Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Key pathway”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,459 records · Page 81Linked to original sources
PubMed2003

Molecular characterization of the canine HMGB1.

Due to the close similarities of numerous canine diseases to their human counterparts, the dog could join the mouse as the species of choice to unravel the genetic background of complex diseases as e.g. cancer and metabolic diseases. Accordingly, the role of the dog as a model for therapeutic approaches is strongly increasing. However, prerequisite for such studies is the characterization of the corresponding canine genes. Recently, the human high mobility group protein B1 (HMGB1) has attracted considerable interest of oncologists because of what is called its "double life". Besides its function as an architectural transcription factor HMGB1 can also be secreted by certain cells and then acts as a ligand for the receptor for advanced glycation end products (RAGE). The binding of HMGB1 to RAGE can activate key cell signaling pathways, such as p38(MAPK), JNK, and p42/p44(MAPK) emphasizing the important role of HMGB1 in inflammation and tumor metastasis. These results make HMGB1 a very interesting target for therapeutic studies done in model organisms like the dog. In this study we characterized the molecular structure of the canine HMGB1 gene on genomic and cDNA levels, its predicted protein, the gene locus and a basic expression pattern.

Amino Acid Sequence↗
PubMed2003

Molecular biology of medulloblastoma therapy.

Molecular biological studies have created a new understanding of medulloblastomas, revealing key cell signaling pathways that promote tumor growth. These studies have identified molecular markers that can serve as prognostic indicators and which will provide therapeutic targets in the very near future. In contrast to conventional histological techniques, molecular biological methods are designed to detect highly unstable molecules degraded by conventional tissue collection and fixation protocols. Consequently, a new approach to tissue collection is required for molecular analysis as we enter the next era of brain tumor therapy.

Biomarkers, Tumor↗
PubMed2005

Understanding platelets. Lessons from proteomics, genomics and promises from network analysis.

New large-scale analysis techniques such as bioinformatics, mass spectrometry and SAGE data analysis will allow a new framework for understanding platelets. This review analyses some important options and tasks for these tools and examines an outline of the new, refined picture of the platelet outlined by these new techniques. Looking at the platelet-specific building blocks of genome, (active) transcriptome and proteome (notably secretome and phospho-proteome), we summarize current bioinformatical and biochemical approaches, tasks as well as their limitations. Understanding the surprisingly complex platelet regarding compartmentalization, key cascades, and pathways including clinical implications will remain an exciting and hopefully fruitful challenge for the future.

Animals↗
PubMed2006

Soluble CD40L levels are regulated by the -3459 A>G polymorphism and predict myocardial infarction and the efficacy of antithrombotic treatment in non-ST elevation acute coronary syndrome.

OBJECTIVE: Current evidence suggests the CD40-CD40L pathway as a key process in the development, progression, and outcome of acute coronary syndrome (ACS). The aim was to investigate the prognostic importance of soluble (s) CD40L levels, single nucleotide polymorphisms (SNP) in the CD40LG gene, and the relation between sCD40L and SNPs in patients with acute coronary syndromes (ACS). METHODS AND RESULTS: Samples were obtained on admission from 2359 patients with non-ST elevation ACS randomized to an early invasive versus a conservative and to placebo controlled long-term dalteparin treatment in the FRISC-II study. The -3459 A>G SNP was identified as a novel regulator of sCD40L levels (P = 0.001). In the placebo-treated group, sCD40L levels above median were associated with a 2.5-fold increased risk of myocardial infarction (MI) (P < or = 0.001) but not with raised mortality. In the dalteparin treated group, sCD40L showed no association with MI (P = 0.75). Consequently, dalteparin treatment was effective in reducing the risk of MI only in patients with sCD40L levels above median. A combined assessment of troponin-T and sCD40L complemented the prognostic information on risk of MI. CONCLUSIONS: We identified a SNP in the CD40LG gene as a novel regulator of sCD40L plasma concentrations. Soluble CD40L levels above median reflect a prothrombotic state, which can be managed with the use of intense anti-thrombotic treatments.

Acute Disease↗
PubMed2003

Phosphorylation of the IKs channel complex inhibits drug block: novel mechanism underlying variable antiarrhythmic drug actions.

BACKGROUND: IKs, an important repolarizing current in heart, is an antiarrhythmic drug target and is markedly increased by activation of protein kinase A (PKA; eg, by beta-adrenergic stimulation). Because beta-adrenergic stimulation is a frequent trigger of arrhythmias, we hypothesized that PKA stimulation inhibits drug block. METHODS AND RESULTS: CHO cells were transfected with KCNQ1 cDNA (encoding the pore-forming subunit) with or without the ancillary subunit KCNE1. IC50 for quinidine block of basal IKs was 5.8+/-1.2 micromol/L, versus 19.9+/-3.2 micromol/L (P<0.01) for PKA-stimulated current. A similar >3-fold shift was apparent in the absence of KCNE1 and with the IKs-specific blocker chromanol 293B. The first current recorded after channels were held at rest and exposed to the drug was reduced approximately 40%, and further depolarizations increased the block with a time constant (tau) of 181+/-27 seconds. By contrast, PKA-stimulated channels displayed a <5% first-pulse block and much slower block development (tau=405+/-85 seconds). Alanine substitution at 3 potential PKA target sites (S27, S468, and T470) generated an IKs that did not increase with PKA stimulation; this mutant retained wild-type drug sensitivity that was unaffected by PKA. CONCLUSIONS: Activation of this key intracellular signaling pathway blunts drug block. The onset of block and the data with the PKA-resistant mutant support the concept that phosphorylation of the KCNQ1 subunit directly modulates drug access to a binding site on the channel. These data identify a novel mechanism for modulation of drug-channel interactions that may be especially important during beta-adrenergic stimulation.

Adrenergic alpha-Antagonists↗
PubMed1995

Tetrahydrobiopterin and dysfunction of endothelial nitric oxide synthase in coronary arteries.

BACKGROUND: The L-arginine/nitric oxide pathway plays a key role in the regulation of arterial tone. Biosynthesis of nitric oxide requires activation of nitric oxide synthase in the presence of tetrahydrobiopterin as a cofactor. Biochemical studies demonstrated that activation of purified nitric oxide synthase at suboptimal concentrations of tetrahydrobiopterin leads to production of hydrogen peroxide. The present experiments were designed to determine whether in coronary arteries inhibition of tetrahydrobiopterin synthesis may favor nitric oxide synthase-catalyzed production of hydrogen peroxide. METHODS AND RESULTS: Primary branches of canine left anterior descending artery were incubated for 6 hours in minimum essential medium in the presence or in the absence of the tetrahydrobiopterin synthesis inhibitor 2,4-diamino-6-hydroxypyrimidine (DAHP; 10(-2) mol/L). Arterial rings were suspended for isometric tension recording. Production of cGMP was measured by radioimmunoassay. Experiments were performed in the presence of indomethacin (10(-5) mol/L). During contractions to the thromboxane A2/prostaglandin H2 receptor agonist U46619 (10(-7) mol/L), calcium ionophore A23187 (10(-9) to 10(-6) mol/L) caused endothelium-dependent relaxations. A nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (3 x 10(-4) mol/L), significantly inhibited these relaxations. In DAHP-treated arteries, relaxations to A23187 and its stimulating effect on cGMP production were significantly reduced in the presence of catalase (1200 U/mL). By contrast, catalase did not exert any effect in rings incubated in the absence of DAHP. Furthermore, the inhibitory effect of catalase on A23187-induced relaxations was abolished when coronary arteries were incubated in the presence of DAHP plus a liposoluble analogue of tetrahydrobiopterin, 6-methyltetrahydropterin (10(-4) mol/L). CONCLUSIONS: The present study suggests that hydrogen peroxide may be a mediator of endothelium-dependent relaxations in coronary arteries depleted of tetrahydrobiopterin. This initially compensatory response, triggered by a dysfunctional nitric oxide synthase, may represent an important mechanism underlying oxidative vascular injury.

Amino Acid Oxidoreductases↗
PubMed1994

Role of the lipoxygenase pathway in angiotensin II-induced vascular smooth muscle cell hypertrophy.

The 12-lipoxygenase pathway is a key mediator of angiotensin II (Ang II)-induced effects in the adrenal cortex. We also recently demonstrated that Ang II increases 12- and 15-lipoxygenase product levels in vascular smooth muscle cells. However, the relation between lipoxygenase activation and Ang II-induced vascular smooth muscle cell hypertrophy is not known. We studied the effects of Ang II and 12-lipoxygenase products on both total cell protein content and the levels of the matrix protein fibronectin in quiescent porcine aortic smooth muscle cells. Ang II-induced increases in cellular protein content were attenuated by the specific 12-lipoxygenase inhibitor baicalein; in contrast, the cyclooxygenase inhibitor ibuprofen had no effect. Direct addition of the 12-lipoxygenase product 12-S-hydroxyeicosatetraenoic acid increased total cell protein content. We have recently shown that porcine vascular smooth muscle cell growth is potentiated in high glucose (25 mmol/L) culture conditions. We observed that both Ang II and 12-S-hydroxyeicosatetraenoic acid induced a greater increase in protein content in cells cultured for two passages in high glucose. Furthermore, Ang II and 12-S-hydroxyeicosatetraenoic acid also markedly increased fibronectin levels in cells cultured in high glucose. These results suggest that 12-lipoxygenase activation plays a key role in Ang II-induced vascular smooth muscle cell hypertrophy. Furthermore, both Ang II and lipoxygenase effects are enhanced in cells cultured under hyperglycemic conditions.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed2003

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) sequentially upregulates nitric oxide and prostanoid production in primary human endothelial cells.

Endothelial cells express tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors, but the function of TRAIL in endothelial cells is not completely understood. We explored the role of TRAIL in regulation of key intracellular signal pathways in endothelial cells. The addition of TRAIL to primary human endothelial cells increased phosphorylation of endothelial nitric oxide synthase (eNOS), NOS activity, and NO synthesis. Moreover, TRAIL induced cell migration and cytoskeleton reorganization in an NO-dependent manner. TRAIL did not activate the NF-kappaB or COX-2 pathways in endothelial cells. Instead, TRAIL increased prostanoid production (PGE2=PGI2>TXA2), which was preferentially inhibited by the COX-1 inhibitor SC-560. Because NO and prostanoids play a crucial role in the state of blood vessel vasodilatation and angiogenesis, our data suggest that TRAIL might play an important role in endothelial cell function.

Actins↗
PubMed2006

Regulation of smooth muscle cell proliferation by beta-catenin/T-cell factor signaling involves modulation of cyclin D1 and p21 expression.

We previously observed that stimulation of vascular smooth muscle cell (VSMC) proliferation with growth factors is associated with dismantling of cadherin junctions and nuclear translocation of beta-catenin. In this study we demonstrate directly that growth factors stimulate beta-catenin/T-cell factor (TCF) signaling in primary VSMCs. To determine whether beta-catenin/TCF signaling regulates VSMC proliferation via modulation of the beta-catenin/TCF responsive cell cycle genes, cyclin D1 and p21, we inhibited beta-catenin/TCF signaling by adenoviral-mediated over-expression of N-Cadherin, ICAT (an endogenous inhibitor of beta-catenin/TCF signaling), or a dominant negative (dn) mutant of TCF-4. N-cadherin, ICAT or dnTCF-4 over-expression significantly reduced proliferation of isolated human VSMCs by approximately 55%, 80%, and 45% respectively. Similar effects were observed in human saphenous vein medial segments where proliferation was reduced by approximately 55%. Transfection of dnTCF-4 in the ISS10 human VSMC line significantly lowered TCF and cyclin D1 reporter activity but significantly elevated p21 reporter activity, indicating regulation of these genes by beta-catenin/TCF signaling. In support of this, over-expression of N-cadherin, ICAT or dnTCF-4 in isolated human VSMCs significantly lowered levels of cyclin D1 mRNA and protein levels. In contrast, over-expression of N-Cadherin, ICAT or dnTCF4 significantly elevated p21 mRNA and protein levels. In summary, we have demonstrated that increasing N-cadherin and inhibiting beta-catenin/TCF signaling reduces VSMC proliferation, decreases the expression of cyclin D1 and increases levels of the cell cycle inhibitor, p21. We therefore suggest that the N-cadherin and beta-catenin/TCF signaling pathway is a key modulator of VSMC proliferation via regulation of these 2 beta-catenin/TCF responsive genes.

Aorta↗
PubMed1994

A monoclonal antibody against rabbit tissue factor inhibits thrombus formation in stenotic injured rabbit carotid arteries.

Tissue factor (TF) is a transmembrane protein that binds factor VII/VIIa, thus activating the extrinsic blood coagulation pathway. Since this pathway appears to be involved in the formation of intravascular thrombi, the anti-rabbit TF monoclonal antibody, AP-1, was produced and tested as an antithrombotic agent in a rabbit model of recurrent intravascular thrombosis. In this model, a plastic constrictor is positioned around the injured rabbit carotid arteries, and flow is monitored with a Doppler flow probe. This produces cyclic flow variation (CFV) in the carotid artery, which is caused by recurrent formation and dislodgment of thrombi at the site of the stenosis. After monitoring CFV pattern for 30 minutes, AP-1 was infused intravenously into nine rabbits at doses of 0.05 to 1.5 mg/kg body weight, and a control monoclonal antibody that does not react with rabbit TF was infused into four additional rabbits. In all rabbits receiving AP-1, CFV was abolished, and a steady normal blood flow was restored, indicating that thrombus formation had been blocked by AP-1. By contrast, in all rabbits that received the control monoclonal antibody, CFV continued unaltered. There was no change in the partial thromboplastin time and ex vivo platelet aggregation to several different agonists after infusion of AP-1, indicating an absence of systemic effects on the coagulation process. We conclude that activation of the extrinsic coagulation pathway has a key role in triggering intravascular thrombosis and that an anti-TF monoclonal antibody is an effective antithrombotic agent that could have therapeutic potential for humans.

Animals↗
PubMed1993

Brain stem infarction and diaschisis. A SPECT cerebral perfusion study.

BACKGROUND AND PURPOSE: We studied six patients suffering from pure, unilateral brain stem infarction to explore the association of remote cerebral and cerebellar blood flow changes with damage at different sites of this region of the brain. METHODS: We used single-photon emission computed tomography and [123I]iodoamphetamine to measure regional differences in tracer uptake. Qualitative image analysis and calculated asymmetry indexes were correlated to the location of the infarcted area on magnetic resonance imaging and to the patients' clinical findings. RESULTS: Significant perfusion asymmetries were noted in the two patients with infarction in the upper pons but not in those with lesions below this level. They comprised a contralateral cerebellar and ipsilateral supratentorial hypoactivity that was most marked in the frontoparietal cortex. There was no clear relation between the patterns of cerebral or cerebellar tracer uptake and specific neurological findings. CONCLUSIONS: Remote perfusion changes after pure brain stem infarction may be seen both infratentorially and supratentorially and depend on the lesion site rather than on the neurological deficit. In this context, our study confirmed damage to the corticopontocerebellar pathways as the key event in the genesis of a crossed cerebellar diaschisis. The exact mechanisms causing ipsilateral cerebral hemispheric diaschisis await further clarification.

Aged↗
PubMed2002

Cysteinyl leukotrienes promote human airway smooth muscle migration.

Cysteinyl leukotrienes promote airway smooth muscle (ASM) contraction and proliferation. Little is known about their role in ASM migration. We investigated this using cultured human ASMs (between the second and fifth passages) obtained from the large airways of resected nonasthmatic lung. Platelet-derived growth factor-BB (1 ng/ml) promoted significant (3.5-fold) ASM migration of myocytes across collagen-coated 8- micro m polycarbonate membranes in Transwell culture plates. Leukotriene E(4) (10(-7), 10(-8), 10(-9) M) did not demonstrate a chemotactic effect; it did promote chemokinesis. Priming by leukotriene E(4) (10(-7) M) significantly augmented the directional migratory response to platelet-derived growth factor (1.5-fold, p < 0.05). This was blocked by montelukast (10(-6) M), demonstrating the effect to be mediated by the cysteinyl leukotriene receptor. The "priming effect" was also partially attenuated by prostaglandin E(2) (10(-7) M). Whereas both the chemokinetic and the chemotactic "primed" responses were equally attenuated by a p38 mitogen-activated protein kinase inhibitor (SB203580, 25 micro M) and by a Rho-kinase inhibitor (Y27632, 10 micro M), the chemotactic response showed greater inhibition than chemokinesis by a phosphatidylinositol-3 kinase inhibitor (LY294002, 50 micro M). These experiments suggest that cysteinyl leukotrienes play an augmentary role in human ASM migration. The phosphatidylinositol-3 kinase pathway is a key signaling mechanism in the chemotactic migration of ASM cells in response to cysteinyl leukotrienes.

Cell Movement↗
PubMed2000

Interleukin-9 upregulates mucus expression in the airways.

Interleukin (IL)-9 has recently been shown to play an important role in allergic disease because its expression is strongly associated with the degree of airway responsiveness and the asthmatic-like phenotype. IL-9 is a pleiotropic cytokine that is active on many cell types involved in the allergic immune response. Mucus hypersecretion is a clinical feature of chronic airway diseases; however, the mechanisms underlying the induction of mucin are poorly understood. In this report, we show that IL-9 regulates the expression of a subset of mucin genes in lung cells both in vivo and in vitro. In vivo, the constitutive expression of IL-9 in transgenic mice results in elevated MUC2 and MUC5AC gene expression in airway epithelial cells and periodic acid-Schiff-positive staining (reflecting mucous glycogenates). Similar results were observed in C57BL/6J mice after IL-9 intratracheal instillation. In contrast, instillation of the T helper 1-associated cytokine interferon gamma failed to induce mucin production. In vitro, our studies showed that IL-9 also induces expression of MUC2 and MUC5AC in human primary lung cultures and in the human muccoepidermoid NCI-H292 cell line, indicating a direct effect of IL-9 on inducing mucin expression in these cells. Altogether, these results suggest that upregulation of mucin by IL-9 might contribute to the pathogenesis of human inflammatory airway disorders, such as asthma. These data extend the role of the biologic processes that IL-9 has on regulating the many clinical features of asthma and further supports the IL-9 pathway as a key mediator of the asthmatic response.

Animals↗
PubMed2003

Differential activation of phosphatidylinositol 3-kinase signaling during proliferation and differentiation of lens epithelial cells.

PURPOSE: To investigate whether phosphatidylinositol 3-kinase (PI-3K) signaling is involved in lens epithelial cell proliferation and differentiation promoted by growth factors. METHODS: Proliferation of rabbit lens epithelial cells grown in culture was measured with a DNA-binding fluorescent dye in a proliferation assay. Primary cultures of embryonic chicken lens epithelial cells that develop lentoids were used for differentiation-related studies, and delta-crystallin synthesis in these cultures was determined by metabolic labeling with [(35)S]methionine. Immunoprecipitation and immunoblot analyses were also used. RESULTS: The PI-3K inhibitors wortmannin and LY294002 blocked the insulin-, insulin-like growth factor (IGF)-1-, and fibroblast growth factor (FGF)-2-promoted cell proliferation in rabbit lens epithelial cells. Inhibition of PI-3K activity by these inhibitors unexpectedly increased the synthesis of early differentiation marker protein delta-crystallin in chicken lens epithelial cells. Insulin and IGF-1 stimulated activation of PI-3K in proliferating and differentiating cultures. FGF-2 showed no direct effect on PI-3K activation. Platelet-derived growth factor (PDGF) did not induce significant proliferation or increased expression of delta-crystallin, but stimulated PI-3K. The presence of FGF-2 in proliferating rabbit lens epithelial cells enhanced the IGF-1-, but not the PDGF-mediated PI-3K activation, suggesting a possible integration of FGF-2 signals with IGF-1. Whereas there was a gradual decrease in insulin/IGF-1-mediated activation of PI-3K and its downstream target Akt, with progression of differentiation in chicken lens epithelial cells, Erk2 phosphorylation induced by these growth factors was not decreased; rather, it remained increased in early stages of differentiation. CONCLUSIONS: The results reveal significant differences in the modulation of PI-3K signaling by different growth factors during proliferation in rabbit lens epithelial cells and differentiation in chicken lens epithelial cells and demonstrate that regulation of the PI-3K pathway plays a key role in these processes. A balance between the nonactivation of PI-3K and the activation of Erk2 may be necessary during early stages of epithelial cell transformation.

Animals↗
PubMed1987

Specific action of the lipoxygenase pathway in mediating angiotensin II-induced aldosterone synthesis in isolated adrenal glomerulosa cells.

Angiotensin II (AII) in adrenal glomerulosa cells activates phospholipase C resulting in the formation of inositol phosphates and diacylglycerol rich in arachidonic acid (AA). Although glomerulosa cells can metabolize AA via cyclooxygenase (CO), this pathway plays little role in aldosterone synthesis. Recent evidence suggests that the lipoxygenase (LO) pathway may be important for hormonal secretion in endocrine tissues such as the islet of Langerhans. However, the capacity of the glomerulosa cell to synthesize LO products and their role in aldosterone secretion is not known. To study this, the effect of nonselective and selective LO inhibitors on AII, ACTH, and potassium-induced aldosterone secretion and LO product formation was evaluated in isolated rat glomerulosa cells. BW755c, a nonselective LO inhibitor dose dependently reduced the AII-stimulated level of aldosterone without altering AII binding (91 +/- 6 to 36 +/- 4 ng/10(6) cells/h 10(-4) M, P less than 0.001). The same effect was observed with another nonselective LO blocker, phenidone, and a more selective 12-LO inhibitor, Baicalein. In contrast U-60257, a selective 5-LO inhibitor did not change the AII-stimulated levels of aldosterone (208 +/- 11% control, AII 10(-9) M vs. 222 +/- 38%, AII + U-60257). The LO blockers action was specific for AII since neither BW755c nor phenidone altered ACTH or K+-induced aldosterone secretion. AII stimulated the formation of the 12-LO product 12-hydroxyeicosatetraenoic acid (12-HETE) as measured by ultraviolet detection and HPLC in AA loaded cells and by a specific RIA in unlabeled cells (501 +/- 50 to 990 +/- 10 pg/10(5) cells, P less than 0.02). BW755c prevented the AII-mediated rise in 12-HETE formation. In contrast, neither ACTH nor K+ increased 12-HETE levels. The addition of 12-HETE or its unstable precursor 12-HPETE (10(-9) or 10(-8) M) completely restored AII action during LO blockade. AII also produced an increase in 15-HETE formation, but the 15-LO products had no effect on aldosterone secretion. These studies suggest that the 12-LO pathway plays a key role as a new specific mediator of AII-induced aldosterone secretion.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed2005

Megakaryocyte biology and related disorders.

Platelets, derived from megakaryocytes, have an essential role in thrombosis and hemostasis. Over the past 10 years, a great deal of new information has been obtained concerning the various aspects of hematopoiesis necessary to maintain a steady-state platelet level to support physiologic hemostasis. Here we discuss the differentiation of HSCs into megakaryocytes, with emphasis on the key cytokine signaling pathways and hematopoietic transcription factors. Recent insight into these processes elucidates the molecular bases of numerous acquired and inherited hematologic disorders. It is anticipated that the growing knowledge in these areas may be exploited for new therapeutic strategies to modulate both platelet numbers and their thrombogenicity.

Animals↗
PubMedDate not supplied

P2Y2 receptor up-regulation induced by guanosine or UTP in rat brain cultured astrocytes.

Among P2 metabotropic ATP receptors, P2Y2 subtype seems to be peculiar as its upregulation triggers important biological events in different cells types. In non-stimulated cells including astrocytes, P2Y2 receptors are usually expressed at levels lower than P2Y1 sites, however the promoter region of the P2Y2 receptors has not yet been studied and little is known about the mechanisms underlying the regulation of the expression of this ATP receptor. We showed that not only UTP and ATP are the most potent and naturally occurring agonist for P2Y2 sites, but also guanosine induced an up-regulation of astrocyte P2Y2 receptor mRNA evaluated by Northern blot analysis. We also focused our attention on this nucleoside since in our previous studies it was reported to be released by cultured astrocytes and to exert different neuroprotective effects. UTP and guanosine-evoked P2Y2 receptor up-regulation in rat brain cultured astrocytes was linked to an increased P2Y2-mediated intracellular calcium response, thus suggesting an increased P2Y2 activity. Actinomycin D, a RNA polymerase inhibitor, abrogated both UTP and guanosine-mediated P2Y2 up-regulation, thus indicating that de novo transcription was required. The effect of UTP and guanosine was also evaluated in astrocytes pretreated with different inhibitors of signal transduction pathways including ERK, PKC and PKA reported to be involved in the regulation of other cell surface receptor mRNAs. The results show that ERK1-2/MAPK pathway play a key role in the P2Y2 receptor up-regulation mediated by either UTP or guanosine. Moreover, our data suggest that PKA is also involved in guanosine-induced transcriptional activation of P2Y2 mRNA and that increased intracellular calcium levels and PKC activation may also mediate P2Y2 receptor up-regulation triggered by UTP. The extracellular release of ATP under physiological and pathological conditions has been widely studied. On the contrary, little is known about the release of pyrimidines and in particular of UTP. Here we show that astrocytes are able to release UTP, either at rest or during and following hypoxia/hypoglycemia obtained by submitting the cells to glucose-oxygen deprivation (OGD). Interestingly, also P2Y2 receptor mRNA increased by about two-fold the control values when the cultures were submitted to OGD. It has been recently reported that P2Y2 receptors can play a protective role in astrocytes, thus either guanosine administration or increased extracellular concentrations of guanosine and UTP reached locally following CNS injury may increase P2Y2-mediated biological events aimed at promoting a protective astrocyte response.

Adenosine Triphosphate↗
PubMed1996

Analysis of polymorphisms of the 2',3'-cyclic nucleotide-3'-phosphodiesterase gene in patients with multiple sclerosis.

Susceptibility to multiple sclerosis (MS) is widely held to have a genetic component. Possible candidate genes conferring this susceptibility include those coding for proteins specific to central nervous system (CNS) myelin. 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNPase) is an enzyme found at high concentrations in CNS myelin, however its function is unknown. The amino acid sequence of CNPase shows a C-terminal motif characteristic of proteins involved in signal transduction pathways, suggesting a key role in myelin function. We have analysed the entire expressed sequence of the human CNPase gene in patients with multiple sclerosis and in healthy controls using single strand conformation polymorphism (SSCP) analysis. Nine previously undescribed mutations were detected, most of these occurred with equal frequency in both groups. However, a T-->C transition at nucleotide position 4306 in the region of the gene coding for the 3' untranslated region of the mature mRNA was found in a homozygous form in two out of 54 patients but in none of 100 controls. While the significance of this is unclear, it would appear unlikely that mutations in the expressed regions of the human CPNase gene contribute to genetic susceptibility to MS in the majority of sufferers.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗