共查询到20条相似文献,搜索用时 15 毫秒
1.
Tarzami ST Calderon TM Deguzman A Lopez L Kitsis RN Berman JW 《Biochemical and biophysical research communications》2005,335(4):1008-1016
Chemokines, in addition to their chemotactic properties, act upon resident cells within a tissue and mediate other cellular functions. In a previous study, we demonstrated that CCL2 protects cultured mouse neonatal cardiac myocytes from hypoxia-induced cell death. Leukocyte chemotaxis has been shown to contribute to ischemic injury. While the chemoattractant properties of CCL2 have been established, the protective effects of this chemokine suggest a novel role for CCL2 in myocardial ischemia/reperfusion injury. The present study examined the cellular signaling pathways that promote this protection. Treatment of cardiac myocyte cultures with CCL2 protected them from hypoxia-induced apoptosis. This protection was not mediated through the activation of G(alphai) signaling that mediates monocyte chemotaxis. Inhibition of the ERK1/2 signaling pathway abrogated CCL2 protection. Caspase 3 activation and JNK/SAPK phosphorylation were decreased in hypoxic myocytes co-treated with CCL2 as compared to hypoxia only-treated cultures. Expression of the Bcl-2 family proteins, Bcl-xL and Bag-1, was increased in CCL2-treated myocytes subjected to hypoxia. There was also downregulation of Bax protein levels as a result of CCL2 co-treatment. These data suggest that CCL2 cytoprotection and chemotaxis may occur through distinct signaling mechanisms. 相似文献
2.
The induction of ischemic tolerance by preconditioning provides a platform to elucidate endogenous mechanisms of stroke protection. In these studies, we characterize the relationship between hypoxia‐inducible factor (HIF), sphingosine kinase 2 (SphK2), and chemokine (C–C motif) ligand 2 (CCL2) in models of hypoxic or pharmacological preconditioning‐induced ischemic tolerance. A genetics‐based approach using SphK2‐ and CCL2‐null mice showed both SphK2 and CCL2 to be necessary for the induction of ischemic tolerance following preconditioning with hypoxia, the hypoxia‐mimetic cobalt chloride, or the sphingosine‐1‐phosphate (S1P) agonist FTY720. A pharmacological approach confirmed the necessity of HIF signaling for all three preconditioning stimuli, and showed that the SphK/S1P pathway transduces tolerance via the S1P1 receptor. In addition, our data suggest significant cross‐talk between HIF and SphK2‐produced S1P signaling, which together act to up‐regulate CCL2 expression. Overall, HIF, SphK, S1P, and CCL2 participate in a signaling cascade to induce the gene expression responsible for the stroke‐tolerant phenotype established by hypoxic and FTY720 preconditioning. The identification of these common molecular mediators involved in signaling the genomic response to multiple preconditioning stimuli provides several targets for therapeutic manipulation. 相似文献
3.
Hypoxia up-regulates telomerase activity via mitogen-activated protein kinase signaling in human solid tumor cells. 总被引:7,自引:0,他引:7
H Seimiya M Tanji T Oh-hara A Tomida I Naasani T Tsuruo 《Biochemical and biophysical research communications》1999,260(2):365-370
Solid tumor cells are often exposed to hypoxia in vivo, which has been suggested to promote genetic instability in those cells. Telomere elongation by telomerase is implicated in chromosome stabilization in immortal cells. Here we found that hypoxia enhanced telomerase activity in the solid tumor A2780 and HT-29 cells but not in the leukemia U937 cells. The telomerase activation correlated with activation of mitogen-activated protein kinase (MAPK) and c-fos expression. The MEK1 inhibitor PD98059 repressed telomerase activation in the hypoxic cells. Consistently, a dominant negative MEK1 inhibited telomerase activation by hypoxia. Finally, we found a good correlation between telomerase activation and resistance to apoptotic cell death under hypoxic conditions. These findings indicate that hypoxia up-regulates telomerase activity via MAPK cascade signaling especially in solid tumor cells and suggest that solid tumor cells might enhance the telomerase activity as a stress response against genotoxicity induced by hypoxia. 相似文献
4.
Yilin Yang Feng Zhi Xiaozhou He Meredith L. Moore Xuezhi Kang Dongman Chao Rong Wang Dong H. Kim Ying Xia 《PloS one》2012,7(12)
Prolonged hypoxic/ischemic stress may cause cortical injury and clinically manifest as a neurological disability. Activation of the δ-opioid receptor (DOR) may induce cortical protection against hypoxic/ischemic insults. However, the mechanisms underlying DOR protection are not clearly understood. We have recently found that DOR activation modulates the expression of microRNAs (miRNAs) in the kidney exposed to hypoxia, suggesting that DOR protection may involve a miRNA mechanism. To determine if the miRNAs expressed in the cortex mediated DOR neuroprotection, we examined 19 miRNAs that were previously identified as hypoxia- and DOR-regulated miRNAs in the kidney, in the rat cortex treated with UFP-512, a potent and specific DOR agonist under hypoxic condition. Of the 19 miRNAs tested, 17 were significantly altered by hypoxia and/or DOR activation with the direction and amplitude varying depending on hypoxic duration and times of DOR treatment. Expression of several miRNAs such as miR-29b, -101b, -298, 324-3p, -347 and 466b was significantly depressed after 24 hours of hypoxia. Similar changes were seen in normoxic condition 24 hours after DOR activation with one-time treatment of UFP-512. In contrast, some miRNAs were more tolerant to hypoxic stress and showed significant reduction only with 5-day (e.g., miR-31 and -186) or 10-day (e.g., miR-29a, let-7f and -511) exposures. In addition, these miRNAs had differential responses to DOR activation. Other miRNAs like miRs-363* and -370 responded only to the combined exposure to hypoxia and DOR treatment, with a notable reduction of >70% in the 5-day group. These data suggest that cortical miRNAs are highly yet differentially sensitive to hypoxia. DOR activation can modify, enhance or resolve the changes in miRNAs that target HIF, ion transport, axonal guidance, free radical signaling, apoptosis and many other functions. 相似文献
5.
Oxygen-sensitive {delta}-opioid receptor-regulated survival and death signals: novel insights into neuronal preconditioning and protection 总被引:4,自引:0,他引:4
The detrimental effect of severe hypoxia (SH) on neurons can be mitigated by hypoxic preconditioning (HPC), but the molecular mechanisms involved remain unclear, and an understanding of these may provide novel solutions for hypoxic/ischemic disorders (e.g. stroke). Here, we show that the delta-opioid receptor (DOR), an oxygen-sensitive membrane protein, mediates the HPC protection through specific signaling pathways. Although SH caused a decrease in DOR expression and neuronal injury, HPC induced an increase in DOR mRNA and protein levels and reversed the reduction in levels of the endogenous DOR peptide, leucine enkephalin, normally seen during SH, thus protecting the neurons from SH insult. The HPC-induced protection could be blocked by DOR antagonists. The DOR-mediated HPC protection depended on an increase in ERK and Bcl 2 activity, which counteracted the SH-induced increase in p38 MAPK activities and cytochrome c release. The cross-talk between ERK and p38 MAPKs displays a "yinyang" antagonism under the control of the DOR-G protein-protein kinase C pathway. Our findings demonstrate a novel mechanism of HPC neuroprotection (i.e. the intracellular up-regulation of DOR-regulated survival signals). 相似文献
6.
Postovit LM Adams MA Lash GE Heaton JP Graham CH 《The Journal of biological chemistry》2002,277(38):35730-35737
Tumor hypoxia is associated with a poor prognosis for patients with various cancers, often resulting in an increase in metastasis. Moreover, exposure to hypoxia increases the ability of breast carcinoma cells to invade the extracellular matrix, an important aspect of metastasis. Here, we demonstrate that the hypoxic up-regulation of invasiveness is linked to reduced nitric oxide signaling. Incubation of human breast carcinoma cells in 0.5% versus 20% oxygen increased their in vitro invasiveness and their expression of the urokinase receptor, an invasion-associated molecule. These effects of hypoxia were inhibited by nitric oxide-mimetic drugs; and in a manner similar to hypoxia, pharmacological inhibition of nitric oxide synthesis increased urokinase receptor expression. The nitric oxide signaling pathway involves activation of soluble guanylyl cyclase (sGC) and the subsequent activation of protein kinase G (PKG). Culture of tumor cells under hypoxic conditions (0.5% versus 20% oxygen) resulted in lower cGMP levels, an effect that could be prevented by incubation with glyceryl trinitrate. Inhibition of sGC activity with a selective blocker or with the heme biosynthesis inhibitor desferrioxamine increased urokinase receptor expression. These compounds also prevented the glyceryl trinitrate-mediated suppression of urokinase receptor expression in cells incubated under hypoxic conditions. In contrast, direct activation of PKG using 8-bromo-cGMP prevented the hypoxia- and desferrioxamine-induced increases in urokinase receptor expression as well as the hypoxia-mediated enhanced invasiveness. Further involvement of PKG in the regulation of invasion-associated phenotypes was established using a selective PKG inhibitor, which alone increased urokinase receptor expression. These findings reveal that an important mechanism by which hypoxia increases tumor cell invasiveness (and possibly metastasis) requires inhibition of the nitric oxide signaling pathway involving sGC and PKG activation. 相似文献
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8.
D. Leshem-Lev E. Hochhauser B. Chanyshev A. Isak A. Shainberg 《Molecular and cellular biochemistry》2010,345(1-2):153-160
Activation of either the A1 adenosine receptor (A1R) or the A3 adenosine receptor (A3R), by their specific agonists CCPA and Cl-IB-MECA, respectively, protects cardiac cells in culture against ischemic injury. Yet the full protective mechanism remains unclear. In this study, we therefore examined the involvement of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases (ERK) phosphorylation in this protective intracellular signaling mechanism. Furthermore, we investigated whether p38 MAPK phosphorylation occurs upstream or downstream from the opening of mitochondrial ATP-sensitive potassium (KATP) channels. The role of p38 MAPK activation in the intracellular signaling process was studied in cultured cardiomyocytes subjected to hypoxia, that were pretreated with CCPA or Cl-IB-MECA or diazoxide (a mitochondrial KATP channel opener) with and without SB203580 (a specific inhibitor of phosphorylated p38 MAPK). Cardiomyocytes were also pretreated with anisomycin (p38 MAPK activator) with and without 5-hydroxy decanoic acid (5HD) (a mitochondrial KATP channel blocker). SB203580 together with the CCPA, Cl-IB-MECA or diazoxide abrogated the protection against hypoxia as shown by the level of ATP, lactate dehydrogenase (LDH) release, and propidium iodide (PI) staining. Anisomycin protected the cardiomyocytes against ischemic injury and this protection was abrogated by SB203580 but not by 5HD. Conclusions Activation of A1R or A3R by CCPA or Cl-IB-MECA, respectively, protects cardiomyocytes from hypoxia via phosphorylation of p38 MAPK, which is located downstream from the mitochondrial KATP channel opening. Elucidating the signaling pathway by which adenosine receptor agonists protect cardiomyocytes from hypoxic damage, will facilitate the development of anti ischemic drugs. 相似文献
9.
Importance of FADD signaling in serum deprivation- and hypoxia-induced cardiomyocyte apoptosis 总被引:2,自引:0,他引:2
Although cardiomyocyte (CM) apoptosis has been well described in both in vitro and in vivo models of ischemic heart disease, the intracellular pathways leading to CM death have not been fully characterized. To define the role of death receptor signaling in CM apoptosis, we constructed recombinant adenoviral vectors carrying wild-type (wt) or dominant negative (dn) forms of the death receptor adaptor protein FADD (Fas-associated death domain protein) and used these vectors to transduce rat neonatal CMs in models of hypoxia- and serum deprivation (SD)-induced apoptosis. The combination of SD and hypoxia induced rapid activation of caspase-3 and -8 as well as DNA fragmentation, reaching a plateau within 4-8 h. Adenoviral expression of FADD-dn inhibited caspase-8 activation as well as hypoxia/SD-induced apoptosis at 24 h in an moi (multiplicity of infection)-dependent manner. In contrast, adenoviral expression of FADD-wt increased apoptosis and caspase-3 activity in CMs under both normoxic and hypoxic conditions. Surprisingly, FADD-dn, as well as the specific caspase-8 inhibitor benzyloxycarbonyl-IETD-fluoromethylketone also inhibited the activation of caspase-9 and -3 in CMs subjected to hypoxia/SD. These data suggest a primary role for FADD/caspase-8 signaling that is necessary and sufficient for apoptosis of CMs subjected to hypoxia/SD. 相似文献
10.
Fabian Doktor Philipp Prager Peter Wiedemann Leon Kohen Andreas Bringmann Margrit Hollborn 《Purinergic signalling》2018,14(4):471-484
Retinal hypoxia is a major condition of the chronic inflammatory disease age-related macular degeneration. Extracellular ATP is a danger signal which is known to activate the NLRP3 inflammasome in various cell systems. We investigated in cultured human retinal pigment epithelial (RPE) cells whether hypoxia alters the expression of inflammasome-associated genes and whether purinergic receptor signaling contributes to the hypoxic expression of key inflammatory (NLRP3) and angiogenic factor (VEGF) genes. Hypoxia and chemical hypoxia were induced by a 0.2%-O2 atmosphere and addition of CoCl2, respectively. Gene expression was determined with real-time RT-PCR. Cytosolic NLRP3 and (pro-) IL-1β levels, and the extracellular VEGF level, were evaluated with Western blot and ELISA analyses. Cell culture in 0.2% O2 induced expression of NLRP3 and pro-IL-1β genes but not of the pro-IL-18 gene. Hypoxia also increased the cytosolic levels of NLRP3 and (pro-) IL-1β proteins. Inflammasome activation by lysosomal destabilization decreased the cell viability under hypoxic, but not control conditions. In addition to activation of IL-1 receptors, purinergic receptor signaling mediated by a pannexin-dependent release of ATP and a release of adenosine, and activation of P2Y2 and adenosine A1 receptors, was required for the full hypoxic expression of the NLRP3 gene. P2Y2 (but not A1) receptor signaling also contributed to the hypoxic expression and secretion of VEGF. The data indicate that hypoxia induces priming and activation of the NLRP3 inflammasome in cultured RPE cells. The hypoxic NLRP3 and VEGF gene expression and the secretion of VEGF are in part mediated by P2Y2 receptor signaling. 相似文献
11.
Xiaozhou He Yilin Yang Feng Zhi Meredith L. Moore Xuezhi Kang Dongman Chao Rong Wang Gianfranco Balboni Severo Salvadori Dong H. Kim Ying Xia 《PloS one》2013,8(4)
Hypoxic/ischemic injury to kidney is a frequently encountered clinical problem with limited therapeutic options. Since microRNAs are differentially involved in hypoxic/ischemic events and δ-opioid receptor (DOR) activation is known to protect against hypoxic/ischemic injury, we speculated on the involvement of DOR activation in altering the microRNA (miRNA) expression in kidney under hypoxic condition. We selected 31 miRNAs based on microarray data for quantitative PCR analysis. Among them, 14 miRNAs were significantly altered after prolonged hypoxia, DOR activation or a combination of both. We found that 1) DOR activation alters miRNA expression profiles in normoxic conditions; 2) hypoxia differentially alters miRNA expression depending on the duration of hypoxia; and 3) DOR activation can modify hypoxia-induced changes in miRNA expression. For example, 10-day hypoxia reduced the level of miR-212 by over 70%, while DOR activation could mimic such reduction even in normoxic kidney. In contrast, the same stress increased miR-29a by >100%, which was reversed following DOR activation. These first data suggest that hypoxia comprehensively modifies the miRNA profile within the kidney, which can be mimicked or modified by DOR activation. Ascertaining the targeted pathways that regulate the diverse cellular and molecular functions of miRNA may provide new insights into potential therapies for hypoxic/ischemic injury of the kidney. 相似文献
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Erythropoietin protects cardiac myocytes from hypoxia-induced apoptosis through an Akt-dependent pathway 总被引:41,自引:0,他引:41
Tramontano AF Muniyappa R Black AD Blendea MC Cohen I Deng L Sowers JR Cutaia MV El-Sherif N 《Biochemical and biophysical research communications》2003,308(4):990-994
Apoptosis is a contributing cause of myocyte loss in ischemic heart disease. Recent work has shown that erythropoietin (EPO) offers protection against apoptosis in a wide variety of tissues. We demonstrate that the erythropoietin receptor (EPOR) is expressed in the neonatal rat ventricular myocyte (NRVM). Exposure of NRVMs to hypoxia, with recombinant human EPO, significantly decreased apoptosis as measured by TUNEL, flow cytometry, and caspase 3/7 like activity when compared to hypoxia treatment alone. EPO administered at the initiation of coronary artery occlusion in the rat significantly decreased apoptosis in the myocardial ischemic region. In the NRVM, EPO increased the activity of Akt. The anti-apoptotic effect of EPO was abrogated by co-treatment with LY294002, a specific blocker of phosphatidylinositol 3-kinase (PI3-K). Our study demonstrates that EPO inhibits apoptosis in the NRVM exposed to hypoxia, through an Akt-dependent pathway. EPO also inhibits apoptosis in the in vivo rat model of myocardial ischemia. 相似文献
15.
Wright G Higgin JJ Raines RT Steenbergen C Murphy E 《The Journal of biological chemistry》2003,278(22):20235-20239
Recently an oxygen-sensing/transducing mechanism has been identified as a family of O2-dependent prolyl hydroxylase domain-containing enzymes (PHD). In normoxia, PHD hydroxylates a specific proline residue that directs the degradation of constitutively synthesized hypoxia-inducible factor-1alpha. During hypoxia, the cessation of hydroxylation of this proline results in less degradation and thus increases hypoxia-inducible factor-1alpha protein levels. In this study we have examined the consequences of activating the PHD oxygen-sensing pathway in cultured neonatal myocytes using ethyl-3,4 dihydroxybenzoate and dimethyloxalylglycine, inhibitors that, similar to hypoxia, inhibit this family of O2-dependent PHD enzymes. Increased glucose uptake and enhanced glycolytic metabolism are classical cellular responses to hypoxia. Ethyl-3,4 dihydroxybenzoate treatment of cardiomyocyte cultures for 24 h increased [3H]deoxy-4-glucose uptake concurrent with an induction of GLUT1 protein. In addition, ethyl-3,4 dihydroxybenzoate, dimethyloxalylglycine, and hypoxia treatments were found to induce protein levels of nitricoxide synthase-2 and heme oxygenase-1, two important cardioregulatory proteins whose expression in response to hypoxic conditions is poorly understood. In conjunction with these changes in gene expression, activation of the PHD oxygen-sensing mechanism was found to preserve myocyte viability in the face of metabolic inhibition with cyanide and 2-deoxyglucose. These results point to a key role for the PHD pathway in the phenotypic changes that are observed in a hypoxic myocyte and may suggest a strategy to pharmacologically induce protection in heart. 相似文献
16.
D'Angelo G Ladoux A Frelin C 《Biochemical and biophysical research communications》2000,267(1):334-338
Expression of vascular endothelial growth factor (VEGF) by cultured vascular smooth muscle cells was analyzed. Serum and hypoxia had nearly additive actions on VEGF mRNA expression. The function of the VEGF promoter in smooth muscle cells was analyzed using transient luciferase reporter assays. Serum and hypoxia stimulated expression of luciferase. The presence of hypoxia response element (HRE) was necessary for the hypoxic induction. AP-1 sequences located upstream of HRE and AP-2/Sp-1 sequences located downstream of HRE are not necessary. Hypoxic responses were best observed in serum-deprived cells. They were largely absent in serum-stimulated cells. Serum did not suppress the hypoxic response by interfering with the hypoxia sensor mechanism or with the signaling cascade that leads to the activation of HIF-1. It is concluded that growth-promoting cytokines regulate hypoxic gene induction in smooth muscle cells. 相似文献
17.
Pitts KR Toombs CF 《American journal of physiology. Heart and circulatory physiology》2004,287(4):H1801-H1812
In vitro experimental models designed to study the effects of hypoxia and ischemia typically employ oxygen-depleted media and/or hypoxic chambers. These approaches, however, allow for metabolites to diffuse away into a large volume and may not replicate the high local concentrations that occur in ischemic myocardium in vivo. We describe herein a novel and simple method for creating regional hypoxic and ischemic conditions in neonatal rat cardiac myocyte monolayers. This method consists of creating a localized diffusion barrier by placing a glass coverslip over a portion of the monolayer. The coverslip restricts covered myocytes to a thin film of media while leaving uncovered myocytes free to access the surrounding bulk media volume. Myocytes under the coverslip undergo marked morphology changes over time as assessed by video microscopy. Fluorescence microscopy shows that these changes are accompanied by alterations in mitochondrial membrane potential and plasma membrane dynamics and eventually result in myocyte death. We also show that the metabolic activity of myocytes drives cell necrosis under the coverslip. In addition, the intracellular pH of synchronously contracting myocytes under the coverslip drops rapidly, which further implicates metabolic activity in regulating cell death under the coverslip. In contrast with existing models of hypoxia/ischemia, this technique provides a simple and effective way to create hypoxic/ischemic conditions in vitro. Moreover, we conclude that myocyte death is hastened by the combination of hypoxia, metabolites, and acidosis and is facilitated by a reduction in media volume, which may better represent ischemic conditions in vivo. 相似文献
18.
Felaco M Grilli A Gorbunov N Di Napoli P De Lutiis MA Di Giulio C Taccardi AA Barsotti A Barbacane RC Reale M Conti P 《Biochimica et biophysica acta》2000,1524(2-3):203-211
Induction of endothelial nitric oxide synthase (eNOS) contributes to the mechanism of heart protection against ischemia-reperfusion damage. We analyzed the effects of hypoxia and hyperoxia on eNOS expression in isolated working rat hearts after ischemia-reperfusion damage. Adult male Wistar rats were submitted to chronic hypoxia (2 weeks) and hyperoxia (72 h). The hearts were submitted to 15 min of ischemia and reperfused for 60 min, then we evaluated hemodynamic parameters and creatine phosphokinase (CPK) release. eNOS expression was estimated by RT-PCR; enzyme localization was evaluated by immunohistochemistry and the eNOS protein levels were detected by Western blot. All hemodynamic parameters in hypoxic conditions were better with respect to other groups. The CPK release was lower in hypoxic (P<0.01) than in normoxic and hyperoxic conditions. The eNOS deposition was significantly higher in the hypoxic group versus the normoxic or hyperoxic groups. The eNOS protein and mRNA levels were increased by hypoxia versus both other groups. Chronic hypoxic exposure may decrease injury and increase eNOS protein and mRNA levels in heart subjected to ischemia-reperfusion. 相似文献
19.
E Nobili MD Salvado L Folkersen L Castiglioni J Kastrup A Wetterholm E Tremoli GK Hansson L Sironi JZ Haeggström A Gabrielsen 《PloS one》2012,7(7):e41786