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ABSTRACT: Abstract Aims: Oxidative stress and inflammation are leading risk factors for age-associated functional declines. We assessed aspirin effects on endogenous oxidative-stress levels, lifespan, and age-related functional declines, in the nematode Caenorhabditis elegans. Results: Both aspirin and its salicylate moiety, at nontoxic concentrations (0.5-1 mM), attenuated endogenous levels of reactive oxygen species (p<0.001), and upregulated antioxidant genes encoding superoxide dismutases (especially sod-3, p<0.001), catalases (especially ctl-2, p<0.0001), and two glutathione-S-transferases (gst-4 and gst-10; each p<0.005). Aspirin, and to a lesser degree salicylate, improved survival of hydrogen peroxide, and in the absence of exogenous stress aspirin extended lifespan by 21%-23% (each p<10(-9)), while salicylate added 14% (p<10(-6)). Aspirin and salicylate delayed age-dependent declines in motility and pharyngeal pumping (each p<0.005), and decreased intracellular protein aggregation (p<0.0001)-all established markers of physiological aging-consistent with slowing of the aging process. Aspirin fails to improve stress resistance or lifespan in nematodes lacking DAF-16, implying that it acts through this FOXO transcription factor. Innovation: Studies in mice and humans suggest that aspirin may protect against multiple age-associated diseases by reducing all-cause mortality. We now demonstrate that aspirin markedly slows many measures of aging in the nematode. Conclusions: Aspirin treatment is associated with diminished endogenous oxidant stress and enhanced resistance to exogenous peroxide, both likely mediated by activation of antioxidant defenses. Our evidence indicates that aspirin attenuates insulin-like signaling, thus protecting against oxidative stress, postponing age-associated functional declines and extending C. elegans lifespan under benign conditions. Antioxid. Redox Signal. 00, 000-000.
Antioxidants & Redox Signaling 08/2012; · 8.20 Impact Factor
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Changping Hu, Abhijit Dandapat,
Liuqin Sun,
Muhammad R Marwali,
Nobutaka Inoue,
Fumiaki Sugawara,
Kazuhiko Inoue,
Yosuke Kawase,
Kou-ichi Jishage,
Hiroshi Suzuki,
Paul L Hermonat,
Tatsuya Sawamura,
Jawahar L Mehta
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ABSTRACT: Angiotensin II via type 1 receptor activation upregulates the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and LOX-1 activation, in turn, upregulates angiotensin II type 1 receptor expression. We postulated that interruption of this positive feedback loop might attenuate the genesis of angiotensin II-induced hypertension and subsequent cardiac remodeling. To examine this postulate, LOX-1 knockout and wild-type mice were infused with angiotensin II or norepinephrine (control for angiotensin II) for 4 weeks. Angiotensin II-, but not norepinephrine-, induced hypertension was attenuated in LOX-1 knockout mice. Angiotensin II-induced cardiac remodeling was also attenuated in LOX-1 knockout mice. Importantly, angiotensin II type 1 receptor expression was reduced, and the expression and activity of endothelial NO synthase were preserved in the tissues of LOX-1 knockout mice given angiotensin II. Reactive oxygen species generation, nicotinamide-adenine dinucleotide phosphate oxidase expression, and phosphorylation of p38 and p44/42 mitogen-activated protein kinases were also much less pronounced in the LOX-1 knockout mice given angiotensin II. These alterations in biochemical and structural abnormalities were associated with preservation of cardiac hemodynamics in the LOX-1 knockout mice. To confirm that fibroblast function is modulated in the absence of LOX-1, cardiac fibroblasts from wild-type and LOX-1 knockout mice were treated with angiotensin II. Indeed, LOX-1 knockout mice cardiac fibroblasts revealed an attenuated profibrotic response on treatment with angiotensin II. These observations provide strong evidence that LOX-1 is a key modulator of the development of angiotensin II-induced hypertension and subsequent cardiac remodeling.
Hypertension 09/2008; 52(3):556-62. · 6.21 Impact Factor
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ABSTRACT: Collagen, as a component of the extracellular matrix, has been linked to atherosclerotic plaque formation and stability. Activation of LOX-1, a lectin-like oxidized low-density lipoprotein (LDL) receptor-1, exerts a significant role in collagen formation. We examine the hypothesis that LOX-1 deletion may inhibit collagen accumulation in atherosclerotic arteries in LDL receptor (LDLR) knockout (KO) mice.
We generated LOX-1 KO and LOX-1/LDLR double KO mice on a C57BL/6 (wild-type mice) background and fed a 4% cholesterol/10% cocoa butter diet for 18 weeks. Vessel wall collagen accumulation was increased in association with atherogenesis in the LDLR KO mice (P < 0.01 vs. wild-type mice), but much less so in the double KO mice (P < 0.01 vs. LDLR KO mice). Collagen accumulation data were corroborated with pro-collagen I measurements. Expression/activity of osteopontin, fibronectin, and matrix metalloproteinases (MMP-2 and MMP-9) was also increased in the LDLR KO mice (P < 0.01 vs. wild-type mice), but not in the mice with LOX-1 deletion (P < 0.01 vs. LDLR KO mice). The expression of NADPH oxidase (p47(phox), p22(phox), gp91(phox), and Nox-4 subunits) and nitrotyrosine was increased in the LDLR KO mice (P < 0.01 vs. wild-type mice) and not in mice with LOX-1 deletion (P < 0.01 vs. LDLR KO mice). Phosphorylation of Akt-1 and endothelial nitric oxide synthase and expression of haem-oxygenase-1 were found to be reduced in the LDLR KO mice (P < 0.01 vs. wild-type mice), but not in the mice with LOX-1 deletion (P < 0.01 vs. LDLR KO mice).
LOX-1 deletion reduces enhanced collagen deposition and MMP expression in atherosclerotic regions via inhibition of pro-oxidant signals.
Cardiovascular Research 07/2008; 79(2):287-93. · 6.06 Impact Factor
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ABSTRACT: Transforming growth factor beta(1) (TGFbeta(1)) activation leads to tissue fibrosis. Here, we report on the role of LOX-1, a lectin-like 52-kDa receptor for oxidized low density lipoprotein, in TGFbeta(1)-mediated collagen expression and underlying signaling in mouse cardiac fibroblasts. TGFbeta(1) was overexpressed in wild-type (WT) and LOX-1 knock-out mouse cardiac fibroblasts by transfection with adeno-associated virus type 2 vector carrying the active TGFbeta(1) moiety (AAV/TGFbeta (ACT)(1)). Transfection of WT mouse cardiac fibroblasts with AAV/TGFbeta (ACT)(1) markedly enhanced the expression of NADPH oxidases (p22(phox), p47(phox), and gp91(phox) subunits) and LOX-1, formation of reactive oxygen species, and collagen synthesis, concomitant with an increase in the activation of p38 and p44/42 mitogen-activated protein kinases (MAPK). The TGFbeta(1)-mediated increase in collagen synthesis was markedly attenuated in the LOX-1 knock-out mouse cardiac fibroblasts as well as in WT mouse cardiac fibroblasts treated with a specific anti-LOX-1 antibody. Treatment with anti-LOX-1 antibody also reduced NADPH oxidase expression and MAPK activation. The NADPH oxidase inhibitors and gp91phox small interfering RNA reduced LOX-1 expression, MAPK activation, and collagen formation. The p38 MAPK inhibitors as well as the p44/42 MAPK inhibitors reduced collagen formation without affecting LOX-1 expression in cardiac fibroblasts. These observations suggest that collagen synthesis in cardiac fibroblasts involves a facilitative interaction between TGFbeta(1)-NADPH oxidase and LOX-1. Further, the activation of MAPK pathway appears to be downstream of TGFbeta(1)-reactive oxygen species-LOX-1 cascade.
Journal of Biological Chemistry 05/2008; 283(16):10226-31. · 4.77 Impact Factor
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ABSTRACT: Angiotensin (Ang) II, via type 1 receptor activation, exerts a significant role in atherogenesis and collagen synthesis. To test the hypothesis that Ang II type 2 receptor (AT2R) upregulation delivered with adeno-associated virus type 2 (AAV/AT2R) would inhibit collagen synthesis in atherosclerotic arteries, LDLR knockout mice were injected with AAV/AT2R and fed 4% cholesterol diet for 18 weeks. LDLR knockout mice treated with saline or AAV/Neo exhibited extensive vessel wall collagen accumulation, which was reduced by about 50% with AT2R over-expression. AT2R upregulation completely blocked the alterations in the expression of procollagen-I, osteopontin, fibronectin, CD68, and matrix metalloproteinases (MMP-2 and MMP-9), as well as phosphorylation of p38 and p44/42 MAPKs. Activity of superoxide dismutase was reduced in the LDLR KO mice and it increased with AT2R upregulation. This study demonstrates that AT2R over-expression reduces enhanced collagen accumulation, MMP expression and activity in atherosclerotic regions via inhibition of pro-oxidant signals.
Biochemical and Biophysical Research Communications 03/2008; 366(4):871-7. · 2.48 Impact Factor
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Changping Hu,
Jiawei Chen, Abhijit Dandapat,
Yoshiko Fujita,
Nobutaka Inoue,
Yosuke Kawase,
Kou-ichi Jishage,
Hiroshi Suzuki,
Dayuan Li,
Paul L Hermonat,
Tatsuya Sawamura,
Jawahar L Mehta
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ABSTRACT: LOX-1 is a newly described lectin-like receptor for oxidized-LDL (ox-LDL), which is over-expressed in the ischemic myocardium. To examine the pathogenic role of LOX-1 in the determination of ischemia-reperfusion (I-R) injury to the heart, we developed LOX-1 knockout (KO) mice, and subjected these mice to 60 min of left coronary artery occlusion followed by 60 min of reperfusion. I-R in the LOX-1 KO mice resulted in a significant reduction in myocardial injury as well as in accumulation of inflammatory cells in the I-R myocardium and lipid peroxidation (P<0.01 vs. wild-type mice). Concomitantly, there was significant preservation of cardiac function in the LOX-1 KO mice despite I-R (P<0.01 vs. the wild-type mice). The phosphorylation of oxidative stress-sensitive mitogen-activated protein kinase (p38MAPK) and protein kinase B/Akt-1, expression of nitrotyrosine and inducible nitric oxide synthase (iNOS), and superoxide dismutase activity were enhanced during I-R in the wild-type mice. These alterations in p38MAPK, Akt-1 and iNOS were much less pronounced in the LOX-1 KO mice. The superoxide dismutase activity increased further in the LOX-1 KO mice. These observations provide compelling evidence that LOX-1 may be a key modulator of myocardial I-R injury, and its effect is mediated by pro-oxidant signals. LOX-1 may be a potential target for therapy of myocardial ischemic injury.
Journal of Molecular and Cellular Cardiology 01/2008; 44(1):76-83. · 5.17 Impact Factor
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ABSTRACT: Atherogenesis is associated with inflammation and oxidative stress. Activation of renin-angiotensin system with generation of angiotensin II and type 1 receptor (AT1R) stimulation has been amply reported in atherosclerosis. Since angiotensin II type 2 receptor (AT2R) activity is purported to oppose the effects of AT1R, we hypothesized that AT2R (agtr2) over-expression would inhibit atherogenesis. We prepared recombinant adeno-associated virus type-2 (AAV) carrying AT2R cDNA (AAV/AT2R), and homozygous LDLR-deficient (KO) mice were given AAV/AT2R, AAV/Neo or saline. All mice were placed on a high cholesterol diet. After 18 weeks, AT2R was found to be over-expressed systemically in AAV/AT2R-treated mice. Atherogenesis in aorta was reduced in the AAV/AT2R group by approximately 50% compared to other LDLR KO mice groups. Expression of NADPH oxidase, nitrotyrosine and NF-kappaB was increased in aortic tissues of the LDLR KO mice given saline or AAV/Neo, but not in mice with AT2R upregulation. Expression of endothelial nitric oxide synthase (eNOS) and heme-oxygenase-1 (HO-1) was decreased and that of the lectin-like oxidized-LDL receptor (LOX-1) increased in the LDLR KO mice, but not in the mice with AT2R over-expression. Further, Akt-1 phosphorylation was reduced in the LDLR KO mice, but not in the mice with AT2R over-expression. Thus, AT2R upregulation can reduce atherogenesis, possibly by modulating oxidative stress and the pro-inflammatory cascade, mediated via Akt-1. Over-expression of AT2R may be an important therapeutic approach in atherosclerosis.
Atherosclerosis 01/2008; 199(2):288-94. · 3.79 Impact Factor
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ABSTRACT: Angiotensin II (Ang II) induces angiogenesis by stimulating reactive oxygen species-dependent vascular endothelial growth factor (VEGF) expression. Ang II via type 1 receptor upregulates the expression of LOX-1, a lectin-like receptor for oxidized low-density lipoprotein. LOX-1 activation, in turn, upregulates Ang II type 1 receptor expression. We postulated that interruption of the feedback loop between Ang II and LOX-1 might attenuate Ang II-induced VEGF expression and capillary formation. In vitro experiments showed that Ang II (1 nmol/L) induced the expression of LOX-1 and VEGF and enhanced capillary formation from human coronary endothelial cells in Matrigel assay. Ang II-mediated expression of LOX-1 and VEGF, capillary formation, intracellular reactive oxygen species generation, and phosphorylation of p38 as well as p44/42 mitogen-activated protein kinases, were suppressed by anti-LOX-1 antibody, nicotinamide-adenine dinucleotide phosphate oxidase inhibitor apocynin and the Ang II type 1 receptor blocker losartan, but not by the Ang II type 2 receptor blocker PD123319. Expression of VEGF and capillary formation induced by Ang II were also inhibited by the p44/42 mitogen-activated protein kinase inhibitor U0126 and the p38 mitogen-activated protein kinase inhibitor SB203580. In ex vivo experiments, Ang II stimulated capillary sprouting from aortic rings from wild-type mice, and this phenomenon was significantly attenuated by pretreatment of aortic rings with anti-LOX-1 antibody, apocynin, and losartan, but not by PD123319. Importantly, Ang II-induced capillary sprouting was minimal from aortic rings from LOX-1 null mice compared with wild-type mice. These findings suggest that small concentrations of Ang II promote capillary formation by inducing the expression of VEGF via Ang II type 1 receptor/LOX-1-mediated stimulation of the reactive oxygen species-mitogen-activated protein kinase pathway.
Hypertension 12/2007; 50(5):952-7. · 6.21 Impact Factor
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ABSTRACT: Vascular endothelial growth factor (VEGF), a key angiogenic growth factor, stimulates angiogenesis. Low levels of reactive oxygen species (ROS) function as signaling molecules for angiogenesis. We postulated that low concentrations of oxLDL might induce low levels of ROS and initiate angiogenesis.
An in vitro model of tube formation from human coronary artery endothelial cells (HCAECs) was used. oxLDL (0.1, 1, 2, 5 microg/mL) induced VEGF expression and enhanced tube formation. oxLDL-mediated VEGF expression and tube formation were suppressed by a specific blocking anti-LOX-1 antibody. Anti-LOX-1 antibody also reduced oxLDL-induced increase in the expression of NADPH oxidase (gp91(phox) and p47(phox) subunits) and subsequent intracellular ROS generation, phosphorylation of p38 as well as p44/42MAPK, and NF-kappaB p65 expression. gp91(phox) siRNA had a similar effect. The expression of VEGF and NF-kappaB p65 induced by oxLDL was also inhibited by the specific extracellular signal-regulated kinase (ERK) 1/2 inhibitor U0126 and the p38 MAPK inhibitor SB203580. Importantly, the NADPH oxidase inhibitor apocynin, gp91(phox) siRNA, U0126, and SB203580 all reduced tube formation in response to oxLDL.
These findings suggest that small concentrations of oxLDL promote capillary tube formation by inducing the expression of VEGF via LOX-1-mediated activation of NADPH oxidase- MAPKs-NF-kappaB pathway.
Arteriosclerosis Thrombosis and Vascular Biology 12/2007; 27(11):2435-42. · 6.37 Impact Factor
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ABSTRACT: Chronic ischemia is associated with alterations in genes that result in myocardial remodeling. An important biochemical basis of cardiac remodeling is generation of reactive oxygen species (ROS). A few studies have suggested that acute ischemia triggers signals for remodeling. We examined the hypothesis that targeted deletion of lectin-like oxidized-LDL receptor (LOX-1) may inhibit signals related to cardiac remodeling.
We generated LOX-1 knockout (KO) mice on C57BL/6 (wild-type mice) background, and subjected wild-type and KO mice to ischemia-reperfusion (I-R). The wild-type mice developed a marked reduction in left ventricular systolic pressure and +/-dp/dt(max) and an increase in left ventricular end-diastolic pressure following I-R, and this change was much less in the LOX-1 KO mice, indicating preservation of left ventricular function with LOX-1 deletion. There was evidence for marked oxidative stress (NADPH oxidase expression, malondialdehyde and 8-isoprostane) following I-R in the wild-type mice, much less so in the LOX-1 KO mice (P<0.01). In concert, collagen deposition (Masson's trichrome and Picro-sirius red staining) increased dramatically in the wild-type mice, but only half as much in the LOX-1 KO mice (P<0.01). Collagen staining data was corroborated with procollagen-I expression. Further, fibronectin and osteopontin expression increased in the wild-type mice, but to a much smaller extent in the LOX-1 KO mice (P<0.01).
These findings provide compelling evidence that LOX-1 is a key modulator of cardiac remodeling which starts immediately following I-R.
Cardiovascular Research 11/2007; 76(2):292-302. · 6.06 Impact Factor
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ABSTRACT: Transforming growth factor (TGF)-beta(1) is one of the most pleiotropic and multifunctional peptides known. While the cardioprotective effect of TGF-beta(1) during ischemia is well known, the specific role of TGF-beta(1) in altering the cardiac remodeling process remains unclear. This study was designed to examine the regulation of hypoxia-reoxygenation-mediated collagen type I expression and activity of matrix metalloproteinases (MMPs) by overexpression of TGF-beta(1) in cultured HL-1 mouse cardiomyocytes. TGF-beta(1) was overexpressed in cardiomyocytes by transfection with adeno-associated virus (AAV)/TGF-beta(1)(Latent) or with AAV/TGF-beta(1)(ACT) (active TGF-beta(1)). Twenty-four hours of hypoxia followed by 3 h of reoxygenation (H-R) markedly enhanced (pro)collagen type I expression and activity of MMPs concomitant with an increase in reactive oxygen species (ROS) release and LOX-1 expression. Overexpression of TGF-beta(1) reduced these alterations induced by H-R. TGF-beta(1) overexpression also blocked H-R-mediated p38 and p44/42 MAPK activation. Transfection with AAV/TGF-beta(1)(ACT) was superior to that with AAV/TGF-beta(1)(Latent). These data for the first time demonstrate that H-R induces signals for cardiac remodeling in cardiomyocytes and TGF-beta(1) can modulate, possibly via antioxidant mechanism, these signals. These findings contribute to further understanding of the role of TGF-beta(1) in the cardiac remodeling process.
AJP Heart and Circulatory Physiology 10/2007; 293(3):H1833-8. · 3.71 Impact Factor
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ABSTRACT: Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1), a receptor for oxidized-LDL, is up-regulated in activated endothelial cells, and it plays a role in atherothrombosis. However, its role in platelet aggregation is unclear. Both aspirin and HMG CoA reductase inhibitors (statins) reduce LOX-1 expression in endothelial cells. In this study, we investigated the effect of aspirin and pravastatin on LOX-1 expression on plate-lets. After ADP stimulation, mean fluorescence intensity of LOX-1 expression on platelets increased 1.5- to 2.0-fold. Blocking LOX-1 inhibited ADP-induced platelet aggregation in a concentration- and time-dependent manner. We also established that LOX-1 is important for ADP-stimulated inside-out activation of platelet alpha(IIb)beta(3) and alpha(2)beta(1) integrins (fibrinogen receptors). The specificity of this interaction was determined by arginine-glycine-aspartate-peptide inhibition. Furthermore, we found that LOX-1 inhibition of integrin activation is mediated by inhibition of protein kinase C activity. In other experiments, treatment with aspirin (1-10 mM) and pravastatin (1-5 microM) reduced platelet LOX-1 expression, with a synergistic effect of the combination of aspirin and pravastatin. Aspirin and pravastatin both reduced reactive oxygen species (ROS) released by activated platelets measured as malonyldialdehyde (MDA) release and nitrate/nitrite ratio. Aspirin and pravastatin also enhanced nitric oxide (NO) release measured as nitrite/nitrite + nitrate (NOx) ratio in platelet supernates. Small concentrations of aspirin and pravastatin had a synergistic effect on the inhibition of MDA release and enhancement of nitrite/NOx. Thus, LOX-1 is important for ADP-mediated platelet integrin activation, possibly through protein kinase C activation. Furthermore, aspirin and pravastatin inhibit LOX-1 expression on platelets in part by favorably affecting ROS and NO release from activated platelets.
Journal of Pharmacology and Experimental Therapeutics 10/2007; 322(3):1324-32. · 3.83 Impact Factor
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Jawahar L Mehta,
Nobuhito Sanada,
Chang Ping Hu,
Jiawei Chen, Abhijit Dandapat,
Fumiaki Sugawara,
Hiroo Satoh,
Kazuhiko Inoue,
Yosuke Kawase,
Kou-ichi Jishage,
Hiroshi Suzuki,
Motohiro Takeya,
Laura Schnackenberg,
Richard Beger,
Paul L Hermonat,
Maria Thomas,
Tatsuya Sawamura
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ABSTRACT: Atherosclerosis is associated with oxidative stress and inflammation, and upregulation of LOX-1, an endothelial receptor for oxidized LDL (oxLDL). Here, we describe generation of LOX-1 knockout (KO) mice in which binding of oxLDL to aortic endothelium was reduced and endothelium-dependent vasorelaxation preserved after treatment with oxLDL (P<0.01 versus wild-type mice). To address whether endothelial functional preservation might lead to reduction in atherogenesis, we crossed LOX-1 KO mice with LDLR KO mice and fed these mice 4% cholesterol/10% cocoa butter diet for 18 weeks. Atherosclerosis was found to cover 61+/-2% of aorta in the LDLR KO mice, but only 36+/-3% of aorta in the double KO mice. Luminal obstruction and intima thickness were significantly reduced in the double KO mice (versus LDLR KO mice). Expression of redox-sensitive NF-kappaB and the inflammatory marker CD68 in LDLR KO mice was increased (P<0.01 versus wild-type mice), but not in the double KO mice. On the other hand, antiinflammatory cytokine IL-10 expression and superoxide dismutase activity were low in the LDLR KO mice (P<0.01 versus wild-type mice), but not in the double KO mice. Endothelial nitric oxide synthase expression was also preserved in the double KO mice. The proinflammatory signal MAPK P38 was activated in the LDLR KO mice, and LOX-1 deletion reduced this signal. In conclusion, LOX-1 deletion sustains endothelial function leading to a reduction in atherogenesis in association with reduction in proinflammatory and prooxidant signals.
Circulation Research 07/2007; 100(11):1634-42. · 9.49 Impact Factor
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ABSTRACT: The lipid peroxidation product 4-hydroxynon-2-enal (4-HNE) forms as a consequence of oxidative stress, and acts as a signaling molecule or, at superphysiological levels, as a toxicant. The steady-state concentration of the compound reflects the balance between its generation and its metabolism, primarily through glutathione conjugation. Using an RNAi-based screen, we identified in Caenorhabditis elegans five glutathione transferases (GSTs) capable of catalyzing 4-HNE conjugation. RNAi knock-down of these GSTs (products of the gst-5, gst-6, gst-8, gst-10, and gst-24 genes) sensitized the nematode to electrophilic stress elicited by exposure to 4-HNE. However, interference with the expression of only two of these genes (gst-5 and gst-10) significantly shortened the life span of the organism. RNAi knock-down of the other GSTs resulted in at least as much 4-HNE adducts, suggesting tissue specificity of effects on longevity. Our results are consistent with the oxidative stress theory of organismal aging, broadened by considering electrophilic stress as a contributing factor. According to this extended hypothesis, peroxidation of lipids leads to the formation of 4-HNE in a chain reaction which amplifies the original damage. 4-HNE then acts as an "aging effector" via the formation of 4-HNE-protein adducts, and a resulting change in protein function.
Mechanisms of Ageing and Development 03/2007; 128(2):196-205. · 3.44 Impact Factor
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ABSTRACT: Electrophilic stress caused by lipid peroxidation products such as 4-hydroxynonenal (4-HNE) and/or related compounds may contribute to aging. The major mode of 4-HNE metabolism involves glutathione conjugation catalyzed by specialized glutathione transferases. We have previously shown that glutathione transferase CeGSTP2-2, the product of the Caenorhabditis elegans gst-10 gene, has the ability to conjugate 4-HNE, and that its overexpression extends lifespan of C. elegans. We now demonstrate that the expression level of CeGSTP2-2 correlates highly with lifespan in a series of hypomorphic daf-2 mutants of C. elegans. The overexpression of CeGSTP2-2 in daf-2 is abrogated in daf-16; daf-2 mutants, indicating that expression of the gst-10 gene is modulated by insulin-like growth factor signaling. To determine whether the relationship between CeGSTP2-2 and lifespan is causal, we used RNAi to knock down CeGSTP2-2. Treatment with gst-10-specific dsRNA decreased CeGSTP2-2 protein in wild-type N2 and in daf-2 strains to an approximately equal level. The ability to conjugate 4-HNE was similarly decreased by RNAi, suggesting that the increment of that activity in daf-2 over N2 is due largely to the overexpression of CeGSTP2-2. RNAi-mediated knock-down of CeGSTP2-2 led to an increased susceptibility to 4-HNE, paraquat, and heat shock, and to a shortening of lifespan by 13% in both N2 and daf-2 strains. These results indicate that CeGSTP2-2 significantly contributes to the maintenance of the soma, and that this function is augmented in daf-2 mutants concordantly with other longevity assurance genes, probably via insulin-like growth factor signaling.
Aging Cell 01/2006; 4(6):299-307. · 6.26 Impact Factor
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ABSTRACT: Caenorhabditis elegans expresses a glutathione transferase (GST) belonging to the Pi class, for which we propose the name CeGSTP2-2. CeGSTP2-2 (the product of the gst-10 gene) has the ability to conjugate the lipid peroxidation product 4-hydroxynonenal (4-HNE). Transgenic C. elegans strains were generated in which the 5'-flanking region and promoter of gst-10 were placed upstream of gst-10 and mGsta4 cDNAs, respectively. mGsta4 encodes the murine mGSTA4-4, an enzyme with particularly high catalytic efficiency for 4-HNE. The localization of both transgenes was similar to that of native CeGSTP2-2. The 4-HNE-conjugating activity in worm lysates increased in the order: control<mGsta4 transgenic<gst-10 transgenic; and the amount of 4-HNE-protein adducts decreased in the same order, indicating that the transgenic enzymes were active and effective in limiting electrophilic damage by 4-HNE. Stress resistance and lifespan were measured in transgenic animals (five independent lines each) and were compared with two independent control lines. Resistance to paraquat, heat shock, ultraviolet irradiation and hydrogen peroxide was greater in transgenic strains. Median lifespan of mGsta4 and gst-10 transgenic strains vs. control strains was increased by 13% and 22%, respectively. In addition to the cause-effect relationship between GST expression and lifespan observed in the transgenic lines, correlative evidence was also obtained in a series of congenic lines of C. elegans in which lifespan paralleled the 4-HNE-conjugating activity in whole-animal lysates. We conclude that electrophilic damage by 4-HNE may contribute to organismal aging.
Aging Cell 11/2005; 4(5):257-71. · 6.26 Impact Factor
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ABSTRACT: Caenorhabditis elegans expresses a glutathione transferase (GST) belonging to the Pi class, for which we propose the name CeGSTP2-2. CeGSTP2-2 (the product of the gst-10 gene) has the ability to conjugate the lipid peroxidation product 4-hydroxynonenal (4-HNE). Transgenic C. elegans strains were generated in which the 5′-flanking region and promoter of gst-10 were placed upstream of gst-10 and mGsta4 cDNAs, respectively. mGsta4 encodes the murine mGSTA4-4, an enzyme with particularly high catalytic efficiency for 4-HNE. The localization of both transgenes was similar to that of native CeGSTP2-2. The 4-HNE-conjugating activity in worm lysates increased in the order: control < mGsta4 transgenic < gst-10 transgenic; and the amount of 4-HNE-protein adducts decreased in the same order, indicating that the transgenic enzymes were active and effective in limiting electrophilic damage by 4-HNE. Stress resistance and lifespan were measured in transgenic animals (five independent lines each) and were compared with two independent control lines. Resistance to paraquat, heat shock, ultraviolet irradiation and hydrogen peroxide was greater in transgenic strains. Median lifespan of mGsta4 and gst-10 transgenic strains vs. control strains was increased by 13% and 22%, respectively. In addition to the cause–effect relationship between GST expression and lifespan observed in the transgenic lines, correlative evidence was also obtained in a series of congenic lines of C. elegans in which lifespan paralleled the 4-HNE-conjugating activity in whole-animal lysates. We conclude that electrophilic damage by 4-HNE may contribute to organismal aging.
Aging cell 09/2005; 4(5):257 - 271. · 7.55 Impact Factor
