Modulation of (Na,K)-ATPase activity by membrane fatty acid composition: therapeutic implications in human hypertension

Oxidative stress (OS) plays a key role in the pathophysiology of essential hypertension and is associated with changes in the cell membrane fatty acid composition and fluidity. As (Na,K)-ATPase is modulated by the surrounding lipid microenvironment, lipid peroxidation could alter the interactions of this enzyme with the membrane components. Thus, modifications in the membrane fatty acid profile will translate into effects on (Na,K)-ATPase activity. Accordingly, a decrease in this enzyme activity has been reported in hypertensive patients. The aim of this study was to evaluate the relationship between membrane fluidity and fatty acid composition and (Na,K)-ATPase activity in erythrocytes of essential hypertensive patients supplemented with antioxidant vitamins C and E. A double-blind, randomized, placebo-controlled study was conducted in 120 men with essential hypertension assigned to receive vitamin C (1?g/day)?+?E (400?IU/day) or placebo for 8 weeks. Measurements included OS related parameters: GSH/GSSG ratio, F2-isoprostanes and antioxidant capacity of plasma, (Na,K)-ATPase activity and erythrocytes membrane fatty acid composition (PUFA, polyunsaturated fatty acids; SAFA, saturated fatty acids). Associations were assessed by Pearson correlation and the differences by Student t-test (p?相似文献   

Ctp1 and Exonuclease 1, alternative nucleases regulated by the MRN complex,are required for efficient meiotic recombination

Double-strand breaks (DSBs) in DNA are lethal unless repaired. Faithful repair requires processing of the DSB ends and interaction with intact homologous DNA, which can produce genetic recombinants. To determine the role of nucleases in DSB end-processing and joint molecule resolution, we studied recombination at the site of a single DSB, generated by induction of the I-SceI endonuclease, during meiosis of fission yeast lacking Rec12 (Spo11 homolog) and, hence, other DSBs. We find that in the presence of the MRN (Rad32-Rad50-Nbs1) complex efficient recombination requires Ctp1, the ortholog of the nuclease Sae2, but not the nuclease activity of MRN. In the absence of MRN, exonuclease 1 (Exo1) becomes the major nuclease required for efficient recombination. Our data indicate that MRN enables access of Ctp1 to the DSB but blocks access of Exo1. In our assay, the Rad16-Swi10 nuclease, required for nucleotide excision-repair, is required for efficient recombination, presumably to remove heterologous DNA at the end of the I-SceI cut site. Another nuclease, the Mus81-Eme1 Holliday junction resolvase, is required to generate crossovers accompanying gene conversion at the I-SceI cut site. Additional, previously published evidence indicates that these 5 nucleases play similar roles in wild-type fission yeast meiotic recombination and in the repair of spontaneous and damage-induced mitotic DSBs. We propose that in wild-type meiosis MRN, in conjunction with Ctp1, removes the covalently attached Rec12 protein from the DNA end, which is then resected by Ctp1 and other activities to produce the single-stranded DNA necessary for further steps of DSB repair.     

Ubiquitination, localization, and stability of an anti-apoptotic BCL2-like protein, BCL2L10/BCLb, are regulated by Ubiquilin1

We have previously shown that all six members of the anti-apoptotic BCL2 gene family can cooperate with (myelocytomatosis oncogene) MYC in a mouse model of leukemia, but three of them are significantly less potent contributors to leukemogenicity than the other three. The protein encoded by one of these less potent genes, BCL2L10/BCLb, was recently shown to vary dramatically in many primary human cancers by immunohistochemistry, and the protein levels were inversely correlated with survival in patients with several cancer types. We examined BCLb mRNA in a panel of human cancer cell lines and did not observe the extensive variation in mRNA that would be required to explain the vast differences in protein levels. We found that the levels of BCLb protein diminish quickly after inhibition of protein synthesis with cycloheximide, so we searched for interacting proteins that might affect posttranslational stability of BCLb. Using a variety of approaches, including immunoaffinity and mass spectrometry, we identified a protein, Ubiquilin1 (Ubqln), that specifically interacts with BCLb, and not with other anti-apoptotic BCL2-like proteins. Ubqln stabilizes BCLb protein, while also promoting monoubiquitination on multiple lysine residues and relocation to the cytosol. Furthermore, primary lung adencarcinomas have more Ubqln mRNA than normal adjacent lung tissue, and higher Ubqln mRNA levels are associated with shorter survival of lung cancer patients, suggesting that potentiation of the anti-apoptotic potential of BCLb through regulation of its stability by Ubqln may be an important factor in tumor progression.     

麝香保心丸对H<,2>O<,2>诱导人脐静脉内皮细胞增殖及氧化应激的影响

目的 麝香保心丸时H<,2>O<,2>诱导人脐静脉内皮细胞(HUVEC)增殖活性、氧化因子丙二醛(MDA)、超氧化物歧化酶(SOD)及烟酰胺腺嘌呤二核苷酸磷酸(NADPH)氧化酶亚基gp91、p22 mRNA表达的影响.方法 体外胶原酶消化法培养人脐静脉内皮细胞;溴脱氧尿嘧啶核苷(BrdU)插入法测定细胞增殖活性;RT-PCR法测定NADPH氧化酶亚基gp91、p22 mRNA的表达;比色法检测细胞上清液MDA、SOD含量.结果 与对照组相比,H<,2>O<,2>组细胞增殖活性明显降低(P<0.01).与对照组相比,1 g麝香保心丸药物血清组细胞增殖活性明显增高(P<0.01);与对照组相比,H<,2>O<,2>组人脐静脉内皮细胞上清液MDA含量显著升高,SOD活性明显降低(P<0.01),而麝香保心丸药物血清呈浓度依赖性抑制H<,2>O<,2>诱导HUVEC细胞上清液MDA水平升高及SOD活性降低,1 g药物血清组上清液MDA含量显著低于H<,2>O<,2>组(P<0.01),SOD活性明显高于H<,2>O<,2>组(P<0.05);RT-PCR结果显示:与对照组相比,H<,2>O<,2>组p22 mRNA表达水平明显升高,对照血清组p22 mRNA表达进一步增加;与对照血清组相比,麝香保心丸1 g、2 g药物血清组p22 mRNA的表达显著降低;麝香保心丸药物血清对H<,2>O<,2>诱导HUVEC细胞NADPH氧化酶gp91 mRNA表达无显著影响.结论 麝香保心丸保护血管内皮细胞可能与抑制H<,2>O<,2>诱导人脐静脉内皮细胞氧化应激有关.     

Blood pressure variability,impaired autonomic function and vascular senescence in aged spontaneously hypertensive rats are ameliorated by angiotensin blockade

Objective

Elderly hypertensive patients are characterized by blood pressure (BP) variability, impaired autonomic function, and vascular endothelial dysfunction and stiffness. However, the mechanisms causing these conditions are unclear. The present study examined the effect of angiotensin receptor blockers (ARBs) on aged spontaneously hypertensive rats (SHR).

Methods

We surgically implanted telemetry devices in SHR and WKY at the age of 15 weeks (Young) and 80 weeks (Aged). Aged SHR were orally administered either olmesartan or valsartan once daily at 19:00 h (at the beginning of the dark period (active phase)) for 4 weeks to examine the effects on BP variability, impaired autonomic function, and vascular senescence.

Results

Aging and hypertension in SHR additively caused the following: increased low frequency (LF) power of systolic BP, a decreased spontaneous baroreceptor reflex gain (sBRG), increased BP variability, increased urinary norepinephrine excretion, increased vascular senescence-related beta-galactosidase positive cells and oxidative stress. Treatment with olmesartan or valsartan significantly ameliorated these changes in aged SHR. However, olmesartan ameliorated these changes in aged SHR better than valsartan. The reductions in BP caused by olmesartan in aged SHR were sustained longer than reductions by valsartan. This result indicates longer-lasting inhibition of the AT1 receptor by olmesartan than by valsartan.

Conclusion

ARBs ameliorated autonomic dysfunction, BP variability, and vascular senescence in aged SHR. Olmesartan ameliorated the aging-related disorders better than valsartan and was associated with longer-lasting AT1 receptor inhibition by olmesartan. Thus, the magnitude of improvement of these aging-related abnormalities differs for ARBs.     

Phosphorylation of extracellular signal‐regulated kinase 1/2, p38 mitogen‐activated protein kinase and nuclear translocation of nuclear factor‐κB are involved in upregulation of matrix metalloproteinase‐9 by tumour necrosis factor‐α

Background: Upregulation of matrix metalloproteinase‐9 (MMP‐9) induced by tumour necrosis factor‐α (TNF‐α) is reportedly involved in a variety of non‐neoplastic and neoplastic diseases. In this study, we examined which signalling pathways are involved in TNF‐α‐induced MMP‐9 upregulation in cholangiocarcinoma (CC). Methods: We used two CC cell lines: HuCCT‐1 and CCKS‐1. Results: In an ex vivo study using HuCCT‐1 and CCKS‐1 cells, TNF‐α treatment induced MMP‐9 production and activation via interaction with TNF receptor‐1 (TNF‐R1) but not with TNF receptor‐2 (TNF‐R2), shown by zymography, and increased MMP‐9 promoter activity (luciferase assay). As for the signalling pathway, TNF‐α stimulation led to the phosphorylation of extracellular signal‐regulated kinase 1/2 (Erk1/2) and p38 mitogen‐activated protein kinase (p38MAPK) and translocation of nuclear factor κB (NF‐κB) (p65) into the nuclei. Inhibition studies using SB203580 (inhibitor of p38MAPK), U0126 (inhibitor of mitogen‐activated or extracellular signal‐regulated protein kinase 1/2) and MG132 (inhibitor of NF‐κB) showed that the phosphorylation of Erk1/2 and p38MAPK with activation of NF‐κB was closely related to MMP‐9 upregulation in both cell lines. Conclusion: These data suggest that TNF‐α/TNF‐R1 interaction leads to the phosphorylation of Erk1/2 and p38MAPK and nuclear translocation of NF‐κB, which is closely associated with the production and activation of MMP‐9 in cultured CC cells of HuCTT‐1 and CCKS‐1. Upregulation of MMP‐9 with NF‐κB activation may be involved in the tumour invasion of CC.