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)

We have identified many dark-inducible (din) genes that are expressed in Arabidopsis leaves kept in the dark. In the present study we addressed the question of how plant cells sense the depletion of sugars, and how sugar starvation triggers din gene expression in suspension-cultured cells of Arabidopsis. Depletion of sucrose in the medium triggered marked accumulation of din transcripts. Suppression of din gene expression by 2-deoxy-Glc, and a non-suppressive effect exerted by 3-O-methyl-Glc, suggested that sugar-repressible expression of din genes is mediated through the phosphorylation of hexose by hexokinase, as exemplified in the repression of photosynthetic genes by sugars. We have further shown that the signaling triggered by sugar starvation involves protein phosphorylation and dephosphorylation events, and have provided the first evidence that multiple pathways of protein dephosphorylation exist in sugar starvation-induced gene expression. An inhibitor of serine/threonine protein kinase, K-252a, inhibited din gene expression in sugar-depleted cells. Okadaic acid, which may preferentially inhibit type 2A protein phosphatases over type 1, enhanced the transcript levels of all din genes, except din6 and din10, under sugar starvation. Conversely, a more potent inhibitor of type 1 and 2A protein phosphatases, calyculin A, increased transcripts from din2 and din9, but decreased those from other din genes, in sugar-depleted cells. On the other hand, calyculin A, but not okadaic acid, completely inhibited the gene expression of chlorophyll a/b-binding protein under sugar starvation. These results indicate that multiple signaling pathways, mediated by different types of protein phosphatases, regulate gene expression during sugar starvation.
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PMID:Multiple signaling pathways in gene expression during sugar starvation. Pharmacological analysis of din gene expression in suspension-cultured cells of Arabidopsis. 1108 Feb 91

Sugar starvation exerted by sub-10 mM levels of sucrose on Arabidopsis T87 suspension-cultured cells triggered marked accumulation of the transcripts of genes for E1beta and E2 subunit of the branched-chain alpha-keto acid dehydrogenase complex. Similar levels of sugar starvation increased the luciferase activity in transgenic tobacco BY-2 lines expressing the Arabidopsis E1beta- or E2-promoter-luciferase fusion gene. These results indicate that sugar levels tightly regulate the E1beta and E2 promoter activity in the heterologous plant system. We further showed in the transgenic tobacco BY-2 lines that sugar-starvation-induced activation of the E1beta and E2 promoters was prevented by K-252a, an inhibitor of Ser/Thr protein kinase, and was enhanced by okadaic acid, an inhibitor of protein phosphatases. By contrast, the cauliflower mosaic virus 35S promoter activity in sugar-starved BY-2 cells was not significantly affected by K-252a and only slightly enhanced by okadaic acid. Taken together, we propose that transcriptional activation of genes for the branched-chain alpha-keto acid dehydrogenase complex and its modulation by specific protein kinases/phosphatases are of critical importance in branched-chain amino acid catabolism in plant cells under sugar starvation.
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PMID:Activation of the promoters of Arabidopsis genes for the branched-chain alpha-keto acid dehydrogenase complex in transgenic tobacco BY-2 cells under sugar starvation. 1191 81

Cyclic AMP-dependent proteolysis of GATA-6 was characterized by fusing GATA-6 with the carboxyl-terminal membrane domain of SREBP-2. When the fusion protein was stably expressed in CHO-K1 cells, it was recovered in the ER membrane. This protein was processed in a similar manner to SREBP-2 upon cholesterol starvation, and the GATA-6 moiety moved into the nucleus. The GATA-6 moiety on the membrane became undetectable in the presence of dbcAMP or cholera toxin. However, H-89, K-252a, MG115 and lactacystin inhibited this decrease, suggesting that the cytoplasmic GATA-6 moiety of the fusion protein was degraded by proteasomes though A-kinase upon elevation of the cellular cAMP concentration.
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PMID:Cyclic AMP-dependent proteolysis of GATA-6 expressed on the intracellular membrane. 1807 65