Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

AMP-activated protein kinase influences cellular metabolism, glucose-regulated gene expression, and insulin secretion of pancreatic beta cells. Its sustained activation by culture at low glucose concentrations or in the presence of 5-aminoimidazole-4-carboxamide riboside (AICAR) was shown to trigger apoptosis in beta cells. This study shows that both low glucose- and AICAR-induced apoptosis are associated with increased formation of mitochondrial superoxide-derived radicals and decreased mitochondrial activity. Mitochondrial dysfunction was reflected by an increased oxidized state of the mitochondrial flavins (FMN/FAD) but not of NAD(P)H. It was accompanied by suppression of glucose oxidation and glucose-induced insulin secretion, while palmitate oxidation appeared unaffected. When the cellular accumulation of superoxide-derived radicals was quenched by the ROS scavengers vitamin E, N-acetylcysteine, or the SOD-mimetic compound MnTBAP, apoptosis was significantly inhibited. Both low glucose and AICAR also elevated the expression of BH3-domain-only Bcl-2 antagonists, and induced caspase-3 activation, causing caspase-dependent truncation of Bcl-2. Overexpression of recombinant human Bcl-2 prevented caspase-3 activation, endogenous Bcl-2 processing, and apoptosis, but did not attenuate oxygen radical formation, AMPK activation, or JNK phosphorylation. We conclude that apoptosis by prolonged AMPK activation in beta cells results from enhanced production of mitochondria-derived oxygen radicals and onset of the intrinsic mitochondrial apoptosis pathway, followed by caspase activation and Bcl-2 cleavage which may amplify the death signal.
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PMID:Increased oxygen radical formation and mitochondrial dysfunction mediate beta cell apoptosis under conditions of AMP-activated protein kinase stimulation. 1715 94

Drosophila cryptochrome (dCRY) is a FAD-dependent circadian photoreceptor, whereas mammalian cryptochromes (CRY1/2) are integral clock components that repress mCLOCK/mBMAL1-dependent transcription. We report crystal structures of full-length dCRY, a dCRY loop deletion construct, and the photolyase homology region of mouse CRY1 (mCRY1). Our dCRY structures depict Phe534 of the regulatory tail in the same location as the photolesion in DNA-repairing photolyases and reveal that the sulfur loop and tail residue Cys523 plays key roles in the dCRY photoreaction. Our mCRY1 structure visualizes previously characterized mutations, an NLS, and MAPK and AMPK phosphorylation sites. We show that the FAD and antenna chromophore-binding regions, a predicted coiled-coil helix, the C-terminal lid, and charged surfaces are involved in FAD-independent mPER2 and FBXL3 binding and mCLOCK/mBMAL1 transcriptional repression. The structure of a mammalian cryptochrome1 protein may catalyze the development of CRY chemical probes and the design of therapeutic metabolic modulators.
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PMID:Structures of Drosophila cryptochrome and mouse cryptochrome1 provide insight into circadian function. 2374 49