Gata4 and Gata6 are closely related transcription factors that are essential for the development of a number of embryonic tissues. While they have nearly identical DNA-binding domains and similar patterns of expression, Gata4 and Gata6 null embryos have strikingly different embryonic lethal phenotypes. Conditional deletion of these genes in the pancreas has also revealed specific functions for each factor in this organ. To investigate the role of these genes in pancreatic development, we performed a number of biochemical experiments on pancreatic cell lines and mutant tissues. We found that Gata4 and Gata6 regulate overlapping sets of genes in the developing pancreas. To determine whether the lack of global redundancy between Gata4 and Gata6 is due to differences in protein function or Gata4 and Gata6 expression domains, we generated mice that contained the Gata6 cDNA in place of the Gata4 genomic locus. Gata4Gata6/Gata6 embryos survived through embryonic day (e)12.5 and successfully underwent ventral folding morphogenesis, demonstrating that Gata6 is able to replace Gata4 function in extraembryonic tissues. Interestingly, Gata6 is unable to replace Gata4 function in the septum transversum mesenchyme or the epicardium, leading to liver agenesis and lethal heart defects in Gata4Gata6/Gata6 embryos. These studies suggest that Gata4 has evolved distinct functions in the development of these tissues that cannot be performed by Gata6, even when it is provided in the identical expression domain. Our work has important implications for the respective mechanisms of Gata function during development, as well as the functional evolution of these essential transcription factors.

No description available.

No description available.

Optimisation of the conventional tripartite of pancreatic cancer (PC) treatment have led to significant improvements in mortality, however further knowledge of the underlying molecular processes is still required. Transcript profiling of mRNA expression of over 44K genes with microarray technology demonstrated upregulation of secreted frizzled related protein 4 (sFRP4) and ??-catenin in PC compared to normal pancreata. Their pathway ??? Wnt signalling is integral to transcriptional regulation and aberrations in these molecules are critical in the development of many human malignancies. Immunohistochemistry protocols were evaluated by two independent blinded examiners for antigen expression differences associated with survival patterns in 140 patients with biopsy verified PC and a subset of 23 normal pancreata with substantial observer agreement (kappa value 0.6-0.8). A retrospective cohort was identified from 6 Sydney hospitals between 1972-2003 and archival formalin fixed tissue was collected together with clinicopathological data. Three manual stepwise regression models were fitted for overall, disease-specific and relapse-free survival to determine the value of significant prognostic variables in risk stratification. The models were fitted in a logical order using a careful strategy with step by step interpretation of the results. Immunohistochemistry demonstrated increased sFRP4 membranous expression (&gt 10%) in 49/95 PC specimens and this correlated with improved overall survival (HR:0.99;95%CI:0.97-6.40;LRchi2=134.75; 1df; ??&lt 0.001). Increased sFRP4 cytoplasmic staining (&gt 2/3) in 46/85 patients increased the disease-specific survival (HR:0.52;95%CI:0.31-0.89;LR test statistic =248.40;1df;??&lt 0.001). Increasing ??-catenin membranous expression (&lt _60%) in 26/116 patients was associated with an increased risk of overall death (HR:3.18;95%CI:1.14-8.89;LR test statistic =4.61;1df,??&lt 0.05). Increasing cytoplasmic expression in 65/114 patients was protective and was associated with prolonged survival on univariate, but not multivariate analysis (Disease specific survival HR:0.75;95%CI:0.56-1.00;logrank chi2=3.91;1df; ??=0.05). Increased nuclear ??-catenin expression in 65/114 patients was associated with prolonged survival (disease-specific HR:0.92;95%CI:0.83-1.02; LR test statistic= 49.72;1df;??&lt 0.001). At the conclusion, 12 patients (8.6%) remained alive, 122 died of their disease (68 males versus 54 females). They were followed for a median of 8.7 months (range 1.0-131.3) months. The median age was 66.5 years (range 34.4-96.0, standard deviation 10.9) years. Pancreatic resection was achieved in 79 patients with 46.8% achieving RO resection. The 30 day post-operative mortality was 2.1%. The overall 1 year survival rate was (33.7% ; 95%CI: 25.78-33.79) with a 5 year survival of (2.87%, 95%CI: 2.83-6.01) and a median survival of (8.90 months; 95%CI: 7.5-10.2). The median disease-specific survival was (9.40; 95%CI: 7.9-10.5 months) and the median time to relapse was 1.2 months (95%CI 1.0-1.2 months). A central tenet of contemporary cancer research is that an understanding of the genetic and molecular abnormalities that accompany the development and progression of cancer is critical to further advances in diagnosis, treatment and eventual prevention. High throughput tissue microarrays were used to study expression of two novel tumour markers in a cohort of pancreatic cancer patients and identified sFRP4 and ??-catenin as potential novel prognostic markers.

Thesis--Lund. / Extra t.p. with thesis statement inserted.

Pax4 is a paired-domain-containing transcription factor that plays a crucial role in the development of pancreatic β- and δ-cells. In the absence of Pax4, no β- or δ-cells develop, but an increase in the number of α-cells is observed. To gain insight into Pax4 function, a rat insulinoma cDNA library was screened and two Pax4-related clones were isolated. One clone encoded a 349 amino acid protein with a molecular weight of 38K that corresponded to the full-length sequence of Pax4. The second cDNA, termed Pax4c, was identical to Pax4 but lacked the sequences encoding 117 amino acids at the COOH-terminus. Intracellular localisation studies indicated that Pax4 was sequestered specifically in the cytoplasm of β-cells. To determine the effect of Pax4 on islet cell gene expression, Pax4 was co-transfected with a series of human insulin and islet amyloid polypeptide (IAPP) promoter constructs into the β-cell line MIN6, and transcriptional activity was measured by reporter gene assay. Pax4 was found to have an inhibitory effect on the human insulin gene promoter, which was mapped, to the region -229 to -258. Electrophoretic mobility shift assay was used to show that Pax4 could bind to the C2 element located at -253 to -244 within this region. Pax4 was also found to have an inhibitory effect on the IAPP promoter, which was mapped to a sequence downstream of -138. Using a GAL4 reporter system, the repressive properties of Pax4 was further mapped to separate regions of the promoter between amino acids 2-230 and 231-349.

Optimisation of the conventional tripartite of pancreatic cancer (PC) treatment have led to significant improvements in mortality, however further knowledge of the underlying molecular processes is still required. Transcript profiling of mRNA expression of over 44K genes with microarray technology demonstrated upregulation of secreted frizzled related protein 4 (sFRP4) and ??-catenin in PC compared to normal pancreata. Their pathway ??? Wnt signalling is integral to transcriptional regulation and aberrations in these molecules are critical in the development of many human malignancies. Immunohistochemistry protocols were evaluated by two independent blinded examiners for antigen expression differences associated with survival patterns in 140 patients with biopsy verified PC and a subset of 23 normal pancreata with substantial observer agreement (kappa value 0.6-0.8). A retrospective cohort was identified from 6 Sydney hospitals between 1972-2003 and archival formalin fixed tissue was collected together with clinicopathological data. Three manual stepwise regression models were fitted for overall, disease-specific and relapse-free survival to determine the value of significant prognostic variables in risk stratification. The models were fitted in a logical order using a careful strategy with step by step interpretation of the results. Immunohistochemistry demonstrated increased sFRP4 membranous expression (&gt 10%) in 49/95 PC specimens and this correlated with improved overall survival (HR:0.99;95%CI:0.97-6.40;LRchi2=134.75; 1df; ??&lt 0.001). Increased sFRP4 cytoplasmic staining (&gt 2/3) in 46/85 patients increased the disease-specific survival (HR:0.52;95%CI:0.31-0.89;LR test statistic =248.40;1df;??&lt 0.001). Increasing ??-catenin membranous expression (&lt _60%) in 26/116 patients was associated with an increased risk of overall death (HR:3.18;95%CI:1.14-8.89;LR test statistic =4.61;1df,??&lt 0.05). Increasing cytoplasmic expression in 65/114 patients was protective and was associated with prolonged survival on univariate, but not multivariate analysis (Disease specific survival HR:0.75;95%CI:0.56-1.00;logrank chi2=3.91;1df; ??=0.05). Increased nuclear ??-catenin expression in 65/114 patients was associated with prolonged survival (disease-specific HR:0.92;95%CI:0.83-1.02; LR test statistic= 49.72;1df;??&lt 0.001). At the conclusion, 12 patients (8.6%) remained alive, 122 died of their disease (68 males versus 54 females). They were followed for a median of 8.7 months (range 1.0-131.3) months. The median age was 66.5 years (range 34.4-96.0, standard deviation 10.9) years. Pancreatic resection was achieved in 79 patients with 46.8% achieving RO resection. The 30 day post-operative mortality was 2.1%. The overall 1 year survival rate was (33.7% ; 95%CI: 25.78-33.79) with a 5 year survival of (2.87%, 95%CI: 2.83-6.01) and a median survival of (8.90 months; 95%CI: 7.5-10.2). The median disease-specific survival was (9.40; 95%CI: 7.9-10.5 months) and the median time to relapse was 1.2 months (95%CI 1.0-1.2 months). A central tenet of contemporary cancer research is that an understanding of the genetic and molecular abnormalities that accompany the development and progression of cancer is critical to further advances in diagnosis, treatment and eventual prevention. High throughput tissue microarrays were used to study expression of two novel tumour markers in a cohort of pancreatic cancer patients and identified sFRP4 and ??-catenin as potential novel prognostic markers.

Thesis (Ph. D.)--University of Adelaide, 1985. / Includes bibliographical references (leaves 358-406).

Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisors: Norman J. Wagner, Dept. of Chemical Engineering, University of Delaware; Eric Wickstrom, Dept. of Biochemistry and Molecular Biology, Thomas Jefferson University. Includes bibliographical references.

Thesis--Lund. / Extra t.p. with thesis statement inserted.