associate professor of biology
Field of Interest
Genetic approaches towards the cell biology of Toxoplasma gondii.
The protozoan parasite Toxoplasma gondii is a member of the phylum Apicomplexa and can cause severe disease in humans. This parasite is easily grown and manipulated in vitro and has in recent years developed as a safe and versatile model for other apicomplexan parasites (e.g. malaria). We are using and developing forward, reverse and functional genetic tools using enzymatic as well as fluorescent protein reporter assays in combination with cell sorting and fluorescence microscopy to learn more about the parasite’s cell biology.
Parasite replication is conserved, yet are variations on a theme in different apicomplexan parasites. Toxoplasma divides by an internal budding process called endodyogeny where two daughters are being assembled inside the mother, which is significantly different from mammalian cell division. The parasite’s cytoskeleton, consisting of microtubules as well as a membrane skeleton in combination with intermediate protein filaments (the inner membrane complex or IMC) serves as a scaffold for daughter assembly. Recently, we identified several components that act in the cytoskeleton assembly as well as daughter formation which are currently being characterized in detail.
Host cell invasion is an essential step in the life cycle of Apicomplexa and identifying essential steps and/or molecules in the process would provide attractive potential therapeutic targets. To identify key molecules in invasion, a set of conditional parasite invasion mutants has been generated through chemical as well as insertional (conditional) mutagenesis. Mutants are being analyzed through a set of cell biological assays while at the same time the mutated genes are being identified using cosmid library complementations as well as plasmid rescues.
Gubbels, M.-J., and M.D. Duraisingh. 2012. TEvolution of apicomplexan secretory organelles. Int. J. Parasitol., In press (invited review)
Lorestani, A., F.D. Ivey, S. Thirugnanam, M.A. Busby, G.T. Marth, I. Cheeseman, and M.-J. Gubbels. 2012. Targeted proteomic dissection of Toxoplasma, cytoskeleton sub-compartments using MORN1. Cytoskeleton, In press
Bushkin, G.G., P. Magnelli, E. Motari, M.-J. Gubbels, J.P. Dubey, K. Miska, E. Bullitt, C.E. Costello, P.W. Robbins, and J. Samuelson. 2012. β-1,3-glucan, a druggable target, is part of a trabecular scaffold in inner layer of the oocyst wall of Toxoplasma and Eimeria. mBio. In press
Anderson-White, B.R., J.R. Beck, C.-T. Chen, M. Meissner, P.J. Bradley, and M.-J. Gubbels. 2012. Cytoskeleton development of Toxoplasma gondii. Int. Rev. Cell Mol. Biol. 298:1-31. (invited review)
Fung, C., J.R. Beck, S.D. Robertson, M.-J. Gubbels, and P.J. Bradley. Toxoplasma ISP4 is a central IMC sub-compartment protein whose localization depends on palmitoylation but not myristoylation. Mol. Biochem Parasitol. 184:99-108. PMCID: PMC3383393
Szatanek, T., B.R. Anderson-White, M. White, J. Saeij, and M.-J. Gubbels. 2012. Cactin is essential for G1 progression in Toxoplasma gondii. Mol. Micro. 84:566-577. PMCID: PMC3331927
Coleman, B.I., and M.-J. Gubbels. 2012. A genetic screen to isolate Toxoplasma gondii host cell egress mutants. J. Vis. Exp. 60:e3807. PMCID: PMC3350636
Farrell, A. S. Thirugnanam, A. Lorestani, J.D. Dvorin, K.P. Eidell, B.R. Anderson-White, D.J.P. Ferguson, M.T. Duraisingh, G.T. Marth, and M.-J. Gubbels. 2012. A DOC2 protein identified by mutational profiling is essential for apicomplexan parasite exocytosis. Science. 335:218-221.
link to: http://www.sciencemag.org/content/335/6065/218.short
Jammallo*, L., K. Eidell*, P.H. Davis, F.J. Dufort, C. Cronin, S. Thirugnanam, T.C. Chiles, D.S. Roos, and M.-J. Gubbels. 2011. An insertional trap for conditional gene expression in Toxoplasma gondii: identification of TAF250 as an essential gene. Mol. Biochem. Parasitol. 175:133-143. (*equal contribution). PubMed: http://www.ncbi.nlm.nih.gov/pubmed/21035508
Anderson-White, B.R., Ivey, F.D., Cheng, K. K., Szatanek, T., Lorestani, A., Beckers, C.J., Ferguson, D.J.P., Sahoo, N., and Gubbels, M.-J. 2010. A family of intermediate filament-like proteins is sequentially assembled into the cytoskeletal scaffold of Toxoplasma gondii. Cellular Microbiology 13:18-31. PubMed: http://www.ncbi.nlm.nih.gov/pubmed/20698859
Lorestani, A., L. Sheiner, K. Yang, S.D. Robertson, N. Sahoo, C.F. Brooks, D.P.J. Ferguson, B. Striepen, and M.-J. Gubbels. 2010. A Toxoplasma MORN1 null mutant is defective in basal complex assembly and apicoplast division. PLoS ONE. 5:e12302. PubMed: http://www.ncbi.nlm.nih.gov/pubmed/20808817
Eidell, K., Burke, T., and Gubbels, M.-J. 2010. Development of a screen to dissect Toxoplasma gondii egress. Molecular and Biochemical Parasitology 171(2): 97–10 (link to PubMed abstract).
Wilson, D.C., Grotenbreg, G.M., Liu, K.N., Zhao, Y., Frickel, E.-M., Gubbels, M.-J., Ploegh, H.L., and Yap, G.S. 2010. Differential regulation of effector- and central-memory responses to Toxoplasma gondii infection by IL-12 revealed by tracking of Tgd057-specific CD8+ T cells. PLoS Pathogens 6(3): e1000815.
Bushkin, G.G., Ratner, D.M., Cui, J., Banerjee, S., Duraisingh, M.T., Jennings, C.V., Dvorin, J.D., Gubbels, M.-J., Robertson, S.D., Steffen, M., O’Keefe, B.R., Robbins, P.W., and Samuelson, J. 2010. Evidence for Darwinian selection against asparagine-linked glycans of Plasmodium and Toxoplasma. Eukaryotic Cell 9: 228–241 (link to PubMed abstract).
Frickel, E.M., Sahoo, N., Hopp, J., Gubbels, M.-J., Craver, M.P., Knoll, L.J., Ploegh, H., and Grotebreg, G. 2008. Parasite stage-specific recognition of endogenous Toxoplasma gondii epitopes by CD8+T cells. The Journal of Infectious Diseases 198: 1625–1633 (link to PubMed abstract).
Gubbels, M.-J., White, M., and Szatanek, T. 2008. The cell cycle and Toxoplasma gondii cell division: tightly knit or loosely stitched? International Journal for Parasitology 38: 1343–1358 (Invited Review) (link to PubMed abstract).
Muskavitch, M., Barteneva, N., and Gubbels, M.-J. 2008. Chemogenomics and parasitology: small molecules and cell-based assays to study infectious processes. Combinatorial Chemistry & High Throughput Screening 11: 629–649 (Invited Review) (link to PubMed abstract).
Ferguson, D.J.P., Sahoo, N., Pinches, R.A., Bumstead, J.M., Tomley, F.M., and Gubbels, M.-J. 2008. MORN1 has a conserved role in asexual and sexual development across the Apicomplexa. Eukaryotic Cell 7: 698–711. Featured in ASM Microbe, June 2008 (link to PubMed abstract).
Gubbels, M.-J., Brooks, C.F., Muthalagi, M., Szatanek, T., Flynn, J., Parrot, B., Striepen, B., and White, M.W. 2008. Forward genetic analysis of the apicomplexan cell and division cycle in Toxoplasma gondii. PLoS Pathogens 4(2): e36 (0001–0015) (Editor’s Pick) (link to PubMed abstract).
Frickel, E.-M., Quesada, V., Muething, L., Gubbels, M.-J., Spooner, E., Ploegh, H., and Artavanis-Tsakonas, K. 2007. UCHL3 retains dual specificity for ubiquitin and Nedd8 throughout evolution. Cellular Microbiology 6: 1601–1610 (link to PubMed abstract).
Gubbels, M.J., Mazumdar, J., van Dooren, G., and Striepen, B. 2006. Manipulating the Toxoplasma genome. In "The biology of Toxoplasma gondii." Soldati, D., and Ajioka, J. (Eds.). Horizon Scientific Pres, Norwich, UK (link to Publisher).
Gubbels, M.-J., Vaishnava, S., Boot, N., Dubremetz, J.-F., and Striepen, B. 2006. A MORN-repeat protein is a dynamic component of the cell division apparatus of the parasite Toxoplasma gondii. Journal of Cell Science 119: 2236–2245 (link to PubMed abstract).