My laboratory uses methods drawn from both biology and chemistry to study host-pathogen interactions at the molecular and pathway levels. We develop tools to precisely manipulate and monitor the infection of host cells by viruses and then use these tools to 1) understand how viruses perturb normal biochemical equilibria in the host cell, 2) define the consequences of these perturbations, and 3) exploit this knowledge in the design of therapeutic strategies to prevent disease associated with viral infection. Our current research models are hepatitis B virus (HBV), hepatitis C virus (HCV), and dengue virus (DENV) because they are scientifically interesting but, more importantly, because they are significant causes of human morbidity and mortality.
I. Small molecule inhibitors and RNAi: complementary tools for the discovery and characterization of cellular pathways utilized by DENV We are using small molecules to identify the cellular pathways and potential pharmacological intervention points associated with DENV infection of the host cell. By screening libraries of known kinase inhibitors, we have shown that Abl and Src kinases play a critical role in dengue virus infection. We have also used RNAi as a complementary method to identify host factors that are required for DENV infection and replication in human and insect cells. While continuing our screening efforts, we are now focusing also on mechanistic studies to characterize the function of host factors in the DENV life cycle and to identify mechanisms by which these host-virus interactions may be manipulated for anti-viral effect.
II. Discovery and development of novel small molecule inhibitors of DENV entry We are developing new small molecule tools that enable us to probe DENV processes within infected host cells. We recently discovered a novel class of small molecules that appear to inhibit dengue virus infection through action against a target on the virion early in the viral life cycle. Hypothesizing that these compounds inhibit a step in viral entry, we have optimized the anti-DENV activity and used medicinal chemistry to define structure-activity relationships (SAR) for this class of compounds in virological assays and are now using a variety of biochemical methods including assays for viral binding, fusion, capsid release, to define their molecular target and detailed mechanism of action.
III. Lipidomics of viral infection Despite growing appreciation of the role of cellular lipids in the replication of viruses, relatively little is known about the impact of viral infection on cellular lipid metabolism and the specific lipid metabolites utilized by viruses. We are using liquid chromatography-mass spectroscopy (LC-MS) based discovery metabolite profiling (DMP) to identify lipid metabolites whose steady-state abundance is significantly altered by the replication of viruses such as HBV and HCV, that cause chronic infections of the liver, the primary site of lipid metabolism in humans. Our goal is to study the mechanisms by which specific metabolites are differentially regulated during viral replication and the biological consequences of this for both host and pathogen.
Zhang, Z., Kwiatkowski, N., Zeng, H., Lim, S.M., Gray, N.S., Zhang, W., and Yang, P.L. (2012) Leveraging kinase inhibitors to develop small molecule tools for imaging kinases by fluorescence microscopy. Molecular BioSystems, in press published ahead of print 10 May 2012, DOI: 10.1039/C2MB25099C. Highlighted as a HOT Article. PMCID in progress.
de Wispelaere, M. and Yang, P.L. (2012) Mutagenesis of the domain I - domain III linker in the Dengue Virus envelope protein impairs viral particle assembly. Journal of Virology, 86(13):7072-7083. PMCID in progress.
Rodgers, M.A., Villareal, V.A., Schaefer, E.A., Peng, L.F., Corey, K.E., Chung, R.T., and Yang, P.L. (2012) Lipid metabolite profiling identifies desmosterol metabolism as a new antiviral target for hepatitis C virus. Journal of the American Chemical Society, 134(16):6896-6899. NIHMS370147, PMCID: PMC3375380.
Schmidt, A., Lee, K., Yang, P.L., and Harrison, S.L. (2012) Small molecules of dengue virus entry. PLoS Pathogens 8(4): e1002627. PMCID: PMC3320583.
Yang, P.L., Gao, M., Lin, K., Liu, Q., Villareal V.A. (2011) Anti-HCV drugs in the pipeline. Current Opinion in Virology, 1(6):607-616.
Schmidt, A., Yang, P.L., and Harrison, S.L. (2010) Peptide inhibitors of flavivirus entry derived from the E-protein stem. Journal of Virology, 84(24):12549-54. PMCID: PMC3004314.
Schmidt, A., Yang, P.L., and Harrison, S.L. (2010) Peptide inhibitors of dengue-virus entry target a late-stage fusion intermediate. PLOS Pathogens 6(4):e1000851.doi:10.1371/journal.ppat.1000851. PMCID: PMC2851732
Yang, P.L.*, Althage, A., Chung, J.S., Maier, H., Wieland, S., Isogawa, M., and Chisari, F.V. (2010) Immune effectors required for hepatitis B virusclearance. Proc Natl Acad Sci USA, 107(2), 798-802. * corresponding author. PMCID: PMC2818933
O.M. Sessions, N.J. Barrows, J.A. Souza-Neto, T.J. Robinson, C.L. Hershey, M.A. Rodgers, J.L. Ramirez, G. Dimopoulos, P.L. Yang, J.L. Pearson, and M.A. Garcia-Blanco. (2009) Discovery of dengue virus host factors in insects and humans. Nature 458(7241):1047-1050.
M.A. Rodgers, A. Saghatelian, P.L. Yang. (2009) Identification of an overabundant cholesterol precursor in hepatitis B virus replicating cells by untargeted lipid metabolite profiling. Journal of the American Chemical Society. 131(14):5030-5031.
J. Zhang, P.L. Yang, N.S. Gray. (2009) Targeting cancer with small molecule kinase inhibitors. Nat Rev Cancer 9:28-39.
Chu, J.J.H and P.L. Yang. c-Src protein kinase inhibitors block assembly and maturation of dengue virus. Proc Natl Acad Sci USA 104:3520-25 (2007).