On the functional diversity of glyceraldehyde-3-phosphate dehydrogenase: biochemical mechanisms and regulatory control.
TL;DR: Fundamental roles of GAPDH in vivo, dynamic changes in its subcellular localization, and the importance of posttranslational modifications as well as protein:protein interactions as regulatory control mechanisms are demonstrated.
About: This article is published in Biochimica et Biophysica Acta.The article was published on 2011-08-01. It has received 277 citations till now.
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TL;DR: Results indicate that plant GAPDHs can affect multiple aspects of plant immunity in diverse sub-cellular compartments.
Abstract: Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an important enzyme in energy metabolism with diverse cellular regulatory roles in vertebrates, but few reports have investigated the importance of plant GAPDH isoforms outside of their role in glycolysis. While animals possess one GAPDH isoform, plants possess multiple isoforms. In this study, cell biological and genetic approaches were used to investigate the role of GAPDHs during plant immune responses. Individual Arabidopsis GAPDH knockouts (KO lines) exhibited enhanced disease resistance phenotypes upon inoculation with the bacterial plant pathogen Pseudomonas syringae pv. tomato. KO lines exhibited accelerated programmed cell death and increased electrolyte leakage in response to effector triggered immunity. Furthermore, KO lines displayed increased basal ROS accumulation as visualized using the fluorescent probe H2DCFDA. The gapa1-2 and gapc1 KOs exhibited constitutive autophagy phenotypes in the absence of nutrient starvation. Due to the high sequence conservation between vertebrate and plant cytosolic GAPDH, our experiments focused on cytosolic GAPC1 cellular dynamics using a complemented GAPC1-GFP line. Confocal imaging coupled with an endocytic membrane marker (FM4-64) and endosomal trafficking inhibitors (BFA, Wortmannin) demonstrated cytosolic GAPC1 is localized to the plasma membrane and the endomembrane system, in addition to the cytosol and nucleus. After perception of bacterial flagellin, GAPC1 dynamically responded with a significant increase in size of fluorescent puncta and enhanced nuclear accumulation. Taken together, these results indicate that plant GAPDHs can affect multiple aspects of plant immunity in diverse sub-cellular compartments.
310 citations
TL;DR: The ability of TIGAR to function as a Fru-2,6-BPase was independent of HK2 binding and mitochondrial localization, although both of these activities can contribute to the full activity of TigAR in limiting mitochondrial ROS levels and protecting from cell death.
Abstract: The p53-inducible protein TIGAR (Tp53-induced Glycolysis and Apoptosis Regulator) functions as a fructose-2,6-bisphosphatase (Fru-2,6-BPase), and through promotion of the pentose phosphate pathway, increases NADPH production to help limit reactive oxygen species (ROS). Here, we show that under hypoxia, a fraction of TIGAR protein relocalized to mitochondria and formed a complex with hexokinase 2 (HK2), resulting in an increase in HK2 activity. Mitochondrial localization of TIGAR depended on mitochondrial HK2 and hypoxia-inducible factor 1 (HIF1α) activity. The ability of TIGAR to function as a Fru-2,6-BPase was independent of HK2 binding and mitochondrial localization, although both of these activities can contribute to the full activity of TIGAR in limiting mitochondrial ROS levels and protecting from cell death.
196 citations
TL;DR: Because moonlighting functions can play important roles in disease processes, an improved understanding of moonlighting proteins will provide new opportunities for pharmacological manipulations that specifically target a function involved in pathology while sparing physiologically important functions.
Abstract: Moonlighting – the performance of more than one function by a single protein – is becoming recognized as a common phenomenon with important implications for systems biology and human health. The different functions of a moonlighting protein may use different regions of the protein structure, or alternative structures that occur due to post-translational modifications and/or differences in binding partners. Often the different functions of moonlighting proteins are used at different times or in different places. The existence of moonlighting functions complicates efforts to understand metabolic and regulatory networks, as well as physiological and pathological processes in organisms. Because moonlighting functions can play important roles in disease processes, an improved understanding of moonlighting proteins will provide new opportunities for pharmacological manipulations that specifically target a function involved in pathology while sparing physiologically important functions.
178 citations
Cites background from "On the functional diversity of glyc..."
...For example, different moonlighting functions of GAPDH are correlated with post-translational modifications such as phosphorylation, nitrosylation and acetylation [16, 38]....
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...Even more functions are discussed in recent reviews [16, 38]....
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TL;DR: State-of-the-art ultra-high-pressure liquid chromatography-mass spectrometry metabolic flux analysis with redox and switch-tag proteomics identifies for the first time ex vivo functionally relevant reversible and irreversible oxidations of GAPDH without exogenous supplementation of excess pro-oxidant compounds in clinically relevant blood products.
162 citations
TL;DR: The temporal sequence through which subcellular translocation and the acquisition of new GAPDH functions is considered as well as post‐translational modification as a basis for its intracellular transport is considered.
Abstract: Multidimensional proteins such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) exhibit distinct activities unrelated to their originally identified functions. Apart from glycolysis, GAPDH participates in iron metabolism, membrane trafficking, histone biosynthesis, the maintenance of DNA integrity and receptor mediated cell signaling. Further, multifunctional proteins exhibit distinct changes in their subcellular localization reflecting their new activities. As such, GAPDH is not only a cytosolic protein but is localized in the membrane, the nucleus, polysomes, the ER and the Golgi. In addition, although the initial subcellular localizations of multifunctional proteins may be of significance, dynamic changes in intracellular distribution may occur as a consequence of those new activities. As such, regulatory mechanisms may exist through which cells control multifunctional protein expression as a function of their subcellular localization. The temporal sequence through which subcellular translocation and the acquisition of new GAPDH functions is considered as well as post-translational modification as a basis for its intracellular transport.
157 citations
References
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01 Jan 2000
TL;DR: This paper showed that hyperglycaemia increases the production of reactive oxygen species inside cultured bovine aortic endothelial cells and that this increase in reactive oxygen can be prevented by an inhibitor of electron transport chain complex II, an uncoupler of oxidative phosphorylation, by uncoupling protein-1 and by manganese superoxide dismutase.
Abstract: Diabetic hyperglycaemia causes a variety of pathological changes in small vessels, arteries and peripheral nerves. Vascular endothelial cells are an important target of hyperglycaemic damage, but the mechanisms underlying this damage are not fully understood. Three seemingly independent biochemical pathways are involved in the pathogenesis: glucose-induced activation of protein kinase C isoforms; increased formation of glucose-derived advanced glycation end-products; and increased glucose flux through the aldose reductase pathway. The relevance of each of these pathways is supported by animal studies in which pathway-specific inhibitors prevent various hyperglycaemia-induced abnormalities. Hyperglycaemia increases the production of reactive oxygen species inside cultured bovine aortic endothelial cells. Here we show that this increase in reactive oxygen species is prevented by an inhibitor of electron transport chain complex II, by an uncoupler of oxidative phosphorylation, by uncoupling protein-1 and by manganese superoxide dismutase. Normalizing levels of mitochondrial reactive oxygen species with each of these agents prevents glucose-induced activation of protein kinase C, formation of advanced glycation end-products, sorbitol accumulation and NFκB activation.
3,814 citations
TL;DR: This work shows that hyperglycaemia increases the production of reactive oxygen species inside cultured bovine aortic endothelial cells and is prevented by an inhibitor of electron transport chain complex II, by an uncoupler of oxidative phosphorylation, by uncoupling protein-1 and by manganese superoxide dismutase.
Abstract: Normalizing mitochondrial superoxide production blocks three pathways
of hyperglycaemic damage
3,750 citations
TL;DR: The current knowledge on the key genes composing the autophagy machinery in eukaryotes from yeast to mammalian cells and the signaling pathways that sense the status of different types of stress and induce autophagic for cell survival and homeostasis are presented.
Abstract: Autophagy is a process of self-degradation of cellular components in which double-membrane autophagosomes sequester organelles or portions of cytosol and fuse with lysosomes or vacuoles for breakdown by resident hydrolases. Autophagy is upregulated in response to extra- or intracellular stress and signals such as starvation, growth factor deprivation, ER stress, and pathogen infection. Defective autophagy plays a significant role in human pathologies, including cancer, neurodegeneration, and infectious diseases. We present our current knowledge on the key genes composing the autophagy machinery in eukaryotes from yeast to mammalian cells and the signaling pathways that sense the status of different types of stress and induce autophagy for cell survival and homeostasis. We also review the recent advances on the molecular mechanisms that regulate the autophagy machinery at various levels, from transcriptional activation to post-translational protein modification.
3,249 citations
TL;DR: Using AP Endonucleases as Metalloproteins as TrimMing for Reduction of DEOXYRIBOSE DAMages is suggested.
Abstract: DNA GL YCOSYLASES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 921 Thymine Glycol Glycosylases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 921 ForfTUlmidopyrimidine Glycosylase (Fpg/MutM) . . . . . . . . . . . . .. . . . . . . . 924 MutY: A DNA MisfTUltch Glycosylase for Oxidative DafTUlge . . . . . . . . . . . . . 927 Hypoxanthine-DNA Glycosylase 927 5-Hydroxymethyluracil and 5-Hydroxymethylcytosine DNA Glycosylases . . . . . . 928 UV Endonucleases 929 REPAIR OF DEOXYRIBOSE DAMAGES: AP ENDONUCLEASES AND 3'-TRIMMING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 931 Exonuclease III of E. coli 931 Eukaryotic AP Endonucleases Related to Exonuclease III . . . . . . . . . . . . . . . 933 E. coli Endonuclease IV 937 S. cerevisiae ApnI Protein 938 AP Endonucleases as Metalloproteins 939
1,437 citations
TL;DR: Hyperglycemia-induced mitochondrial superoxide overproduction increases hexosamine synthesis and O-glycosylation of Sp1, which activates expression of genes that contribute to the pathogenesis of diabetic complications.
Abstract: The hexosamine pathway has been implicated in the pathogenesis of diabetic complications. We determined first that hyperglycemia induced a decrease in glyceraldehyde-3-phosphate dehydrogenase activity in bovine aortic endothelial cells via increased production of mitochondrial superoxide and a concomitant 2.4-fold increase in hexosamine pathway activity. Both decreased glyceraldehyde-3-phosphate dehydrogenase activity and increased hexosamine pathway activity were prevented completely by an inhibitor of electron transport complex II (thenoyltrifluoroacetone), an uncoupler of oxidative phosphorylation (carbonyl cyanide m-chlorophenylhydrazone), a superoxide dismutase mimetic [manganese (III) tetrakis(4-benzoic acid) porphyrin], overexpression of either uncoupling protein 1 or manganese superoxide dismutase, and azaserine, an inhibitor of the rate-limiting enzyme in the hexosamine pathway (glutamine:fructose-6-phosphate amidotransferase). Immunoprecipitation of Sp1 followed by Western blotting with antibodies to O-linked GlcNAc, phosphoserine, and phosphothreonine showed that hyperglycemia increased GlcNAc by 1.7-fold, decreased phosphoserine by 80%, and decreased phosphothreonine by 70%. The same inhibitors prevented all these changes. Hyperglycemia increased expression from a transforming growth factor-β1 promoter luciferase reporter by 2-fold and increased expression from a (−740 to +44) plasminogen activator inhibitor-1 promoter luciferase reporter gene by nearly 3-fold. Inhibition of mitochondrial superoxide production or the glucosamine pathway prevented all these changes. Hyperglycemia increased expression from an 85-bp truncated plasminogen activator inhibitor-1 (PAI-1) promoter luciferase reporter containing two Sp1 sites in a similar fashion (3.8-fold). In contrast, hyperglycemia had no effect when the two Sp1 sites were mutated. Thus, hyperglycemia-induced mitochondrial superoxide overproduction increases hexosamine synthesis and O-glycosylation of Sp1, which activates expression of genes that contribute to the pathogenesis of diabetic complications.
1,071 citations