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Epigenetic regulation of viral gene expression in yeast. RNA targeted therapeutics. molecular pharmacologyThe prion-like [KIL-d] cytoplasmic genetic element of yeast places the M double-stranded RNA genome segment of killer virus of yeast under epigenetic regulation in cells carrying [KIL-d] and the virus. The molecular nature of the [KIL-d] element and the mechanism of epigenetic regulation are being studied. The prion hypothesis is being tested by cloning the putative prion-encoding gene. Group I self-splicing introns are ribozymes whose function is essential to various microorganisms that harbor these insertions in essential genes. Since group I introns are not found in humans. inhibitors of group I intron splicing are potential antimicrobial agents. We have characterized several group I introns of pathogenic fungi. and have shown that the antifungal drug pentamidine inhibits group I intron splicing in Candida albicans. In collaboration with Y. Zhang we are studying the molecular basis of small molecule inhibition of group I intron ribozyme catalysis. Novel therapeutic agents and delivery systems are being studied (collaboration with S. Stein and P.J. Sinko). Multipartite antisense compounds targeting the 5'-untranslated region of mRNA have been shown capable of down-regulation of the HER-2/neu oncogene in cell-free expression systems; their action in cells is now being studied. Novel inhibitors of HIV-1 replication have been developed including a peptide-derived inhibitor of the viral Tat regulatory protein and a novel non-nucleoside reverse transcriptase inhibitor. In order to deliver these therapeutic agents and target them to specific cells and tissues. a series of novel polymeric drug delivery technologies have been developed. These include a carrier molecule that can transport and target therapeutic agents to specific cells. and an injectable hydrogel system for long-term delivery of drugs. These technologies are being developed for delivery of small molecule drugs as well as proteins and antisense agents. as well as for immunotherapy applications. Selected PublicationsZhang L, Bao P, Leibowitz MJ, Zhang Y. (2009) Slow formation of a pseudoknot structure is rate limiting in the productive co-transcriptional folding of the self-splicing Candida intron. RNA. 15(11):1986-92. Zhang L, Leibowitz MJ, Zhang Y. (2009) Antisense oligonucleotides effectively inhibit the co-transcriptional splicing of a Candida group I intron in vitro and in vivo: Implications for antifungal therapeutics. FEBS Lett. 583(4):734-8. Miletti-González KE, Leibowitz MJ. (2008) Molecular characterization of two types of rDNA units in a single strain of Candida albicans. J Eukaryot Microbiol. 55(6):522-9. Wan L, Zhang X, Pooyan S, Palombo MS, Leibowitz MJ, Stein S, Sinko PJ. (2008) Optimizing size and copy number for PEG-fMLF (N-formyl-methionyl-leucyl-phenylalanine) nanocarrier uptake by macrophages. Bioconjug Chem. 19(1):28-38. Wan L, Pooyan S, Hu P, Leibowitz MJ, Stein S, Sinko PJ. (2007) Peritoneal macrophage uptake, pharmacokinetics and biodistribution of macrophage-targeted PEG-fMLF (N-formyl-methionyl-leucyl-phenylalanine) nanocarriers for improving HIV drug delivery. Pharm Res. 24(11):2110-9. Wan L. Zhang X. Gunaseelan S. Pooyan S. Debrah O. Leibowitz MJ. Rabson AB. Stein S. Sinko PJ. (2006) Novel multi-component nanopharmaceuticals derived from poly(ethylene) glycol. retro-inverso-Tat nonapeptide and saquinavir demonstrate combined anti-HIV effects. AIDS Res Ther. 3:12. Zhang X. Wan L. Pooyan S. Su Y. Gardner CR. Leibowitz MJ. Stein S. Sinko PJ. (2004) Quantitative assessment of the cell penetrating properties of RI-Tat-9: evidence for a cell type-specific barrier at the plasma membrane of epithelial cells. Mol Pharm. 1(2):145-55. Gunaseelan. S.. Debrah. O.. Wan. L.. Leibowitz. M.J.. Rabson. A.B.. Stein. S.. and Sinko. P.J. (2004). Synthesis of poly(ethylene glycol)-based saquinavir prodrug conjugates and assessment of release and anti-HIV-1 bioactivity using a novel protease inhibition assay. Bioconjug Chem.. 15:1322-1333. Zhang. G.. Leibowitz. M.J.. Sinko. P.J.. and Stein. S. (2003). Multiple-peptide conjugates for binding beta-amyloid plaques of Alzheimer's disease. Bioconjug. Chem:14:86-92. Qiu. B.. Stefanos. S.. Ma. J.. Lalloo. A.. Perry. B.A.. Leibowitz. M.J.. Sinko. P.J.. Stein. S. A. (2002). Hydrogel prepared by in situ cross-linking of a thiol-containing poly(ethylene glycol)-based copolymer: A new biomaterial for protein drug delivery. Biomaterials. 24:11-18. Zhang. Y.. Li. Z.. Pilch. D.S.. and Leibowitz. M.J. (2002). Pentamidine inhibits catalytic activity of group I intron Ca.LSU by altering RNA folding. Nucleic Acids Res. 30:2961-2971. Pooyan. S.. Qiu. B.. Chan. M.M.. Fong. D.. Sinko. P.J.. Leibowitz. M.J.. and Stein. S. (2002). Conjugates bearing multiple formyl-methionyl peptides display enhanced binding to but not activation of phagocytic cells. Bioconjugate Chem. 13:216-223. |
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