Lysophosphatidic acid (LPA) is a mitogenic lipid that enhances cell growth, proliferation and motility through binding and activation of at least four receptors, LPA1/Edg2, LPA2/Edg4, LPA3/Edg7, and PPAR and #947;. Here, we show that LPA stimulation inhibits the cell cycle regulator and tumor suppressor, p53. Ten M LPA reduced the cellular levels of total p53 and p53 phosphorylated at serine 15 by approximately 50% in A549 cells and this effect was sustained for at least 6 h. This resulted in a corresponding decrease in p53-mediated transcription. Transient-transfection of the Edg-family LPA receptors, LPA1-3 in HepG2 cells, which do not respond to LPA, also showed this inhibitory response. The response was specific to LPA receptors since neither Gi-coupled M2 muscarinic acetylcholine receptors, nor a mutant LPA1 receptor (LPA1 R124A), which is unable to bind LPA, inhibited p53 activity. Both transient-transfection of the LPA-degrading lipid phosphate phosphatase-1 (LPP-1), or exogenous addition of phospholipase B, which decreases exogenous lysophosphatidate, reversed the LPA receptor-induced decrease in p53-mediated transcription. Although pertussis toxin did not prevent the inhibition of p53, a mutant LPA1 receptor (LPA1 and #8710;361), which lacks the C-terminal PDZ-binding domain, failed to inhibit p53 function. This establishes LPA-mediated inhibition of p53 function requires an interaction with PDZ-containing proteins. These data establish a novel role for LPA-mediated receptor activation in diminishing p53 activity; which, in addition to LPAs well-characterized effects on growth-promoting signaling pathways, is likely to contribute to the survival and proliferation of cancer cells. Of the Edg-family LPA receptors, the LPA1 receptor is the most widely expressed. In the next study, we investigated the agonist-induced endocytosis of the human LPA1 receptor, bearing an N-terminal FLAG epitope tag, in stably transfected HeLa cells. LPA treatment induced the rapid endocytosis of approximately 40% of surface LPA1 within 15 minutes. Internalization was dose dependent and LPA specific since neither lysophophatidylcholine nor sphingosine-1-phosphate induced LPA1 endocytosis. Removing agonist following incubation resulted in LPA1 recycling back to the surface. LPA1 internalization was strongly inhibited by dominant-inhibitory mutants of both dynamin2 (K44A) and Rab5a (S34N). Finally, our results indicate that LPA1 exhibits basal, LPA-dependent internalization in the presence of serum-containing medium.

The following thesis research was undertaken to gain a better understanding of the mechanisms that regulate the cellular trafficking and signaling of the endothelial differentiation gene (EDG) family of G-protein coupled receptors, LPA1, LPA2, and LPA3. This thesis will specifically focus on the regulation of the trafficking of the LPA1 Lysophosphatidic acid receptor, which is the most widely expressed and has been shown to be a major regulator of migration of cells expressing it. The initial studies undertaken in this project were aimed at understanding the endocytic pathway followed by the LPA1 receptor. Lysophosphatidic acid (LPA), an abundant serum phospholipid, stimulates heterotrimeric G protein signaling by activating three closely related receptors, termed LPA1, LPA2 and LPA3. In the first part of the project we show that in addition to promoting LPA1 signaling, membrane cholesterol is essential for the association of LPA1 with β-arrestin, which leads to signal attenuation and clathrin dependent endocytosis of LPA1. The second phase of the project was aimed at elucidating the different structural motifs required for the trafficking and signaling of the LPA1 receptor and helping us gain a more mechanistic view of the processes involved in its regulation. In the second part of the project we show that agonist-independent internalization of the LPA1 receptor is clathrin adaptor, AP-2 dependent and PKC-dependent and that it requires a distal dileucine motif, whereas agonist-dependent internalization of the LPA1 receptor is β-arrestin and clathrin-dependent and requires a cluster of serine residues in the tail region, which is upstream of the dileucine motif. These studies collectively vastly enhance our understanding of mechanisms that regulate LPA1 trafficking and signaling. These studies can also be applied to other G-protein coupled receptors making the task easier for other scientists to understand this vast family of receptors.

Les métastases sont des conséquences dramatiques lors de la progression des cancers. Malgré les traitements actuels la médiane de survie de patients atteints de métastases osseuses n'est que de 24 mois. Donc l'identification de nouvelles cibles thérapeutiques dans le traitement ou la prévention des métastases revêt un caractère crucial. L'objectif de ce travail de thèse est d'étudier le rôle de l'acide lysophosphatidique (LPA) et de l'autotaxine (ATX) dans la dissémination métastatique des cancers du sein. Notre laboratoire a montré que le LPA contrôle la croissance tumorale et la progression des métastases osseuses dans le contexte des cancers du sein. On sait depuis peu qu'en raison de son activité lysophospholipase D, ATX produit du LPA à partir de la lysophosphatidylcholine et contrôle les niveaux de LPA dans la circulation sanguine. ATX est une protéine sécrétée présentant des propriétés métastatiques. Les travaux présentés dans cette thèse montrent que l'expression d'ATX par les cellules tumorales contrôle les événements précoces de la dissémination métastatique des cancers du sein ainsi que le processus plus tardif de formation et de progression des métastases osseuses en agissant sur la fonction ostéoclastique. Il existe un grand nombre de récepteurs capables de transmettre l'activation cellulaire par le LPA (LPA1-6). Ce travail de thèse montre également que le niveau d'expression du récepteur LPA1 au niveau de la tumeur primaire est un facteur prédictif de la rechute métastatique chez les patientes ayant un cancer du sein. D'autre part dans un modèle animal préclinique, nous avons observé que le ciblage thérapeutique précoce de LPA1 par le DEBIO-0719 bloque efficacement la dissémination métastatique des cellules de cancer du sein. En conclusion, nos résultats montrent que le ciblage de l'axe ATX/LPA/LPA1 présente un haut potentiel thérapeutique chez des patientes atteintes d'un cancer du sein à fort risque métastatique

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Made available in DSpace on 2014-12-17T13:53:35Z (GMT). No. of bitstreams: 1 MarcosFMM.pdf: 635029 bytes, checksum: b517d0638c5e4f61120d0493d4c6b238 (MD5) Previous issue date: 2007-07-21 / Este estudo aborda a utiliza??o da tecnologia da informa??o de forma competitiva em um Arranjo Produtivo Local (APL). Realizou-se no APL da carcinicultura no Estado do Rio Grande do Norte e teve por objetivo buscar a compreens?o de como o uso da tecnologia da informa??o (TI) contribui para o aumento da competitividade na atividade do APL citado. APL pode ser conceituado como uma alian?a entre organiza??es que possuem um projeto coletivo, para elevar a sua competitividade e participa??o no mercado. Para atingir este objetivo, foi realizada uma pesquisa descritiva, atrav?s da utiliza??o de m?ltiplos casos selecionados dentre as empresas que comp?em o APL da carcinicultura no RN. Os dados coletados foram analisados qualitativamente. Os resultados da pesquisa indicaram que as empresas percebem a import?ncia do uso da TI, mas que, na pr?tica, a sua utiliza??o ? limitada, principalmente em se tratando de Sistemas Integrados de Gest?o e Com?rcio Eletr?nico. Outro resultado encontrado foi que as empresas, embora fa?am parte do APL, ainda n?o colaboram entre si, seja atrav?s da troca de informa??es, ou atrav?s de Sistemas de Informa??o Interorganizacional. As principais recomenda??es diante destes resultados ? que as empresas atuem ativamente para o fortalecimento do APL. No que se refere ao uso da TI faz-se necess?rio que elas invistam na aquisi??o de sistemas integrados de gest?o e sistemas de informa??o interorganizacional para o melhor gerenciamento das informa??es ao longo da cadeia

O avanço da terapia intensiva na medicina veterinária vem permitindo a realização de um melhor suporte e monitorização dos animais com sepse grave. Esta é uma síndrome clínica caracterizada por alterações inflamatórias sistêmicas (SIRS) associadas a disfunções orgânicas, como, por exemplo, lesão pulmonar aguda (LPA) e síndrome do desconforto respiratório agudo (SARA). No homem, esta síndrome resulta em uma significante taxa de mortalidade, porém, na medicina veterinária ainda faltam estudos sobre este assunto. Assim, o objetivo deste estudo foi avaliar a ocorrência de complicações respiratórias em animais com sepse grave submetidos à terapia intensiva. Neste estudo foram incluídos 14 animais com sepse grave secundária à piometra. Durante o período de tratamento intensivo os pacientes foram monitorados por meio de: freqüências cardíaca e respiratória, pressão arterial sistólica, débito urinário, pressão venosa central, lactato, saturação venosa central de oxigênio, hemogasometria arterial e radiografias torácicas. Todos os animias (100%) apresentaram alterações respiratórias, destes três cadelas vieram a óbito (21,42%) e 11 (78,57%) receberam alta do tratamento intensivo.Os animais submetidos à terapia intensiva devido ao desenvolvimento de sepse grave secundária à piometra, necessitam de um acompanhamento radiográfico torácico diário, a fim de se estabelecer medidas de suporte respiratório adequadas e, consequentemente, obter menores taxas de mortalidade. / The advances in intensive care has allowed to offer better support to animals with severe sepsis. This is a clinical syndrome characterized by systemic inflammatory response associated with organic dysfunction, such as acute pulmonary injury (ALI) and acute respiratory distress syndrome (ARDS). In humans, this syndrome results in significant mortality, but, in veterinary medicine there are not many studies about this. The aim of this study was to evaluate the development the pulmonary complications in animals submitted to intensive care. In this study were included 14 animals with severe sepsis secondary to pyometra. During the period of intensive care the animals were evaluated: heart and respiratory rates, systolic blood pression, urine output, central venous pression lactate, lactate, central venous saturation, arterial hemogasometric and thoracic x-ray. All animals (100%) had abnormal breathing, three of these dogs eventually died (21.42%) and 11 (78.57%) out of intensive care. Animals with severe sepse secondary to pyometra underwent intensive therapy, requiring a chest radiographic daily in order to establish adequate respiratory support, and thus achieve lower mortality rates.

Made available in DSpace on 2014-06-12T18:02:20Z (GMT). No. of bitstreams: 2 arquivo3641_1.pdf: 6593022 bytes, checksum: 0f5771c7ba5a598c9b448775b9fef6c4 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A leucemia promielocítica aguda (LPA) corresponde a cerca de 20-28% das LMAs nos países latino-americanos, sendo caracterizada pelo acúmulo de células leucêmicas na medula óssea semelhantes a promielócitos e clinicamente associada à coagulopatia, que é responsável pela alta mortalidade precoce nas fases iniciais de tratamento. Apesar da LPA ser geralmente reconhecida por seus caracteres morfológicos, existem casos atípicos. A LPA é uma patologia beneficiada pelo tratamento com ATRA e, portanto, um rápido e eficiente diagnóstico é essencial. A citogenética em geral e a RT-PCR são amplamente utilizadas na detecção da fusão gênica PML-RARα. Estas técnicas fornecem informações adicionais sobre a presenca de outras anormalidades citogenéticas, porém consomem tempo e requerem laboratórios especializados. O padrão da PML provou-se útil ao diagnostico da LPA clássica através de técnicas imunológicas utilizando anticorpos monoclonais ou policlonais. Neste estudo foram analisados 15 pacientes, de ambos os sexos, idade variando de 4 a 17 anos, diagnosticados com LPA no Centro de Oncohematologia Pediátrica do HUOC ou Instituto Nacional do Câncer entre os anos de 2004 a 2008. As amostras de medula óssea dos pacientes foram tratadas de acordo com protocolos padrões sendo realizadas as técnicas de bandeamento G, RT-PCR, FISH usando sonda para o rearranjo PML-RARα e imunofluorescência com anticorpo monoclonal PG-M3. A análise por bandeamento G revelou alterações cromossômicas, com excessão de dois casos que apresentaram cariótipos normais. O estudo apresentou: um cariótipo complexo 47,XX,del(12p),add(14q),del(15q),i(19q),+mar, onde não foi detectada a fusão PML-RARα pela RT-PCR, nem pela FISH; um 48,XX,+2mar, no qual também não foi detectada a fusão PMLRARα pelas técnicas moleculares. Estes dois casos podem conter fusões variantes. Sete casos com t(15;17) foram detectados pela citogenética e confirmados pela FISH; cinco casos com t(15;17) confirmados pela FISH quando não foi possível realizar a análise citogenética. Em três casos a RT-PCR mostrou-se divergente da FISH. A imunofluorescência foi realizada em cinco casos e todos confirmaram o diagnóstico da LPA clássica. Sete pacientes estão vivos, seis em remissão, um em tratamento e oito foram a óbito. Estes dados mostram a importância da união de diversas metodologias para o aperfeiçoamento da eficiência e sensibilidade do diagnóstico e do tratamento desta doença

京都大学 / 0048 / 新制・課程博士 / 博士(医科学) / 甲第21025号 / 医科博第86号 / 新制||医科||6(附属図書館) / 京都大学大学院医学研究科医科学専攻 / (主査)教授 斎藤 通紀, 教授 渡邊 直樹, 教授 岩井 一宏 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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Ductal adenocarcinomas of the pancreas are the 4th most common cause of cancer death. The 1 and 5 year survival rates for all stages combined are currently 26% and 5% respectively. Median survival is less than 6 months. Despite remarkable progress in the fields of genetics, cancer biology, and advances in surgical techniques as well as chemotherapeutics, our ability to recognize and treat patients with pancreatic cancer remains poor. GPCR signaling modules have been increasingly implicated in the genesis and progression of pancreatic cancers. Aberrant agonist production, receptor expression and dysfunctional signaling resulting from genomic instability in a background of a heterotopic tumor-stromal microenvironment, contribute to the initiation, progression, and eventual metastasis of the disease. Numerous GPCR agonists, including lysophosphatidic acid (LPA), along with their cognate receptors have been implicated in this oncogenic process. LPA, one of the simplest bioactive lipids, has been shown to be a potent stimulant of metastatic behavior in in vitro models. It also acts as a mitogen by inducing proliferation and cell survival pathways in various normal and transformed cell lines. In patients with pancreatic cancer both the receptors and ligand have been found to be overexpressed. It has been noted that pancreatic cancer cell lines expressing higher levels of the LPA receptors present with greater motility. This has led to the hypothesis that LPA contributes to the progression of pancreatic cancer through the promotion of a metastatic phenotype. However, the underlying mechanisms have not been well described. LPA receptors have been shown to couple to the Gi, Gq, or G12 family of heterotrimeric G proteins. Consequently, signals transduced through these receptors have been shown to stimulate Gαi, Gαq, and Gα12/13 dependent pathways. While earlier studies have linked Gαi to LPA induced migration, there is recent evidence to suggest that Gα13 may provide a major signaling mechanism for LPA receptors stimulating migration in diverse cell types including cancer cell lines. Given the ominous nature of pancreatic cancers it is of critical importance to understand the mechanisms that promote more malignant phenotypes and to assess the role of Gα13 in this process. The goal of this thesis therefore is to define the role of Gα13 in LPA-mediated migration of pancreatic cancer cells. To assess the oncogenic potential of LPA and the role of Gα13 in stimulating the migration of pancreatic cancer cells, a panel of pancreatic cancer cell lines was assembled and characterized with regard to their expression of the LPA receptors as well as the Gα subunits of the heterotrimeric G proteins. These cell lines were further studied through a series of proliferation, wound healing, and transwell migration assays to assess the role of LPA in the induction of proliferation and migration in pancreatic cancer cells. The results demonstrated that LPA functions as a mitogen in certain pancreatic cancer cell lines, but is a potent stimulant of cell motility and invasive migration. Interestingly, these studies indicated that this response proceeds through routes that may not involve Gαi, as a potent migratory response was observed in MDAPanc28 cells which lack expression of the Gαi subunit. This was verified through the transwell assays conducted in the presence of PTX demonstrating that migration occurs independently of PTX sensitive mechanism and thus independently of Gαi.. Using a dominant negative mutant strategy, the studies presented in this thesis establishes the role of Gα13 in mediating LPA-LPAR stimulated migration of pancreatic cancer cells. Using pancreatic cancer cell lines that stably express the competitively inhibitory dominant negative mutant of Gα13, the ability of these mutants to inhibit a LPA mediated migratory response was monitored by wound-healing as well as transwell migration assays The results of these studies indicated a substantial attenuation of the migratory response and demonstrated for the first time the critical role of Gα13in LPA induced migration in a pancreatic cancer cell line. / Molecular Biology and Genetics