Transcriptional Response to Hypoxia in the Aquatic Fungus Blastocladiella emersonii

Camilo, César M.; Gomes, Suely L.

doi:10.1128/ec.00047-10

Cited by 11 publications

(8 citation statements)

References 56 publications

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“…PiSLC9M and PiCP450 were found to be upregulated in WT P. indica during colonization as compared to KD- PiHOG1 P. indica colonizing host plant under salinity stress. SLC9M has been reported to be involved in acid stress tolerance in gastrointestinal bacteria and in hypoxia condition in an aquatic fungus Blastocladiella emersonii 5455. CP450 has been reported in salinity and drought stress tolerance in case of A. thaliana and Oryza sativa 5657 therefore support our data.…”

Section: Discussionsupporting

confidence: 89%

PiHOG1, a stress regulator MAP kinase from the root endophyte fungus Piriformospora indica, confers salinity stress tolerance in rice plants

Jogawat

Vadassery

Verma

et al. 2016

Sci Rep

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In this study, yeast HOG1 homologue from the root endophyte Piriformospora indica (PiHOG1) was isolated and functionally characterized. Functional expression of PiHOG1 in S. cerevisiae ∆hog1 mutant restored osmotolerance under high osmotic stress. Knockdown (KD) transformants of PiHOG1 generated by RNA interference in P. indica showed that genes for the HOG pathway, osmoresponse and salinity tolerance were less stimulated in KD-PiHOG1 compared to the wild-type under salinity stress. Furthermore, KD lines are impaired in the colonization of rice roots under salinity stress of 200 mM NaCl, and the biomass of the host plants, their shoot and root lengths, root number, photosynthetic pigment and proline contents were reduced as compared to rice plants colonized by WT P. indica. Therefore, PiHOG1 is critical for root colonisation, salinity tolerance and the performance of the host plant under salinity stress. Moreover, downregulation of PiHOG1 resulted not only in reduced and delayed phosphorylation of the remaining PiHOG1 protein in colonized salinity-stressed rice roots, but also in the downregulation of the upstream MAP kinase genes PiPBS2 and PiSSK2 involved in salinity tolerance signalling in the fungus. Our data demonstrate that PiHOG1 is not only involved in the salinity response of P. indica, but also helping host plant to overcome salinity stress.

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Section: Discussionsupporting

confidence: 89%

PiHOG1, a stress regulator MAP kinase from the root endophyte fungus Piriformospora indica, confers salinity stress tolerance in rice plants

Jogawat

Vadassery

Verma

et al. 2016

Sci Rep

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“…7) resemble those reported in other fungi such as S. cerevisiae (48,49,90), S. pombe (38), Candida parapsilosis (66), and the aquatic ascomycete Blastocladiella emersonii (11) and in hypoxic mammalian cells (27). Hypoxic induction of glycolytic gene expression is an ancient conserved response and probably represents a shift to fermentative metabolism in the absence of oxygen (81).…”

Section: Discussionmentioning

confidence: 66%

Regulation of the Hypoxic Response in Candida albicans

et al. 2010

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The regulation of the response of Candida albicans to hypoxic (low-oxygen) conditions is poorly understood. We used microarray and other transcriptional analyses to investigate the role of the Upc2 and Bcr1 transcription factors in controlling expression of genes involved in cell wall metabolism, ergosterol synthesis, and glycolysis during adaptation to hypoxia. Hypoxic induction of the ergosterol pathway is mimicked by treatment with sterol-lowering drugs (ketoconazole) and requires UPC2. Expression of three members of the family CFEM (common in several fungal extracellular membranes) of cell wall genes (RBT5, PGA7, and PGA10) is also induced by hypoxia and ketoconazole and requires both UPC2 and BCR1. Expression of glycolytic genes is induced by hypoxia but not by treatment with sterol-lowering drugs, whereas expression of respiratory pathway genes is repressed. However, Upc2 does not play a major role in regulating expression of genes required for central carbon metabolism. Our results indicate that regulation of gene expression in response to hypoxia in C. albicans is complex and is signaled both via lowered sterol levels and other unstudied mechanisms. We also show that induction of filamentation under hypoxic conditions requires the Ras1-and Cdc35-dependent pathway.The human fungal pathogen Candida albicans grows on superficial and internal sites in the infected host, areas that differ significantly in the availability of oxygen (26). Under low-oxygen (hypoxic) conditions, C. albicans switches from yeast to hyphal growth, a phenotypic change that has been associated with invasion and virulence (24,30,54). Exposure to hypoxia results in increased expression of genes involved in ergosterol synthesis and glycolysis and reduced expression of oxidative phosphorylation (3, 69). There is also an increase in expression of some cell wall and hyphal-specific genes (69), which is reflected in changes in the cell wall proteome (72).Although the response to hypoxia has been well studied in fungi such as Saccharomyces cerevisiae and Schizosaccharomyces pombe, much less is known about the response in C. albicans. In S. pombe, a decrease in oxygen is detected by the reduction in sterol synthesis, which requires 12 molecules of oxygen to convert one squalene to ergosterol (38). Sterol content is sensed by Sre1 and Scp1, which are homologs of the human sterol regulatory element binding protein (SREBP) and Scap (SREBP cleavage-activating protein) (38, 77). Sre1 and Scp1 are localized in the membrane, where they remain when sterol and oxygen levels are high. When sterol levels drop, the N terminus of Sre1 is cleaved off, and it enters the nucleus, where it acts as a transcriptional regulator. Sre1 is the major regulator of the hypoxic response in S. pombe and regulates expression of Ͼ100 genes (38). It also functions in a sterol-independent manner (39). SREBPs are also important for sensing oxygen levels in the pathogenic fungi Cryptococcus neoformans and Aspergillus fumigatus (7,13,85).There are no obvious SREBP orthologs in...

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“…However, because the reductive transport system in species such as C. albicans requires oxidation of Fe 2+ , it is hard to separate the direct effects of low oxygen from those of low iron (reviewed in 3). It is possible that iron is used as an oxygen sensor, distinct from its previously described role in heme-activated proteins, but this remains to be characterized (22).…”

Section: Regulation Of Sterol Lipid and Iron Metabolism Genesmentioning

confidence: 98%

“…Induction of sterol synthesis gene expression is one of the most conserved responses to hypoxia in fungi and has been reported in every species studied (e.g., 9,16,22,27,29,62,141). Genes required for the oxygen-dependent steps are particularly upregulated (9, 127).…”

Section: Regulation Of Sterol Lipid and Iron Metabolism Genesmentioning

confidence: 99%

Hypoxia and Gene Expression in Eukaryotic Microbes

Butler

2013

Annu. Rev. Microbiol.

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The response of eukaryotic microbes to low-oxygen (hypoxic) conditions is strongly regulated at the level of transcription. Comparative analysis shows that some of the transcriptional regulators (such as the sterol regulatory element-binding proteins, or SREBPs) are of ancient origin and probably regulate sterol synthesis in most eukaryotic microbes. However, in some fungi SREBPs have been replaced by a zinc-finger transcription factor (Upc2). Nuclear localization of fungal SREBPs is determined by regulated proteolysis, either by site-specific proteases or by an E3 ligase complex and the proteasome. The exact mechanisms of oxygen sensing are not fully characterized but involve responding to low levels of heme and/or sterols and possibly to levels of nitric oxide and reactive oxygen species. Changes in central carbon metabolism (glycolysis and respiration) are a core hypoxic response in some, but not all, fungal species. Adaptation to hypoxia is an important virulence characteristic of pathogenic fungi.

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Transcriptional Response to Hypoxia in the Aquatic Fungus Blastocladiella emersonii

Cited by 11 publications

References 56 publications

PiHOG1, a stress regulator MAP kinase from the root endophyte fungus Piriformospora indica, confers salinity stress tolerance in rice plants

PiHOG1, a stress regulator MAP kinase from the root endophyte fungus Piriformospora indica, confers salinity stress tolerance in rice plants

Regulation of the Hypoxic Response in Candida albicans

Hypoxia and Gene Expression in Eukaryotic Microbes

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