Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The transcription of meiosis-specific genes, as well as the initiation of meiosis, in the budding yeast Saccharomyces cerevisiae depends on IME1. IME1 encodes a transcriptional activator which lacks known DNA binding motifs. In this study we have determined the mode by which Ime1 specifically activates the transcription of meiotic genes. We demonstrate that Ime1 is recruited to the promoters of meiotic genes by interacting with a DNA-binding protein, Ume6. This association between Ime1 and Ume6 depends on both starvation and the activity of a protein kinase, encoded by RIM11 In the absence of Ime1, Ume6 represses the transcription of meiotic genes. However, in the presence of Ime1, or when Ume6 is fused in frame to the Gal4 activation domain, Ume6 is converted from a repressor to an activator, resulting in the transcription of meiosis-specific genes and the formation of asci.
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PMID:Induction of meiosis in Saccharomyces cerevisiae depends on conversion of the transcriptional represssor Ume6 to a positive regulator by its regulated association with the transcriptional activator Ime1. 862 20

Progression through early Myxococcus xanthus multicellular fruiting body development requires the generation of and response to extracellular A signal. Extracellular A signal is a specific set of amino acids at an extracellular concentration greater than 10 muM. It functions as a cell density signal during starvation that allows the cells to sense that a minimal cell density has been reached and development can proceed. The generation of extracellular A signal requires the products of three asg genes. They have recently been identified as AsgA, a fused two-component histidine protein kinase and response regulator; AsgB, a putative DNA-binding protein; and AsgC, the M, xanthus major sigma factor. Other elements of the A signaling pathway map to the sasB locus and appear to be A signal transducers. These elements are regulators of the earliest A signal-dependent gene, whose promoter is a member of the sigma-54 family. Continued study of the A signaling pathway is expected to identify additional components of this network required for the complex behavioural response of fruiting body formation.
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PMID:A Myxococcus xanthus cell density-sensing system required for multicellular development. 867 94

The stress-activated Wis1-Spc1 protein kinase cascade links mitotic control with environmental signals in Schizosaccharomyces pombe. Fission yeast spc1- mutants are delayed in G2 during normal growth and undergo G2 arrest when exposed to osmotic or oxidative stress. Here we report that Spc1 also has an important role in regulating sexual development in S. pombe. This discovery arose from the observation that Spc1 is activated in response to nitrogen limitation, a key signal that promotes conjugation in fission yeast. Mutant spc1- cells are defective at arresting in G2 during nitrogen starvation and exhibit a poor mating ability. These deficiencies correlate with a failure to induce transcription of ste11+, a gene that encodes a transcription factor responsible for expression of various meiotic genes. Two genes, atf1+ and atf21+, were cloned as multicopy suppressors of the spc1- mating defect. Atf1 and Atf21 are bZIP transcription factors that are most closely related to human ATF-2/CRE-BP1. Spc1 is required for stress-induced phosphorylation of Atf1. Atf1 is required for induction of meiotic genes and stress-response genes, such as gpd1+ and pyp2+, that are transcriptionally regulated by Spc1. atf1- and spc1- mutants are sensitive to osmotic stress and impaired for sexual development, showing that fission yeast uses a common pathway to respond to cytotoxic stress and nitrogen starvation. However, unlike spc1- mutants, atf1- cells have no mitotic cell-cycle defect, indicating that the stress response pathway bifurcates at Spc1 to regulate independently meiosis and mitosis.
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PMID:Conjugation, meiosis, and the osmotic stress response are regulated by Spc1 kinase through Atf1 transcription factor in fission yeast. 882 87

The Pho regulon of Bacillus subtilis is controlled by three two-component signal-transduction systems: PhoP/PhoR, ResD/ResE, and the phosphorelay leading to the phosphorylation of SpoOA. Two of these systems act as positive regulators, while the third is involved in negative regulation of the Pho regulon. Under phosphate-starvation-induction conditions, the response regulator (RR) PhoP, and the histidine protein kinase (HK) PhoR, are involved in the induction of Pho-regulon genes including the phoPR operon and genes encoding the major vegetative alkaline phosphatases, phoA and phoB. ResD (the RR) and ResE (the HK) are positive regulators of both aerobic and anaerobic respiration in B. subtilis. Current data suggest that they are also positive regulators of the Pho regulon, as is the transition-state regulatory protein AbrB. Data presented reveal that ResDE and AbrB are involved in activation of the Pho regulon through separate regulatory pathways. SpoOA approximately P (RR) exerts a negative effect on the Pho regulon through its repression of AbrB, and possibly through repression of ResDE. Both pathways converge to regulate transcription of the phoPR operon.
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PMID:Three two-component signal-transduction systems interact for Pho regulation in Bacillus subtilis. 883 Feb 75

The wis1 protein kinase of Schizosaccharomyces pombe is a member of the MAP kinase kinase family. Loss of wis1 function has previously been reported to lead to a delay in the G2-mitosis transition, loss of viability in stationary phase, and hypersensitivity to osmotic shock. It acts at least in part by activating the MAP kinase homologue sty1; loss-of-function sty1 mutants share many phenotypes with wis1 deletion mutants. We show here that, in addition, loss of wis1 function leads to defective conjugation, and to suppression of the hyperconjugation phenotype of the pat1-114 mutation. Consistent with this, the induction of the mei2 gene, which is normally induced by nitrogen starvation, is defective in wis1 mutants. In wild-type cells, nitrogen starvation leads to mei2 induction through a fall in intracellular cyclic AMP (cAMP) level and activity of the cAMP-dependent protein kinase. We show here that wis1 function is required for mei2 induction following nitrogen starvation. Expression of the fbp1 gene is negatively regulated by cAMP in response to glucose limitation: induction of fbp1 also requires wis1 and sty1 function. Loss of wis1 is epistatic over increased fbp1 expression brought about by loss of adenylate cyclase (git2/cyr1) or cAMP-dependent protein kinase (pka1) function. These observations can be explained by a model in which the pka1 pathway negatively regulates the wis1 pathway, or the two pathways might act independently on downstream targets. The latter explanation is supported, at least as regards regulation of cell division, by the observation that loss of function of the regulatory subunit of the cAMP-dependent protein kinase (cgs1) brings about a modest increase in cell length at division in both wis1+ and wis1 delta genetic backgrounds.
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PMID:The wis1 signal transduction pathway is required for expression of cAMP-repressed genes in fission yeast. 883 15

Starvation for nitrogen in the absence of a fermentable carbon source causes diploid Saccharomyces cerevisiae cells to leave vegetative growth, enter meiosis, and sporulare; the former nutritional condition also induces expression of the YVH1 gene that encodes a protein phosphatase. This correlation prompted us to determine whether the Yvh1p phosphatase was a participant in the network that controls the onset of meiosis and sporulation. We found that expression of the IME2 gene, encoding a protein kinase homologue required for meiosis- and sporulation-specific gene expression, is decreased in a yvh1 disrupted strain. We also observed a decrease, albeit a smaller one, in the expression of IME1 which encodes an activator protein required for IME2 expression. Under identical experimental conditions, expression of the MCKI and IME4 genes (which promote sporulation but do not require Ime1p for expression) was not affected. These results demonstrate the specificity of the yvh1 disruption phenotype. They suggest that decreased steady-state levels of IME1 and IME2 mRNA were not merely the result of non-specific adverse affects on nucleic acid metabolism caused by the yvh1 disruption. Sporulation of a homozygous yvh1 disruption mutant was delayed and less efficient overall compared to an isogenic wild-type strain, a result which correlates with decreased IME1 and IME2 gene expression. We also observed that expression of the PTP2 tyrosine phosphatase gene (a negative regulator of the osmosensing MAP kinase cascade), but not the PTP1 gene (also encoding a tyrosine phosphatase) was induced by nitrogen-starvation. Although disruption of PTP2 alone did not demonstrably affect sporulation or IME2 gene expression, sporulation was decreased more in a yvh1, ptp2 double mutant than in a yvh1 single mutant; it was nearly abolished in the double mutant. These data suggest that the YVH1 and PTP2 encoded phosphatases likely participate in the control network regulating meiosis and sporulation. Expression of YVH1 and PTP2 was not affected by nitrogen source quality (asparagine compared to proline) suggesting that nitrogen starvation-induced YVH1 and PTP2 expression and sensitivity to nitrogen catabolite repression are on two different branches of the nitrogen regulatory network.
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PMID:The S. cerevisiae nitrogen starvation-induced Yvh1p and Ptp2p phosphatases play a role in control of sporulation. 889 80

Schizosaccharomyces pombe cells take up D-gluconate, as an alternative carbon source for growth, during glucose starvation or when cultured on glycerol-containing medium. Gluconate uptake is not detectable while cells are growing logarithmically on glucose. The addition of D-glucose as well as its non-metabolizable analogues to glycerol-grown cells causes an immediate loss of gluconate transport within 1 min. The reversible down-regulation of the gluconate carrier occurs after glucose has been internalized. This regulation is triggered not only by D-glucose but also by extracellular cAMP even in the absence of the cAMP-dependent protein kinase (PKA1).
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PMID:The activity of the gluconate-H+ symporter of Schizosaccharomyces pombe cells is down-regulated by D-glucose and exogenous cAMP. 889 10

Phosphate starvation induces the transcription of several genes involved in phosphate metabolism in the budding yeast Saccharomyces cerevisiae. The signal transduction pathway that mediates this response consists of components that resemble those used to regulate the eukaryotic cell cycle; these include a cyclin-dependent kinase or CDK (Pho85), a cyclin (Pho80) and a CDK inhibitor (Pho81). The possibility that this pathway mediates cell-cycle responses to phosphate starvation is discussed.
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PMID:Signaling phosphate starvation. 891 92

Y-1 adrenal cells were cell cycle arrested by serum starvation to characterize a G0-->G1-->S transition in these cells. Cycle arrested Y-1 cells start to enter S phase 8h after serum feeding, reaching more than 90% cells synthesizing DNA by 24h. ACTH displays a dual effect in the G0-->G1-->S transition: 2h ACTH treatment stimulates DNA synthesis initiation, but longer treatments inhibit S phase entry. This dual effect of ACTH is similar to the antagonistic actions of PMA (phorbol-12-miristate-13-acetate) on the G0-->G1-->S transition. However ACTH and PMA are likely to have different mechanisms of action. ACTH inhibitory effect requires PKA, whereas PMA inhibitory effect is not dependent on PKA. ACTH induces the proto-oncogenes c-fos and c-jun, but inhibits the expression of the c-myc proto-oncogene. PMA, on the other hand, induces equally well c-fos, c-jun and c-myc. We hypothesize that ACTH promotes G0-->G1 transition by induction of c-fos and c-jun and blocks G1-->S transition by c-myc inhibition.
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PMID:Regulation of growth by ACTH in the Y-1 line of mouse adrenocortical cells. 896 86

The Saccharomyces cerevisiae GCN4 gene which encodes the transcription activator Gcn4, is under translational regulation. Derepression of GCN4 mRNA translation is mediated by the Gcn2 protein kinase which phosphorylates the alpha subunit of eIF-2, upon amino-acid starvation. Here, we report that overexpression of certain Saccharomyces cerevisiae genes generates intracellular conditions that alleviate the requirement for a functional Gcn2 kinase to induce GCN4 mRNA translation. Our findings, combined with the fact that Gcn2 kinase is dispensable during the initiation phase of the cellular response to amino-acid limitation, provide the grounds to further elucidate the mechanisms underlying the physiology of this homeostatic response.
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PMID:Gene overexpression reveals alternative mechanisms that induce GCN4 mRNA translation. 897 11


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