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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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MAPK responses in C. albicans during growth in galactose.A) Immunoblot analysis of P∼CaHog1p. Wild-type (PC6111) cells were grown in YEPD and YEP-GAL medium (5.5 hrs) and treated with TUN (tunicamycin) (2.5 µg for 3 hrs), MYR (myriocin) (2.5 µg for 3 hrs) and 0.5M NaCl (10 min). B) Phosphorylation of CaHog1p requires the CaIre1p. Wild-type (PC6116), ire1Δ/ire1Δ (PC6144), and ire1Δ/pIRE1 (PC6145) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). C) P∼Cek1p levels in the hog1Δ/hog1Δ mutant at 30°C and 37°C. Wild-type (PC6111) and hog1Δ/hog1Δ (PC5008) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). D) Plate-washing assay of wild-type cells (PC6111) and the hog1Δ/hog1Δ mutant (PC5008) on YEP-GAL medium at 37°C for 48 hrs. The plate was photographed, washed, and photographed again to reveal invaded cells. E) P∼CaHog1p and P∼Cek1p levels in the cek1Δ/cek1Δ mutant at 30°C and 37°C. Wild-type (PC6111) and cek1Δ/cek1Δ (PC6114) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). F) Model showing the roles of the HOG and filamentous growth pathways in the response to growth in galactose. Galactose is transported into cells and metabolized by genes under the control of Snf1p. As a result, metabolic respiration is increased, which by some mechanism (?) induces the UPR. Ire1p mediates activation of the HOG and filamentous growth pathways (Adhikari et al. SUBMITTED). The HOG and filamentous growth pathways induce different target genes to redundantly promote growth under this condition. The antagonistic roles of these pathways on each other's activities optimize the response.
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pgen-1004734-g007: MAPK responses in C. albicans during growth in galactose.A) Immunoblot analysis of P∼CaHog1p. Wild-type (PC6111) cells were grown in YEPD and YEP-GAL medium (5.5 hrs) and treated with TUN (tunicamycin) (2.5 µg for 3 hrs), MYR (myriocin) (2.5 µg for 3 hrs) and 0.5M NaCl (10 min). B) Phosphorylation of CaHog1p requires the CaIre1p. Wild-type (PC6116), ire1Δ/ire1Δ (PC6144), and ire1Δ/pIRE1 (PC6145) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). C) P∼Cek1p levels in the hog1Δ/hog1Δ mutant at 30°C and 37°C. Wild-type (PC6111) and hog1Δ/hog1Δ (PC5008) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). D) Plate-washing assay of wild-type cells (PC6111) and the hog1Δ/hog1Δ mutant (PC5008) on YEP-GAL medium at 37°C for 48 hrs. The plate was photographed, washed, and photographed again to reveal invaded cells. E) P∼CaHog1p and P∼Cek1p levels in the cek1Δ/cek1Δ mutant at 30°C and 37°C. Wild-type (PC6111) and cek1Δ/cek1Δ (PC6114) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). F) Model showing the roles of the HOG and filamentous growth pathways in the response to growth in galactose. Galactose is transported into cells and metabolized by genes under the control of Snf1p. As a result, metabolic respiration is increased, which by some mechanism (?) induces the UPR. Ire1p mediates activation of the HOG and filamentous growth pathways (Adhikari et al. SUBMITTED). The HOG and filamentous growth pathways induce different target genes to redundantly promote growth under this condition. The antagonistic roles of these pathways on each other's activities optimize the response.

Mentions: The signaling circuit characterized here might be specific to S. cerevisiae or extend to other species. To address this question, pathways of the fungal pathogen Candida albicans were examined. Like budding yeast, C. albicans has a Kss1p-type pathway (Cek1p pathway [123]–[125]), and a p38-type pathway (CaHOG pathway [126]). The CaHOG MAPK CaHog1p is activated by osmotic stress (Fig. 7A[127]) and was also induced by tunicamycin, myriocin, and growth in galactose (Fig. 7A, 5 h at 30°C). Thus, the versatility of HOG pathway in sensing diverse stresses is conserved among several fungal species.


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

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

MAPK responses in C. albicans during growth in galactose.A) Immunoblot analysis of P∼CaHog1p. Wild-type (PC6111) cells were grown in YEPD and YEP-GAL medium (5.5 hrs) and treated with TUN (tunicamycin) (2.5 µg for 3 hrs), MYR (myriocin) (2.5 µg for 3 hrs) and 0.5M NaCl (10 min). B) Phosphorylation of CaHog1p requires the CaIre1p. Wild-type (PC6116), ire1Δ/ire1Δ (PC6144), and ire1Δ/pIRE1 (PC6145) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). C) P∼Cek1p levels in the hog1Δ/hog1Δ mutant at 30°C and 37°C. Wild-type (PC6111) and hog1Δ/hog1Δ (PC5008) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). D) Plate-washing assay of wild-type cells (PC6111) and the hog1Δ/hog1Δ mutant (PC5008) on YEP-GAL medium at 37°C for 48 hrs. The plate was photographed, washed, and photographed again to reveal invaded cells. E) P∼CaHog1p and P∼Cek1p levels in the cek1Δ/cek1Δ mutant at 30°C and 37°C. Wild-type (PC6111) and cek1Δ/cek1Δ (PC6114) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). F) Model showing the roles of the HOG and filamentous growth pathways in the response to growth in galactose. Galactose is transported into cells and metabolized by genes under the control of Snf1p. As a result, metabolic respiration is increased, which by some mechanism (?) induces the UPR. Ire1p mediates activation of the HOG and filamentous growth pathways (Adhikari et al. SUBMITTED). The HOG and filamentous growth pathways induce different target genes to redundantly promote growth under this condition. The antagonistic roles of these pathways on each other's activities optimize the response.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4214603&req=5

pgen-1004734-g007: MAPK responses in C. albicans during growth in galactose.A) Immunoblot analysis of P∼CaHog1p. Wild-type (PC6111) cells were grown in YEPD and YEP-GAL medium (5.5 hrs) and treated with TUN (tunicamycin) (2.5 µg for 3 hrs), MYR (myriocin) (2.5 µg for 3 hrs) and 0.5M NaCl (10 min). B) Phosphorylation of CaHog1p requires the CaIre1p. Wild-type (PC6116), ire1Δ/ire1Δ (PC6144), and ire1Δ/pIRE1 (PC6145) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). C) P∼Cek1p levels in the hog1Δ/hog1Δ mutant at 30°C and 37°C. Wild-type (PC6111) and hog1Δ/hog1Δ (PC5008) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). D) Plate-washing assay of wild-type cells (PC6111) and the hog1Δ/hog1Δ mutant (PC5008) on YEP-GAL medium at 37°C for 48 hrs. The plate was photographed, washed, and photographed again to reveal invaded cells. E) P∼CaHog1p and P∼Cek1p levels in the cek1Δ/cek1Δ mutant at 30°C and 37°C. Wild-type (PC6111) and cek1Δ/cek1Δ (PC6114) cells were grown in YEPD and YEP-GAL medium (5.5 hrs). F) Model showing the roles of the HOG and filamentous growth pathways in the response to growth in galactose. Galactose is transported into cells and metabolized by genes under the control of Snf1p. As a result, metabolic respiration is increased, which by some mechanism (?) induces the UPR. Ire1p mediates activation of the HOG and filamentous growth pathways (Adhikari et al. SUBMITTED). The HOG and filamentous growth pathways induce different target genes to redundantly promote growth under this condition. The antagonistic roles of these pathways on each other's activities optimize the response.
Mentions: The signaling circuit characterized here might be specific to S. cerevisiae or extend to other species. To address this question, pathways of the fungal pathogen Candida albicans were examined. Like budding yeast, C. albicans has a Kss1p-type pathway (Cek1p pathway [123]–[125]), and a p38-type pathway (CaHOG pathway [126]). The CaHOG MAPK CaHog1p is activated by osmotic stress (Fig. 7A[127]) and was also induced by tunicamycin, myriocin, and growth in galactose (Fig. 7A, 5 h at 30°C). Thus, the versatility of HOG pathway in sensing diverse stresses is conserved among several fungal species.

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