Limits...
Toxicity mechanisms of the food contaminant citrinin: application of a quantitative yeast model.

Pascual-Ahuir A, Vanacloig-Pedros E, Proft M - Nutrients (2014)

Bottom Line: Additionally, genes in various multidrug resistance transport systems are functionally involved in the resistance to citrinin.Our study identifies the antioxidant defense as a major physiological response in the case of citrinin.In general, our results show that the use of live cell gene expression reporters in yeast are a powerful tool to identify toxicity targets and detoxification mechanisms of a broad range of food contaminants relevant for human nutrition.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia, Ingeniero Fausto Elio s/n, 46022 Valencia, Spain. apascual@ibmcp.upv.es.

ABSTRACT
Mycotoxins are important food contaminants and a serious threat for human nutrition. However, in many cases the mechanisms of toxicity for this diverse group of metabolites are poorly understood. Here we apply live cell gene expression reporters in yeast as a quantitative model to unravel the cellular defense mechanisms in response to the mycotoxin citrinin. We find that citrinin triggers a fast and dose dependent activation of stress responsive promoters such as GRE2 or SOD2. More specifically, oxidative stress responsive pathways via the transcription factors Yap1 and Skn7 are critically implied in the response to citrinin. Additionally, genes in various multidrug resistance transport systems are functionally involved in the resistance to citrinin. Our study identifies the antioxidant defense as a major physiological response in the case of citrinin. In general, our results show that the use of live cell gene expression reporters in yeast are a powerful tool to identify toxicity targets and detoxification mechanisms of a broad range of food contaminants relevant for human nutrition.

Show MeSH

Related in: MedlinePlus

Citrinin activates gene expression from stress responsive yeast promoters in a dose dependent fashion. A fusion of the stress inducible GRE2 promoter with destabilized luciferase was used as a real time reporter for gene expression. Citrinin doses from 100–800 ppm were applied to the yeast cultures. Alternatively the GRE2-luciferase reporter was activated by the indicated concentrations of NaCl. Data shown are mean values from three independent biological samples. SD < 15%.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4042565&req=5

nutrients-06-02077-f001: Citrinin activates gene expression from stress responsive yeast promoters in a dose dependent fashion. A fusion of the stress inducible GRE2 promoter with destabilized luciferase was used as a real time reporter for gene expression. Citrinin doses from 100–800 ppm were applied to the yeast cultures. Alternatively the GRE2-luciferase reporter was activated by the indicated concentrations of NaCl. Data shown are mean values from three independent biological samples. SD < 15%.

Mentions: We tested whether exposure to the mycotoxin citrinin caused a rapid adaptation of gene expression in yeast. An immediate and transient activation of defense gene expression is a common adaptive response of this organism to a great variety of environmental threats or stresses. Live cell reporters based on the expression of a destabilized luciferase enzyme represent a sensitive method to monitor this adaptive response in real time and upon a gradual range of stress conditions. We first examined a reporter based on a natural yeast promoter (GRE2), which is responsive to different types of stress such as hyperosmotic stress or oxidative stress [17]. As shown in Figure 1, the GRE2-luciferase reporter is readily activated upon acute exposure to citrinin. Robust reporter activation was observed for citrinin doses equal or greater than 100 ppm. Importantly the citrinin response of GRE2 was comparable to the activation of the same reporter by salt stress (Figure 1), which is known to trigger a very strong increase of GRE2 expression [16,18]. A dose dependent increase in the luciferase reporter activity was observed in a citrinin concentration range from 100 to 400 ppm. Further increases in the toxin dose did not yield a significantly enhanced gene expression response. These results made us confident that the citrinin response of the GRE2-luciferase reporter reflected a biologically meaningful adaptation of yeast to its toxicity, which was further investigated with refined reporter systems.


Toxicity mechanisms of the food contaminant citrinin: application of a quantitative yeast model.

Pascual-Ahuir A, Vanacloig-Pedros E, Proft M - Nutrients (2014)

Citrinin activates gene expression from stress responsive yeast promoters in a dose dependent fashion. A fusion of the stress inducible GRE2 promoter with destabilized luciferase was used as a real time reporter for gene expression. Citrinin doses from 100–800 ppm were applied to the yeast cultures. Alternatively the GRE2-luciferase reporter was activated by the indicated concentrations of NaCl. Data shown are mean values from three independent biological samples. SD < 15%.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4042565&req=5

nutrients-06-02077-f001: Citrinin activates gene expression from stress responsive yeast promoters in a dose dependent fashion. A fusion of the stress inducible GRE2 promoter with destabilized luciferase was used as a real time reporter for gene expression. Citrinin doses from 100–800 ppm were applied to the yeast cultures. Alternatively the GRE2-luciferase reporter was activated by the indicated concentrations of NaCl. Data shown are mean values from three independent biological samples. SD < 15%.
Mentions: We tested whether exposure to the mycotoxin citrinin caused a rapid adaptation of gene expression in yeast. An immediate and transient activation of defense gene expression is a common adaptive response of this organism to a great variety of environmental threats or stresses. Live cell reporters based on the expression of a destabilized luciferase enzyme represent a sensitive method to monitor this adaptive response in real time and upon a gradual range of stress conditions. We first examined a reporter based on a natural yeast promoter (GRE2), which is responsive to different types of stress such as hyperosmotic stress or oxidative stress [17]. As shown in Figure 1, the GRE2-luciferase reporter is readily activated upon acute exposure to citrinin. Robust reporter activation was observed for citrinin doses equal or greater than 100 ppm. Importantly the citrinin response of GRE2 was comparable to the activation of the same reporter by salt stress (Figure 1), which is known to trigger a very strong increase of GRE2 expression [16,18]. A dose dependent increase in the luciferase reporter activity was observed in a citrinin concentration range from 100 to 400 ppm. Further increases in the toxin dose did not yield a significantly enhanced gene expression response. These results made us confident that the citrinin response of the GRE2-luciferase reporter reflected a biologically meaningful adaptation of yeast to its toxicity, which was further investigated with refined reporter systems.

Bottom Line: Additionally, genes in various multidrug resistance transport systems are functionally involved in the resistance to citrinin.Our study identifies the antioxidant defense as a major physiological response in the case of citrinin.In general, our results show that the use of live cell gene expression reporters in yeast are a powerful tool to identify toxicity targets and detoxification mechanisms of a broad range of food contaminants relevant for human nutrition.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia, Ingeniero Fausto Elio s/n, 46022 Valencia, Spain. apascual@ibmcp.upv.es.

ABSTRACT
Mycotoxins are important food contaminants and a serious threat for human nutrition. However, in many cases the mechanisms of toxicity for this diverse group of metabolites are poorly understood. Here we apply live cell gene expression reporters in yeast as a quantitative model to unravel the cellular defense mechanisms in response to the mycotoxin citrinin. We find that citrinin triggers a fast and dose dependent activation of stress responsive promoters such as GRE2 or SOD2. More specifically, oxidative stress responsive pathways via the transcription factors Yap1 and Skn7 are critically implied in the response to citrinin. Additionally, genes in various multidrug resistance transport systems are functionally involved in the resistance to citrinin. Our study identifies the antioxidant defense as a major physiological response in the case of citrinin. In general, our results show that the use of live cell gene expression reporters in yeast are a powerful tool to identify toxicity targets and detoxification mechanisms of a broad range of food contaminants relevant for human nutrition.

Show MeSH
Related in: MedlinePlus