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Metabolic respiration induces AMPK- and Ire1p-dependent activation of the p38-Type HOG MAPK pathway.

Adhikari H, Cullen PJ - PLoS Genet. (2014)

Bottom Line: Such cross-modulation was critical to optimize the differentiation response.The human fungal pathogen Candida albicans showed a similar regulatory circuit.Thus, an evolutionarily conserved regulatory axis links metabolic respiration and AMPK to Ire1p, which regulates a differentiation response involving the modulated activity of ERK and p38 MAPK pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America.

ABSTRACT
Evolutionarily conserved mitogen activated protein kinase (MAPK) pathways regulate the response to stress as well as cell differentiation. In Saccharomyces cerevisiae, growth in non-preferred carbon sources (like galactose) induces differentiation to the filamentous cell type through an extracellular-signal regulated kinase (ERK)-type MAPK pathway. The filamentous growth MAPK pathway shares components with a p38-type High Osmolarity Glycerol response (HOG) pathway, which regulates the response to changes in osmolarity. To determine the extent of functional overlap between the MAPK pathways, comparative RNA sequencing was performed, which uncovered an unexpected role for the HOG pathway in regulating the response to growth in galactose. The HOG pathway was induced during growth in galactose, which required the nutrient regulatory AMP-dependent protein kinase (AMPK) Snf1p, an intact respiratory chain, and a functional tricarboxylic acid (TCA) cycle. The unfolded protein response (UPR) kinase Ire1p was also required for HOG pathway activation in this context. Thus, the filamentous growth and HOG pathways are both active during growth in galactose. The two pathways redundantly promoted growth in galactose, but paradoxically, they also inhibited each other's activities. Such cross-modulation was critical to optimize the differentiation response. The human fungal pathogen Candida albicans showed a similar regulatory circuit. Thus, an evolutionarily conserved regulatory axis links metabolic respiration and AMPK to Ire1p, which regulates a differentiation response involving the modulated activity of ERK and p38 MAPK pathways.

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Gene expression profiling by RNA seq analysis and qPCR.A) Genes induced by salt, tunicamycin (TUN), or galactose (GAL). All RNA seq comparisons are provided in Table S1. B) Genes induced in a Pbs2p-dependent manner under the indicated conditions. Genes outlined by the dark blue circle (Pbs2p-dependent GAL specific) were functionally annotated in a pie chart in Fig. S2. C) Heat map of genes induced by the indicated stresses. Common targets and targets unique to each stimulus is shown. Asterisk, target of ESR. D) qPCR of HOG pathway target mRNAs in wild type and the pbs2Δ mutant grown in glucose (GLU, YEPD) and galactose (GAL, YEP-GAL). Error bars indicate +/−S.E.M. of three independent experiments. Actin (ACT1) mRNA was used as a control. E) Activity of p8XCRE-lacZ in wild-type cells (PC313) and pbs2Δ mutant (PC5035) grown in YEPD (5.5 hr), YEP-GAL (5.5 hr), and YEPD+0.4 M KCl (30 min). F) qPCR of Ste12p target mRNAs in wild type (PC538) and the ste12Δ (PC2382) mutant grown in glucose (YEPD) and galactose (YEP-GAL). See panel D for details.
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pgen-1004734-g001: Gene expression profiling by RNA seq analysis and qPCR.A) Genes induced by salt, tunicamycin (TUN), or galactose (GAL). All RNA seq comparisons are provided in Table S1. B) Genes induced in a Pbs2p-dependent manner under the indicated conditions. Genes outlined by the dark blue circle (Pbs2p-dependent GAL specific) were functionally annotated in a pie chart in Fig. S2. C) Heat map of genes induced by the indicated stresses. Common targets and targets unique to each stimulus is shown. Asterisk, target of ESR. D) qPCR of HOG pathway target mRNAs in wild type and the pbs2Δ mutant grown in glucose (GLU, YEPD) and galactose (GAL, YEP-GAL). Error bars indicate +/−S.E.M. of three independent experiments. Actin (ACT1) mRNA was used as a control. E) Activity of p8XCRE-lacZ in wild-type cells (PC313) and pbs2Δ mutant (PC5035) grown in YEPD (5.5 hr), YEP-GAL (5.5 hr), and YEPD+0.4 M KCl (30 min). F) qPCR of Ste12p target mRNAs in wild type (PC538) and the ste12Δ (PC2382) mutant grown in glucose (YEPD) and galactose (YEP-GAL). See panel D for details.

Mentions: Comparative RNA sequencing (RNA seq, [65]) was performed to examine the response of S. cerevisiae cells to different stimuli. The response to osmotic stress (YEPD+0.4M KCl [23]), the non-preferred carbon source galactose (YEP-GAL, 2% GAL [66]), and an inhibitor of N-linked glycosylation (YEPD+2.5 µg tunicamycin [67]) were examined. Each stimulus induced the expression of overlapping and non-overlapping genes (Fig. 1A). As reported, salt induced targets of the HOG pathway (Table S1, [12], [24]), galactose induced the GAL genes and other starvation-responsive genes (Table S1, [68], [69]), and tunicamycin induced targets of the UPR and other genes (Table S1, [70], [71]). The different stimuli also induced an overlapping gene set (Fig. 1A, 504 genes). Common genes included targets of the ESR (150 of 504 total, Table S1[61], [62]) and targets of the HOG pathway. Likewise, a partially overlapping set of repressed genes was also identified that included ESR targets (Fig. S2A).


Metabolic respiration induces AMPK- and Ire1p-dependent activation of the p38-Type HOG MAPK pathway.

Adhikari H, Cullen PJ - PLoS Genet. (2014)

Gene expression profiling by RNA seq analysis and qPCR.A) Genes induced by salt, tunicamycin (TUN), or galactose (GAL). All RNA seq comparisons are provided in Table S1. B) Genes induced in a Pbs2p-dependent manner under the indicated conditions. Genes outlined by the dark blue circle (Pbs2p-dependent GAL specific) were functionally annotated in a pie chart in Fig. S2. C) Heat map of genes induced by the indicated stresses. Common targets and targets unique to each stimulus is shown. Asterisk, target of ESR. D) qPCR of HOG pathway target mRNAs in wild type and the pbs2Δ mutant grown in glucose (GLU, YEPD) and galactose (GAL, YEP-GAL). Error bars indicate +/−S.E.M. of three independent experiments. Actin (ACT1) mRNA was used as a control. E) Activity of p8XCRE-lacZ in wild-type cells (PC313) and pbs2Δ mutant (PC5035) grown in YEPD (5.5 hr), YEP-GAL (5.5 hr), and YEPD+0.4 M KCl (30 min). F) qPCR of Ste12p target mRNAs in wild type (PC538) and the ste12Δ (PC2382) mutant grown in glucose (YEPD) and galactose (YEP-GAL). See panel D for details.
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Related In: Results  -  Collection

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pgen-1004734-g001: Gene expression profiling by RNA seq analysis and qPCR.A) Genes induced by salt, tunicamycin (TUN), or galactose (GAL). All RNA seq comparisons are provided in Table S1. B) Genes induced in a Pbs2p-dependent manner under the indicated conditions. Genes outlined by the dark blue circle (Pbs2p-dependent GAL specific) were functionally annotated in a pie chart in Fig. S2. C) Heat map of genes induced by the indicated stresses. Common targets and targets unique to each stimulus is shown. Asterisk, target of ESR. D) qPCR of HOG pathway target mRNAs in wild type and the pbs2Δ mutant grown in glucose (GLU, YEPD) and galactose (GAL, YEP-GAL). Error bars indicate +/−S.E.M. of three independent experiments. Actin (ACT1) mRNA was used as a control. E) Activity of p8XCRE-lacZ in wild-type cells (PC313) and pbs2Δ mutant (PC5035) grown in YEPD (5.5 hr), YEP-GAL (5.5 hr), and YEPD+0.4 M KCl (30 min). F) qPCR of Ste12p target mRNAs in wild type (PC538) and the ste12Δ (PC2382) mutant grown in glucose (YEPD) and galactose (YEP-GAL). See panel D for details.
Mentions: Comparative RNA sequencing (RNA seq, [65]) was performed to examine the response of S. cerevisiae cells to different stimuli. The response to osmotic stress (YEPD+0.4M KCl [23]), the non-preferred carbon source galactose (YEP-GAL, 2% GAL [66]), and an inhibitor of N-linked glycosylation (YEPD+2.5 µg tunicamycin [67]) were examined. Each stimulus induced the expression of overlapping and non-overlapping genes (Fig. 1A). As reported, salt induced targets of the HOG pathway (Table S1, [12], [24]), galactose induced the GAL genes and other starvation-responsive genes (Table S1, [68], [69]), and tunicamycin induced targets of the UPR and other genes (Table S1, [70], [71]). The different stimuli also induced an overlapping gene set (Fig. 1A, 504 genes). Common genes included targets of the ESR (150 of 504 total, Table S1[61], [62]) and targets of the HOG pathway. Likewise, a partially overlapping set of repressed genes was also identified that included ESR targets (Fig. S2A).

Bottom Line: Such cross-modulation was critical to optimize the differentiation response.The human fungal pathogen Candida albicans showed a similar regulatory circuit.Thus, an evolutionarily conserved regulatory axis links metabolic respiration and AMPK to Ire1p, which regulates a differentiation response involving the modulated activity of ERK and p38 MAPK pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America.

ABSTRACT
Evolutionarily conserved mitogen activated protein kinase (MAPK) pathways regulate the response to stress as well as cell differentiation. In Saccharomyces cerevisiae, growth in non-preferred carbon sources (like galactose) induces differentiation to the filamentous cell type through an extracellular-signal regulated kinase (ERK)-type MAPK pathway. The filamentous growth MAPK pathway shares components with a p38-type High Osmolarity Glycerol response (HOG) pathway, which regulates the response to changes in osmolarity. To determine the extent of functional overlap between the MAPK pathways, comparative RNA sequencing was performed, which uncovered an unexpected role for the HOG pathway in regulating the response to growth in galactose. The HOG pathway was induced during growth in galactose, which required the nutrient regulatory AMP-dependent protein kinase (AMPK) Snf1p, an intact respiratory chain, and a functional tricarboxylic acid (TCA) cycle. The unfolded protein response (UPR) kinase Ire1p was also required for HOG pathway activation in this context. Thus, the filamentous growth and HOG pathways are both active during growth in galactose. The two pathways redundantly promoted growth in galactose, but paradoxically, they also inhibited each other's activities. Such cross-modulation was critical to optimize the differentiation response. The human fungal pathogen Candida albicans showed a similar regulatory circuit. Thus, an evolutionarily conserved regulatory axis links metabolic respiration and AMPK to Ire1p, which regulates a differentiation response involving the modulated activity of ERK and p38 MAPK pathways.

Show MeSH
Related in: MedlinePlus