Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
 2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Incubation of isolated hepatocytes with glutamine or proline or in hypotonic media is known to activate glycogen synthase and acetyl-CoA carboxylase as a result of cell swelling. We report here that the same experimental conditions caused an activation of phosphatidylinositol 3-kinase and p70 ribosomal protein S6 kinase (p70 S6 kinase) but did not modify the activity of p42 mitogen-activated protein kinase. In addition, rapamycin, an inhibitor of p70 S6 kinase activation, prevented the amino acid- and hypotonicity-induced activation of p70 S6 kinase but did not block the activation of glycogen synthase and acetyl-CoA carboxylase, thus ruling out p70 S6 kinase as a necessary component in the activation pathway. By contrast, wortmannin or LY294002, inhibitors of phosphatidylinositol 3-kinase, completely blocked the activation of phosphatidylinositol 3-kinase and p70 S6 kinase and partly blocked the activation of glycogen synthase and acetyl-CoA carboxylase. Therefore, phosphatidylinositol 3-kinase might be a component of the signaling pathway that is triggered by cell swelling and is responsible, at least in part, for the activation of glycogen synthase and acetyl-CoA carboxylase. Incubation of hepatocytes with 0.1 microM epidermal growth factor doubled the activity of p42 mitogen-activated protein kinase without activating glycogen synthase.
 ...
PMID:Protein kinase signaling pathway triggered by cell swelling and involved in the activation of glycogen synthase and acetyl-CoA carboxylase in isolated rat hepatocytes. 866 1

The metabolic effects of insulin are initiated by the binding of insulin to the extracellular domain of the insulin receptor within the plasma membrane of muscle and adipose and liver cells. The subsequent activation of the intracellular tyrosine protein kinase activity of the receptor leads to autophosphorylation of the receptor as well as phosphorylation of a number of intracellular proteins. This gives rise to the activation of Ras and phosphatidylinositol 3-kinase and hence to the activation of a number of serine/threanine protein kinases. Many of these kinases appear to be arranged in cascades, including a cascade that results in the activation of mitogen-activated protein kinase and another that may result in the activation of protein kinase B, leading to the inhibition of glycogen synthase kinase-3 and the activation of the 70 kiloDalton ribosomal S6 protein kinase (p70 S6 kinase). We have explored the role of these early events in the the stimulation of glycogen, fatty acid, and protein synthesis by insulin in rat epididymal fat cells. Comparisons have been made between the metabolic effects of insulin and those of epidermal growth factor, since these 2 agents have contrasting effects on p70 S6 kinase and mitogen-activated protein kinase. The effects of wortmannin (which inhibits phosphatidylinositol 3-kinase), and rapamycin (which blocks the activation of p70 S6 kinase) have also been studied. These and other studies indicate that the mitogen-activated protein kinase cascade is probably not important in the acute metabolic effects of insulin, but may have a role in the regulation of gene transcription and hence the more long-term effects of insulin. The short-term metabolic effects of insulin appear to involve at least 3 distinct signaling pathways: (1) those leading to increases in glucose transport and the activation of glycogen synthase, acetyl-CoA carboxylase, eukaryotic initiation factor-2B, and phosphodiesterase, which may involve phosphatidylinositol 3-kinase and protein kinase B; (2) those leading to some of the effects of insulin on protein synthesis (formation of eukaryotic initiation factor-4F complex, S6 phosphorylation, and activation of eukaryotic elongation factor-2), which may involve phosphatidylinositol 3-kinase and p70 S6 kinase; and finally, (3) that leading to the activation of pyruvate dehydrogenase, which is unique in apparently not requiring activation of phosphatidylinositol 3-kinase.
 ...
PMID:Multiple signaling pathways involved in the metabolic effects of insulin. 929 55

We examined the role of AMP-activated protein kinase (AMPK) in modulating the viability of cultured kidney proximal tubular cells subjected to metabolic stress induced by either dextrose deprivation, inhibition of glycolysis, or inhibition of mitochondrial respiration. We used BU.MPT cells, a conditionally immortalized kidney epithelial cell line derived from the proximal tubules of transgenic mice bearing a temperature-sensitive mutation of the simian virus 40 large-tumor antigen. All three forms of metabolic stress increased the phosphorylation and activity of AMPK. Activation of AMPK led to changes in the phosphorylation of two downstream targets of AMPK, acetyl coenzyme A carboxylase and p70 S6 kinase. Inhibition of AMPK, either pharmacologically with compound C (CC) or by gene silencing, significantly increased the amount of apoptosis in response to all three forms of metabolic stress. Although the amount of apoptosis was directly related to the severity of ATP depletion, inhibition of AMPK had no effect on cellular ATP levels. Notably, metabolic stress increased the phosphorylation and activity of Akt. Furthermore, inhibition of AMPK, with CC or gene silencing, abrogated the ability of metabolic stress to activate Akt. The augmentation of apoptosis induced by inhibition of AMPK was comparable to that induced by inhibition of Akt. We conclude that activation of AMPK following acute metabolic stress plays a major role in promoting the viability of cultured proximal tubular cells. Protection by AMPK appears to be due not to AMPK-mediated conservation of cell energy stores, but rather, at least in part, to AMPK-mediated activation of Akt.
 ...
PMID:AMPK protects proximal tubular cells from stress-induced apoptosis by an ATP-independent mechanism: potential role of Akt activation. 2195 77