Decrease in thromboxane A₂ receptor expression by differentiation with dibutyryl cyclic AMP in 1321N1 human astrocytoma cells

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• 作者：Shigeyoshi Honma ; Norimichi Nakahata ; Hiroshi Kobayashi ; Shizuyo Ikeda ; Noriko Takeda ; Yasushi Ohizumi
• 关键词：Glial cells ; G_q/11 ; Phospholipase C ; Immunoblotting ; TXA₂ receptor mRNA
• 刊名：Prostaglandins and Other Lipid Mediators
• 出版年：1999
• 出版时间：August 1999
• 年：1999
• 卷：58
• 期：1
• 页码：51-62
• 全文大小：270 K

文摘

Thromboxane A₂ (TXA₂) receptor expression with its signaling was investigated in 1321N1 human astrocytoma cells differentiated with dibutyryl cyclic AMP (dbcAMP). The cells cultured in 0.5 % fetal calf serum containing 0.5 mM dbcAMP for 3 days showed the star-shaped morphology, accompanied with the reduction of a TXA₂ mimetic U46619-induced phosphoinositide hydrolysis and Ca²⁺ mobilization. Immunoblotting analysis revealed that human astrocytoma cells expressed phospholipase C (PLC)-β1 and -β3, but not PLC-β2. The contents of PLC-β1 and β3 were not changed by the differentiation. The α subunit of G_q/11 bound to TXA₂-receptor was reduced by the differentiation, determined by immunoblotting after immunoprecipitation with an anti-TXA₂-receptor antibody. Scatchard analysis of the binding of [³H]SQ29548, a TXA₂ receptor antagonist, to the membranes revealed that the maximum binding site was reduced by the differentiation. The expression of TXA₂ receptor mRNA also was reduced by the differentiation, determined by reverse-transcribed-polymerase chain reaction. Although placental type of TXA₂ receptor mRNA expression increased after the differentiation, endothelial type of TXA₂ receptor mRNA expression slightly decreased. The results suggest that 1321N1 human astrocytoma cells differentiated with dbcAMP show impaired TXA₂ receptor-mediated phosphoinositide hydrolysis and Ca²⁺ mobilization, due to the decrease in TXA₂ receptor number.