The broad, long-term objectives of this project are to define the mechanisms involved in the interaction between hepatocytes and malaria sporozoites and to develop specific inhibitors that prevent the crucial hepatic stage of the disease.
The specific aims are to characterize the heparan sulfate proteoglycans (HSPG) from hepatocytes which bind to the malaria circumsporozoite protein (CS) by 1) defining the oligosaccharide which recognizes the ligand region II-plus of the CS protein, 2)characterizing athe core protein, 3) demonstrating at the electron microscopical level the morphology of the CS-binding HSPG, and 4) examining at the cellular level the consequences of the interaction between the HSPG and CS, in particular, whether there is CS interiorization and signal transduction. Heparan sulfate oligosaccharides with avidity to the CS region II-plus will be isolated, depolymerized an their structure characterized by HPLC. Definition of the core protein includes the determination of its Mr in SDS- PAGE, of its reactivity with various monoclonal antibodies to cell surface HSPGs, and cloning of the corresponding gene. We will study the turnover of the cell surface HSPGs of HepG2 cells in the absence of CS, and then determine the fate of CS and of the HSPG receptors following their interaction. For this purpose, the HSPGs will be radiolabeled with [35S]- sulfate, and the CS (or region II-plus peptides) radiolabeled with 125I]- iodine. Changes in the phosphorylation patterns of HepG2 cells upon CS, or region II-plus peptide binding will be examined by phosphoamino acid analysis, and by means of antibodies to phosphotyrosine. Small oligosaccharides (or mimics) which bind to region II-plus and inhibit attachment of sporozoites to hepatocytes may have medical applications in the prophylaxis of malaria infection, and in addition may be valuable tools to study the function of host proteins which display the region II-plus motif, such as thrombospondin, properdin, the terminal complement components and F-spondin, a molecule involved in the development of the nervous system.
|Marshall, P; Rohlmann, A; Nussenzweig, V et al. (2000) Plasmodium sporozoites invade cells with targeted deletions in the LDL receptor related protein. Mol Biochem Parasitol 106:293-8|
|Frevert, U (1999) Heparan sulphate and RNA-binding motifs in the malaria circumsporozoite protein. Biochem Soc Trans 27:482-7|
|Nardin, E; Zavala, F; Nussenzweig, V et al. (1999) Pre-erythrocytic malaria vaccine: mechanisms of protective immunity and human vaccine trials. Parassitologia 41:397-402|
|Moreno, C A; Rodriguez, R; Oliveira, G A et al. (1999) Preclinical evaluation of a synthetic Plasmodium falciparum MAP malaria vaccine in Aotus monkeys and mice. Vaccine 18:89-99|
|Frevert, U; Galinski, M R; Hugel, F U et al. (1998) Malaria circumsporozoite protein inhibits protein synthesis in mammalian cells. EMBO J 17:3816-26|
|Gantt, S M; Clavijo, P; Bai, X et al. (1997) Cell adhesion to a motif shared by the malaria circumsporozoite protein and thrombospondin is mediated by its glycosaminoglycan-binding region and not by CSVTCG. J Biol Chem 272:19205-13|
|Ying, P; Shakibaei, M; Patankar, M S et al. (1997) The malaria circumsporozoite protein: interaction of the conserved regions I and II-plus with heparin-like oligosaccharides in heparan sulfate. Exp Parasitol 85:168-82|
|Briones, M R; Tsuji, M; Nussenzweig, V (1996) The large difference in infectivity for mice of Plasmodium berghei and Plasmodium yoelii sporozoites cannot be correlated with their ability to enter into hepatocytes. Mol Biochem Parasitol 77:7-17|
|Shakibaei, M; Frevert, U (1996) Dual interaction of the malaria circumsporozoite protein with the low density lipoprotein receptor-related protein (LRP) and heparan sulfate proteoglycans. J Exp Med 184:1699-711|
|Hugel, F U; Pradel, G; Frevert, U (1996) Release of malaria circumsporozoite protein into the host cell cytoplasm and interaction with ribosomes. Mol Biochem Parasitol 81:151-70|
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