A região N-terminal de OTI-VIT-1 foi expressa e os polipeptídeos recombinantes foram purificados. OTI-VIT-1 pode ser homólogo da vitelina YP170B de C. elegans. Foram identificados um intron na região 5´ e dois na região 3´ do gene Oti-vit-1. Antissoro monoespecífico para PVIT1HisC confirmou que o gene Oti-vit-1 codifica VT1. O polipeptídeo recombinante P40-H, correspondente à região N-terminal da proteína OTI-VIT-6 interage com um polipeptídeo de aproximadamente 100 kDa (P100) presente em extratos proteicos totais de O. tipulae. Estudamos também o papel da Proteína Microssômica Transportadora de Triglicerídeos (MTP) na biossíntese de Vitelogenina do nematoide C. elegans. Ensaios de RNAi em C. elegans, utilizando parte da sequência do gene da MTP (Cel-dsc-4) foram realizados nas linhagens N2 e DH1033. Microscopia de fluorescência de vermes adultos da linhagem DH1033, submetidos a RNAi, mostrou acúmulo de YP170B::GFP no interior dos enterócitos. Este acúmulo sugere a participação da MTP na secreção de VTG. Análise imunológica da vitelogenina nestes mesmos vermes não detectaram alterações no processamento de CEL-VIT-6, sugerindo que o mesmo ocorra não só no pseudoceloma, mas também no interior dos enterócitos. / The N-terminal region of OTI-VIT-1 was expressed and the recombinant polypeptides were purified. OTI-VIT-1 may be homologous to the vitellin YP170B from C. elegans. We identified an intron in the 5 \'region and two in 3\' region from Oti-vit-1. Monospecific antisera to PVIT1HisC confirmed that the gene Oti-vit-1 encodes VT1. The recombinant polypeptide P40-H, corresponding to the N-terminal region of the protein OTI-VIT-6, interacts with a polypeptide of approximately 100 kDa (P100) present in total protein extracts of O. tipulae. The role of microsomal triglyceride transfer protein (MTP) in the biosynthesis of vitellogenin was studied in the nematode C. elegans. Trials of RNAi in C. elegans, using the sequence of the MTP gene (Cel-dsc-4) were performed in the strains N2 and DH1033. Fluorescence microscopy of adult worms of strain DH1033, subjected to RNAi, showed accumulation of YP170B:: GFP within the enterocytes. This accumulation suggests the involvement of MTP in the secretion of VTG. Analysis using anti-vitellogenin immune serum did not detect changes in the processing of CEL-VIT-6, suggesting that it occurs not only in pseudocoelom but also within the enterocytes.

A região N-terminal de OTI-VIT-1 foi expressa e os polipeptídeos recombinantes foram purificados. OTI-VIT-1 pode ser homólogo da vitelina YP170B de C. elegans. Foram identificados um intron na região 5´ e dois na região 3´ do gene Oti-vit-1. Antissoro monoespecífico para PVIT1HisC confirmou que o gene Oti-vit-1 codifica VT1. O polipeptídeo recombinante P40-H, correspondente à região N-terminal da proteína OTI-VIT-6 interage com um polipeptídeo de aproximadamente 100 kDa (P100) presente em extratos proteicos totais de O. tipulae. Estudamos também o papel da Proteína Microssômica Transportadora de Triglicerídeos (MTP) na biossíntese de Vitelogenina do nematoide C. elegans. Ensaios de RNAi em C. elegans, utilizando parte da sequência do gene da MTP (Cel-dsc-4) foram realizados nas linhagens N2 e DH1033. Microscopia de fluorescência de vermes adultos da linhagem DH1033, submetidos a RNAi, mostrou acúmulo de YP170B::GFP no interior dos enterócitos. Este acúmulo sugere a participação da MTP na secreção de VTG. Análise imunológica da vitelogenina nestes mesmos vermes não detectaram alterações no processamento de CEL-VIT-6, sugerindo que o mesmo ocorra não só no pseudoceloma, mas também no interior dos enterócitos. / The N-terminal region of OTI-VIT-1 was expressed and the recombinant polypeptides were purified. OTI-VIT-1 may be homologous to the vitellin YP170B from C. elegans. We identified an intron in the 5 \'region and two in 3\' region from Oti-vit-1. Monospecific antisera to PVIT1HisC confirmed that the gene Oti-vit-1 encodes VT1. The recombinant polypeptide P40-H, corresponding to the N-terminal region of the protein OTI-VIT-6, interacts with a polypeptide of approximately 100 kDa (P100) present in total protein extracts of O. tipulae. The role of microsomal triglyceride transfer protein (MTP) in the biosynthesis of vitellogenin was studied in the nematode C. elegans. Trials of RNAi in C. elegans, using the sequence of the MTP gene (Cel-dsc-4) were performed in the strains N2 and DH1033. Fluorescence microscopy of adult worms of strain DH1033, subjected to RNAi, showed accumulation of YP170B:: GFP within the enterocytes. This accumulation suggests the involvement of MTP in the secretion of VTG. Analysis using anti-vitellogenin immune serum did not detect changes in the processing of CEL-VIT-6, suggesting that it occurs not only in pseudocoelom but also within the enterocytes.

Humans have two plasminogen activators (PAs), tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA), which generate plasmin to breakdown fibrin and other barriers to cell migration. Both PAs are used as pharmaceuticals but their efficacies are limited by their rapid clearance from the circulation, predominantly by parenchymal cells of the liver. At the commencement of the work presented here, the hepatic receptors responsible for mediating the catabolism of the PAs were little understood. tPA degradation by hepatic cell lines was known to depend on the formation of binary complexes with the major PA inhibitor, plasminogen activator inhibitor type-1 (PAI-1). Initial studies presented here established that uPA was catabolised in a fashion similar to tPA by the hepatoma cell line, HepG2. Other laboratories around this time found that the major receptor mediating the binding and endocytosis of the PAs is Low Density Lipoprotein Receptor-related Protein (LRP1). LRP1 is a giant 600 kDa protein that binds a range of structurally and functionally diverse ligands including, activated α2 macroglobulin, apolipoproteins, β amyloid precursor protein, and a number of serpin-enzymes complexes, including PA??PAI-1 complexes. Further studies for the work presented here centred on this receptor. By using radiolabelled binding assays, ligand blots, and Western blots on cultured cells, the major findings are that: (1) basal LRP1 expression on HepG2 is low compared to a clone termed, HepG2a16, but appears to increase in long term culture; (2) a soluble form of LRP1, which retains ligand-binding capacity, is present in human circulation; (3) soluble LRP1 is also present in cerebral spinal fluid where its role in neurological disorders such as Alzheimer??s disease is a developing area of interest; and (4) the release of LRP1 is a mechanism conserved in evolution, possibly as distantly as molluscs. The discovery, identification, and characterisation of soluble LRP1 introduces this protein in the human circulation, and presents a possible further level of regulation for its associated receptor system.