Douglas J. LaCount
Ph.D. - University of Wisconsin-Madison, 1998
Postdoc - University of Iowa, 1998-2001
Postdoc - University of Washington, 2001-2005
The central theme of research in the LaCount lab is the discovery and characterization of protein interaction networks between intracellular pathogens and their host cells. We seek to understand how intracellular pathogens manipulate host cells, how host cells respond to intracellular pathogens, and how this information can be exploited to develop new antimicrobial or antiviral drugs. We are interested in developing new host-pathogen protein interaction networks, comparing host-pathogen interaction networks from different organisms, and performing in-depth analyses of the roles of host proteins in virus and parasite lifecycles. Our research primarily focuses on two mosquito-transmitted pathogens that are major global health problems: the malaria parasite Plasmodium falciparum and dengue virus.
Dengue virus-host cell protein interaction network.
Viruses have limited genetic capacity and must rely on cellular factors in order to reproduce. By identifying and characterizing cellular proteins that bind to viral proteins, we learn more about how viruses replicate and cause disease, and may discover new targets for therapeutic intervention. In collaboration with Dr. Richard Kuhn’s lab, we recently reported the first large-scale protein interaction network between dengue virus and human proteins. We are now exploiting the information contained in this network to identify cellular proteins that are critical for dengue virus replication. We use siRNAs, over-expression, small molecule inhibitors, and mutagenesis to characterize the roles of host factors in dengue virus infection. We are particularly interested in the functional roles of three cellular RNA helicases (DDX3X, DDX5, and DDX24) that bind to dengue viral proteins. We are also
Malaria-host cell protein interaction networks.
The malaria parasite dramatically alters the morphology and biochemistry of the host red blood cell during the course of infection. Since red blood cells lacks nuclei and thus cannot express new genes or make new proteins, these changes must be mediated by the more than 300 P. falciparum proteins that are exported to the host cell. However, the vast majority of these proteins have little homology to known proteins and have not been experimentally characterized. In an effort to understand the functions of exported P. falciparum proteins, we are using biochemical approaches and the yeast two-hybrid assay to identify human and parasite protein-binding partners. We have discovered a conserved motif used by at least 14 exported P. falciparum proteins to bind to the erythrocyte cytoskeleton. We are further characterizing this motif and the roles of proteins containing this motif in the parasite lifecycle. To expand the Plasmodium-red blood cell interactome, we are performing a large-scale biochemical screen for exported P. falciparum proteins that bind to red blood cell proteins. We will continue to characterize the impact of these interactions on red blood cell properties and parasite development.
LaCount DJ. Interactome mapping in malaria parasites: challenges and opportunities. Methods Mol Biol. 2012;812:121-45. PubMed PMID: 22218857.
Lee S, Salwinski L, Zhang C, Chu D, Sampankanpanich C, Reyes NA, Vangeloff A, Xing F, Li X, Wu TT, Sahasrabudhe S, Deng H, LaCount DJ, Sun R. An integrated approach to elucidate the intra-viral and viral-cellular protein interaction networks of a gamma-herpesvirus. PLoS Pathog. 2011 Oct;7(10):e1002297. Epub 2011 Oct 20. PubMed PMID: 22028648; PubMed Central PMCID: PMC3197595.
Khadka S, Vangeloff AD, Zhang C, Siddavatam P, Heaton NS, Wang L, Sengupta R, Sahasrabudhe S, Randall G, Gribskov M, Kuhn RJ, Perera R, LaCount DJ. A physical interaction network of dengue virus and human proteins. Mol Cell Proteomics. 2011 Dec;10(12):M111.012187. Epub 2011 Sep 12. PubMed PMID: 21911577; PubMed Central PMCID: PMC3237087.
Kilili GK, LaCount DJ. An erythrocyte cytoskeleton-binding motif in exported Plasmodium falciparum proteins. Eukaryot Cell. 2011 Nov;10(11):1439-47. Epub 2011 Sep 9. PubMed PMID: 21908595; PubMed Central PMCID: PMC3209045.
Das S, Shevade S, LaCount DJ, Jarori GK. Plasmodium falciparum enolase complements yeast enolase functions and associates with the parasite food vacuole. Mol Biochem Parasitol. 2011 Sep;179(1):8-17. Epub 2011 May 10. PubMed PMID: 21600245; PubMed Central PMCID: PMC3353271.
Brown HF, Wang L, Khadka S, Fields S, LaCount DJ. A densely overlapping gene fragmentation approach improves yeast two-hybrid screens for Plasmodium falciparum proteins. Mol Biochem Parasitol. 2011 Jul-Aug;178(1-2):56-9. Epub 2011 Apr 20. PubMed PMID: 21530591; PubMed Central PMCID: PMC3120127.
Heaton NS, Perera R, Berger KL, Khadka S, LaCount DJ, Kuhn RJ, Randall G. Dengue virus nonstructural protein 3 redistributes fatty acid synthase to sites of viral replication and increases cellular fatty acid synthesis. Proc Natl Acad Sci U S A. 2010 Oct 5;107(40):17345-50. Epub 2010 Sep 20. PubMed PMID: 20855599; PubMed Central PMCID: PMC2951450.
LaCount DJ, Schoenfeld LW, Fields S. Selection of yeast strains with enhanced expression of Plasmodium falciparum proteins. Mol Biochem Parasitol. 2009 Feb;163(2):119-22. Epub 2008 Nov 5. PubMed PMID: 19026694; PubMed Central PMCID: PMC2629795.
Vignali M, McKinlay A, LaCount DJ, Chettier R, Bell R, Sahasrabudhe S, Hughes RE, Fields S. Interaction of an atypical Plasmodium falciparum ETRAMP with human apolipoproteins. Malar J. 2008 Oct 20;7:211. PubMed PMID: 18937849; PubMed Central PMCID: PMC2577112.
LaCount DJ, Vignali M, Chettier R, Phansalkar A, Bell R, Hesselberth JR, Schoenfeld LW, Ota I, Sahasrabudhe S, Kurschner C, Fields S, Hughes RE. A protein interaction network of the malaria parasite Plasmodium falciparum. Nature. 2005 Nov 3;438(7064):103-7. PubMed PMID: 16267556.