Increased Gene Expression of Mitogen-Activated Protein Kinase A is Associated with Attenuated Caspofungin (CAS) Activity in Aspergillus Fumigatus.

N. P. WIEDERHOLD1,2, B. L. WICKES 2, T. F. PATTERSON 2;

Author address: 

1Univ. of Texas, Austin, TX, 2Univ. of Texas Hlth.Sci. Ctr., San Antonio, TX.

Abstract: 

Background: Paradoxical increases in A. fumigatus fungal viability and fungal burden have been reported in vitro and in vivo, respectively, at elevated concentrations of CAS. Up-regulation of genes involved in the cell-wall integrity (CWI) pathway has been associated with tolerance to CAS in S. cerevisiae (SLT2), C. albicans (MKC1), and C. neoformans (MPK1). The objective of this study was to assess changes in gene expression of key components of the CWI pathway in A. fumigatus. Methods: The XTT colorimetric assay was used to assess the viability of A. fumigatus 293 (AF 293, CAS MEC 0.25 mcg/mL) at CAS concentrations ranging from 0 - 32 mcg/mL using previously described methods (Meletiadis et al J Clin Micro 2001; 39: 3402). For gene expression analysis, AF 293 conidia were allowed to incubate at 37°C for 6 hours prior to exposure to CAS (0, 0.125, and 8 mcg/mL). RNA was extracted, reverse transcribed to cDNA, and relative gene expression was determined in triplicate by real-time PCR using primers and probes specific for DNA encoding the putative mitogen-activated protein kinase A (MPKA) and Rho guanyl nucleotide exchange factor (RGN), a putative GTP exchange factor. Results: Maximum activity was observed at CAS 1 mcg/mL (36% reduction in viability vs. control; p
2006

abstract No: 

M-364

Full conference title: 

46th Interscience Conference on Antimicrobial Agents and Chemotherapy
    • ICAAC 46th