Molecular Microbiology and Immunology Major
Dr. Courchesne is the academic advisor for the new undergraduate major. He can be contacted by email:
Institutional Biosafety Committee
Dr. Courchesne is Chair of the IBC, which oversees all issues concerning all biological agents at UNR.
Our research focuses on calcium metabolism in the yeast Saccharomyces cerevisiae and on the molecular mechanism of amiodarone, a novel antifungal that we have identified.
Calcium signaling is involved in myriad cellular processes. We have discovered a new tool, amiodarone, for eliciting calcium influx into the cytosol. We have shown that amiodarone causes a dramatic increase in the free cytoplasmic calcium concentration ([Ca2+]cyt) in S. cerevisiae. About 90% of this increase is dependent on extracellular Ca2+, while 10% of the increase in [Ca2+]cyt is due to release from intracellular stores. The influx of extracellular Ca2+ may be a direct effect of amiodarone on a membrane transporter or may be by a capacitative-calcium entry mechanism. Uptake of the extracellular Ca2+ is inhibited by caffeine and reduced in strains deleted for the MID1 gene but not in cells deleted for CCH1. Our data are the first demonstrating control of yeast calcium channels by amiodarone and caffeine.
Novel Antifungal. Fungal infections are common in patients with acquired immunodeficiency syndrome and pose a major health management problem. There is a need for identification of new antifungals to complement the limited current repertoire and to combat newly arising resistant fungal strains. We have identified a novel antifungal activity for the antiarrhythmic drug amiodarone. Extensive characterization of this activity shows that amiodarone exhibits a growth inhibition for several diverse fungi, including species of Cryptococcus, Saccharomyces, Aspergillus, Candida, and Fusarium. The antifungal activity was shown to be fungicidal; Cryptococcus neoformans treated with amiodarone lost viability within hours of drug exposure. Growth inhibition could be suppressed by addition of very high concentrations (10 mM) of Ca2+ to the medium, suggesting that disruption of calcium homeostasis was involved in the antifungal activity. In conclusion, amiodarone displays broad-based fungicidal activity and may be acting in part by perturbing the calcium balance.
Kotewitz, M., E. Grzesiuk, W.E. Courchesne, R. Fisher, and H. Echols. 1980. Purification and characterization of the integration protein specified by bacteriophage lambda. J. Biol. Chem. 255:2433-2439.
Courchesne, W.E. and B. Magasanik. 1983. Ammonia regulation of amino acid permeases inSaccharomyces cerevisiae. Mol. Cell. Biol. 3:672-683.
Courchesne, W.E. 1985. Nitrogen regulation in Saccharomyces cerevisiae. Ph.D. thesis, Massachusetts Institute of Technology.
Courchesne, W.E. and B. Magasanik. 1988. Regulation of nitrogen assimilation in Saccharomyces cerevisiae: roles of the URE2 and GLN3 genes. J. Bacteriol. 170:708-713.
Blumer, K.J., J.E. Reneke, W.E. Courchesne, and J. Thorner. 1988. Functional domains of a peptide hormone receptor: the a-factor receptor (STE2 gene product) of the yeast Saccharomyces cerevisiae. in Cold Spring Harbor Symposium on Quantitative Biology 53: 591-603.
Reneke, J.E., K.J. Blumer, W.E. Courchesne, and J. Thorner. 1988. The carboxyl-terminal segment of the yeast a-factor receptor is a regulatory domain. Cell 55: 221-234.
Courchesne, W.E., R. Kunisawa, and J. Thorner. 1989. A putative protein kinase overcomes pheromone-induced arrest of cell cycling in S. cerevisiae. Cell 58:1107-1119.
Tolkacheva, T., P. McNamara, E. Piekarz, and W.E. Courchesne. 1994. Cloning of a Cryptococcus neoformans Gene, GPA1, Encoding a G-Protein a Subunit Homolog. Infect. Immun. 62: 2849-2856.
McCracken, A.A., I.V. Karpichev, J.E. Ernaga, E.D. Werner, A.G. Dillin, N.J. Shebib, and W.E. Courchesne. 1996. Yeast mutants deficient in ER-associated degradation of the Z variant of alpha-1-protease inhibitor. Genetics 144: 1355-1362.
Dohlman, H.G., D. Ma, W.E. Courchesne and J. Thorner. 1996. Sst2, a factor required for recovery from pheromone-induced cell cycle arrest in the yeast S. cerevisiae: Expression, co-localization and genetic interactions with Gpa1 (G-protein a subunit). Mol. Cell. Biol. 16: 5194-5209.
Copley, K.S., S.M. Alm, D.A. Schooley, and W.E. Courchesne. 1998. Expression, processing, proteolysis and secretion of Manduca sexta diuretic hormone by Saccharomyces cerevisiae. Biochemical J. 330:1333-1340.
Dong, H. and W.E. Courchesne. 1998. Use of a novel quantitative mating assay on the fungal pathogen Cryptococcus neoformans provides insight into signalling pathways responding to nutrients and temperature. Microbiology 144:1691-1697.
Courchesne, W.E. 2002. Characterization of a novel, broad-based fungicidal activity for the antiarrhythmic drug amiodarone. J.Pharm.Exp.Therap. 300:195-199.
Cao, H., W.E. Courchesne, and C.C. Mastick. 2002. A phosphotyrosine-dependent (PY) dihybrid yeast protein interaction screen reveals a role for phosphorylation of caveolin-1 on tyrosine 14: recruitment of CSK to caveolae, J. Biol. Chem. 277:8771-8774.
Courchesne, W.E. and S. Ozturk. 2003. Amiodarone induces a caffeine-inhibited, MID1-dependent rise in free cytoplasmic calcium in S. cerevisiae. Mol. Micro., 47:223-234.
Courchesne, W.E., M. Tunc, S. Liao. 2009. Amiodarone induces stress responses and calcium flux mediated by the cell wall in S. cerevisiae. Ca. J. Microbiology, 55:288-303.
Courchesne, W.E., C. Vlasek, R. Klukovich, and S. Coffee. 2011. Ethanol induces calcium influx via the Cch1-Mid1 transporter in Saccharomyces cerevisiae. Arch. Microbiol. 193:323–334.
Hejchman, E., K. Ostrowska, D. Maciejewska, J. Kossakowski, and W.E. Courchesne. 2012. Synthesis and antifungal activity of derivatives of 2- and 3-benzofurancarboxylic acids. J. Pharm. Exp. Therap. 343:380-388.