Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. B10 cells, a clonal line of rat brain capillary endothelial cells, exhibit a single P2 purinoceptor, activation of which leads to increases in free intracellular calcium. In the current study the identity of this P2Y receptor was determined by its binding parameters for a range of purinoceptor ligands and by its complementary DNA (cDNA) sequence. The signal transduction mechanism activated by this receptor was also investigated. 2. The radioligand [35S]-dATP alpha S bound with high affinity (Kd = 9.8 nM) to the P2Y purinoceptor expressed on B10 cells, which was found to be extremely abundant (Bmax = 22.5 pmol mg-1 protein). The calculated Ki values of a range of P2 purinoceptor agonists which competitively displaced binding of [35S]-dATP alpha S led to the rank order of affinity: dATP alpha S (Ki 3.4 nM) > 2-chloroATP (2-ClATP) (13 nM), ATP (22 nM) > ATP gamma S (43 nM) > 2-methylthioATP (2-MeSATP) (88 nM) > ADP (368 nM) > > UTP, L-beta,gamma-methyleneATP (both > 10,000 nM). The P2 purinoceptor antagonists, Reactive blue 2 and suramin, were also able to displace binding, with Ki values of 833 and 1358 nM respectively. In contrast pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid 4-sodium (PPADS) was able to displace only 20% of [35S]-dATP alpha S binding at a concentration of 100 microM. 3. 2-ClATP (EC50 = 0.22 microM), 2-MeSATP (0.54 microM), ADP (7.9 microM) and ATP (a partial agonist), but not UTP, inhibited the cyclic AMP formation stimulated by cholera toxin, in a manner that was prevented by pertussis toxin. The purinoceptor antagonist, PPADS, was found to be inactive at a concentration of 100 microM. 4. A P2Y receptor cDNA was derived from mRNA from B10 cells and from C6-2B, a rat glioma cell line known to possess a P2Y receptor that is coupled to the inhibition of adenylate cyclase. Sequence analysis of the entire coding region revealed that both were 100% identical to the rat P2Y1 purinoceptor cDNA. No other P2Y-type receptor mRNA could be detected in B10 cells. Exactly the same sequence was isolated from rat brain cortical astrocytes, where 2-MeSATP has been shown to increase phospholipase C activity. 5. Since the receptor responsible for the transduction shares with the aforementioned binding site significant pharmacological features, including a strong activity of 2-MeSATP (characteristic of P2Y1 receptors alone among all known P2Y purinoceptors) and an unusual insensitivity to PPADS, and since abundant mRNA is present of the P2Y1 receptor but not of any other type resembling the known P2Y receptors, it is concluded that a P2Y1 receptor on rat brain microvascular endothelial cells can account for all of the observations. This single P2Y1 receptor, therefore, appears to couple in different native cell types to either adenylate cyclase inhibition or to phospholipase C activation.
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PMID:The P2Y purinoceptor in rat brain microvascular endothelial cells couple to inhibition of adenylate cyclase. 896 47

Cyclic AMP-dependent differentiation of rat C6 glioma cells into an astrocyte type II is characterized by inhibition of cell growth and induction of glial fibrillary acidic protein (GFAP) synthesis. Activation of the P2Y(12) receptor with 2-methylthioadenosine-5'-diphosphate inhibited beta-adrenergic receptor-induced differentiation. The selective P2Y(12) receptor antagonist N(6)-(2-methylthioethyl)-2-(3,3,3-trifluoropropylthio)-beta,gamma-dichloromethylene ATP abolished the receptor-mediated effect on differentiation. In contrast non-selective antagonists of P2Y receptors did not revert the inhibiting effect of the P2Y(12) receptor on differentiation. Reactive blue 2 (RB2), a potent P2Y(12) receptor antagonist, completely inhibited the synthesis of GFAP, while the P2Y receptor antagonists suramin and pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid were less efficient. However, although P2Y receptor antagonists inhibited GFAP synthesis to a different extent they were unable to relieve the growth inhibition that accompanied induction of differentiation, whereas stimulation of the P2Y(12) receptor with 2-methylthioadenosine-5'-diphosphate inhibited GFAP expression and restored cell proliferation. Assay of the activity of phosphatidylinositol 3-kinase (PI 3-K), an enzyme required for GFAP expression [J. Neurochem. 76 (2001) 610], showed that RB2 inhibited this enzyme after cellular uptake, while suramin and pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid inhibited PI 3-K to a lesser extent. The intracellular concentration of RB2 increased in time and attained the ic(50) for PI 3-K inhibition (4microM) after 40-min incubation with 50microM RB2. In conclusion, cAMP-induced differentiation in C6 cells is inhibited by activation of the P2Y(12) receptor. In addition, synthesis of GFAP is also inhibited by cellular uptake of non-selective nucleotide receptor antagonists that inhibit PI 3-K, a kinase required for the cAMP-dependent induction of differentiation.
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PMID:Reactive blue 2 inhibition of cyclic AMP-dependent differentiation of rat C6 glioma cells by purinergic receptor-independent inactivation of phosphatidylinositol 3-kinase. 1504 66