The Anterior Gradient 2 (AGR2) protein has been implicated in a variety of biological systems linked to cancer and metastasis, tamoxifen-induced drug resistance, pro-inflammatory diseases like IBD and asthma, and limb regeneration. The molecular mechanisms by which AGR2 mediates these various phenotypes in disease progression in both cancer and IBD are poorly understood, as is the biological function(s) of AGR2 under non-disease conditions. Here, we use a combination of biochemical techniques, organ culture, cell biology and mouse genetics to investigate the biological significance of AGR2 both in cell lines and in vivo. We present data based on phage-peptide inter-actomics screens suggesting a role for AGR2 in mediating the maturation and trafficking of a class of membrane and secretory proteins, and investigate a putative interaction between AGR2 and one member of this class of proteins. We also describe the construction of a universal vector for use in making a variety of transgenic animals, and then present data showing its use as a promoter reporter, and attempt to investigate the temporal and spatial expression of AGR2 in the developing and adult mouse. Further, we present data describing the localisation pattern of AGR2 in the developing murine kidney using a combination of organ culture and antibody staining, and suggest a role for AGR2 in the developing kidney based on this data that is in agreement with a chaperone function for membrane and secretory proteins. Together, these data suggest that AGR2 has an intrinsic consensus docking site for a subset of its client proteins, that AGR2 plays a role in protein maturation in ciliated cell types, and provides a novel biological model to dissect the role of AGR2 in ER-trafficking.

This thesis is an investigation of the natural products deriving from marine algae and cyanobacteria and has resulted in the discovery of eleven new secondary metabolites. The structure elucidations of these new molecules were performed using a variety of spectroscopic techniques. Four new macrolides were isolated and characterized from the Madagascar marine cyanobacterium Geitlerinema sp. These ankaraholides are structurally similar to the potently cytotoxic swinholides and were found to have cytotoxicities ranging from 178 nM to 354 nM against human lung cancer (NCI-H460) and mouse neuro-2a cell lines. Since swinholide-type compounds were previously localized to the heterotrophic bacteria of sponges, these findings raise intriguing questions about their true metabolic source. Geitlerinema sp. was found to be particularly rich in chemistry, and also produced the new linear lipopeptide mitsoamide with unusual structural features including an aminal moiety, a homolysine residue and a polyketide unit (3,7- dimethoxy-5-methyl- nonanedioic acid) (DMNA). A collection of the red marine alga Portieria hornemannii from the south of Madagascar (Tolagniaro, Fort Dauphin), led to the isolation of the previously reported halogenated monoterpene, halomon, and the discovery of three new related metabolites. These molecules were found to inhibit DNA methyltransferase 1 (DNMT-1). As a result of efforts to identify bioactive agents from the marine cyanobacterium Lyngbya majuscula, tanikolide dimer, a novel SIRT2 inhibitor (IC50 = 176 nM), and tanikolide seco-acid were isolated. The depside molecular structure of tanikolide dimer, which is likely a meso compound, was established by NMR, MS and chiral HPLC analyses. The structure of tanikolide dimer raises a number of intriguing configurational and biosynthetic questions for further study. The bioassay guided fractionation of a collection of the brown marine alga Dictyota sp. from Netherland Antilles Playa Fort, led to the identification of a novel HDAC inhibitor with a dolastane carbon skeleton. The novel molecule was also found to possess antimalarial activity. Other known HDAC inhibitors with interesting antimalarial activity have been reported previously, and based on this efficacy against malaria, HDAC appears to be a viable target for the development of antiparasitic agents. / Graduation date: 2006