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)

Differential centrifugation and Percoll-gradient centrifugation of protoplast lysates of suspension-cultured cells of sycamore (Acer pseudoplatanus L.) yielded pure amyloplasts. Contamination of the final amyloplast preparation by foreign compartments was assessed by measuring marker enzyme activities. The activity of alkaline pyrophosphatase was taken as a 100% plastid marker; relative to this marker, mitochondria (cytochrome c oxidase) averaged 0.34%, microbodies (catalase) 0.61%, and cytosol (alcohol dehydrogenase) 0.09%. Enzymatic activities of the glycolytic, gluconeogenic, pentose phosphate and the starch degradation pathways were found to be present in these amyloplast extracts in appreciable amounts. But the pyrophosphate-dependent phosphofructokinase and phosphoglyceromutase were judged to be essentially absent from amyloplasts because the activities of these enzymes were not enriched above the level of contaminating enzymatic activities in the amyloplast fractions. Additionally, the in vitro activities of starch phosphorylase, ATP dependent phosphofructokinase, NAD dependent glyceraldehyde-3 phosphate dehydrogenase, and glucose-6 phosphate dehydrogenase did not seem to support carbon fluxes from starch to triose phosphates as calculated from the rate of starch disappearance during carbon starvation of the cells. These results provide additional, indirect evidence for the recently emerged view that, in addition to the well known phosphate-triosephosphate translocator, another hexose phosphate and possibly also an ATP/ADP translocating system play major roles in nongreen plastids.
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PMID:Enzyme Sets of Glycolysis, Gluconeogenesis, and Oxidative Pentose Phosphate Pathway Are Not Complete in Nongreen Highly Purified Amyloplasts of Sycamore (Acer pseudoplatanus L.) Cell Suspension Cultures. 1666 46

The sphingolipid ceramide elicits several stress responses, however, organisms survive despite increased ceramide but how they do so is poorly understood. We demonstrate here that the AKT/FOXO pathway regulates survival in increased ceramide environment by metabolic adaptation involving changes in glycolysis and lipolysis through novel downstream targets. We show that ceramide kinase mutants accumulate ceramide and this leads to reduction in energy levels due to compromised oxidative phosphorylation. Mutants show increased activation of Akt and a consequent decrease in FOXO levels. These changes lead to enhanced glycolysis by upregulating the activity of phosphoglyceromutase, enolase, pyruvate kinase, and lactate dehydrogenase to provide energy. A second major consequence of AKT/FOXO reprogramming in the mutants is the increased mobilization of lipid from the gut through novel lipase targets, CG8093 and CG6277 for energy contribution. Ubiquitous reduction of these targets by knockdown experiments results in semi or total lethality of the mutants, demonstrating the importance of activating them. The efficiency of these adaptive mechanisms decreases with age and leads to reduction in adult life span of the mutants. In particular, mutants develop cardiac dysfunction with age, likely reflecting the high energy requirement of a well-functioning heart. The lipases also regulate physiological triacylglycerol homeostasis and are important for energy metabolism since midgut specific reduction of them in wild type flies results in increased sensitivity to starvation and accumulation of triglycerides leading to cardiac defects. The central findings of increased AKT activation, decreased FOXO level and activation of phosphoglyceromutase and pyruvate kinase are also observed in mice heterozygous for ceramide transfer protein suggesting a conserved role of this pathway in mammals. These data reveal novel glycolytic and non-autonomous lipolytic pathways in response to increased ceramide for sustenance of high energy demanding organ functions like the heart.
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PMID:Survival response to increased ceramide involves metabolic adaptation through novel regulators of glycolysis and lipolysis. 2381 62