Caloric restriction controls stationary phase survival through Protein Kinase A (PKA) and cytosolic pH

ABSTRACT The cyclic AMP/protein kinase A (cAMP/PKA) and r egulation of A ce2 and m orphogenesis (RAM) pathways are important regulators of the yeast-to-hypha transition in Candida albicans that interact genetically during this process. To further understand this interaction, we have characterized the expression of ACE2 during morphogenesis. In normoxic, planktonic conditions, ACE2 expression is very low in stationary-phase cells at both the mRNA and protein levels. Upon shifting to Spider medium, ACE2/ Ace2p levels increase. Although Ace2 is not absolutely required for hypha formation, ace2 Δ/Δ mutants show delayed hypha formation in Spider medium (but not others) and morphological changes to the hyphal tip and lateral yeast. We also show that Efg1 directly binds the promoter of Ace2 in stationary phase, and ACE2 levels are increased in strains lacking Efg1 and the protein kinase A proteins Tpk1 and Tpk2, indicating that the PKA pathway directly regulates ACE2 expression. ACE2 expression is positively regulated by Tec1 and Brg1, which bind the promoters of ACE2 in hyphal cells but not in the yeast phase. Under embedded conditions, Efg1 is dispensable for filamentation and Ace2 is required. We have found that ACE2 expression is much higher in embedded cells than in planktonic cells, providing a potential rationale for this observation. Taken together, our observations indicate that the PKA pathway directly regulates the RAM pathway under specific conditions and are consistent with a model where the two pathways carry out similar functions that depend on the specific environmental context.

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Target of Rapamycin Complex 1 (TORC1), Protein Kinase A (PKA) and Cytosolic pH Regulate a Transcriptional Circuit for Lipid Droplet Formation

International Journal of Molecular Sciences ◽

10.3390/ijms22169017 ◽

2021 ◽

Vol 22 (16) ◽

pp. 9017

Author(s):

Vitor Teixeira ◽

Telma S. Martins ◽

William A. Prinz ◽

Vítor Costa

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Molecular Mechanisms ◽

Nutrient Sensing ◽

Target Of Rapamycin ◽

Significant Advance ◽

Transcriptional Level ◽

Dependent Manner ◽

Cytosolic Ph ◽

Kinase A

Lipid droplets (LDs) are ubiquitous organelles that fulfill essential roles in response to metabolic cues. The identification of several neutral lipid synthesizing and regulatory protein complexes have propelled significant advance on the mechanisms of LD biogenesis in the endoplasmic reticulum (ER). However, our understanding of signaling networks, especially transcriptional mechanisms, regulating membrane biogenesis is very limited. Here, we show that the nutrient-sensing Target of Rapamycin Complex 1 (TORC1) regulates LD formation at a transcriptional level, by targeting DGA1 expression, in a Sit4-, Mks1-, and Sfp1-dependent manner. We show that cytosolic pH (pHc), co-regulated by the plasma membrane H+-ATPase Pma1 and the vacuolar ATPase (V-ATPase), acts as a second messenger, upstream of protein kinase A (PKA), to adjust the localization and activity of the major transcription factor repressor Opi1, which in turn controls the metabolic switch between phospholipid metabolism and lipid storage. Together, this work delineates hitherto unknown molecular mechanisms that couple nutrient availability and pHc to LD formation through a transcriptional circuit regulated by major signaling transduction pathways.

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The Saccharomyces cerevisiae HSP12 gene is activated by the high-osmolarity glycerol pathway and negatively regulated by protein kinase A.

Molecular and Cellular Biology ◽

10.1128/mcb.15.11.6232 ◽

1995 ◽

Vol 15 (11) ◽

pp. 6232-6245 ◽

Cited By ~ 136

Author(s):

J C Varela ◽

U M Praekelt ◽

P A Meacock ◽

R J Planta ◽

W H Mager

Keyword(s):

Saccharomyces Cerevisiae ◽

Heat Shock ◽

Protein Kinase ◽

Stationary Phase ◽

Protein Kinase A ◽

Yeast Cells ◽

Wild Type ◽

High Osmolarity ◽

High Osmolarity Glycerol ◽

Kinase A

The HSP12 gene encodes one of the two major small heat shock proteins of Saccharomyces cerevisiae. Hsp12 accumulates massively in yeast cells exposed to heat shock, osmostress, oxidative stress, and high concentrations of alcohol as well as in early-stationary-phase cells. We have cloned an extended 5'-flanking region of the HSP12 gene in order to identify cis-acting elements involved in regulation of this highly expressed stress gene. A detailed analysis of the HSP12 promoter region revealed that five repeats of the stress-responsive CCCCT motif (stress-responsive element [STRE]) are essential to confer wild-type induced levels on a reporter gene upon osmostress, heat shock, and entry into stationary phase. Disruption of the HOG1 and PBS2 genes leads to a dramatic decrease of the HSP12 inducibility in osmostressed cells, whereas overproduction of Hog1 produces a fivefold increase in wild-type induced levels upon a shift to a high salt concentration. On the other hand, mutations resulting in high protein kinase A (PKA) activity reduce or abolish the accumulation of the HSP12 mRNA in stressed cells. Conversely, mutants containing defective PKA catalytic subunits exhibit high basal levels of HSP12 mRNA. Taken together, these results suggest that HSP12 is a target of the high-osmolarity glycerol (HOG) response pathway under negative control of the Ras-PKA pathway. Furthermore, they confirm earlier observations that STRE-like sequences are responsive to a broad range of stresses and that the HOG and Ras-PKA pathways have antagonistic effects upon CCCCT-driven transcription.

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cAMP has a protein kinase A independent regulatory effect on T cell proliferation, MAP kinase activity and on mRNA levels for IL-2 and INF-gamma

Immunology Letters ◽

10.1016/s0165-2478(97)87084-8 ◽

1997 ◽

Vol 56 (1-3) ◽

pp. 65

Author(s):

B Hofmann

Keyword(s):

Cell Proliferation ◽

T Cell ◽

Protein Kinase ◽

Map Kinase ◽

Protein Kinase A ◽

Kinase Activity ◽

T Cell Proliferation ◽

Mrna Levels ◽

Regulatory Effect ◽

Kinase A

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2068 Human cardiac inward rectifier Kir2.2/Kir2.1b (KCNJ12) potassium channels are antagonistically regulated by protein kinase A and protein kinase C

European Heart Journal ◽

10.1016/s0195-668x(03)95062-7 ◽

2003 ◽

Vol 24 (5) ◽

pp. 382

Author(s):

S KATHOFER

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Potassium Channels ◽

Protein Kinase A ◽

Inward Rectifier ◽

Kinase C ◽

Kinase A

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Expression and mutation analysis of regulatory subunit Iα of protein kinase A in undifferentiated and anaplastic thyroid carcinoma

Experimental and Clinical Endocrinology & Diabetes ◽

10.1055/s-2004-819071 ◽

2004 ◽

Vol 112 (S 1) ◽

Author(s):

M Lippert ◽

SY Sheu ◽

K Worm ◽

M Wichert ◽

KW Schmid ◽

...

Keyword(s):

Protein Kinase ◽

Thyroid Carcinoma ◽

Protein Kinase A ◽

Mutation Analysis ◽

Anaplastic Thyroid Carcinoma ◽

Regulatory Subunit ◽

Kinase A

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cAMP exerts proliferative and anti-proliferative effects in pituitary cells of different types by activating both cAMP-dependent protein kinase A and exchange proteins directly activated by cAMP

Endocrine Abstracts ◽

10.1530/endoabs.32.p827 ◽

2013 ◽

Author(s):

Eleonora Vitali ◽

Erika Peverelli ◽

Giovanna Mantovani ◽

Elena Giardino ◽

Andrea G. Lania ◽

...

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Pituitary Cells ◽

Dependent Protein Kinase ◽

Camp Dependent Protein Kinase ◽

Different Types ◽

Dependent Protein ◽

Kinase A

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Regulation of spontaneous and induced resumption of meiosis in mouse oocytes by different intracellular pathways

Reproduction ◽

10.1530/reprod/120.2.377 ◽

2000 ◽

pp. 377-383 ◽

Cited By ~ 13

Author(s):

L Leonardsen ◽

A Wiersma ◽

M Baltsen ◽

AG Byskov ◽

CY Andersen

Keyword(s):

Signal Transduction ◽

Protein Kinase ◽

Protein Kinase A ◽

Mitogen Activated Protein Kinase ◽

Meiotic Maturation ◽

Mouse Oocytes ◽

Mitogen Activated Protein ◽

Dependent Signal ◽

Kinase Pathway ◽

Kinase A

The mitogen-activated protein kinase-dependent and the cAMP-protein kinase A-dependent signal transduction pathways were studied in cultured mouse oocytes during induced and spontaneous meiotic maturation. The role of the mitogen-activated protein kinase pathway was assessed using PD98059, which specifically inhibits mitogen-activated protein kinase 1 and 2 (that is, MEK1 and MEK2), which activates mitogen-activated protein kinase. The cAMP-dependent protein kinase was studied by treating oocytes with the protein kinase A inhibitor rp-cAMP. Inhibition of the mitogen-activated protein kinase pathway by PD98059 (25 micromol l(-1)) selectively inhibited the stimulatory effect on meiotic maturation by FSH and meiosis-activating sterol (that is, 4,4-dimethyl-5alpha-cholest-8,14, 24-triene-3beta-ol) in the presence of 4 mmol hypoxanthine l(-1), whereas spontaneous maturation in the absence of hypoxanthine was unaffected. This finding indicates that different signal transduction mechanisms are involved in induced and spontaneous maturation. The protein kinase A inhibitor rp-cAMP induced meiotic maturation in the presence of 4 mmol hypoxanthine l(-1), an effect that was additive to the maturation-promoting effect of FSH and meiosis-activating sterol, indicating that induced maturation also uses the cAMP-protein kinase A-dependent signal transduction pathway. In conclusion, induced and spontaneous maturation of mouse oocytes appear to use different signal transduction pathways.

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