Lau Yee Lam. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 147-157). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iv / Abbreviations --- p.v / List of Figures --- p.viii / List of Tables --- p.xi / Contents --- p.xii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Hepatocellular carcinoma (HCC) --- p.1 / Chapter 1.1.1 --- Background of hepatocellular carcinoma (HCC) --- p.1 / Chapter 1.1.2 --- Etiology of HCC --- p.2 / Chapter 1.1.3 --- Relationship between HCC and HBV --- p.3 / Chapter 1.1.4 --- Differential gene expression under induction of HBx protein by microarray analysis --- p.5 / Chapter 1.1.5 --- Confirmation of candidate genes --- p.6 / Chapter 1.2 --- Ras-Oncogene --- p.8 / Chapter 1.2.1 --- Ras superfamily --- p.8 / Chapter 1.2.1.1 --- Rho family --- p.9 / Chapter 1.2.1.2 --- Rab family --- p.10 / Chapter 1.2.2 --- Functional mechanism of small GTPase --- p.11 / Chapter 1.2.3 --- Possible functions of Rho and Rab family members --- p.14 / Chapter 1.3 --- RhoC --- p.16 / Chapter 1.3.1 --- The genomic and protein structures of RhoC --- p.16 / Chapter 1.3.2 --- Relationship between RhoC and tumours --- p.19 / Chapter 1.4 --- Rabl4 --- p.20 / Chapter 1.4.1 --- The genomic and protein structures of Rabl4 --- p.20 / Chapter 1.4.2 --- Relationship between Rabl4 and tumours --- p.23 / Chapter 1.5 --- Aims of study --- p.23 / Chapter Chapter 2 --- Materials and Methods / Chapter 2.1 --- Materials --- p.25 / Chapter 2.1.1 --- Cell lines --- p.25 / Chapter 2.1.2 --- Cell culture reagents --- p.26 / Chapter 2.1.3 --- Reagents for total RNA isolation --- p.29 / Chapter 2.1.4 --- Reagents for reverse transcription polymerase chain reaction (RT-PCR) --- p.30 / Chapter 2.1.5 --- Reagents and buffers for Western blot analysis --- p.31 / Chapter 2.1.6 --- Vectors for cloning --- p.39 / Chapter 2.1.7 --- Reagents for polymerase chain reaction (PCR) --- p.39 / Chapter 2.1.8 --- Restriction digestion reagents --- p.42 / Chapter 2.1.9 --- Reagents for agarose gel electrophoresis --- p.42 / Chapter 2.1.10 --- Ligation reagents --- p.44 / Chapter 2.1.11 --- Bacterial culture medium --- p.44 / Chapter 2.1.12 --- Dyes and reagents for fluorescent microscope --- p.46 / Chapter 2.1.13 --- Reagents for flow cytometry --- p.48 / Chapter 2.1.14 --- Detection of apoptosis --- p.48 / Chapter 2.2 --- Methods --- p.50 / Chapter 2.2.1 --- Identification of gene expression of candidate genes in HCC --- p.50 / Chapter 2.2.1.1 --- cDNA preparation --- p.50 / Chapter (1) --- Cell culture of HepG2 and WRL-68 cell lines --- p.50 / Chapter (2) --- Total RNA isolation --- p.50 / Chapter (3) --- First-strand cDNA synthesis --- p.51 / Chapter 2.2.1.2 --- RT-PCR of candidate genes --- p.52 / Chapter 2.2.1.3 --- Western blotting --- p.53 / Chapter (1) --- Cell culture --- p.53 / Chapter (2) --- Protein extraction --- p.53 / Chapter (3) --- Quantification of proteins --- p.53 / Chapter (4) --- Detection of RhoC and Rabl4 protein by western blot analysis --- p.54 / Chapter (5) --- Western blotting luminol detection --- p.56 / Chapter 2.2.2 --- Cloning protocol --- p.57 / Chapter 2.2.2.1 --- Amplification of RhoC and Rabl4 genes --- p.57 / Chapter 2.2.2.2 --- Purification of PCR product --- p.58 / Chapter 2.2.2.3 --- Restriction enzymes digestion --- p.53 / Chapter 2.2.2.4 --- Insert/vector ligation --- p.59 / Chapter 2.2.2.5 --- Preparation of chemically competent bacterial cells (E. coli strain DH5a) --- p.60 / Chapter 2.2.2.6 --- Transformation of ligation product into chemically competent bacterial cells --- p.61 / Chapter 2.2.2.7 --- Small-scale preparation of bacterial plasmid DNA --- p.61 / Chapter 2.2.2.8 --- Screening for recombinant clones --- p.62 / Chapter 2.2.2.9 --- DNA sequencing of cloned plasmid DNA --- p.63 / Chapter 2.2.2.10 --- Midi-scale preparation of recombinant plasmid DNA --- p.64 / Chapter 2.2.3 --- Visualization of the subcellular localization patterns --- p.66 / Chapter 2.2.3.1 --- Cell culture of AML12 and HepG2 cell lines --- p.66 / Chapter 2.2.3.2 --- Transfection of GFP fusion constructs into cells --- p.66 / Chapter 2.2.3.3 --- DAPI staining --- p.67 / Chapter 2.2.3.4 --- ER-Tracker´ёØ Blue-White DPX staining --- p.68 / Chapter 2.2.3.5 --- Subcellular localization study using Epi-fluorescence microscopy --- p.68 / Chapter 2.2.4 --- Analysis of cell cycle --- p.69 / Chapter 2.2.4.1 --- Transfection of GFP vectors / GFP-tagged proteins into cells --- p.69 / Chapter 2.2.4.2 --- Analysis of cell cycle by flow cytometry --- p.69 / Chapter 2.2.5 --- Detection of apoptosis --- p.70 / Chapter 2.2.5.1 --- Transfection --- p.70 / Chapter 2.2.5.2 --- Detection of DNA fragmentation --- p.70 / Chapter 2.2.6 --- Reorganization of Actin cytoskeleton by RhoC --- p.71 / Chapter 2.2.6.1 --- Transfection of GFP vectors/GFP-tagged proteins into cells --- p.71 / Chapter 2.2.6.2 --- Rhodamine phalloidin (RP) staining --- p.71 / Chapter 2.2.6.3 --- Epi-fluorescence microscopy --- p.72 / Chapter 2.2.7 --- Analysis of cell invasion under induction of RhoC --- p.72 / Chapter 2.2.7.1 --- "Sub-cloning of human RhoC gene into a mammalian expression vector, pHM6" --- p.72 / Chapter 2.2.7.2 --- Transfection of pHM6-RhoC --- p.73 / Chapter 2.2.7.3 --- Cell invasion assay --- p.73 / Chapter 2.2.8 --- Analysis of downstream effectors in RhoC-mediated pathway --- p.75 / Chapter 2.2.8.1 --- RT-PCR --- p.75 / Chapter 2.2.8.2 --- Western blotting --- p.75 / Chapter 2.2.9 --- Analysis of role of Rabl4 in membrane trafficking --- p.76 / Chapter 2.2.9.1 --- Cloning and transfection --- p.76 / Chapter 2.2.9.2 --- Alexa 594 transferrin conjugate staining --- p.76 / Chapter 2.2.9.3 --- Epi-fluorescence microscopy --- p.77 / Chapter 2.2.10 --- Statistics --- p.77 / Chapter Chapter 3 --- Results / Chapter 3.1 --- Expression of RhoC and Rabl4 in hepatoma cells --- p.78 / Chapter 3.1.1 --- RT-PCR --- p.78 / Chapter 3.1.2 --- Western blotting --- p.81 / Chapter 3.2 --- Subcellular localization of RhoC and Rab 14 --- p.85 / Chapter 3.3 --- Characterization of RhoC --- p.93 / Chapter 3.3.1 --- Cell cycle analysis --- p.93 / Chapter 3.3.2 --- Apoptosis --- p.95 / Chapter 3.3.3 --- Actin cytoskeleton reorganization --- p.97 / Chapter 3.3.4 --- Cell invasion ability --- p.99 / Chapter 3.3.5 --- Downstream effectors of RhoC in cytoskeletal reorganization --- p.102 / Chapter 3.4 --- Characterization of Rabl4 --- p.107 / Chapter 3.4.1 --- Cell cycle analysis --- p.107 / Chapter 3.4.2 --- Apoptosis --- p.109 / Chapter 3.4.3 --- Roles in intracellular transportation --- p.111 / Chapter Chapter 4 --- Discussion / Chapter 4.1 --- Strong expression of RhoC and Rabl4 in hepatoma cells --- p.117 / Chapter 4.2 --- Subcellular localization of RhoC and Rabl4 --- p.119 / Chapter 4.3 --- The effects of RhoC in normal liver cells --- p.122 / Chapter 4.3.1 --- Cell cycle progression by RhoC through regulating of G1 to S phase transition --- p.122 / Chapter 4.3.2 --- RhoC shows no apoptotic effect in normal liver cell systems --- p.123 / Chapter 4.3.3 --- Formation of actin filaments and stress fibers --- p.124 / Chapter 4.3.4 --- Induction of cell invasion in RhoC-expressing cells --- p.125 / Chapter 4.3.5 --- Downstream effectors in signaling pathway of RhoC in actin filment reorganization and cell invasion --- p.126 / Chapter 4.4 --- The effects of Rabl4 in normal liver cells --- p.132 / Chapter 4.4.1 --- Cell proliferation effects of Rabl4 by increasing percentage of cells in S phase for DNA synthesis --- p.132 / Chapter 4.4.2 --- Rabl4 has no apoptotic effects --- p.133 / Chapter 4.4.3 --- Roles of Rabl4 in vesicular transport --- p.134 / Chapter 4.5 --- Conclusion --- p.138 / Chapter 4.6 --- Future prospects --- p.140 / Appendix --- p.143 / References --- p.147

No description available.

No description available.

Das Multiple Myelom (MM) ist eine seltene, maligne Störung der Plasmazellen, welche trotz gehöriger Therapiefortschritte in den letzten Jahrzehnten nach wie vor als unheilbare Erkrankung betrachtet werden muss. Obwohl eine sehr große intra- und interindividuelle Heterogenität beim Multiplen Myelom beobachtet werden kann, gibt es verschiedene Mutationen, die mit höherer Frequenz in Myelompatientinnen und -patienten gefunden werden. Eines dieser häufiger betroffenen Proteine ist KRas mit Mutationen in etwa 20% der Fälle. Da die Ras-Proteine und somit auch ihre Isoform KRas zu Beginn der Ras/Raf/Mek/Erk-Signalkaskade stehen und dementsprechend einen großen Einfluss auf die Übermittlung von Wachstums- und Überlebenssignalen in Zellen besitzen, ist eine nähere funktionelle Analyse verschiedener KRas-Mutationen von großer Relevanz. Während für einige Mutationen von KRas bereits funktionelle Analysen existieren, wurden die häufig auftretende Exon 2-Mutation KRasp.G12A, sowie die beiden seltenen Exon 4-Mutationen KRasp.A146T und KRasp.A146V bisher in ihrer funktionellen Rolle im MM noch nicht näher charakterisiert. Um die funktionellen Aspekte dieser genannten Mutationen von KRas näher zu untersuchen, kamen im Rahmen meiner Versuchsreihe Sleeping Beauty Transposon System basierte Expressionsvektoren zur transienten und dauerhaften Proteinexpression in verschiedenen Myelomzelllinien zum Einsatz. Durch Transfektion dieser Plasmide in die KRas-Wildtyp tragenden Zellen mit nachfolgender Transposition in die genomische DNA konnte gezielt die Überexpression der verschiedenen Mutationen realisiert werden. So konnte durch die funktionelle Proteinauslese mittels der Anfertigung von Western Blots gezeigt werden, dass jede der drei getesteten Mutationen zu einer verstärkten Phosphorylierung und damit Aktivierung von KRas-nachgeschalteten Proteinen wie z.B. Erk führt. Zusätzlich wurde für die KRas-Mutationen auch ein aktivierender Effekt auf den PI3K/Akt-Signalweg anhand einer erhöhten Phosphorylierung des Proteins Akt nachgewiesen. Ebenso wie andere bereits besser charakterisierte KRas-Mutationen haben demnach auch die getesteten KRas-Mutationen KRasp.G12A, KRasp.A146T und KRasp.A146V einen positiven Einfluss auf die intrazellulären Überlebenssignale und könnten daher eine elementare Rolle in der Entwicklung des Multiplen Myeloms bei Patientinnen und Patienten spielen. Es gilt daher, die drei in dieser Arbeit untersuchten KRas-Mutationen, zukünftig in die Wirkstoffsuche KRas-spezifischer Therapeutika miteinzubeziehen. / Multiple Myeloma (MM) is a rare, malignant disorder of plasma cells, which despite the progress in therapy over the last decades, must still be considered an incurable disease. Although a very large intra- and interindividual heterogeneity can be observed in multiple myeloma, there are various mutations that are found at higher frequencies in myeloma patients. One of these more common proteins affected by mutations in myeloma patients is KRas, with mutations in about 20% of cases. Since the Ras proteins and thus also their KRas isoform are at the beginning of the Ras/Raf/Mek/Erk signaling cascade and therefore have a major influence on the transmission of survival signals in cells, a closer functional analysis of various KRas mutations is of great relevance. While functional analyses already exist for some KRas mutations, the frequently occurring exon 2 mutation KRasp.G12A and the two rare exon 4 mutations KRasp.A146T and KRasp.A146V have not yet been characterized in their functional role in MM. To further investigate the functional aspects of these KRas mutations, I used protein expression vectors based on the Sleeping Beauty Transposon System for transient and sustained protein expression in different myeloma cell lines. By transfection of these plasmids into KRas wild-type cells the overexpression of the different mutations could be realized. By functional protein readout using Western blots it could be shown that each of the three tested mutations leads to increased phosphorylation and thus activation of KRas downstream proteins such as Erk. In addition, an activating effect on the PI3K/Akt signaling pathway could be demonstrated for the KRas mutations by showing an increased phosphorylation of the Akt protein. As with other KRas mutations that have already been better characterized, the KRas mutations KRasp.G12A, KRasp.A146T and KRasp.A146V have a positive influence on intracellular survival signals and could therefore play a fundamental role in the development of multiple myeloma in patients. It is therefore important to include the three KRas mutations investigated in this work in the drug discovery process for KRas-specific therapeutics in the future.

No description available.

Phosphatidylcholine (PC) is an essential component of biological membranes and is synthesized by the CDP-choline pathway under the control of the rate-limiting enzyme CTP:phosphocholine cytidylyltransferase-alpha (CCT?). Ras transformed cells have increased lipid synthesis; the aim of this study was to determine if upregulation of CCT? was part of this transformed phenotype. Rat intestinal epithelial cell lines (IEC) and three oncogenic H-ras expressing IEC (IEC-Ras) were used to investigate the role of CCT? and phosphatidylcholine (PC) synthesis in resistance to detachment dependant apoptosis, termed anoikis. IEC-Ras have increased CCT? expression within the nucleus. Reduction of CCT? expression with lentiviral short hairpin RNA sensitized IEC-Ras to anoikis and decreased PC degradation, but did not change PC synthesis. Thus, in addition to CCT? being involved in anoikis-resistance in IEC-Ras these data indicate the possibility that it may also have nuclear-specific functions.

Universiẗat, Diss., 2002--Dortmund.

Universiẗat, Diss., 2002--Bonn.

Ras-MAPK signalling regulates key cellular processes such as proliferation, differentiation and survival. Unsurprisingly, mutations in RAS genes are now recognized as potent oncogenic drivers. However, disruption of this pathway during development is associated with a family of disorders termed the Rasopathies. Shared clinical features include cutaneous, neurological and cardiac anomalies. At the outset of this study, the genetic etiology of three neurocutaneous disorders, microcephaly-capillary malformation syndrome (MIC-CAP), encephalocraniocutaneous lipomatosis (ECCL) and PHACE (Posterior fossa malformations, facial Hemangiomas, cerebral Arterial anomalies, Cardiovascular defects and Eye abnormalities) syndrome had not yet been established. This thesis identifies mutations in STAM-binding protein (STAMBP) in a cohort of individuals with MIC-CAP syndrome using whole-exome sequencing (WES). This gene encodes a deubiquitinating isopeptidase that regulates cell surface receptor-mediated endocytosis and sorting. Cell lines of individuals with MIC-CAP show reduced STAMBP expression, associated with accumulation of ubiquitinated protein aggregates, increased apoptosis and constitutive activation of the Ras-MAPK and PI3K-AKT pathways. WES also enabled the identification of post-zygotic mutations within the tyrosine kinase domain of fibroblast growth factor receptor 1 (FGFR1) in individuals with ECCL. Fibroblasts from affected individuals showed increased phosphorylation of the FGFRs consistent with receptor activation as well as insensitive signal transduction through the Ras-MAPK pathway. Neurocutaneous syndromes can feature striking vascular lesions such as the cerebral vasculopathy and large segmented facials hemangiomas seen in PHACE syndrome. The asymmetric and patchy vascular malformations coupled with a sporadic incidence and absence of familial recurrence suggested that PHACE might be caused by post-zygotic mutations. Interrogation of a discordant sib-pair using copy number analysis and WES did not identify causative mutations indicating the need for a comprehensive and targeted –omic approach to elucidate the molecular mechanism of this syndrome. Taken together, these findings expand the spectrum of the Rasopathies while providing novel pathomechanistic insights into the regulation of cellular proliferation and survival during development.

Fam84b is a largely unstudied protein, where its function in eukaryotic cells is unclear. This thesis work presents a FAM84B knockout mouse model and characterises the resulting retinal phenotype in detail. FAM84B KO mice were morphologically assessed by optical coherence tomography and histological processing, revealing dynamic changes stemming from the photoreceptor and pigmented epithelial layers. This potent phenotype progresses with age, spreading inwards towards the inner retinal layers, as well as laterally to adjacent retinal regions. Comparative localisation of standard retinal cell markers demonstrates that FAM84B KO retinal layering becomes increasingly disorganised, together with deformation of the retinal macrostructure. Due to this, KO mice experience reducing responses to light, as demonstrated by electroretinography, where overall retinal efficiency falls. Fam84b shows homology to the HRASLS enzyme family, which are capable of attenuating Ras-associated signalling. To investigate whether Fam84b possesses a similar function, the level of phosphorylated and activated downstream Ras effectors were compared between wild type and FAM84B KO mouse retinal lysates. A reduction of pERK1 (pY204) in KO lysates suggests that Fam84b holds some function related to this pathway downstream of Ras....