Senescence Marker Protein-30 Deficiency Research Articles

Regulation of transgelin and GST-pi proteins in the tissues of hamsters exposed to sodium arsenite

Regulation of transgelin and GST-pi proteins in the tissues of hamsters exposed to sodium arsenite

Senescence marker protein 30 protects intestinal epithelial cells against inflammation-induced cell death by enhancing Nrf2 activity

Senescence marker protein 30 (SMP30) is a calcium-binding protein whose expression decreases during senescence. SMP30 deficiency increases susceptibility to cytokine-induced apoptosis in the liver and to radiation-induced apoptosis in the small intestine. Furthermore, colonic epithelial cell death is associated with the severity of colitis. Therefore, in the present study, we investigated the function of SMP30 during intestinal inflammation. In SMP30 deficient mice, colitis was significantly exacerbated as demonstrated by increased mortality (p = 0.001), body weight loss (p = 0.0105 at day 8), rectal bleeding (p = 0.0047 at day 8) and diarrhea (p = 0.0030 at day 8), histological scores (ulcers, p = 0.0002; edema, p = 0.0125; leukocyte infiltration, p = 0.0016) and productions of pro-inflammatory cytokines (IL-1α, p = 0.0452; IL-6, p = 0.0074; G-CSF, p = 0.0036). In addition, greater proportions of apoptotic cells and lower levels of anti-apoptotic marker proteins (total PARP-1 and Bcl-2) were observed in the inflamed intestines of SMP30 deficient mice than in wild type controls. In vitro experiments on colonic epithelial cells showed that stable SMP30 expression inhibited but that SMP30 siRNA expression increased TNF-α-induced apoptosis. SMP30 inhibition decreased Nrf2 mRNA expression levels (p < 0.0001), but SMP30 overexpression increased Nrf2 mRNA expression levels (p = 0.0495). The underlying mechanism by which SMP30 protected cells appeared to be by inhibiting Nrf2 ubiquitination and Keap1 expression, and thus enhancing Nrf2 activity. Moreover, SMP30 deficiency increased the incidence of colitis-associated colon cancer as determined by increased mortality (p = 0.0572) and average polyp number (p = 0.0277). Collectively, these findings suggest that SMP30 protects intestinal epithelial cells from apoptosis and this can contribute to amelioration of colitis and colitis-associated colon cancer.

Deficiency of Senescence Marker Protein 30 Exacerbates Cardiac Injury after Ischemia/Reperfusion.

Early myocardial reperfusion is an effective therapy but ischemia/reperfusion (I/R) causes lethal myocardial injury. The aging heart was reported to show greater cardiac damage after I/R injury than that observed in young hearts. Senescence marker protein 30 (SMP30), whose expression decreases with age, plays a role in reducing oxidative stress and apoptosis. However, the impact of SMP30 on myocardial I/R injury remains to be determined. In this study, the left anterior descending coronary artery was occluded for 30 min, followed by reperfusion in wild-type (WT) and SMP30 knockout (KO) mice. After I/R, cardiomyocyte apoptosis and the ratio of infarct area/area at risk were higher, left ventricular fractional shortening was lower, and reactive oxygen species (ROS) generation was enhanced in SMP30 KO mice. Moreover, the previously increased phosphorylation of GSK-3β and Akt was lower in SMP30 KO mice than in WT mice. In cardiomyocytes, silencing of SMP30 expression attenuated Akt and GSK-3β phosphorylation, and increased Bax to Bcl-2 ratio and cardiomyocyte apoptosis induced by hydrogen peroxide. These results suggested that SMP30 deficiency augments myocardial I/R injury through ROS generation and attenuation of Akt activation.

Involvement of senescence marker protein-30 in glucose metabolism disorder and non-alcoholic fatty liver disease.

Senescence marker protein-30 (SMP30) was found to decrease in the liver, kidneys and lungs of mice during aging. SMP30 is a pleiotropic protein that acts to protect cells from apoptosis by enhancing plasma membrane Ca(2+) -pump activity and is bona fide gluconolactonase (EC 3.1.1.17) that participates in the penultimate step of the vitamin C biosynthetic pathway. For the past several years, we have obtained strong evidence showing the close relationship between SMP30, glucose metabolism disorder and non-alchoholic fatty liver disease in experiments with SMP30 knockout mice. Emerging proof links the following abnormalities: (i) the reduction of SMP30 by aging and/or excessive dietary fat or genetic deficiency causes a loss of Ca(2+) pumping activity, which impairs acute insulin release in pancreatic β-cells, initiates inflammatory responses with oxidative stress and endoplasmic reticulum stress in non-alchoholic steatohepatitis, exacerbates renal tubule damage, and introduces tubulointerstitial inflammation and fibrosis in diabetic nephropathy; (ii) vitamin C insufficiency also impairs acute insulin secretion in pancreatic β-cells by a mechanism distinct from that of the SMP30 deficiency; and (iii) the increased oxidative stress by concomitant deficiencies of SMP30, superoxide dismutase 1 and vitamin C similarly causes hepatic steatosis. Here, we review recent advances in our understanding of SMP30 in glucose metabolism disorder and non-alchoholic fatty liver disease.

Deficiency of Senescence Marker Protein‐30 Impairs Collateral Growth by Supressing Nitric Oxide Bioactivity under Ischemia

Aging impairs collateral growth under ischemia and reduces the expression of VEGF, however the exact mechanism is unclear. Senescence marker protein‐30 (SMP30) decreases with aging. Mice with SMP30 deficiency, a model of aging, have a short lifespan with increased oxidant stress. To elucidate the effect of SMP30 on ischemia‐induced collateral growth, we examined the recovery of cutaneous blood flow (CBF) after femoral artery ligation by laser Doppler imaging in mice. Recoveries of CBF and tissue capillary density were suppressed in SMP30 knockout (KO) mice compared to those of wild type (WT) mice. Acetylcholine (ACh, 1 µM)‐induced NO generation in aorta of SMP30 KO mice was lower than those of WT mice. Superoxide generation and NADPH oxidase activity were greater in aorta of SMP30 KO mice compared to that of WT mice (superoxide level: 3.3±0.5 vs. 1.6±0.2 nmol/mg protein; NADPH oxidase activity: 3240±254 vs. 982±106 RLU; P&lt;0.01, respectively). VEGF content in the biceps femoris muscle in SMP30 KO mice did not increase in 14 days post‐ischemia compared to that in pre‐ischemia (SMP30 KO mice 1.1±0.2 fold vs. WT mice 2.2±0.3 fold, P&lt;0.01). Akt phosphorylation in the biceps femoris muscle was attenuated in SMP30 KO mice compared to that of WT mice (p‐Akt/Akt: SMP30 KO mice 0.4±0.3 vs. WT mice 1.2±0.4, P&lt;0.01). Thus, SMP30 deficiency exacerbates oxidant stress due to NADPH oxidase activation and impairs eNOS activity, which leads to rarefaction of collateral growth induced by ischemia related to Akt‐VEGF pathway. These results suggest that the decrease of SMP30 in aging impairs VEGF/NO‐dependent angiogenesis associated with overproduction of superoxide.

Abstract 11474: Deficiency of Senescence Marker Protein-30 Impairs Collateral Growth by Supressing Nitric Oxide Bioactivity Under Ischemia

Aging impairs collateral growth under ischemia and reduces the expression of VEGF, however the exact mechanism is unclear. Senescence marker protein-30 (SMP30) decreases with aging. Mice with SMP30 deficiency, a model of aging, have a short lifespan with increased oxidant stress. To elucidate the effect of SMP30 on ischemia-induced collateral growth, we examined the recovery of cutaneous blood flow (CBF) after femoral artery ligation by laser Doppler imaging in mice. Recoveries of CBF and tissue capillary density were suppressed in SMP30 knockout (KO) mice compared to those of wild type (WT) mice (Figure). Acetylcholine (ACh, 1 μM)-induced NO generation, total thiol and reduced glutathione (GSH) levels in aorta of SMP30 KO mice were lower than those of WT mice (NO: 2.6±4.5 vs. 86.2±9.2 nM; total thiol: 6.3±1.6 vs. 33.2±4.6 nmol/mg/protein; GSH: 5.1±0.8 vs. 18.6±2.1 nmol/mg/protein; P&lt;0.01, respectively). Superoxide generation and NADPH oxidase activity were greater in aorta of SMP30 KO mice compared to that of WT mice (superoxide level: 3.3±0.5 vs. 1.6±0.2 nmol/mg protein; NADPH oxidase activity: 3240±254 vs. 982±106 RLU; P&lt;0.01, respectively). Asymmetric dimethylarginine (ADMA) level was higher in aorta of SMP30 KO mice than that of WT mice (6.4±0.8 vs. 2.4±0.4 nmol/mg protein, P&lt;0.01). VEGF content in the crural muscle in SMP30 KO mice did not increase in 14 days post-ischemia compared to that in pre-ischemia (SMP30 KO mice 1.1±0.2 fold vs. WT mice 2.2±0.3 fold, P&lt;0.01). Akt phosphorylation in the crural muscle was attenuated in SMP30 KO mice compared to that of WT mice (p-Akt/Akt: SMP30 KO mice 0.4±0.3 vs. WT mice 1.2±0.4, P&lt;0.01). Thus, SMP30 deficiency exacerbates oxidant stress due to NADPH oxidase activation, which leads to the rarefaction of collateral growth induced by ischemia related to Akt-VEGF pathway. These results suggest that the decrease of SMP30 in aging impairs VEGF/NO-dependent angiogenesis associated with overproduction of superoxide.

Anti-inflammatory activity of SMP30 modulates NF-κB through protein tyrosine kinase/phosphatase balance.

Recent studies on senescence marker protein-30 (SMP30) have shown that it has an important functional role in the aging process, but its precise participation in cellular works has not been fully determined. We hypothesize that SMP30 plays crucial roles in signaling processes by modulating the balance of protein tyrosine kinase (PTK)/protein tyrosine phosphatase (PTP) and in activating proinflammatory NF-κB. An experimental paradigm of gain and loss of SMP30 function was established using SMP30-overexpressed YPEN-1 cells (herein referred to as "SMP30(+) cells") and SMP30 (Y/-) knockout mouse kidneys. The resulting data show that SMP30 expression suppressed oxidative stress-induced PTK/PTP dysregulation and PP1/2A inactivation in SMP30(+) cells, leading to the suppression of NF-κB activation. In the kidneys of SMP30 (Y/-) mice, SMP30 deficiency was found to induce NF-κB activation via the upstream signaling of NIK/IKK and MAPKs and to upregulate downstream NF-κB-responsive gene expression. In this study, we also demonstrate for the first time that SMP30 deficiency induced PTK activity in SMP30 (Y/-) kidneys, thereby significantly increasing the tyrosine phosphorylation of a catalytic subunit of PP2A (PP2Ac-Tyr307). Based on these findings, we propose that SMP30 involves NF-κB regulation through the PTK/PTP balance and that the age-related decrease of SMP30 causes NF-κB activation, which contributes to an exacerbation of the inflammatory process during aging. SMP30-deficient mice induced a shorter lifespan and redox changes. Overexpression of SMP30 prevented oxidative stress insults. The depletion of SMP30 increased redox-related PTK/PTP imbalance and PP1/PP2A inactivation. The depletion of SMP30 caused an elevation of NF-κB-responsive inflammatory markers. SMP30 may be a potent inhibitory protein against oxidative stress and chronic inflammation.

Senescence marker protein-30/gluconolactonase deficiency exacerbates diabetic nephropathy through tubular injury in a mouse model of type1 diabetes.

Aims/IntroductionSenescence marker protein-30 (SMP30) is abundantly expressed in renal proximal tubule cells, but its expression decreases with age. Previous studies have shown that reduced SMP30 expression could contribute to aging-associated deterioration of cellular function and tissue injury. In the present study, we investigated the effects of SMP30 deficiency on the pathogenesis of diabetic nephropathy.Materials and MethodsDiabetes was induced using streptozotocin in male SMP30 knockout mice (KO) and wild-type mice at 7 weeks-of-age. Vitamin C was added to the drinking water to prevent vitamin C deficiency in KO mice. The mice were killed 12 weeks after the induction of diabetes.ResultsUrinary biomarkers for proximal tubule damage were significantly increased in non-diabetic KO mice compared with wild-type mice. Furthermore, diabetes-induced tubular damage was significantly exacerbated by SMP30 deletion. Morphological analysis showed a link between cortical tubulointerstitial fibrosis area and the degree of tubular damage. However, SMP30 deletion did not affect mesangial expansion. Tubular injury was associated with accumulation of hypoxia-inducible factor-1α and increased hypoxia-inducible factor-1α targeted gene expression. SMP30 deletion initiated oxidative stress; however, it did not exacerbate the oxidative stress seen in diabetic mice. In contrast, tubular inflammation was associated with SMP30 deletion only in diabetic mice.ConclusionsBased on this evidence, we concluded that SMP30 deficiency exacerbates proximal tubule injury in diabetic mice. Decreased SMP30 could contribute to the increased incidence of various chronic kidney diseases, including diabetic nephropathy, with age.

Senescence Marker Protein-30 (SMP30) Deficiency Impairs Myocardium-Induced Dilation of Coronary Arterioles Associated with Reactive Oxygen Species

Senescence marker protein-30 (SMP30) decreases with aging. Mice with SMP30 deficiency, a model of aging, have a short lifespan with increased oxidant stress. To elucidate SMP30’s effect on coronary circulation derived from myocytes, we measured the changes in the diameter of isolated coronary arterioles in wild-type (WT) mice exposed to supernatant collected from isolated paced cardiac myocytes from SMP30 KO or WT mice. Pacing increased hydrogen peroxide in myocytes, and hydrogen peroxide was greater in SMP30 KO myocytes compared to WT myocytes. Antimycin enhanced and FCCP (oxidative phosphorylation uncoupler in mitochondria) decreased superoxide production in both groups. Addition of supernatant from stimulated myocytes, either SMP30 KO or WT, caused vasodilation. The degree of the vasodilation response to supernatant was smaller in SMP30 KO mice compared to WT mice. Administration of catalase to arterioles eliminated vasodilation in myocyte supernatant of WT mice and converted vasodilation to vasoconstriction in myocyte supernatant of SMP30 KO mice. This vasoconstriction was eliminated by olmesartan, an angiotensin II receptor antagonist. Thus, SMP30 deficiency combined with oxidant stress increases angiotensin and hydrogen peroxide release from cardiac myocytes. SMP30 plays an important role in the regulation of coronary vascular tone by myocardium.

Coronary Artery Spasm Related to Thiol Oxidation and Senescence Marker Protein-30 in Aging

Senescence marker protein-30 (SMP30) decreases with aging, and SMP30 knockout (KO) mice show a short life with increased oxidant stress. We assessed the effect of oxidant stress with SMP30 deficiency in coronary artery spasm and clarify its underlying mechanisms. We measured vascular responses to acetylcholine (ACh) and sodium nitroprusside (SNP) of isolated coronary arteries from SMP30 KO and wild-type (WT) mice. In SMP30 KO mice, ACh-induced vasoconstriction occurred, which was changed to vasodilation by dithiothreitol (DTT), a thiol-reducing agent. However, Nω-nitro-L-arginine-methyl ester, nitric oxide (NO) synthase inhibitor, or tetrahydrobiopterin did not change the ACh response. In isolated coronary arteries of WT mice, ACh-induced vasodilation occurred. Inhibition of glutathione reductase by 1, 3-bis(2-chloroethyl)-1-nitrosourea decreased ACh-induced vasodilation (n=10, p<0.01), which was restored by DTT. To evaluate the thiol oxidation, we measured the fluorescence of monochlorobimane (MCB) in coronary arteries, which covalently labels the total. The fluorescence level to MCB decreased in SMP30 KO mice, but with DTT treatment restored to a level comparable to that of WT mice. The reduced glutathione and total thiol levels were also low in the aorta of SMP30 KO mice compared with those of WT mice. Administration of ACh into the aortic sinus in vivo of SMP30 KO mice induced coronary artery spasm. The thiol redox state is a key regulator of endothelial NO synthase activity, and thiol oxidation was associated with endothelial dysfunction in the SMP30 deficiency model. These results suggest that chronic thiol oxidation by oxidant stress is a trigger of coronary artery spasm, resulting in impaired endothelium-dependent vasodilation.

Senescence marker protein 30 deficiency increases Parkinson's pathology by impairing astrocyte activation

Senescence marker protein 30 (SMP30) was recently identified as gluconolactonase, which is involved in vitamin C (VC) biosynthesis. Therefore, the antioxidant property of SMP30 is thought to be mediated by its gluconolactonase function. However, pathologic effects of SMP30 deficiency independent of VC biosynthesis have not been studied in models of neurodegenerative diseases. In the present study, we evaluated the effect of SMP30 deficiency on Parkinson’s disease (PD) in SMP30 knockout (KO) mice. Wild type and SMP30 KO mice supplemented with VC were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our results showed that MPTP-induced dopaminergic neuronal loss and motor function impairment were more significant in the SMP30 KO mice. Reactive oxygen species generation and microglia activation were higher in MPTP-treated SMP30 KO mice. However, SMP30 deficiency mitigated MPTP-induced astrocyte activation and glia-derived neurotrophic factor production. Cultures of astrocytes recovered from wild type and SMP30 KO mice revealed that SMP30 deficiency abolished 1-methyl-4-phenyl-pyridinium-induced astroglial activation by blocking the extracellular signal-regulated kinase pathway. Taken together, our findings demonstrate for the first time that SMP30 deficiency increases the severity of PD and suggest a beneficial role of SMP30 in protective astrocyte activation in response to neurodegeneration. The present study shows that modulation of astrocytic SMP30 can be a promising target for treating PD.

SMP30 deficiency causes increased oxidative stress in brain

Senescence marker protein 30 (SMP30), an important aging marker molecule, has been identified functionally as a calcium regulatory protein. Recent evidence showed its new assumed role as an effective anti-oxidative property. However, the role of SMP30 in the brain has not been explored. To delineate its role in the brain, we utilized SMP30 knock-out (SMP30 KO) mice in the current study. We focused on the oxidative status of the brain by examining selected oxidative markers in brains of SMP30 KO mice. Results showed that the generation of reactive species (RS) and NADPH oxidase activities were significantly elevated in SMP30 deficient brain. The increased oxidative status in these mice was further confirmed by increased oxidatively modified proteins such as dityrosine formation and carbonylation in the cortex of SMP30 KO mice. Moreover, SMP30 deficient brain showed the increased Mac-1 protein and myeloperoxidase (MPO) activity in the brain, supporting the putative anti-oxidative action of SMP30. Interestingly, the activities of major antioxidant enzymes, superoxide dismutase, catalase and reduced glutathione peroxidase in the brain were not affected by SMP30 depletion. Our results documented that brain SMP30 has a protective action against oxidative damage, without influencing antioxidant enzyme status.

SMP30 deficiency in mice causes an accumulation of neutral lipids and phospholipids in the liver and shortens the life span

Senescence marker protein-30 (SMP30) is an androgen-independent factor that decreases with aging. SMP30-deficient (SMP30Y/−) mice are viable and fertile but lower in body weight and shorter in life span than the wild-type. In the electron microscope, hepatocytes from SMP30Y/− but not the wild-type mice at 12 months of age clearly contained many lipid droplets, abnormally enlarged mitochondria with indistinct cristae, and enlarged lysosomes filled with electron-dense bodies. In liver specimens from SMP30Y/− mice, the marked number of lipid droplets visible around the central vein increased notably in size and amount as the animals aged. Biochemical analysis of neutral lipids, total hepatic triglyceride, and cholesterol from SMP30Y/− mice showed approximately 3.6- and 3.3-fold higher levels, respectively, than those from age-matched wild-type mice. Moreover, values for total hepatic phospholipids from SMP30Y/− mice were approximately 3.7-fold higher than those for their wild-type counterparts. By thin-layer chromatography analysis, phosphatidylethanolamine, cardiolipin, phosphatidylcholine, phosphatidylserine, and sphingomyelin accumulations were detected separately in lipid extracts from SMP30Y/− mouse livers and provided results that strongly indicate the profound effect of an SMP30 deficiency on the metabolism of these neutral lipids and phospholipids. Conceivably, this abnormality of lipid metabolism is sufficient to curtail the life span of SMP30-deficient mice.