Date of Award

5-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Program

Biomedical Sciences

Track

Microbiology, Immunology, and Biochemistry

Research Advisor

P. David Rogers, PharmD, PhD

Committee

Elizabeth A. Fitzpatrick, PhD Jarrod Ri Fortwendel, PhD Glen Edwin Palmer, PhD Brian M Peters, PhD

Keywords

azole resistance, Candida glabrata, Upc2A

Abstract

Candida glabrata is the second most common cause of invasive candidiasis. Intrinsic resistance has greatly limited the utility of the triazole antifungal, fluconazole, in the treatment of invasive fungal infection. The transcription factor Upc2 regulates the expression of sterol biosynthesis genes in yeast. Disrupting UPC2A in C. glabrata greatly increases its susceptibility to fluconazole (FLU) in both FLU-susceptible and -resistant clinical isolates. Therefore, the Upc2A and its target genes represent a potential pathway for overcoming FLU resistance in C. glabrata. We aimed to delineate the Upc2A regulon to determine its target genes involved in FLU resistance. Transcriptome sequencing (RNA-seq) analysis was used to compare gene expression profiles of: a) wild-type (WT) strains with and without UPC2A under non-stressed conditions; b) those same strains treated with three sterol biosynthesis inhibitors (SBIs; FLU, terbinafine, fenpropimorph); and c) strains with an activating mutation (GOF) in UPC2A. Global chromatin Immunoprecipitation (ChIP-seq) was used to identify genes whose promoters were bound by Upc2A in strains carrying WT and GOF alleles of Upc2A with and without fluconazole exposure. Only three genes (UPC2A, ERG25, and ERG3) were found to be downregulated in the absence of UPC2A. Sixteen genes were commonly upregulated in response to SBIs’ treatment in a Upc2A-dependent way, including ERG2, ERG3, and ERG11, the promoters of 10 of which were bound by Upc2A. A total of 15 genes were upregulated, including ERG2, ERG3, ERG25, and ERG11 in the strain containing GOF mutation and the promoters of 6 of these genes were bound by Upc2A. Based on our data, ERG3, ERG11, HEM13, and CAGL0H09592g (ScTIR1) could be potential targets of Upc2A in C. glabrata. This more comprehensive understanding of the Upc2A regulon in C. glabrata may eventually lead to strategies to overcome FLU resistance and enhance fluconazole activity against this important fungal pathogen.

Declaration of Authorship

Declaration of Authorship is included in the supplemental files.

ORCID

https://orcid.org/0000-0003-4359-4411

DOI

10.21007/etd.cghs.202.0534

Additional Files
2021-007-Li-DOA.pdf (255 kB)
Declaration of Authorship
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