Spermidine/spermine-N1-acetyltransferase: a key metabolic regulator

2008 ◽  
Vol 294 (6) ◽  
pp. E995-E1010 ◽  
Author(s):  
Anthony E. Pegg
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Tissue Growth ◽  
Polyamine Metabolism ◽  
Acetyl Coa ◽  
Futile Cycle ◽  
Α Subunit ◽  
Polyamine Content ◽  
Concentration Changes ◽  
Ssat Activity

Spermidine/spermine- N1-acetyltransferase (SSAT) regulates cellular polyamine content. Its acetylated products are either excreted from the cell or oxidized by acetylpolyamine oxidase. Since polyamines play critical roles in normal and neoplastic growth and in ion channel regulation, SSAT is a key enzyme in these processes. SSAT is very highly regulated. Its content is adjusted in response to alterations in polyamine content to maintain polyamine homeostasis. Certain polyamine analogs can mimic the induction of SSAT and cause a loss of normal polyamines. This may have utility in cancer chemotherapy. SSAT activity is also induced via a variety of other stimuli, including toxins, hormones, cytokines, nonsteroidal anti-inflammatory agents, natural products, and stress pathways, and by ischemia-reperfusion injury. These increases are initiated by alterations in Sat1 gene transcription reinforced by alterations at the other regulatory steps, including protein turnover, mRNA processing, and translation. Transgenic manipulation of SSAT activity has revealed that SSAT activity links polyamine metabolism to lipid and carbohydrate metabolism by means of alterations in the content of acetyl-CoA and ATP. A high level of SSAT stimulates flux through the polyamine biosynthetic pathway, since biosynthetic enzymes are induced in response to the fall in polyamines. This sets up a futile cycle in which ATP is used to generate S-adenosylmethionine for polyamine biosynthesis and acetyl-CoA is consumed in the acetylation reaction. A variety of other effects of increased SSAT activity include death of pancreatic cells, blockage of regenerative tissue growth, behavioral changes, keratosis follicularis spinulosa decalvans, and hair loss. These are very likely due to changes in polyamine and putrescine levels, although increased oxidative stress via the oxidation of acetylated polyamines may also contribute. Recently, it was found that the SSAT protein and/or a related protein, thialysine acetyltransferase, interacts with a number of other important proteins, including the hypoxia-inducible factor-1 α-subunit, the p65 subunit of NF-κB, and α9β1-integrin, altering the function of these proteins. It is not yet clear whether this functional alteration involves protein acetylation, local polyamine concentration changes, or other effects. It has been suggested that SSAT may also be a useful target in diseases other than cancer, but the wide-ranging physiological and pathophysiological effects of altered SSAT expression will require very careful limitation of such strategies to the relevant cells to avoid toxic effects.

Polyamine metabolism and function

1982 ◽  
Vol 243 (5) ◽  
pp. C212-C221 ◽  
Author(s):  
A. E. Pegg ◽  
P. P. McCann
Keyword(s):  
Molecular Weight ◽  
Tissue Growth ◽  
Polyamine Metabolism ◽  
Organic Cations ◽  
Low Molecular Weight ◽  
Polyamine Biosynthesis ◽  
Polyamine Content ◽  
And Function ◽  
Specific Inhibitors

Polyamines are ubiquitous organic cations of low molecular weight. The content of these amines is closely regulated by the cell according to the state of growth. The reactions responsible for the biosynthesis and interconversion of the polyamines and their precursor putrescine are described and the means by which polyamine content can be varied in response to exogenous stimuli are discussed. The role of polyamines in the cell cycle, cell division, tissue growth, and differentiation is considered. Recent studies using highly specific inhibitors of polyamine biosynthesis such as alpha-difluoromethylornithine to prevent accumulation of polyamines have indicated that the synthesis of polyamines is intimately associated with these processes. Such inhibitors have great potential for investigation of the cellular role of polyamines.

scholarly journals Deletion of the Gamma Subunit of ENaC in Endothelial Cells Does Not Protect against Renal Ischemia Reperfusion Injury

2021 ◽  
Vol 22 (20) ◽  
pp. 10914
Author(s):  
Stephanie M. Mutchler ◽  
Mahpara Hasan ◽  
Donald E. Kohan ◽  
Thomas R. Kleyman ◽  
Roderick J. Tan
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Renal Ischemia ◽  
Α Subunit ◽  
Γ Subunit ◽  
Renal Ischemia Reperfusion Injury

Acute kidney injury due to renal ischemia-reperfusion injury (IRI) may lead to chronic or end stage kidney disease. A greater understanding of the cellular mechanisms underlying IRI are required to develop therapeutic options aimed at limiting or reversing damage from IRI. Prior work has shown that deletion of the α subunit of the epithelial Na+ channel (ENaC) in endothelial cells protects from IRI by increasing the availability of nitric oxide. While canonical ENaCs consist of an α, β, and γ subunit, there is evidence of non-canonical ENaC expression in endothelial cells involving the α subunit. We therefore tested whether the deletion of the γ subunit of ENaC also protects mice from IRI to differentiate between these channel configurations. Mice with endothelial-specific deletion of the γ subunit and control littermates were subjected to unilateral renal artery occlusion followed by 48 h of reperfusion. No significant difference was noted in injury between the two groups as assessed by serum creatinine and blood urea nitrogen, levels of specific kidney injury markers, and histological examination. While deletion of the γ subunit did not alter infiltration of immune cells or cytokine message, it was associated with an increase in levels of total and phosphorylated endothelial nitric oxide synthase (eNOS) in the injured kidneys. Our studies demonstrate that even though deletion of the γ subunit of ENaC may allow for greater activation of eNOS, this is not sufficient to prevent IRI, suggesting the protective effects of α subunit deletion may be due, in part, to other mechanisms.

Abstract 532: Protein Analysis of Tongxinluo-modulated Cytokines in Cardiac Microvascular Endothelial Cells via Tandem Mass Tag Quantitative Proteomics After Ischemia/Reperfusion Injury

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Qing Li ◽  
Yuejin Yang
Keyword(s):  
Endothelial Cells ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Tissue Growth ◽  
Microvascular Endothelial Cells ◽  
Heme Oxygenase 1 ◽  
Differential Proteins ◽  
Microvascular Endothelial ◽  
Cardiac Microvascular Endothelial Cells

Background: Proteomics is a potential tool to study the large-scale expression, function and interaction of the complement of proteins in an organism. In this study, we used the TMT-labeled proteomics to detect the various cytokines in an in vitro model of cardiac microvascular endothelial cells (CMECs) ischemia/reperfusion injury with Tongxinluo(TXL) treatment. Our aims are to investigate whether TXL could modulate the secretion function of CMECs, and to synthetically analysis the underlying mechanism of the regulation. Methods: Human CMECs were exposed to different concentrations of TXL, and incubated to scavenge free oxygen for 2 h of hypoxia and were moved to normal conditions for 2 h of reoxygenation. Cell apoptosis was assessed by flow cytometric analysis. CMECs were divided into three groups for TMT-labeled proteomics analysis: CMECs in normal condition (Group N), CMECs in hypoxia and serum deprivation condition (Group HR), CMECs treatment with TXL in hypoxia and serum condition(Group HR+TXL) . We utilized bioinformatics analysis to identify differential proteins. Results: TXL concentration-dependently decreased apoptosis of CMECs. The optimal concentration of TXL to have the maximum protection for CMECs was 800 μg/mL. Both hypoxia/reoxygenation and TXL treatment significantly changed the cytokines level of CMECs. 32 differential proteins between group N and group HR were detected. TXL treatment up-regulated 6 cytokines and down-regulated 6 cytokines in ischemia/reperfusion injury. These proteins mainly had vital functions such as cell proliferation, stress response, regulation of multicelluler organismal metabolic process. We evaluated several proteins played important roles in ischemia/reperfusion injury including Human Heme Oxygenase 1 (HMOX1), angiopoietin 2 (ANGPT2), sequestosome 1 (SQSTM1), and connective tissue growth factor (CTGF). Conclusion: The study presented differential proteins responsible for ischemia/reperfusion injury through TMT-labeled proteomic analysis. We assessed some vital proteins including their characters and roles. These findings may provide new mechanisms of TXL treatment in acute myocardial diseases.

scholarly journals Bradykinin B1 and B2 receptors both have protective roles in renal ischemia/reperfusion injury

2007 ◽  
Vol 104 (18) ◽  
pp. 7576-7581 ◽  
Author(s):  
Masao Kakoki ◽  
Robert W. McGarrah ◽  
Hyung-Suk Kim ◽  
Oliver Smithies
Keyword(s):  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Artery Occlusion ◽  
Tissue Growth ◽  
Renal Ischemia ◽  
Mrna Levels ◽  
Kinin System ◽  
Functional Changes ◽  
Renal Ischemia Reperfusion Injury

To explore the role of the kallikrein–kinin system in relation to ischemia/reperfusion injury in the kidney, we generated mice lacking both the bradykinin B1 and B2 receptor genes (B1RB2R-null, Bdkrb1−/−/Bdkrb2−/−) by deleting the genomic region encoding the two receptors. In 4-month-old mice, blood pressures were not significantly different among B1RB2R-null, B2R-null (Bdkrb2−/−), and WT mice. After 30 min of bilateral renal artery occlusion and 24 h of reperfusion, mortality rates, renal histological and functional changes, 8-hydroxy-2′-deoxyguanosine levels in total DNA, mtDNA deletions, and the number of TUNEL-positive cells in the kidneys increased progressively in the following order (from lowest to highest): WT, B2R-null, and B1RB2R-null mice. Increases in mRNA levels of TGF-β1, connective tissue growth factor, and endothelin-1 after ischemia/reperfusion injury were also exaggerated in the same order (from lowest to highest): WT, B2R-null, and B1RB2R-null. Thus, both the B1 and B2 bradykinin receptors play an important role in reducing DNA damage, apoptosis, morphological and functional kidney changes, and mortality during renal ischemia/reperfusion injury.

scholarly journals Spermidine/spermine-N1-acetyltransferase ablation protects against liver and kidney ischemia-reperfusion injury in mice

2009 ◽  
Vol 296 (4) ◽  
pp. G899-G909 ◽  
Author(s):  
Kamyar Zahedi ◽  
Alex B. Lentsch ◽  
Tomohisa Okaya ◽  
Sharon Barone ◽  
Nozomu Sakai ◽  
...  
Keyword(s):  
Liver Damage ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Tubules ◽  
Wild Type ◽  
Important Mediator ◽  
Liver And Kidney ◽  
Rate Limiting ◽  
Deficient Mice ◽  
Ssat Activity

Expression of spermine/spermidine- N1-acetyltransferase (SSAT), the rate-limiting enzyme of polyamine backconversion cascade, increases after ischemia-reperfusion injuries (IRI). We hypothesized that SSAT plays an important role in the mediation of IRI. To test our hypothesis, wild-type (SSAT-wt) and SSAT-deficient (SSAT-ko) mice were subjected to liver or kidney IRI by ligation of hepatic or renal arteries. The liver and kidney content of putrescine (Put), a downstream by-product of SSAT activity, increased in SSAT-wt animals but not in SSAT-ko animals after IRI, indicating that polyamine backconversion is not functional in SSAT-deficient mice. When subjected to hepatic IRI, SSAT-ko mice were significantly protected against liver damage compared with SSAT-wt mice. Similarly, SSAT-ko animals subjected to renal IRI showed significantly greater protection against damage to kidney tubules than SSAT-wt mice. These studies indicate that SSAT-deficient animals are protected against IRI and suggest that SSAT is an important mediator of the tissue damage in IRI.

Mechanisms of novel cardioprotective functions of CCN2/CTGF in myocardial ischemia-reperfusion injury

2011 ◽  
Vol 300 (4) ◽  
pp. H1291-H1302 ◽  
Author(s):  
M. Shakil Ahmed ◽  
Jørgen Gravning ◽  
Vladimir N. Martinov ◽  
Thomas G. von Lueder ◽  
Thor Edvardsen ◽  
...  
Keyword(s):  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Tissue Growth ◽  
Matricellular Protein ◽  
Ccn Family ◽  
Littermate Control ◽  
Isolated Hearts ◽  
Gsk 3Β

CCN2/connective tissue growth factor (CTGF), a CCN family matricellular protein repressed in healthy hearts after birth, is induced in heart failure of various etiologies. Multiple cellular and biological functions have been assigned to CCN2/CTGF depending on cellular context. However, the functions and mechanisms of action of CCN2/CTGF in the heart as well as its roles in cardiac physiology and pathophysiology remain unknown. Transgenic mice with cardiac-restricted overexpression of CTGF (Tg-CTGF) were generated and compared with nontransgenic littermate control (NLC) mice. Tg-CTGF mice displayed slightly lower cardiac mass and inconspicuous increase of myocardial collagen compared with NLC mice but no evidence of contractile dysfunction. Analysis of the myocardial transcriptome by DNA microarray revealed activation of several distinct gene programs in Tg-CTGF hearts involved in cardioprotection and growth inhibition. Indeed, Tg-CTGF mice subjected to ischemia-reperfusion injury by in situ transient occlusion of the left anterior descending coronary artery in vivo displayed reduced vulnerability with markedly diminished infarct size. These findings were recapitulated in isolated hearts perfused with recombinant human (h)CTGF before the ischemia-reperfusion procedure. Consistently, Tg-CTGF hearts, as well as isolated adult cardiac myocytes exposed to recombinant hCTGF, displayed enhanced phosphorylation and activity of the Akt/p70S6 kinase/GSK-3β salvage kinase pathway and induction of several genes with reported cardioprotective functions. Inhibition of Akt activities also prevented the cardioprotective phenotype of hearts from Tg-CTGF mice. This report provides novel evidence that CTGF confers cardioprotection by salvage phosphokinase signaling leading to inhibition of GSK-3β activities, activation of phospho-SMAD2, and reprogramming of gene expression.

scholarly journals G protein α12(Gα12) is a negative regulator of kidney injury molecule-1-mediated efferocytosis

2016 ◽  
Vol 310 (7) ◽  
pp. F607-F620 ◽  
Author(s):  
Ola Z. Ismail ◽  
Xizhong Zhang ◽  
Joseph V. Bonventre ◽  
Lakshman Gunaratnam
Keyword(s):  
Acute Kidney Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Dominant Negative ◽  
Negative Regulator ◽  
Apoptotic Cells ◽  
Α Subunit ◽  
Therapeutic Implications ◽  
Kidney Injury Molecule 1

Kidney injury molecule-1 (KIM-1) is a receptor for the “eat me” signal, phosphatidylserine, on apoptotic cells. The specific upregulation of KIM-1 by injured tubular epithelial cells (TECs) enables them to clear apoptotic cells (also known as efferocytosis), thereby protecting from acute kidney injury. Recently, we uncovered that KIM-1 binds directly to the α-subunit of heterotrimeric G12protein (Gα12) and inhibits its activation by reactive oxygen species during renal ischemia-reperfusion injury (Ismail OZ, Zhang X, Wei J, Haig A, Denker BM, Suri RS, Sener A, Gunaratnam L. Am J Pathol 185: 1207–1215, 2015). Here, we investigated the role that Gα12plays in KIM-1-mediated efferocytosis by TECs. We showed that KIM-1 remains bound to Gα12and suppresses its activity during phagocytosis. When we silenced Gα12expression using small interefering RNA, KIM-1-mediated engulfment of apoptotic cells was increased significantly; in contrast overexpression of constitutively active Gα12( QLGα12) resulted in inhibition of efferocytosis. Inhibition of RhoA, a key effector of Gα12, using a chemical inhibitor or expression of dominant-negative RhoA, had the same effect as inhibition of Gα12on efferocytosis. Consistent with this, silencing Gα12suppressed active RhoA in KIM-1-expressing cells. Finally, using primary TECs from Kim-1+/+and Kim-1−/−mice, we confirmed that engulfment of apoptotic cells requires KIM-1 expression and that silencing Gα12enhanced efferocytosis by primary TECs. Our data reveal a previously unknown role for Gα12in regulating efferocytosis and that renal TECs require KIM-1 to mediate this process. These results may have therapeutic implications given the known harmful role of Gα12in acute kidney injury.

scholarly journals Does Oxidative Stress Change During Orthotopic Liver Transplantation?

2017 ◽  
Vol 3 (2) ◽  
pp. 1-5
Author(s):  
Dimitrios Tsikas
Keyword(s):  
Oxidative Stress ◽  
Liver Transplantation ◽  
Orthotopic Liver Transplantation ◽  
Nitrosative Stress ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Enzymatic Reactions ◽  
Time Duration ◽  
Oxidative And Nitrosative Stress ◽  
Concentration Changes

In clinical ischemia/reperfusion injury, damage resulting from oxidative and nitrosative stress is generally considered crucial for graft functioning. Yet, there is increasing evidence that modern clinical transplantation including orthotopic liver transplantation (OLT) is not associated with elevation of oxidative and nitrosative stress upon organ reoxygenation. We measured two currently used biomarkers of oxidative stress, i.e., 15(S)-8-iso-prostaglandin F2a  (15(S)-8-iso-PGF2a) and cis-epoxyoctadecanoic acid (cis-EpOA), in human plasma during the entire time duration of OLT in eight patients suffering from end-stage liver disease. No considerable concentration changes of 15(S)-8-iso-PGF2a and cis-EpOA were observed, indicating lack of oxidative stress. Previously, we found in the same patients that nitrosative stress, measured as 3-nitrotyrosine and 3-nitrotyrosinoalbumin. Yet, as 15(S)-8-iso-PGF2a, cis-EpOA and 3-nitrotyrosine are produced both by chemical and enzymatic reactions, the current concepts of oxidative and nitrosative stress require reconsideration.

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