An expanded regulatory network temporally controls Candida albicans biofilm formation.
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ABSTRACT:
SUBMITTER: Fox EP
PROVIDER: S-EPMC4464956 | biostudies-literature | 2015 Jun
REPOSITORIES: biostudies-literature
Publications
An expanded regulatory network temporally controls Candida albicans biofilm formation.
Fox Emily P EP Bui Catherine K CK Nett Jeniel E JE Hartooni Nairi N Mui Michael C MC Andes David R DR Nobile Clarissa J CJ Johnson Alexander D AD
Molecular microbiology 20150423 6
Candida albicans biofilms are composed of highly adherent and densely arranged cells with properties distinct from those of free-floating (planktonic) cells. These biofilms are a significant medical problem because they commonly form on implanted medical devices, are drug resistant and are difficult to remove. C. albicans biofilms are not static structures; rather they are dynamic and develop over time. Here we characterize gene expression in biofilms during their development, and by comparing t ...[more]
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Project description:UnlabelledBiofilm formation by Candida albicans on medically implanted devices poses a significant clinical challenge. Here, we compared biofilm-associated gene expression in two clinical C. albicans isolates, SC5314 and WO-1, to identify shared gene regulatory responses that may be functionally relevant. Among the 62 genes most highly expressed in biofilms relative to planktonic (suspension-grown) cells, we were able to recover insertion mutations in 25 genes. Twenty mutants had altered biofilm-related properties, including cell substrate adherence, cell-cell signaling, and azole susceptibility. We focused on one of the most highly upregulated genes in our biofilm proles, RHR2, which specifies the glycerol biosynthetic enzyme glycerol-3-phosphatase. Glycerol is 5-fold-more abundant in biofilm cells than in planktonic cells, and an rhr2Δ/Δ strain accumulates 2-fold-less biofilm glycerol than does the wild type. Under in vitro conditions, the rhr2Δ/Δ mutant has reduced biofilm biomass and reduced adherence to silicone. The rhr2Δ/Δ mutant is also severely defective in biofilm formation in vivo in a rat catheter infection model. Expression profiling indicates that the rhr2Δ/Δ mutant has reduced expression of cell surface adhesin genes ALS1, ALS3, and HWP1, as well as many other biofilm-upregulated genes. Reduced adhesin expression may be the cause of the rhr2Δ/Δ mutant biofilm defect, because overexpression of ALS1, ALS3, or HWP1 restores biofilm formation ability to the mutant in vitro and in vivo. Our findings indicate that internal glycerol has a regulatory role in biofilm gene expression and that adhesin genes are among the main functional Rhr2-regulated genes.ImportanceCandida albicans is a major fungal pathogen, and infection can arise from the therapeutically intractable biofilms that it forms on medically implanted devices. It stands to reason that genes whose expression is induced during biofilm growth will function in the process, and our analysis of 25 such genes confirms that expectation. One gene is involved in synthesis of glycerol, a small metabolite that we find is abundant in biofilm cells. The impact of glycerol on biofilm formation is regulatory, not solely metabolic, because it is required for expression of numerous biofilm-associated genes. Restoration of expression of three of these genes that specify cell surface adhesins enables the glycerol-synthetic mutant to create a biofilm. Our findings emphasize the significance of metabolic pathways as therapeutic targets, because their disruption can have both physiological and regulatory consequences.
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Project description:Biofilm formation on medically implanted devices by Candida albicans poses a significant clinical challenge. Here we compared biofilm-associated gene expression in two clinical C. albicans isolates, SC5314 and WO-1, to identify shared gene regulatory responses that may be functionally relevant. Among the 50 genes most highly expressed in biofilms relative to planktonic (suspension-grown) cells, we were able to recover insertion mutations in 25 genes. We observed that 20 of the 25 mutants have altered biofilm-related properties, including cell-substrate adherence, cell-cell signaling, and azole susceptibility. We focused on the most highly up-regulated gene in biofilms, RHR2, which specifies the glycerol biosynthetic enzyme glycerol-3-phosphate phosphatase. Glycerol is 5-fold more abundant in biofilm cells than planktonic cells, and an rhr2D/D strain accumulates 2-fold less biofilm glycerol than the wild type. Under in vitro growth conditions, the rhr2D/D mutant has reduced biofilm biomass and reduced adherence to silicone. The rhr2D/D mutant is severely defective in biofilm formation in vivo, in a rat catheter infection model. Expression profiling of the rhr2D/D mutant indicates that it has reduced expression of cell surface adhesin genes ALS1, ALS3, and HWP1, as well as a large fraction of all other biofilm up-regulated genes. Reduced adhesin expression is the cause of the rhr2D/D mutant biofilm defect, because overexpression of ALS1, ALS3, or HWP1 restores biofilm formation ability to the mutant in vitro and in vivo. Our findings indicate that internal glycerol has a regulatory role in biofilm gene expression, and that adhesin genes are among the main functional Rhr2-regulated genes.
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Project description:Biofilm formation on medically implanted devices by Candida albicans poses a significant clinical challenge. Here we compared biofilm-associated gene expression in two clinical C. albicans isolates, SC5314 and WO-1, to identify shared gene regulatory responses that may be functionally relevant. Among the 50 genes most highly expressed in biofilms relative to planktonic (suspension-grown) cells, we were able to recover insertion mutations in 25 genes. We observed that 20 of the 25 mutants have altered biofilm-related properties, including cell-substrate adherence, cell-cell signaling, and azole susceptibility. We focused on the most highly up-regulated gene in biofilms, RHR2, which specifies the glycerol biosynthetic enzyme glycerol-3-phosphate phosphatase. Glycerol is 5-fold more abundant in biofilm cells than planktonic cells, and an rhr2D/D strain accumulates 2-fold less biofilm glycerol than the wild type. Under in vitro growth conditions, the rhr2D/D mutant has reduced biofilm biomass and reduced adherence to silicone. The rhr2D/D mutant is severely defective in biofilm formation in vivo, in a rat catheter infection model. Expression profiling of the rhr2D/D mutant indicates that it has reduced expression of cell surface adhesin genes ALS1, ALS3, and HWP1, as well as a large fraction of all other biofilm up-regulated genes. Reduced adhesin expression is the cause of the rhr2D/D mutant biofilm defect, because overexpression of ALS1, ALS3, or HWP1 restores biofilm formation ability to the mutant in vitro and in vivo. Our findings indicate that internal glycerol has a regulatory role in biofilm gene expression, and that adhesin genes are among the main functional Rhr2-regulated genes. Gene expression profiles, in duplicate; (1) for biofilm vs. planktonic growth conditions for the two wild-type clinical isolates of Candida albicans (SC5314 and WO1-white/WO1-opaque), and (2) for rhr2M-NM-^T/M-NM-^T mutant and complemented strain, via RNA-deep sequencing using Illumina GA2 and HiSeq2000 platforms, respectively
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Project description:The planktonic versus biofilm gene expression arrays were performed in a/alpha cell types. Gene expression arrays were performed on planktonic vs biofilm cells grown in Spider medium at 37C. Normalized data is reported in matrix.
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