonstramos que as células tumorais induzem a transdiferenciação dos fibroblastos em miofibroblastos e que este evento é dependente da secreção de fator de crescimento transformante-β1 (TGF-β1) pelas células tumorais. Adicionalmente, nós demonstramos que os miofibroblastos secretam fatores que estimularam significantemente a proliferação celular e a produção de MMP-2 pelas linhagens celulares de CEC oral. Os resultados deste estudo sugerem que durante a progressão tumoral, as células neoplásicas secretam TGF-β1 que promove a transdiferenciação dos miofibroblastos, e por sua vez, miofibroblastos secretam fatores que induzem a proliferação celular e a produção de MMP-2 pelas células neoplásicas, favorecendo o crescimento e a invasão tumoral / Abstract: Myofibroblasts are characterized by the expression of elevated amounts of growth factors, proteases and extracellular matrix, which may influence the tumor progression. Recent studies have detected myofibroblasts in the stroma of several tumors, including those of breast, kidney, liver, bladder, colon and prostate, being the presence of those cells associated with a worse prognosis for the patient. The goals of this study were to evaluate the presence of myofibroblasts in samples of normal oral mucosa, pre-malignant leucoplakia, and 2 groups of squamous cell carcinomas (SCC), and to determine whether their presence is associated with clinicopathological features of the tumors. The first group was composed exclusively by tongue lesions, whereas the second group was formed by 38 SCCs of several sites of the oral cavity. We also investigated in vitro the mutual paracrine effects of tumor cells and myofibroblasts on fibroblast-myofibroblast transdifferentiation and tumor cell proliferation and production of matrix metalloproteinases (MMP). Immunohistochemical analysis showed the lack of myofibroblasts in the stroma of normal oral mucosa and pre-malignant oral leucoplakias. In contrast, ~60% of the SCCs contained myofibroblasts in the tumor stroma and/or deep invasive front of the tumor. In the first group, the abundant presence of myofibroblasts in the stroma or deep invasive front significantly correlated with N stage, vascular and lymphatic invasion, histopathologically confirmed lymph node metastasis, and extracapsular spread of lymph node metastasis. The abundant presence of myofibroblasts was also correlated with a shorter patientâ?¿s survival and the proliferative potential of the tumor cells. In the second group of oral SCCs, the abundant presence of myofibroblasts correlated significantly with N stage, presence of tumor cells at the surgical margins, and regional recurrence. Using 4 oral SCC cell lines and 3 primary oral normal fibroblasts (ONF) from buccal mucosa, we demonstrated that tumor cells induced transdifferentiation of ONFs to myofibroblasts via secretion of transforming growth factor-beta 1 (TGF-β1). Additionally, we demonstrated that transdifferentiated myofibroblasts secreted factors that significantly stimulated the cellular proliferation and production of MMP-2 by the oral SCC cell lines. The results of this study suggest that during tumor invasion SCC-derived TGF-β1 promote fibroblast to myofibroblast transdifferentiation, and in turn, myofibroblasts synthesize factors that induce cellular proliferation and production of MMP-2 by the tumor cells, favoring tumor growth and invasion / Mestrado / Patologia / Mestre em Estomatopatologia

This on-road field investigation employed, for the first time, a completely automated, trigger-based data collection system capable of evaluating driver performance in an extended duration real-world commercial motor vehicle environment. The complexities associated with the development of the system, both technological and logistical and the necessary modifications to the plan of research are presented herein This study, performed in conjunction with an on-going three year contract with the Federal Highway Administration, examined the use of self-rating of alertness and temporal separation (minimum time-to-collision, minimum headway, and mean headway) as indicators of driver fatigue. Without exception, the regression analyses for both the self-rating of alertness and temporal separation yielded models low in predictive ability; neither metric was found to be a valid indicator of driver fatigue. Various reasons for the failure of self-rating of fatigue as a valid measure are discussed. Dispersion in the data, likely due to extraneous (non-fatigue related) factors (e.g., other drivers) are credited with reducing the sensitivity of the temporal separation indicators. Overall fatigue levels for all temporal separation incidents (those with a time-to-collision equal to or less than four seconds) were found to be significantly higher than for those randomly triggered incidents. On this basis, it is surmised that temporal separation may be a sensitive indicator for time-to-collision values greater than the 4-second criterion employed in this study. Two unexpected relationships in the data are also discussed. A "wall" effect was found to exist for minimum time-to-collision values at 1.9 seconds. That is, none of the participants who participated in this research effort exhibited following behaviors with less than a 1.9-second time-to-collision criterion. In addition, based upon the data collected for this research, anecdotal evidence suggests that commercial motor vehicle operators do not appear to follow the standard progression of events associated with the onset of fatigue. / Ph. D.

Les troubles métaboliques caractéristiques d’une alimentation de type « Western diet », sont à l’origine de pathologies cardiovasculaires, première cause de mortalité dans le monde. Il apparait nécessaire d’améliorer la compréhension des mécanismes impliqués dans l’installation des dysfonctions cardiovasculaires afin de pouvoir proposer des stratégies thérapeutiques ou préventives adaptées. Ainsi, le premier objectif de la thèse a été d’évaluer les effets d’une boisson sucrée sur la fonction vasculaire macro- et micro-circulatoire chez des sujets sains, par une approche translationnelle allant de la clinique humaine à un modèle expérimental de rongeur. Nos résultats montrent une altération de la fonction endothéliale en réponse à une prise de boisson sucrée, dans l’ensemble des lits vasculaires. L’exploration des mécanismes sous-jacents ces altérations nous a permis d’identifier l’implication du couple stress-oxydant/voie du NO. Un second objectif de thèse, a été d’étudier l’impact d’un stress métabolique chronique sur la fonction vasculaire et son incidence sur la régulation de la pression artérielle. Comme observé chez certains sujets souffrant de syndrome métabolique, notre modèle de rat ne présentait pas d’hypertension artérielle, malgré une hyperactivité du système sympathique. Ceci semble être expliqué par une compensation endothéliale eNOS-dépendant, qui permet de garantir le maintien d’une pression artérielle normale en dépit de l’effet vasopresseur adrénergique élevé. Le troisième objectif de thèse a porté sur un nouvel élément participant au maintien de l’homéostasie vasculaire et impacté par les situations pathologiques : le tissu adipeux périvasculaire (PVAT). Nos travaux démontrent dans le contexte du SMet, une altération de la voie adiponectine/eNOS dans le PVAT, en parallèle d’une augmentation de la production d’espèces oxygénées réactives.La pratique régulière d’un exercice physique est aujourd’hui reconnue comme une stratégie non-pharmacologique permettant d’impacter à la fois les désordres métaboliques et cardiovasculaires, notamment via une amélioration de la voie du NO. Nos résultats démontrent une limitation de l’apparition des dysfonctions endothéliales causée par une hyperglycémie aigue lorsqu’un protocole d’exercice physique chronique est réalisé. Enfin, l’exercice physique permet également de prévenir les modifications des propriétés vaso-actives du PVAT dans un modèle de rat SMet. Ce phénomène pourrait être expliqué par une amélioration du statut oxydant de la paroi artérielle, et à une potentialisation de la voie adiponectine/eNOS par l’exercice physique / The globalization of the western diet has mediated prevalence in cardiovascular disease related mortality, the single leading cause of death worldwide. Considering this, it is imperative that the underlying mechanisms of cardiovascular dysfunctions are continually investigated to establish a greater understanding of its pathogenesis from a healthy state to the presence of cardiometabolic diseases; and to improve upon current treatment and preventative strategies. Therefore, the first aim of this research was to identify vascular impact of acute hyperglycaemic stress induced by sweet sugar beverage consumption, with a translational approach. The results of this study demonstrated that consumption of a single commercially available sugar-sweetened beverage (SSB) induced transient micro- and macrovascular endothelial dysfunction, even in a healthy population. Further exploration into the underlying mechanisms of SSB-mediated endothelial dysfunction indicated that an increase in oxidative stress disrupts normal function of the nitric oxide pathway. Although disturbances in cardiovascular function may initially be transient, repetitive acute metabolic stress may translate to chronic cardiometabolic disease. Therefore, the second aim of this research was to assess the impact of a chronic metabolic disorder, metabolic syndrome (MetS), on vascular function in a rat model. Despite increasing sympathetic activity, the MetS rats didn’t present elevated arterial pressure. Such findings may be explained by a compensatory adaptation of endothelial function that increases production of nitric oxide in response to α-adrenergic agonist and, thus, regulates arterial pressure despite sympathetic hyperactivity. Considering this, the third aim of this research evaluated the impact of perivascular adipose tissue (PVAT) on vascular fucntion in MetS rats; demonstrating that MetS altered the adiponectin-endothelial nitric oxide synthase pathway in PVAT, in an oxidative stress-dependant manner.Exercise training is well recognized as a non-pharmacological strategy that has a beneficial impact on both metabolic and cardiovascular disorders via an improvement in function of the nitric oxide pathway. Considering this, research also assessed the efficacy of this approach to prevent vascular injury induced by acute hyperglycaemia in a healthy population and by PVAT in those with MetS. It was demonstrated that exercise attenuated acute hyperglycemia-mediated endothelial dysfunction; and restored endothelium-dependent vascular reactivity in rats with MetS, due to an improvement in the biocommunication between PVAT and arterial tissue and a notable enhancement of the adiponectine-endothelial nitric oxide synthase pathway.

A migração de células musculares lisas (VSMC) da camada média do vaso para a íntima é essencial para vasculogênese e contribui para o processo de aterosclerose e estenose após lesão por cateter-balão, caracterizando-se como um importante alvo terapêutico. Diversos trabalhos já demonstraram que fatores de crescimento (como PDGF e FGF) estimulam a migração de VSMC, inclusive, muitos desses fatores de crescimento induzem sinalização redox associadas à geração de espécies reativas de oxigênio (ROS) (ex. Nox1 NADPH oxidase). Nosso grupo já descreveu interações físicas e regulação funcional da NADPH oxidase por uma chaperona redox do retículo endoplasmático, a Dissulfeto Isomerase Protéica (PDI). Contudo, tanto a relevância fisiológica como os mecanismos desta interação ainda não estão claros. O objetivo geral do presente trabalho é investigar por meio de experimentos de perda e ganho de função da PDI, a importância da PDI na migração celular associada à ativação do complexo NADPH oxidase, bem como possíveis mecanismos envolvidos na interação entre a PDI e esse complexo enzimático durante a migração celular. Os objetivos específicos são: i) avaliar o efeito do silenciamento da PDI, bem como da expressão forçada de PDI wild type na migração de VSMC in vitro; ii) analisar o efeito da transfecção de siRNA da PDI atividade e expressão de distintas isoformas da NADPH oxidase vascular e produção de ROS induzida por PDGF; iii) investigar o envolvimento de RhoGTPases na regulação do complexo NADPH oxidase pela PDI. No presente trabalho, mostramos que o PDGF induz redistribuição da PDI e aumento da produção de ROS. O silenciamento da PDI inibe a produção de ROS e a expressão do mRNA da Nox1, sem alterar a expressão do mRNA da Nox4. Mais ainda, o silenciamento da PDI reduz a migração celular induzida por PDGF, em diferentes modelos de migração, enquanto a super-expressão da PDI induz aumento espontâneo da migração na condição basal. Análise utilizando métodos de Biologia de Sistemas de redes de interação física proteína-proteína em bancos de dados e técnicas de análise de centralidade, topologia e ontologia gênica indicou forte convergência entre PDI e proteínas da família das pequenas RhoGTPases e seus reguladores. Em VSMC com silenciamento da PDI, a presença do PDGF induziu uma redução na atividade de Rac1 e RhoA, sem alterar a expressão total destas proteínas. Estudos mostraram que a PDI colocaliza com Rac1 na região perinuclear e co-imunoprecipita com Rac1 e RhoA, tanto na presença como na ausência de PDGF. Além disso, ocorreu a interação entre PDI e o regulador de GTPases RhoGDI (inibidor da dissociação da guanina) na condição basal (por microscopia confocal e co-imunoprecipitação), diminuída após estimulo com PDGF. O silenciamento da PDI induziu ainda alterações em estrutura de citoesqueleto: desorganização das fibras de estresse, e redução no número e tamanho de adesões focais e vesículas de adesão marcadas por RhoGDI e Rac1. Assim, os dados apresentados no presente trabalho sugerem que a PDI sustenta a migração de VSMC dependente de sinalização redox e RhoGTPases. Além disso, RhoGTPases podem ser um alvo proximal importante mediando a convergência entre PDI e o complexo NADPH oxidase / Vascular Smooth Muscle Cell (VSMC) migration into vessel neointima is a therapeutic target for atherosclerosis and post-injury restenosis. NADPH oxidase-derived oxidants synergize with growth factors to support VSMC migration. We described interaction between NADPH oxidases and the endoplasmic reticulum redox chaperone Protein Disulfide Isomerase (PDI) in many cell types. However, physiological implications as well as mechanisms of such association are yet unclear. The aim of the present work was to investigate, througth experiments of gain or loss of PDI function, the importance of PDI in VSMC migration associated to NADPH oxidase. The specific aims were: i) to evaluate effects of PDI silencing or PDI overexpression in VSMC migration in vitro; ii) to evaluate effects of PDI silencing on PDGF-induced NADPH oxidase isoform expression and ROS production; iii) to evaluate the involvement of RhoGTPases on NADPH oxidase regulation by PDI. We show here that PDGF promoted subcellular redistribution of PDI concomitant to ROS production and that siRNA-mediated PDI silencing inhibited such ROS production, while near-totally suppressing the increase in Nox1 expression, with no change in Nox4. Furthermore, PDI silencing inhibited PDGF-induced VSMC migration assessed by distinct methods, while PDI overexpression increased spontaneous basal VSMC migration. To address possible mechanisms of PDI effects, we searched for PDI interactome by PPPI networks, which indicated convergence with small GTPases and their regulator RhoGDI. PDI silencing decreased PDGF-induced Rac1 and RhoA activities, without change in their expression. PDI displayed small detectable points of perinuclear co-localization with Rac1 and co-immunoprecipitated with Rac1 and RhoA in a PDGF-independent way. Moreover, there was PDI association with RhoGDI at baseline (confocal and co-immunoprecipitation), decreased after PDGF. Of note, PDI silencing promoted strong cytoskeletal changes: branched stress fiber disorganization, markedly decreased number of focal adhesions and reduced number of RhoGDI-containing vesicular recycling adhesion structures. Overall, these data suggest that PDI is required to support redox and GTPase-dependent VSMC migration. Moreover, RhoGTPases are a potential upstream target mediating the convergence between PDI and NADPH oxidase

Organisms inhabit environments that have many dimensions, each of which can vary temporally and spatially. The spatial-temporal variations of environmental stressors and disturbances may have major but different effects on indigenous and invasive species, favouring either of them at different times and places. The invasive mussel Mytilus galloprovincialis invaded the South African coast 30 years ago and, on the south coast of South Africa, it now competes and co-exists with the indigenous Perna perna in the lower eulittoral zone (referred to here as the mussel zone) The invasive and indigenous species dominate the upper and the lower mussel zones respectively, while the two co-exist in the mid-zone. My results show that intertidal mussels experience, and respond to, spatial and temporal fluctuations of several biotic and abiotic stressors. The invasive and the indigenous species adopt different strategies when reacting to environmental factors and their physiological and behavioural responses vary in time and in different habitats as different pressures become of overriding importance. Attachment strength of both species decreased in summer and increased in winter, and was higher on the open coast than in bays for both species, showing a strong positive correlation with wave force in time and space. P. perna had significantly higher attachment strength than M. galloprovincialis but, contrary to previous studies, the difference in gonad index between the two species varied according to the habitat. In bay habitats, M. galloprovincialis had a higher maximum reproductive effort than P. perna, however, on the open coast, there was no significant difference between the two species, suggesting that for the invasive species wave action is a limiting factor not only in terms of the attachment strength but also of energy availability for reproductive tissue development. Major spawning events occurred during periods of low wave action while minor spawning coincided with periods of intense hydrodynamic stress. On the open coast, gonad index was negatively correlated with attachment strength for both species while, in bays, there was no correlation between these two factors for either. The two species also showed different behaviour. In the field, M. galloprovincialis moved significantly more than P. perna over a period of six months. The higher mobility of the invasive species was also confirmed in the laboratory where, in general, M. galloprovincialis formed clumps more readily than P. perna. Taken collectively, these results suggest that channelling more energy into attachment strength limits reproductive tissue development and that, while the indigenous species invests more in byssal production, the invasive species adopts a more dynamic strategy looking for aggregation or a safer arrangement. Higher endolithic infestation and a greater expression of heat shock proteins (Hsps) in mussel populations on the open coast than in bays indicate that this habitat is a more stressful environment not only in terms of wave action. Endolith damaged mussels had significantly lower attachment strengths and condition indices than clean mussels, probably due to the need to channel energy into shell repair. The constant shell repair and expression of Hsps typical of open coast populations are energetically demanding processes. These observations suggest that on the open coast, mussels are subjected to more severe energetic constraints than in bay habitats. Wave and sand stress fluctuated seasonally with the former having a greater effect on mussel mortality on the open coast and the latter a higher impact on bay populations. Overall, mussel mortality rates were higher on the open coast than in bays. My results show that populations on the open coast had fewer private haplotypes and less genetic endemism than those inside bays. Gene flow analysis showed the relatively stable bay habitats act as source populations with greater genetic migration rates out of bays than into them. These differences in genetic structure on scales of las of kilometers show that coastal configuration strongly affects selection, larval dispersal and haplotype diversity. Environmental gradients that are key factors in species distribution over large geographical scales can also be responsible for micro-scale distributions. My results show that M. galloprovincialis colonizes the upper mussel zone where temperature is high, but is less tolerant to this stressor and has to maintain a high expression of Hsps. This suggests that temperature is probably a limiting factor in its invasion towards the sub-tropical east coast. There are inter- and intra-specific differences in responses to the environment which highlight the efforts of M. galloprovincialis and P. perna to optimize resource utilization for survival and reproduction. Determining these differences is crucial to understanding patterns of co-existence between competing indigenous and invasive species.

A migração de células musculares lisas (VSMC) da camada média do vaso para a íntima é essencial para vasculogênese e contribui para o processo de aterosclerose e estenose após lesão por cateter-balão, caracterizando-se como um importante alvo terapêutico. Diversos trabalhos já demonstraram que fatores de crescimento (como PDGF e FGF) estimulam a migração de VSMC, inclusive, muitos desses fatores de crescimento induzem sinalização redox associadas à geração de espécies reativas de oxigênio (ROS) (ex. Nox1 NADPH oxidase). Nosso grupo já descreveu interações físicas e regulação funcional da NADPH oxidase por uma chaperona redox do retículo endoplasmático, a Dissulfeto Isomerase Protéica (PDI). Contudo, tanto a relevância fisiológica como os mecanismos desta interação ainda não estão claros. O objetivo geral do presente trabalho é investigar por meio de experimentos de perda e ganho de função da PDI, a importância da PDI na migração celular associada à ativação do complexo NADPH oxidase, bem como possíveis mecanismos envolvidos na interação entre a PDI e esse complexo enzimático durante a migração celular. Os objetivos específicos são: i) avaliar o efeito do silenciamento da PDI, bem como da expressão forçada de PDI wild type na migração de VSMC in vitro; ii) analisar o efeito da transfecção de siRNA da PDI atividade e expressão de distintas isoformas da NADPH oxidase vascular e produção de ROS induzida por PDGF; iii) investigar o envolvimento de RhoGTPases na regulação do complexo NADPH oxidase pela PDI. No presente trabalho, mostramos que o PDGF induz redistribuição da PDI e aumento da produção de ROS. O silenciamento da PDI inibe a produção de ROS e a expressão do mRNA da Nox1, sem alterar a expressão do mRNA da Nox4. Mais ainda, o silenciamento da PDI reduz a migração celular induzida por PDGF, em diferentes modelos de migração, enquanto a super-expressão da PDI induz aumento espontâneo da migração na condição basal. Análise utilizando métodos de Biologia de Sistemas de redes de interação física proteína-proteína em bancos de dados e técnicas de análise de centralidade, topologia e ontologia gênica indicou forte convergência entre PDI e proteínas da família das pequenas RhoGTPases e seus reguladores. Em VSMC com silenciamento da PDI, a presença do PDGF induziu uma redução na atividade de Rac1 e RhoA, sem alterar a expressão total destas proteínas. Estudos mostraram que a PDI colocaliza com Rac1 na região perinuclear e co-imunoprecipita com Rac1 e RhoA, tanto na presença como na ausência de PDGF. Além disso, ocorreu a interação entre PDI e o regulador de GTPases RhoGDI (inibidor da dissociação da guanina) na condição basal (por microscopia confocal e co-imunoprecipitação), diminuída após estimulo com PDGF. O silenciamento da PDI induziu ainda alterações em estrutura de citoesqueleto: desorganização das fibras de estresse, e redução no número e tamanho de adesões focais e vesículas de adesão marcadas por RhoGDI e Rac1. Assim, os dados apresentados no presente trabalho sugerem que a PDI sustenta a migração de VSMC dependente de sinalização redox e RhoGTPases. Além disso, RhoGTPases podem ser um alvo proximal importante mediando a convergência entre PDI e o complexo NADPH oxidase / Vascular Smooth Muscle Cell (VSMC) migration into vessel neointima is a therapeutic target for atherosclerosis and post-injury restenosis. NADPH oxidase-derived oxidants synergize with growth factors to support VSMC migration. We described interaction between NADPH oxidases and the endoplasmic reticulum redox chaperone Protein Disulfide Isomerase (PDI) in many cell types. However, physiological implications as well as mechanisms of such association are yet unclear. The aim of the present work was to investigate, througth experiments of gain or loss of PDI function, the importance of PDI in VSMC migration associated to NADPH oxidase. The specific aims were: i) to evaluate effects of PDI silencing or PDI overexpression in VSMC migration in vitro; ii) to evaluate effects of PDI silencing on PDGF-induced NADPH oxidase isoform expression and ROS production; iii) to evaluate the involvement of RhoGTPases on NADPH oxidase regulation by PDI. We show here that PDGF promoted subcellular redistribution of PDI concomitant to ROS production and that siRNA-mediated PDI silencing inhibited such ROS production, while near-totally suppressing the increase in Nox1 expression, with no change in Nox4. Furthermore, PDI silencing inhibited PDGF-induced VSMC migration assessed by distinct methods, while PDI overexpression increased spontaneous basal VSMC migration. To address possible mechanisms of PDI effects, we searched for PDI interactome by PPPI networks, which indicated convergence with small GTPases and their regulator RhoGDI. PDI silencing decreased PDGF-induced Rac1 and RhoA activities, without change in their expression. PDI displayed small detectable points of perinuclear co-localization with Rac1 and co-immunoprecipitated with Rac1 and RhoA in a PDGF-independent way. Moreover, there was PDI association with RhoGDI at baseline (confocal and co-immunoprecipitation), decreased after PDGF. Of note, PDI silencing promoted strong cytoskeletal changes: branched stress fiber disorganization, markedly decreased number of focal adhesions and reduced number of RhoGDI-containing vesicular recycling adhesion structures. Overall, these data suggest that PDI is required to support redox and GTPase-dependent VSMC migration. Moreover, RhoGTPases are a potential upstream target mediating the convergence between PDI and NADPH oxidase