Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 75-81).

Thesis (Ph. D.)--University of Washington, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 111-119).

Thesis (Ph.D.)--University of Alabama at Birmingham, 2009. / Title from PDF title page (viewed on Sept. 4, 2009). Includes bibliographical references.

Thesis (Ph.D. in Cell Biology, Stem Cells, and Development) -- University of Colorado Denver, 2008. / Typescript. Includes bibliographical references (leaves 105-116).

The photon receptor, rhodopsin, and the GTP-binding regulatory protein, transducin, belong to a family of G protein-coupled receptors. The activation process through which guanine nucleotide exchange of the G protein is accomplished was investigated utilizing these components of the visual transduction system. Rhodopsin, modelled as an enzyme in its interaction with substrates, transducin and guanine nucleotides, was characterized to catalyze the G protein's activation by a double-displacement mechanism. Remarkable allosteric behavior was observed in these kinetic studies. Equilibrium binding studies were performed to investigate the molecular basis of the positive cooperative behavior between transducin and rhodopsin. These experiments show that the origins of the allosterism must arise from oligomeric assemblies between receptor and G protein. The determined Hill coefficient, nH = 2, suggests that at least two transducin molecules are involved, and the Bmax parameter a1so indicates that multimeric assemblies of rhodopsin may participate in the positive cooperative interactiions. Physical studies of transducin in solution were performed and do not indicate the existence of a dimeric structure, in contrast to the kinetic and binding experiments which analyze interactions at the membrane surface. Since the latter environment represents the native surroundings in vivo, aspects of the allosteric behavior must be considered for a complete understanding of the signal transduction mechanism. The reported findings are interpreted in the context of homologies between other G protein-coupled receptor systems in order to develop a model for the molecular basis of the mechanism and regulation of this mode of signal transduction.

As critical regulators of vesicular trafficking, Rab proteins comprise the largest GTPase family, with thirty-eight functionally distinct members and another twenty isoforms in the human genome. Activated Rab GTPases interact with effector proteins involved in vesicle formation, transport, tethering, docking and fusion. The specificity of Rab interactions with effectors and regulatory factors plays a central role with respect to the fidelity of membrane trafficking. Rab recognition determinants and the mechanisms underlying interactions with structurally diverse regulatory factors and effectors are complex and poorly understood. Using Rab5 mediated endocytic transport as a model system, the work described in this thesis provides insight into the structural basis underlying the interaction of effectors and regulatory factors with Rab GTPases. In addition, structural and biochemical approaches have been used to define how specific Rab5 interacting proteins function in the endocytic and recycling pathways. These results establish novel structural and functional concepts that can be tested using family wide analyses of Rab GTPase recognition determinants and regulatory roles in the cell.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Escherichia coli enteropatogÃnica (EPEC) à um importante patÃgeno associado Ãs doenÃas diarreicas. InfecÃÃes intestinais ocasionam comprometimento da barreira intestinal e um dos primeiros mecanismos de resposta à recuperaÃÃo à a migraÃÃo das cÃlulas intestinais. As principais proteÃnas que regulam esse processo sÃo as pequenas GTPases Rho, Rac1, RhoA e Cdc42A. A alanil-glutamina (Ala-Gln) estimula este processo migratÃrio, entretanto os mecanismos envolvidos nesta resposta ainda sÃo desconhecidos. Desse modo, investigou-se o efeito de uma cepa selvagem e padrÃo (E2348/69) de EPEC, e de uma cepa comensal E. coli HS na migraÃÃo celular intestinal, bem como a regulaÃÃo da transcriÃÃo e expressÃo gÃnica das GTPases Rho e o papel da suplementaÃÃo com Ala-Gln no processo de migraÃÃo na presenÃa ou ausÃncia da infecÃÃo. A infecÃÃo pelas cepas de EPEC e pela cepa comensal reduziram significativamente a migraÃÃo celular intestinal. Entretanto, houve uma maior reduÃÃo desse efeito nas cÃlulas infectadas pelas cepas de EPEC quando comparado Ãquelas infectadas pela cepa comensal de E. coli HS. Observou-se um alto percentual de cÃlulas necrÃticas, cerca de 30%, induzido pela cepa padrÃo de EPEC apenas nos tempo de 12 e 24 horas apÃs infecÃÃo. A adiÃÃo da Ala-Gln em cÃlulas nÃo infectadas estimulou significativamente e de modo dose dependente a migraÃÃo apÃs 24 horas. PorÃm, quando esse nutriente foi adicionado durante 12 e 24 horas na presenÃa da infecÃÃo, nÃo houve uma reversÃo do dano. Em relaÃÃo à expressÃo gÃnica das GTPases Rho, observou-se um aumento da transcriÃÃo de rac1 nas cÃlulas que haviam sido infectadas pelas cepas de EPEC e E. coli HS, bem como um aumento da transcriÃÃo de rhoA nas cÃlulas infectadas pela cepa padrÃo de EPEC apÃs 2 horas da infecÃÃo. Todavia, na anÃlise das proteÃnas por imunofluorescÃncia, RhoA e Cdc42 mostraram-se aumentadas nas cÃlulas infectadas pela EPEC padrÃo quando comparado ao controle. Enquanto que as cÃlulas infectadas com a cepa selvagem de EPEC observou-se um aumento de Rac1 e reduÃÃo de RhoA. Esses dados mostraram que a migraÃÃo das cÃlulas intestinais à reduzida principalmente pelas cepas patogÃnicas de EPEC, ao regular a transcriÃÃo e expressÃo gÃnicas das proteÃnas GTPases Rho. A suplementaÃÃo com Ala-Gln em cÃlulas intestinais promoveu a migraÃÃo celular apenas na ausÃncia da infecÃÃo. / Enteropathogenic Escherichia coli (EPEC) is an important pathogen associated with diarrheal diseases. Intestinal infections cause impairment of the intestinal barrier and one of the earliest response mechanisms to recover is migration of the intestinal cells to cover the injured area. The key proteins that regulate cell migration are small Rho GTPases, Rac1, Cdc42 and RhoA. The alanyl-glutamine (Ala-Gln) increases this migration process, however the mechanisms involved in this response are still unknown. Thus, we investigated the effect of a wild type strain and standard (E2348/69) of EPEC strain and a commensal E. coli HS on intestinal cell migration, as well as transcriptional regulation and gene expression of Rho GTPases and the role of supplemental Ala-Gln in the migration process in the presence or absence of infection. Infection by EPEC strains and commensal E. coli HS significantly reduced intestinal cell migration. However, this effect was more pronounced in cells infected by the strains of EPEC compared to those infected by the commensal strain of E. coli HS. We observed a high percentage of necrotic cells, about 30%, induced only by EPEC strain pattern 12 and 24 hours after infection. The addition of Ala-Gln in uninfected cells significantly stimulated in a dose dependent migration after 24 hours. However, when this nutrient was added over 12 and 24 hours in the presence of infection, there was no reversion of the damage. Regarding the gene expression of Rho GTPases, we observed an increase in transcription of rac1 in cells that had been infected by the strains of EPEC and E. coli HS as well as an increase in rhoA transcription in cells infected with EPEC strain pattern at 2 hours after infection. However, the analysis of proteins by immunofluorescence, RhoA and Cdc42 shown to be elevated in cells infected with EPEC pattern when compared to the control. Whereas cells infected with wild EPEC strain was observed an increase of Rac1 and reduction of RhoA. These data showed that cell migration is reduced mainly by the intestinal pathogenic strains of EPEC, in regulating gene transcription and expression of the protein Rho GTPases. Supplementation with Ala-Gln in intestinal cells only promoted cell migration in the absence of infection.

Orientadores: Carla Fernanda Franco Penteado, Fernando Ferreira Costa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T18:17:52Z (GMT). No. of bitstreams: 1 Pallis_FlaviaRubia_D.pdf: 2236341 bytes, checksum: 3d0b519ba21fcfbc645749dccc82a06a (MD5) Previous issue date: 2015 / Resumo: A vaso-oclusão compreende um processo complexo e multicelular iniciado pela adesão de hemácias e leucócitos ao endotélio ativado, causando a obstrução vascular, ativação de células endoteliais vasculares e lesões que podem induzir uma resposta inflamatória contínua na anemia falciforme (AF). Estudos preliminares mostraram que os eosinófilos de pacientes com AF encontram-se ativados no sangue periférico, porém o envolvimento dessa célula no processo de vaso-oclusão ainda não está bem caracterizado. Pouco se sabe sobre o papel das proteínas da via das Rho GTPases na adesão dos eosinófilos ao endotélio vascular, bem como nas complicações pulmonares da doença. O objetivo desse trabalho foi avaliar in vitro o papel dos eosinófilos e das proteínas pertencentes à família das Rho GTPases na fisiopatologia da AF, e avaliar in vivo o papel dessa via na resposta inflamatória pulmonar induzida pela OVA em camundongos com AF. Sangue periférico de indivíduos saudáveis (controles) e pacientes com AF, em terapia com hidroxiureia (SSHU) ou não (SS), foi coletado para avaliar a adesão estática e em fluxo. A adesão dos eosinófilos de pacientes com AF à HUVEC estimulada com TNF-'alfa' foi significativamente maior quando comparado a adesão dos eosinófilos á HUVEC de indivíduos controle, em condições de fluxo e estática. No entanto, a adesão dessas células à HUVEC estimulada com TNF-? foi menor nos pacientes SSHU, quando comparada com o com aos SS. O pré-tratamento das HUVEC com o inibidor de Rac1, reduziu a adesão dos eosinófilos de pacientes SS ou SSHU. Em condições de fluxo, o número de eosinófilos aderidos à HUVEC reduziu significativamente quando estas foram tratadas com Y-27632 ou NSC23766 nos três grupos avaliados, porém essa inibição foi maior no grupo SS. In vivo a OVA induziu inflamação pulmonar caracterizada pelo aumento na contagem de leucócitos, principalmente eosinófilos, no lavado broncoalveolar dos camundongos. Essa inflamação foi potencializada nos camundongos com AF (Berkeley e Transplantados) quando comparados aos controles (C57BL6). Os camundongos Transplantados apresentaram níveis elevados de mediadores pró-inflamatórios, tais como, IL-4, IL-5, IL-6, IL-13, RANTES, Eotaxina, MCP-1, MMP-9 e TIMP-1 quando comparados aos camundongos do grupo não sensibilizado (NS). Nenhuma diferença foi observada nos níves de RNAm pulmonar das metaloproteinases e seus inibidores quando comparados os camundongos Transplantados do grupo OVA com os NS, porém a expressão de IL-6 é significativamente maior no pulmão dos animais falciformes desafiados com OVA. Na avaliação funcional dos brônquios, os dados mostraram que a potência para metacolina foi maior nos camundongos Berkeley, quando comparados aos Transplantados e ainda maior quando comparados com os C57BL6. Os animais que foram tratados com os inibidores da via RhoA/ROCK, Y-27632 ou Fasudil, apresentaram menor contagem total e diferencial das células que migraram para os pulmões e níveis reduzidos dos mediadores pró-inflamatórios avaliados. O pré-tratamento com o Fasudil reduziu a potência e a resposta máxima para metacolina dos brônquios da linhagem Berkeley. Não foi observada diferença na avaliação funcional da reatividade da traqueia no modelo de asma experimental nos grupos avaliados. Tomados em conjunto, os resultados indicam que a via RhoA/ROCK tem papel importante na adesão dos eosinófilos ao endotélio e que a inibição dessa via pode atenuar a asma associada a doença falciforme. Deste modo, sugerimos que os inibidores dessa via podem ser novos agentes terapêuticos para o tratamento das manifestações clínicas da AF / Abstract: Vaso-occlusion, comprising a complex and multicellular process, initiated by the adhesion of erythrocytes and leukocytes to the activated endothelium, leading to vascular obstruction, activation of vascular endothelial cells and continuous lesions in patients with sickle cell anemia (SCA). Preliminary results demonstrated that eosinophils from SCA patients exist in an activated state, however the participation of this cell in the vasooclusive process in not well establish. The role of proteins via the Rho GTPases in the adhesion of eosinophils to the vascular endothelium and in the pulmonary complications of SCA disease it is unknown. The aim of this study was to evaluate in vitro the role of the eosinophils and proteins belonging to the Rho GTPases family in SCA pathophysiology, and evaluate in vivo the role of this pathway in pulmonary inflammatory responses induced by OVA in SCA mice. Peripheral blood of healthy individuals (controls) and SCA patients in therapy or not with hydroxyurea (SCAHU) was collected for static and flow adhesion experiments. For static adhesion assays, eosinophils were isolated from control subjects or SCA patients on or off HU therapy. Adhesion of SCA eosinophils to HUVEC (Human Umbilical Vein Endothelial Cells) under TNF-'alfa'-stimulated conditions was higher when compared with control eosinophils, in flow conditions and static assay. Furthermore, SCAHU eosinophils demonstrated significantly lower adhesive properties, compared to SCA eosinophils. The adhesion of eosinophils from SCA or SCAHU patients were reduced when HUVEC were pretreated with NSC23766 inhibitor, compared to non-treated HUVEC. Under flow conditions, the number of eosinophils adhered to HUVEC cells was reduced when they were treated with Y-27632 or NSC23766 in the three groups investigated, however this inhibition was higher in the SCA patients. In vivo OVA induced lung inflammation, characterized by increased leukocyte particularly eosinophils, counts in the mice bronchoalveolar fuid (BALF). This inflammation was enhanced in SCA mice (Berkeley and Transplanted) when compared to controls (C57BL6). Transplanted mice showed high levels of pro-inflammatory mediators such as IL-4, IL-5, IL-6, IL-13, RANTES, Eotaxin, MCP-1, MMP-9 and TIMP-1 as compared to the control mice group (NS). Furthermore, the SCA mice induced with OVA showed higher lung gene expression of IL-6; however, there was no difference in the expression of MMP-2, MMP-8, MMP-9, MMP-12, TIMP-1 and TIMP-2, compared to NS. In the functional assessment of the bronchi reactivy, data showed that the potency to methacholine in asthmatic model was was greater in the SCA mice (Berkeley), compared to the Transplanted SCA mice, and even greater when compared to C57BL6. The animals treated with the inhibitors of the RhoA/ROCK pathway, Y-27632 or Fasudil, showed lower total and differential cells counts due to migration to the lungs. Pretreatment with the RhoA/ROCK pathway inhibitor significantly reduced the proinflammatory mediator levels evaluated. Treatment with Fasudil reduced maximal response for methacholine in bronchi from Berkeley model. No significant difference was observed in the tracheal reactivity after OVA challenge in all groups investigated. Taken together, our data indicated that RhoA/ROCK pathway play an important role in the eosinophil adhesion to the endothelium and, the inhibition of this pathway could alleviates asthma in SCA patients. Thus, we suggest that RhoA/ROCK inhibitors represents novel therapeutic agents for the treatment of SCA clinical manifestations / Doutorado

Substance P (SP) is an undecapeptide whose functions are as varied as its locations. In the nervous system, it is thought to act as a neurotransmitter. In the peripheral vasculature, it has hypotensive effects and it causes contraction in the smooth muscle of the gut. In salivary gland, it is a potent secretagogue and it is how this effect is transduced that is the subject of this dissertation. Activation of the SP receptor in rat submaxillary gland by SP results in the hydrolysis of inositol phospholipids and the mobilization of intracellular Ca2+. These second messengers are then able to activate a pathway(s) which results in the secretion of electrolytes, water and macromolecules. The production of these second messengers, however, is thought to require the participation of a guanine nucleotide binding protein (G protein). The G protein that couples to the SP receptor (Gp), has not yet been identified. Although several investigators have recently reported the purification of G protein α subunits that are capable of activating phospholipase C, it is not known if they couple to receptors in order to activate phospholipase C. In an effort to learn more about the mechanisms of signal transduction by SP in salivary gland, the interactions of the SP receptor with G proteins were studied. In the first study, the question of whether the SP receptor functionally couples to a G protein was investigated. Alkaline treatment was used to deplete membranes containing SP receptors of endogenous G proteins. These membranes were not capable of binding SP with high affinity. High affinity binding capability was restored in those membranes, however, by reconstituting them with exogenous G proteins. Thus, it was concluded that that SP receptor agonist affinity is regulated by a G protein. It was also determined that the G proteins (a Go/Gi mixture) used to reconstitute the membranes may not be those that couple to the SP receptor in vivo, since the reconstituted Go/Gi mixture was inactivated by treatment with pertussis toxin, while Gp was not. The next study was undertaken in an effort to identify other G proteins that are able to interact with the SP receptor. G proteins were chromatographically purified from horse submaxillary gland membranes, and assayed for characteristics that could identify one or more G proteins as potential physiological couplers to the SP receptor. G proteins were identified in fractions by the ability to bind [35S]GTPγS. These GTP-binding proteins were further characterized by testing their susceptibility to ADP- ribosylation catalyzed by pertussis toxin and their ability to restore high affinity agonist binding in membranes containing the SP receptor, but no endogenous G proteins. In addition to identifying G proteins that are substrates for pertussis toxin-catalyzed ADP-ribosylation (e.g. Go and/or Gi), a GTP-binding protein was identified which possesses characteristics that are unlike those of the well-known G proteins, Go, Gi and Gs. This protein elutes from anion exchange resins at a high salt concentration, is not susceptible to ADP- ribosylation catalyzed by pertussis toxin, is able to reconstitute high affinity binding in G protein depleted rat submaxillary gland membranes and is not recognized by antibodies to Go, Gi, Gs or Gz. Finally, a direct characterization of the G protein coupled to the SP receptor in rat submaxillary gland was undertaken. Using photo-affinity labelling techniques in conjunction with chemical crosslinking techniques, a covalent 96 kDa SP receptor complex was identified. The generation of this 96 kDa complex was inhibited by a nonhydrolyzable analog of GTP, but not a nonhydrolyzable analog of ATP. Furthermore, the complex could not be produced in membranes that had been depleted of G proteins by alkaline treatment. Reversal of the chemical crosslink yielded only the 53 kDa SP receptor, showing that the protein crosslinking to the SP receptor possesses a molecular weight of about 43 kDa. This molecular weight is typical of G protein α subunits. It was concluded that the 96 kDa crosslinked receptor complex consisted of the SP receptor, the radioiodinated SP derivative and the α subunit of Gp. The studies show that the SP receptor may be coupled to a novel G protein, whose purification characteristics differ from those of the known G proteins. Although Gp has yet to be identified, comparisons of the results of these investigations with those of several recent articles in which the purification of G protein α subunits that are capable of stimulating phospholipase C is reported, suggests that Gp is similar, if not identical to those proteins. Furthermore, this dissertation describes a unique reconstitution system and crosslinking techniques which should prove useful in the identification of Gp, as well as in the study of other receptor-G protein interactions and perhaps, the reconstitution of the receptor-G protein-phospholipase C signal transduction pathway.