Abstract The homeobox gene prox1 is a transcription factor related to the Drosophila gene Prospero. It play an essential role in the development of central nervous system, lens, liver and pancreas. In addition, prox1 is a master gene controlling the early development of the lymphatic vasculature. In tumorigenesis, prox1 has been shown to function as a tumor suppressor gene in hepatocellular carcinoma and breast cancer. Conversely, prox1 is over-expressed in the majority of colorectal cancer (CRC) and it promotes dysplasia, tumor growth and malignant progression. I report the findings here and show that ectopic expression of prox1 in prox1-null DLD-1 colon cancer cells will increase cell invasion but decrease cell adhesion. In addition, prox1 may induce epithelia- mesenchymal transition (EMT) by attenuating E-cadherin expression and up-regulating other EMT markers. On the contrary, knockdown of prox1 increases E-cadherin expression in SW620 cells; reduction of prox1 increases cell adhesion but decreases invasion. In short, the transcription factor prox1 plays an oncogenic role and promotes cancer metastasis in CRC.

To elucidate the correlation between host susceptible genes and the carcinogenesis of gastric cancer and duodenal ulcer, myeloperoxidase (MPO) -463 G/A polymorphism was detected by PCR-RFLP and nucleotide autosequencing, respectively. On the other hand, E-cadherin (CDH1) -160 C/A polymorphism was analyzed by nucleotide autosequencing. No positive correlation among MPO genotype distributions, gastric cancer (p=0.26,

b-catenin plays a dual role as a structural component of adherens junctions and as a transcriptional coactivator through its interactions with E-cadherin and TCF/LEF transcription factors, respectively. Normally, free b-catenin in cytoplasma is regulated by proteosome-dependent degradation system. In malignant tumor cell , deregulation of b-catenin degradation results in its aberrant accumulation, and leading to cancer. The goals of this study were to explore the reason of aberrant b-catenin accumulation in cervical carcinoma and evaluate the correlation between b-catenin¡BE-cadherin and p53 in different FIGO stage. Seventy paraffin embedded specimen with different FIGO stage were included in this study. Immunohistochemical staining was performed using anti-b-catenin polyclonal antibody and anti-p53 polyclonal antibody respectively and direct sequencing methods to analyze the mutation of CTNNB1 exon 13. The results showed 58 cases (82.8%) displayed cytoplasmic/nuclear b-catenin and no mutations in exon 13 of b-catenin gene, whereas no significant correlation between b-catenin expression level and tumor metastasis. However, b-catenin expression intensity had significant correlation with tumor size (p=0.008) and inversely correlated with E-cadherin (p=0.027) in different FIGO stage. The other way, the p53 staining intensity was significant correlated with b-catenin expression intensity (p=0.013) . Therefore, we suggest that mutations of CTNNB1 exon 13 may not be a reason for aberrant b-catenin accumulation in cervical carcinoma and aberrant p53 may play an important factor in accumulation of b-catenin.

In the Xenopus embryo, cell rearrangements during early development require the dynamic modulation of adhesion. Cells primarily use the integrin family of transmembrane receptors for attachment to and interpretation of the extracellular environment. While acting as adhesion receptors, integrins also have bidirectional signalling properties essential for driving cellular movements. The regulation of integrin activity is thought to stem from cytoplasmic assemblies of constitutively expressed molecules. PINCH (Particularly Interesting New cysteine-histidine rich protein), an adapter protein, is part of an IPP complex that has emerged as a key signalling scaffold indispensable for integrin function in vitro. As such, I tested the hypothesis that PINCH regulates integrin function in the Xenopus embryo. Xenopus PINCH was successfully cloned using RT-PCR. The predicted amino acid sequence of PINCH shares a 98% similarity with mammalian orthologs, and comprises of five highly conserved LIM domains. PINCH mRNA and protein are ubiquitously expressed throughout embryogenesis. In situ hybridization indicates that PINCH mRNA is expressed in the blastocoel roof and the pre-involution mesoderm. The localization and temporal expression of PINCH suggests a role in mediating cell adhesive events during gastrulation. A functional approach was used to examine the role of PINCH during gastrulation. I used site-directed mutagenesis to generate non-functional LIM1 (LIM1mut) and LIM4 (LIM4mut) domains that have been proposed to bind ILK and Grb4 respectively. Over-expression of PINCH leads to a delay in blastopore closures, while the expression of both LIM1mut and LIM4mut relieve this inhibition at lower concentrations. Further analysis indicates that PINCH, LIM1mut, and LIM4mut inhibit FN matrix assembly independent of integrin adhesion. Contradictory to in vitro studies, co-immunoprecipitation analysis indicates that endogenous PINCH does not bind ILK, confirming an integrin-independent role during gastrulation. Furthermore, in the embryo PINCH is found at cell boundaries but does not appear to directly modulate cadherin adhesion. As such this thesis provides evidence that PINCH regulates cell intercalation movements independent of integrin and cadherin receptors and raises the possibility that the LIM4 domain is involved in PINCH regulation of cell adhesion during early development.

E–cadherin (CDH1) is a cell–cell adhesion molecule expressed in the epithelium to coordinate key morphogenetic processes, establish cell polarity, and regulate epithelial differentiation and proliferation. CDH1 forms adherens junctions that mediate intercellular adhesion through dynamic interactions with β–catenin (CTNNB1). To determine the role of CDH1 in the mouse uterus, Cdh1 was conditionally ablated by crossing Pgr–Cre and Cdh1–flox mice. Animals with the resulting genotype of Pgrcre/+Cdh1f/f had Cdh1 conditionally ablated in the Pgr expressing tissue, which includes the uterus (referred to as Cdh1d/d). We characterized the phenotype and found that loss of Cdh1 in the neonatal uterus results in a disorganized cellular structure of the epithelium and ablation of endometrial glands. Cdh1d/d mice lost adherens junction (CTNNB1 and CTNNA1) and tight junction (claudin, occludin and ZO–1) in the neonatal uterus leading to loss of epithelial cell–cell interaction. Ablation of Cdh1 induced abnormal epithelial proliferation and massive apoptosis, and disrupted Wnt and Hox gene expression in the neonatal uterus. Although the uteri of Cdh1d/d mice did not show any defect of myometrium, ablation of Cdh1 inhibited stromal (CD10) markers. In addition, a conditional knockout of Ctnnb1 in the uterus and a double conditional knockout of Cdh1&Ctnnb1 in the uterus were created to determine if the uterine defects were caused by an alteration in CDH1, CTNNB1, or a combination of both. Ctnnb1 and Cdh1&Ctnnb1 were conditionally ablated in the uterus by crossing Pgr–Cre and Ctnnb1–flox mice or Cdh1&Ctnnb1–flox mice. The Ctnnb1d/d mice maintained adhesive epithelial characteristics and did not lose adherens junction or tight junction proteins; however ablation of Ctnnb1 induced epithelial hyperplasia and disrupted Wnt and Hox gene expression in the neonatal uterus. The Cdh1d/dCtnnb1d/d mice carried a similar phenotype to the Cdh1d/d mice. Adult Cdh1d/d mice were infertile due to defects during implantation and decidualization. Collectively, these findings suggest that CDH1 has an important role in structural and functional development of the uterus as well as adult uterine function. CDH1 has a capacity to control cell fate by altering directional cell proliferation and apoptosis.

Les organismes multicellulaires, tels les mammifères, possèdent plusieurs organes constitués de couches de cellules, par exemple la peau ou l’intestin. Ces couches, appelées épithelia, fonctionnent comme des barrières. Une protéine nommée E-Cadhérine agit comme une colle moléculaire et procure l’adhésion cellule-cellule qui est nécessaire à la fonction de barrière. Les épithelia changent aussi leur structure pendant le développement de l’organisme ou pendant les maladies. Nous étudions un exemple d’un tel changement structurel. Pendant le développement de la mouche du vinaigre, à un stade précis, le tissu épithélial change de forme au travers d’un réarrangement des cellules. C’est un procédé complexe, car les cellules doivent maintenir l’adhésion tout en échangeant de voisin. Les forces requises pour ce procédé sont générées par une activité et une distribution spécifiques des moteurs moléculaires nommés Myosine. Nous voulons comprendre comment la distribution de la Myosine change l’adhésion entre les cellules pour permettre cet échange de voisins. Nous répondons à cette question en changeant la distribution de la Myosine et en regardant l’effet sur la E-Cadhérine. Sur la base de nos expériences nous sommes à même de conclure que l’orientation des forces est un facteur important (et précédemment négligé) de leur effet sur l’adhésion. / Multicellular organisms, such as mammals, have several organs that are made of sheets of cells e.g. skin or intestine. These sheets, called epithelia, function as barriers. A protein called E-Cadherin acts as molecular glue and mediates cell-cell adhesion that is essential for barrier function. Epithelia also change their structure during organismal development or during diseases. We are looking at one such example of structural change. During embryonic development of fruit fly, at specific stage, epithelial tissue changes shape due to cell mixing. It is a complex process, as cells have to maintain adhesion all around while they exchange neighbors. The forces required for this process are generated by specific activity and distribution of molecular motors, called Myosin. We want to understand how Myosin distribution changes adhesion between cells to allow neighbor exchange. We answer this question by changing the distribution of Myosin and seeing its effects on E-Cadherin. Based on our experiments we could conclude that orientation of forces is an important (and previously neglected) factor to predict their effects on adhesion.

Pemphigus vulgaris (PV) ist eine blasenbildende Autoimmunerkrankung, die durch Autoantikörper gegen Dsg1 und Dsg3 gekennzeichnet ist. Der genaue Pathomechanismus, der zu einem PV-IgG vermittelten Verlust der interzellulären Adhäsion führt, ist noch unklar. Die Dsg3-Depletion und die Modulation von Signalkaskaden stellen hierbei kennzeichnende Merkmale der Erkrankung dar. Mit den Ergebnissen der vorliegenden Arbeit ist eine bessere Einordnung der Dsg3-Depletion in den pathogenetischen Kontext von Pemphigus vulgaris möglich. Die Experimente zeigen, dass die Dsg3-Depletion von Differenzierungsprozessen abhängig ist und mit einem Adhäsionsverlust einhergehen kann. Die Hemmung der PKC verhindert hierbei sowohl die PV-IgG vermittelten Effekte in der Zellkultur als auch die Blasenbildung im Mausmodell in vivo und in humaner Haut ex vivo. Des Weiteren liefert die Arbeit neue Erkenntnisse, welche für die suprabasale Lokalisation der Blasenbildung bedeutsam sein könnten. / Pemphigus vulgaris (PV) is a blistering autoimmune disease characterised by antibodies directed against Dsg1 (desmoglein 1) and Dsg3 (desmoglein 3). The exact pathomechanism leading to PV-IgG induced loss of intercellular adhesion is still unclear. The Dsg3-depletion and the modulation of signaling pathways are characteristics of the disease. With the results of this study, a better classification of Dsg3-depletion in the pathogenetic context of pemphigus vulgaris becomes possible. The experiments show that the Dsg3-depletion is dependent on differentiation processes and can be accompanied by a loss of adhesion. Inhibition of PKC in this case prevents PV-IgG-mediated effects in the cell culture as well as blistering in murine skin in vivo and in human skin ex vivo. Furthermore, this work provides new insights that could be significant for the suprabasal localisation of blistering.

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