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The incorporation of a propargyl group to a natural product target allows for a streamlined approach to the investigation of structure activity relationships (SARs) and target identification in forward chemical genetics programmes using a ‘click’-based approach. To this end, an efficient synthesis of O-propargylated tyrosine derivatives was designed, and these have been used in the construction of peptide motifs both (a) derived from phage display libraries and (b) found in natural products. The L-tyrosine derivative Y* (compound I, X=H, R=H) was incorporated into a peptide sequence, PTTIYY, which is known to prevent the inhibition of p53 by the AG-2 protein. Y* has been included as both the terminal and the internal tyrosine in the peptide sequence. ELISA assays were carried out to determine how the binding of PTTIYY* and PTTIY*Y to AG-2 compared to that of the un-marked PTTIYY sequence. The results of these assays allowed new conclusions to be drawn regarding the important binding features of the peptide and possible sites for further optimisation of the AG-2 binding properties of this peptide through ‘click’ functionalisation of the modified tyrosine. The binding of the peptides incorporating Y* was also assessed using MCF-7 breast cancer cell lysate, known to contain the AG-2 protein. These results confirmed those seen for the purified AG-2 ELISA. The related bromo-D-tyrosine derivative (compound I, X=Br, R=Me) has been prepared and employed towards the synthesis of a bisebromoamide derivative. Bisebromoamide is a newly discovered polypeptide, and a promising anti-cancer agent. The bisebromoamide derivative contains a thiazole unit (Tzl), two N-methylated amino acids, and an oxopropyl pyrrolidine (Opp) moiety, which is unique to bisebromoamide in natural products. The activity of this bisebromoamide derivative will be investigated via ‘click’-based affinity chromatography using a new supported linker recently developed within the Hulme group.

The Gab2 docking protein is a target of several oncogenic protein tyrosine kinases and potentiates activation of the Ras/extracellular signal regulated kinase and phosphatidylinositol 3-kinase (PI3-kinase) pathways. The prototypical member of the Src family of protein tyrosine kinases, c-Src, phosphorylates Gab2 and both proteins are overexpressed in breast cancers. However, whether overexpression of these two proteins contributes to mammary tumourigenesis had not been previously investigated. Pharmacological inhibition of c-Src in breast cancer cell lines reduced Gab2 tyrosine phosphorylation while overexpression of these two proteins increased this effect, demonstrating a contribution of c-Src to Gab2 tyrosine phosphorylation in breast cancer cells. The biological effects of Gab2 and c-Src overexpression were determined in a three-dimensional cell culture model using the human mammary epithelial cell line MCF-10A. When cultured on a basement membrane, MCF10A cells form acini that model mammary lobules in vivo. Overexpression of Gab2 in MCF10As conferred increased acinar size and independence of the morphogenetic program from exogenous EGF. While overexpression of c-Src alone did not affect acinar morphogenesis, it potentiated the EGF-independent acinar growth induced by Gab2 overexpression. As enhanced c-Src kinase activity is often observed in breast cancer, the effect of Gab2 co-expression with active Src constructs was next determined. Expression of v-Src or c-SrcY527F altered acinar morphology and the resulting structures were categorised as spheroidal, discohesive or dispersed, according to the degree of phenotypic disruption. Gab2 co-expression shifted the proportion of structures towards the dispersed phenotype. This shift reflects a negative role for Gab2 at adherens junctions in the context of active Src expression, as in monolayer cells Gab2 significantly decreased E-cadherin-based adhesive strength without altering the surface expression of this adhesion molecule. Furthermore, Gab2 associated with the E-cadherin complex. The ability of Gab2 to weaken the strength of cell-cell contacts in active Src-expressing cells may be due to enhanced activation of PI3-kinase signalling at adherens junctions, as the potentiating effects of Gab2 in both monolayer and three-dimensional cultures were dependent upon Gab2 recruitment of the p85 subunit of PI3-kinase. Finally, Gab2 increased migration and invasion of v-Src-expressing cells in transwell assays, however these effects were p85-independent. This is the first study to demonstrate Gab2 co-operation with various forms of Src to augment proliferative, invasive and migratory signals, as well as revealing a novel mechanism whereby Gab2 may promote metastatic spread. This study thus demonstrates multiple roles for Gab2 in contributing to breast cancer progression.

This thesis reports the synthesis and copper coordination chemistry of covalently-linked aryl-imidazole derivatives designed as models for the crosslinked imidazole-phenol sidechains of the His-Tyr cofactor in the CcO. Three new imidazole- (HL1 - HL3) and three new indole- (HL4 - H2L6) containing tripodal ligands were synthesised. The conjugate addition of an imidazole to activated quinone derivatives was developed as a new route to organic models for the Tyr His cofactor. Two monodentate imidazole-aryl, Im-hq(OH)2 and Im-ArOH, and an imidazole-quinone, Im bq were obtained using this route. The X-ray crystal structure of Im-hq(OH)2.EtOH was determined. The route was also used to give new chelating ligands, H2L10 and HL12, containing a cross-linked imidazole-phenol surrogate for the Tyr244-His240 cofactor. Copper complexes of Im-hq(OH)2, Im-bq, Im-ArOH, H2L10-HL12, and HL1-H2L6 were prepared, and the X-ray crystal structures of [Cu(terpy)(Im-bq)][BF4]2 and five other copper complexes were determined. The physiochemical properties of the copper complexes were characterized by FT-IR, UV-Vis-NIR, EPR and (spectro)electrochemical studies. Key results include: the oxidation of Im-ArO- anion affords the semiquinone radical, Im-sq(4OH)(1O??????), in a hydrous solvent. However, the oxidations of neutral Im-ArOH and [Cu(tpa)(Im-ArOH)]2+ produce the corresponding phenoxy radical species that rapidly and reversibly dimerise to give quinol cyclohexadienone, QCHD, dimers. Significantly [Cu(tpa)(Im-sq(4OH)(1O??????))]2+ was EPR silent, perhaps due to antiferromagnetic coupling between the Cu(II) (S=1/2) and semiquinonyl radical (S=1/2) centres. Deprotonation of the hydroquinone in [Cu(tpa)(Im-hq(OH)2]2+ produces the hydroquinone dianion which reduces the Cu(II) centre. The semiquinone radical is coordinatively labile and dissociates from the Cu(I) centre. The biological implications of these results are mentioned.

"March, 2003" / Ammendments to chapter 9 and a journal article co-authored by the author in back pocket. / Includes bibliographical references (leaves 162-205) / xviii, 211 leaves : ill. (some col.), plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2003

"October 2004" / Includes bibliographical references (leaves 201-256) / xiv, 256 leaves, [9] p. : ill., plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2005

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Fps/Fes and Fer are members of a distinct subfamily of cytoplasmic protein tyrosine kinases that have recently been implicated in the regulation of innate immunity. Previous studies showed that mice lacking Fps/Fes are hyper-sensitive to systemic lipopolysaccharide (LPS) challenge. This study identifies physiological, cellular and molecular defects that contribute to the hyper-inflammatory phenotype in Fps/Fes-null mice. We showed that plasma tumour necrosis factor (TNF) - levels were elevated in LPS challenged Fps/Fes-null mice as compared to wild type mice, and cultured Fps/Fes-null peritoneal macrophages treated with LPS showed increased TNF- production. Cultured Fps/Fes-null macrophages also displayed prolonged LPS-induced degradation of IB-, increased phosphorylation of the p65 subunit of NF-B, and defective TLR4 internalization. Next, we showed a role for Fps in the regulation of recruitment of inflammatory leukocytes. Using the cremaster muscle intravital microscopy model, we observed increased leukocyte adherence to venules, and increased rates and degrees of transendothelial migration in Fps/Fes-null mice, compared to wild type. There was also increased neutrophil migration into the peritoneal cavity subsequent to thioglycollate challenge. Using flow cytometry, we observed prolonged expression of the selectin ligand PSGL-1 on peripheral blood neutrophils from Fps/Fes-knockout mice stimulated ex-vivo with LPS. Finally, we examined the role of Fps/Fes in regulating apoptosis in response to inflammation. Upon intra-peritoneal challenge with LPS, Fps/Fes-null mice displayed a decreased depletion of macrophages from the peritoneal cavity. In response to ex-vivo TNF- stimulation, macrophages from Fps/Fes-null mice underwent decreased apoptosis and necrosis as assessed by flow cytometry. Immunoblot analysis revealed that Fps/Fes-null macrophages displayed more TNF--induced degradation of IB-α in Fps/Fes-null cells, with corresponding increases in the phosphorylation of the p65 subunit of NF-B. In addition, stimulation of macrophages with TNF-α up-regulated PARP expression in wild-type macrophages; this up-regulation was not observed in Fps/Fes-null macrophages. Finally we observed a decreased recruitment of macrophages to the peritoneal cavities of Fps/Fes-null mice, with a corresponding increase in neutrophil recruitment, 5 days after thioglycollate challenge. Overall, we show that there is a role for Fps/Fes in regulating inflammation at the physiological, cellular, and molecular levels, and that this might be relevant in inflammatory disease. / Thesis (Ph.D, Biochemistry) -- Queen's University, 2007-08-27 11:39:23.393