Metastasis is the leading cause of mortality in human breast cancer. However, there are few predictive, prognostic, or therapeutic targets of breast cancer metastasis. Ezrin, a membrane cytoskeletal cross-linker, is frequently over-expressed in human breast cancer and is required for motility and invasion by cultured epithelial cells. Our group has recently shown that ezrin acts co-operatively with the non-receptor tyrosine kinase, Src, in the transformation of epithelial cells, in which ezrin is phosphorylated on specific tyrosines, such as Y477, by Src (91, 93). We therefore examined whether Src/ezrin interaction also regulates invasion and metastasis of breast cancer. This thesis presents the following results: 1) In a murine system, ezrin and Src are differentially localized in nulliparous, lactating mammary glands and PyMT-induced tumours, with pronounced apical expression in nulliparous mammary glands but non-polarized strong cytoplasmic expression in PyMT-induced tumours. 2) Increased expression and activation of ezrin, Src and Met in PyMT-induced tumours compared to normal breast tissues was observed. A concomitant increased expression of activated Stat3 and HGF was also observed in PyMT-induced tumours, consistent with the establishment of an HGF/Met autocrine loop. 3) In invasive human breast tumours, from a premenopausal patient cohort, ezrin showed significantly greater cytoplasmic localization compared to non-neoplastic epithelial ducts in normal mammoplasties. 4) In a mouse breast carcinoma xenograft model, a Y477F ezrin mutant (not phosphorylatable by Src), significantly reduced local invasion of primary tumours and spreading into visceral organs, yet, it did not significantly affect primary tumour growth rate. 5) Y477F ezrin-expressing tumours exhibited focal areas of incomplete membranous ezrin staining which was absent in control tumours. Moderate/strong cytoplasmic ezrin staining was evident in both tumour groups. Thus, ezrin is differentially localized in non-invasive versus invasive mammary tumours. Our study implicates a role of the Src/ezrin pathway in regulating local invasion and metastasis of breast carcinoma cells and provides a clinically relevant model for assessing the Src/ezrin pathway as a potential prognostic marker and treatment target for invasive breast cancer. / Thesis (Master, Pathology & Molecular Medicine) -- Queen's University, 2010-04-28 12:24:25.286

No description available.

In order to fertilize the egg, sperm cell undergoes several subsequent maturation processes. The final one called acrosome reaction is an exocytosis of acrosome vesicle, which is filled with lytic enzymes. Acrosome reaction is crucial for penetration of the sperm cell through the egg surroundings, especially zona pellucida, as well as for reorganization of a membrane protein composition on its surface. This rearrangement leads to the exposure of proteins essential for fertilization, mainly for gamete recognition, binding and fusion in specific compartments of the sperm head. One of such protein is CD46, which is located in the acrosomal membrane of an intact sperm and after acosomal exocytosis it relocates to the equatorial segment of a sperm head, which is known to be the initial site of interaction of sperm with the egg plasma membrane. The relocation of CD46 is disrupted by inhibition of actin, which reorganization within sperm head is known to play a role in onset of acrosome reaction, however, the precise mechanism of CD46 interaction with actin in sperm is unknown. In this thesis, ezrin - a crosslinker of membrane proteins and actin - has been studied in context of CD46 and its relocation across the sperm head. Analysis of the immunofluorescent detection of ezrin revealed its mutual...

Die in der vorliegenden Habilitationsschrift zusammengefaßten Publikationen stellen Untersuchungen zu zwei Themenschwerpunkten dar: 1. Verankerungsmechanismen von Membranproteinen der basolateralen und der apikalen Plasmamembrandomäne der Parietalzellen mit dem Membranzytoskelett und 2. die regulierte Fusion von zytoplasmatischen Vesikeln mit der apikalen Plasmamembran dieser Zellen. Die strukturell und molekular sehr unterschiedlich gestaltete apikale und basolaterale Membrandomäne der Parietalzellen sollte funktionell charakterisiert und die Mechanismen der Membranumbauvorgänge aufgeklärt werden, die nach Aktivierung der Zellen im apikalen Membrankompartiment ablaufen. Für die strukturelle Stabilität der basolateralen Domäne spielt wahrscheinlich die Verankerung von AE2 über das Verknüpfungsprotein Ankyrin mit dem Membranzytoskelett eine wichtige Rolle. Die apikale Membrandomäne der Parietalzellen kann in drei Kompartimente unterteilt werden. Die freie apikale Membran, die canalikuläre Membran und die Membranen der tubulären Vesikel. Entlang der freien apikalen und der canaliculären Plasmamembran kommen wie auf der basolateralen Seite die Zytoskelett-Proteine Actin und Spectrin vor. Nach unseren Untersuchungen könnte es während der Sekretionsphase zu einer temporären Verbindung von H+,K+-ATPase Molekülen mit dem Membranzytoskelett kommen. Diese Verbindung wird wahrscheinlich durch das Verknüpfungsprotein Ezrin vermittelt. Der Mechanismus des Fusionsvorgangs der tubulären Vesikel mit der canaliculären Membran war bisher nicht bekannt. In Parietalzellen konnten die neuronalen SNARE-Proteine Synaptobrevin 2, Syntaxin 1 und SNAP25 sowie das zur Familie der kleinen G-Proteine gehörende Protein Rab3A und die Regulatorproteine NSF und alpha/beta SNAP nachgewiesen werden. Das in Parietalzellen gefundene Verteilungsmuster der SNARE-Proteine entspricht nicht der klassischen Vorstellung einer heterotypischen Membranfusion, vielmehr entspricht diese Verteilung einer homotypischen Fusion, wie sie für Vakuolen in Hefezellen beschrieben wurde. Die Bedeutung der SNARE-Proteine für die Fusion der tubulären Vesikel mit der canaliculären Membran und damit für die Steigerung der HCl-Sekretion konnte durch Inkubation der Zellen mit Tetanus Neurotoxin (TeNt) gezeigt werden. Die Behandlung der Parietalzellen mit TeNt führte zum vollständigen Ausbleiben der, nach Stimulation mit cAMP bei Kontrollzellen beobachteten Erhöhung, der Säuresekretion / The publications summarized here cover two topics: 1. the anchorage mechanism of membrane proteins of the basolateral and the apical plasma membrane with the membrane cytoskeleton of parietal cells and 2. the regulated fusion of cytoplasmic vesicles with the apical plasma membrane of these cells. It was the aim of these studies to characterize the structural and molecular differences between the apical and basolateral membrane domains in parietal cells. Moreover the mechanisms involved in membrane traffic within the apical membrane compartment following stimulation were investigated. We found that anchorage of AE2 with the membrane cytoskeleton through the linkage protein ankyrin seems to be important for the stability of the basolateral membrane. The apical membrane domain of parietal cells can be subdivided into three compartments. The free apical membrane, the canalicular membrane and the tubulovesicular membrane. The cytoskeletal proteins spectrin and actin can be found at the basolateral, the free apical and the canalicular membrane. We have shown that the H+K+-ATPase molecules appear to be temporary linked to the membrane cytoskeleton during acid-secretion. This contact is most likely mediated by the linker-protein ezrin. Until now the mechanism of fusion of the tubulovesicles with the canalicular membrane was unknown. In parietal cells the neuronal SNARE-proteins synaptobrevin 2, Syntaxin 1, SNAP25, the small G-protein rab3A, and the regulatory proteins NSF and alpha/beta-SNAP were detected. The subcellular distribution of these proteins does not support the notion of a neuron-like heterotypic fusion. Instead it shows similarity with the homotypic fusion process of vacuoles in yeast. The importance of SNARE-proteins for the fusion of tubulovesicles with the canalicular membrane and, by consequence also for the increase of acid-secretion was shown by incubation of the cells with tetanus neurotoxin (TeNt). The measurable increase of acid secretion by parietal cells after stimulation with c-AMP was inhibited completely through an incubation with TeNt.

No description available.

Die dynamische Verknüpfung zwischen Plasmamembran und dem unterliegenden Zytoskelett der Zelle ist fundamental für zelluläre Prozesse wie Zellmorphogenese, Zellmotilität und Zelladhäsion. Ezrin als Bestandteil der ERM (Ezrin, Radixin, Moesin) Proteinfamilie verbindet L-α-Phosphatidylinositol-4,5-bisphosphat (PIP2) der Plasmamembran mit filamentösem Aktin (F-Aktin) des Zytoskeletts. Die Ezrinbindung an F-Aktin wird reguliert über den Aktivierungsgrad des Proteins, welcher von der N-terminalen PIP2 Bindung und der Phosphorylierung des Threoninrests 567 abhängt. Aufgrund der Bindung an PIP2 und der Phosphorylierung wechselt Ezrin von einer inaktiven, N- und C-terminal assoziierten Konformation in einen aktivierten, geöffneten Zustand, welcher die C-terminale F-Aktinbindung ermöglicht. Ziel dieser Arbeit war es Aspekte der Verknüpfung zwischen Plasmamembran und Zytoskelett zu untersuchen. Basierend auf Bindung von Ezrin an PIP2-haltige artifizielle Lipidmembranen und der anschließenden F-Aktinbindung, wurden Bindungseigenschaften, die Organisation des F-Aktinnetzwerkes und die durch das Aktinnetzwerk beeinflusste Lipidmembranmechanik untersucht. Im ersten Abschnitt dieser Arbeit wurde der molekulare Aktivierungsprozess von Ezrin anhand der Charakterisierung von Bindungsaffinitäten und der Organisation von Ezrin an Lipidmembranen untersucht. Aufgrund einer reduzierten Proteinhöhe und FRET (FÖRSTER-Resonanzenergietransfer)-Effizienz im Fall der vollständigen Aktivierung (PIP2-Bindung und Phosphorylierung) wurde postuliert, dass Ezrin eine weniger dicht gepackte, geöffnete Konformation gebunden an Lipidmembranen ausbildet. Dies ermöglicht dem Protein C-terminal F-Aktin zu binden. Im zweiten Teil der Arbeit wurden Aktinnetzwerke an festkörperunterstützten Lipidmembranen (SLBs) immobilisiert und über Ezrin an PIP2- oder elektrostatisch an 1,2-Dioleoyl-sn-glycero-3-ethylphosphocholin (DOEPC)-haltige SLBs gebunden. Die Netzwerkorganisation wurde mit Hilfe der Fluoreszenzmikroskopie untersucht und unter Berücksichtigung der Immobilisierungsstrategie in Hinblick auf den Einfluss der Anzahl an Verknüpfungspunkten und aktinbindender Proteine (Fascin und α-Actinin) analysiert. Es konnte gezeigt werden, dass beide Immobilisierungsstrategien zu Aktinnetzwerken mit ähnlichen Eigenschaften führten, bezugnehmend auf Maschengröße und Filamentsegmentlänge. Die Aktinnetzwerkdichte konnte direkt über die Anzahl an Verknüpfungspunkten und aktinbindende Proteine (ABPs) reguliert werden, dies demonstriert die physiologische Relevanz der Ergebnisse. Es ist bekannt, dass die Aktindichte in Zellen über PIP2- und ABP-Konzentration gesteuert wird. Im dritten Teil der Arbeit wurde das etablierte Modelsystem auf poröse Substrate übertragen. Unter Kenntnis der vorangegangenen Teile der Arbeit wurde der Einfluss des F-Aktinnetzwerkes auf die Lipidmembranmechanik untersucht. Mit Hilfe der Rasterkraftmikroskopie wurden Indentationsexperimente an porenüberspannenden Lipidmembranen (PSLBs) durchführt, welche zeigten, dass ein aufliegendes F-Aktinnetzwerk die PSLBs versteift. Dies ließ sich auf die reduzierte laterale Mobilität der Lipide innerhalb der PSLBs aufgrund des Aktinnetzwerkes zurückführen, vergleichbar mit dem Picket-Fence-Modell der Plasmamembran bei welchem die Mobilität der Lipide und (Membran-)Proteine, aufgrund der Kompartimentierung der Membran durch das Aktin-Zytoskelett, eingeschränkt ist.

Willin is a novel member of the Four-point-one Ezrin Radixin Moesin (FERM) protein superfamily, containing an N-terminal FERM domain most like the Ezrin-Radixin-Moesin (ERM) family but also the closely related protein Merlin. Willin was initially discovered as a yeast two-hybrid binding partner of neurofascin155, and this interaction has now been confirmed by both co-localisation studies and the use of two different biochemical methods. Like neurofascin155, Willin also localises to detergent resistant membranes, and like the ERM family, it is able to bind to phospholipids. The expression of Willin appears to be toxic as the production of cell-lines stably expressing Willin proved to be not possible and this appears to be because it induces apoptosis in cultured cells. This is a proliferation control function consistent with the suggestion that Willin is the human homologue of the Drosophila tumour suppressor ‘Expanded’. Three antibodies to Willin were also characterised and a novel splice variant, Willin2, subcloned into a GFP-tagged plasmid for comparison with the original form.

Breast cancer (BC) is one of the leading causes of cancer-related deaths in Canadian women. Aggressive BCs (e.g. triple-negative subtype; TN) present a clinical challenge as defined biomarkers, particularly those indicative of unique cancer-associated signaling pathways, are needed to improve prognostication and prediction of therapeutic response. Overexpression of Src and its substrates, Ezrin and Tks5, have been associated with poor prognosis in many cancers. We have previously shown that Ezrin regulates proteolytic-independent invasion, while others have shown that Tks5 is associated with proteolytic-dependent invasion. Thus, expression of Ezrin versus Tks5 in BC cases may represent different invasion modalities. Additionally, immunofluorescence (IF)-based technologies may provide a more quantitative and objective approach for analysis of biomarker expression and subcellular compartmentalization compared to immunohistochemistry (IHC). In this study, I hypothesize that expression and subcellular localization of Src, Ezrin and Tks5, have improved prognostic significance in BCs, compared to current clinico-pathological parameters. To assess this, I optimized an IF-based automated quantification analysis (AQUA) system to measure subcellular expression in a 63-patient BC cohort and tested associations with clinico-pathological data. This thesis presents that: 1) Expression of Src and Ezrin increased, but that of Tks5 decreased in breast tumours compared to normal breast. 2) Src and Ezrin localized to the apical regions of normal breast epithelia but shifted to the cytoplasm in breast tumours. Tks5 exhibited a granular basal expression in normal breast epithelia, and is weakly expressed in tumour cellular compartments. 3) In our 63-patient cohort, Src and Ezrin had significant correlations with multiple clinico-pathological parameters, including TN status and lymphovascular invasion. 4) Clinico-pathological associations with IF-based AQUA scoring are directly comparable to conventional manual IHC scoring. Our study supports the role of Src and Ezrin as potential prognostic biomarkers for BC. / Thesis (Master, Pathology & Molecular Medicine) -- Queen's University, 2013-07-09 12:51:09.527

A localização da podoplanina e da ezrina nas células malignas sugere uma ligação dessas proteínas nos processos de migração e invasão tumoral, ativadas mediante a fosforilação de Rho-A. O objetivo desse estudo foi avaliar a distribuição e a correlação da podoplanina, da ezrina e da Rho-A em 91 carcinomas espinocelulares de lábio inferior, e verificar a associação dessas proteínas com as variáveis clínicas e patológicas, com a evolução e com o prognóstico dos pacientes. Os pacientes foram analisados quanto ao gênero, idade, tabagismo, etilismo, classificação pelo sistema TNM, tratamento, ocorrência de recidivas locorregionais, segundo tumor primário, além da presença de embolização vascular, infiltração perineural, muscular, glandular e comprometimento linfonodal histopatológico. Analisou-se também as expressões imuno-histoquímicas de podoplanina, ezrina e Rho-A no front de invasão tumoral e o índice de malignidade tumoral. A associação entre a podoplanina, a ezrina e a Rho-A com as variáveis clínico-patológicas e a correlação entre as proteínas foram analisadas pelos testes do qui-quadrado e de Spearman, respectivamente. A análise da sobrevivência global em 5 e 10 anos foi feita pelo estimador produto-limite Kaplan-Meier e a comparação da curva de sobrevivência pelo teste log-rank. Os resultados demonstraram uma forte expressão de podoplanina, de ezrina e de Rho-A no front de invasão dos carcinomas espinocelulares de lábio inferior. Houve uma associação significativa entre a expressão citoplasmática de podoplanina com o etilismo (p=0,024), com a recidiva locorregional (p=0,028) e com comprometimento linfonodal histopatológico (p=0,010), porém não foi detectada nenhuma associação significativa entre a ezrina e a Rho-A com as variáveis clínicas e microscópicas analisadas. Uma correlação positiva e estatisticamente significativa entre a expressão de podoplanina membranosa (p=0,000 e r =0,384) e citoplasmática (p=0,000 e r=0,344) com a expressão de ezrina, e da podoplanina membranosa com a expressão de Rho-A (p=0,006 e r=0,282) foi detectada. Nenhuma das três proteínas se mostrou fator de prognóstico significativo para os pacientes com câncer de lábio. Concluímos que a forte expressão membranosa de podoplanina nos carcinomas espinocelulares de lábio inferior pode ajudar a identificar pacientes com menor risco de recidiva locorregional. Além disso, a correlação entre as expressões da podoplanina, da ezrina e da Rho-A pelas células neoplásicas sugere uma participação conjunta destas proteínas nos processos de movimentação celular e invasão tumoral do câncer de lábio. / Immunolocalization of podoplanin and ezrin suggests a connection between these proteins in migration and tumoral invasion process, activated through Rho-A phosphorylation. The aim of this study was to evaluate the distribution and the correlation of podoplanin, ezrin and Rho-A in 91 squamous cells carcinomas of the lower lip and to verify its association with clinical and pathological features, evolution and prognostic of the patients. Patients were analyzed concerning gender, age, tobacco, alcohol, TNM classification, local and regional recurrences, second primary tumor, perineural, muscle and glandular infiltration, and histopahological lymph node metastasis. The association of podoplanin, ezrin and Rho-A expressions at tumoral invasion front and histological risk assessment of tumors were verified by chi-square test. The association between podoplanin, ezrin and Rho-A expressions with clinical and pathological variables, and the correlation of these variables were analyzed by chi-square and Spearman test, respectively. Overall survival in 5 and 10 years was calculated by Kaplan Meier method and overall curves were compared by log rank test. The results showed strong expression of podoplanin, ezrin and Rho-A at tumoral invasion front of squamous cell carcinomas of the lower lip. A significant association of strong cytoplasmic podoplanin expression and alcoholism (p=0,024), local recurrences (p=0,028) and lymph node metastasis (p=0,010) was found, although ezrin and Rho-A expressions were not associated with clinical and microscopic features analyzed. A statistically significant correlation between membranous (p=0,000 e r =0,384) and cytoplasmic (p=0,000 e r=0,344) podoplanin expressions and ezrin, and membranous podoplanin and Rho-A (p=0,006 e r=0,282) was observed. None of the proteins analyzed can be considered as prognostic factor for lip cancer. We can conclude that strong membranous podoplanin expression in squamous cell carcinoma of the lower lip can help to identify patients with lower risk of local and regional recurrences. Furthermore, the correlation of podopolanin, ezrin and Rho-A expressions suggest a cooperative participation in cell movement and tumoral invasion.

A localização da podoplanina e da ezrina nas células malignas sugere uma ligação dessas proteínas nos processos de migração e invasão tumoral, ativadas mediante a fosforilação de Rho-A. O objetivo desse estudo foi avaliar a distribuição e a correlação da podoplanina, da ezrina e da Rho-A em 91 carcinomas espinocelulares de lábio inferior, e verificar a associação dessas proteínas com as variáveis clínicas e patológicas, com a evolução e com o prognóstico dos pacientes. Os pacientes foram analisados quanto ao gênero, idade, tabagismo, etilismo, classificação pelo sistema TNM, tratamento, ocorrência de recidivas locorregionais, segundo tumor primário, além da presença de embolização vascular, infiltração perineural, muscular, glandular e comprometimento linfonodal histopatológico. Analisou-se também as expressões imuno-histoquímicas de podoplanina, ezrina e Rho-A no front de invasão tumoral e o índice de malignidade tumoral. A associação entre a podoplanina, a ezrina e a Rho-A com as variáveis clínico-patológicas e a correlação entre as proteínas foram analisadas pelos testes do qui-quadrado e de Spearman, respectivamente. A análise da sobrevivência global em 5 e 10 anos foi feita pelo estimador produto-limite Kaplan-Meier e a comparação da curva de sobrevivência pelo teste log-rank. Os resultados demonstraram uma forte expressão de podoplanina, de ezrina e de Rho-A no front de invasão dos carcinomas espinocelulares de lábio inferior. Houve uma associação significativa entre a expressão citoplasmática de podoplanina com o etilismo (p=0,024), com a recidiva locorregional (p=0,028) e com comprometimento linfonodal histopatológico (p=0,010), porém não foi detectada nenhuma associação significativa entre a ezrina e a Rho-A com as variáveis clínicas e microscópicas analisadas. Uma correlação positiva e estatisticamente significativa entre a expressão de podoplanina membranosa (p=0,000 e r =0,384) e citoplasmática (p=0,000 e r=0,344) com a expressão de ezrina, e da podoplanina membranosa com a expressão de Rho-A (p=0,006 e r=0,282) foi detectada. Nenhuma das três proteínas se mostrou fator de prognóstico significativo para os pacientes com câncer de lábio. Concluímos que a forte expressão membranosa de podoplanina nos carcinomas espinocelulares de lábio inferior pode ajudar a identificar pacientes com menor risco de recidiva locorregional. Além disso, a correlação entre as expressões da podoplanina, da ezrina e da Rho-A pelas células neoplásicas sugere uma participação conjunta destas proteínas nos processos de movimentação celular e invasão tumoral do câncer de lábio. / Immunolocalization of podoplanin and ezrin suggests a connection between these proteins in migration and tumoral invasion process, activated through Rho-A phosphorylation. The aim of this study was to evaluate the distribution and the correlation of podoplanin, ezrin and Rho-A in 91 squamous cells carcinomas of the lower lip and to verify its association with clinical and pathological features, evolution and prognostic of the patients. Patients were analyzed concerning gender, age, tobacco, alcohol, TNM classification, local and regional recurrences, second primary tumor, perineural, muscle and glandular infiltration, and histopahological lymph node metastasis. The association of podoplanin, ezrin and Rho-A expressions at tumoral invasion front and histological risk assessment of tumors were verified by chi-square test. The association between podoplanin, ezrin and Rho-A expressions with clinical and pathological variables, and the correlation of these variables were analyzed by chi-square and Spearman test, respectively. Overall survival in 5 and 10 years was calculated by Kaplan Meier method and overall curves were compared by log rank test. The results showed strong expression of podoplanin, ezrin and Rho-A at tumoral invasion front of squamous cell carcinomas of the lower lip. A significant association of strong cytoplasmic podoplanin expression and alcoholism (p=0,024), local recurrences (p=0,028) and lymph node metastasis (p=0,010) was found, although ezrin and Rho-A expressions were not associated with clinical and microscopic features analyzed. A statistically significant correlation between membranous (p=0,000 e r =0,384) and cytoplasmic (p=0,000 e r=0,344) podoplanin expressions and ezrin, and membranous podoplanin and Rho-A (p=0,006 e r=0,282) was observed. None of the proteins analyzed can be considered as prognostic factor for lip cancer. We can conclude that strong membranous podoplanin expression in squamous cell carcinoma of the lower lip can help to identify patients with lower risk of local and regional recurrences. Furthermore, the correlation of podopolanin, ezrin and Rho-A expressions suggest a cooperative participation in cell movement and tumoral invasion.