Release and extracellular metabolism of ATP by ecto-nucleotidase eNTPDase 1-3 in hypothalamic and pituitary cells.
Release and extracellular metabolism of ATP by ecto-nucleotidase eNTPDase 1-3 in hypothalamic and pituitary cells.
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DOI：
10.1007/s11302-005-6208-y
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发表时间：
2005-06
影响因子：
3.5
通讯作者：
Stojilkovic, Stanko S
中科院分区：
文献类型：
--
作者：
He, Mu-Lan;Gonzalez-Iglesias, Arturo E;Tomic, Melanija;Stojilkovic, Stanko S
下丘脑和垂体细胞表达G蛋白偶联的腺苷和P2 Y受体和阳离子传导P2 X受体通道，表明细胞外ATP和其他核苷酸可能在这些细胞中起自分泌和/或旁分泌信号传导因子的作用。与这一假设相一致，我们表明，培养的正常和永生化的垂体和下丘脑细胞释放ATP在静息条件下。RT-PCR分析还揭示了这些细胞中存在外核苷酸酶eNTPDase 1-2的转录物。这些酶是功能性的，如通过内源性释放和外源性添加的ATP的降解所记录的。ARL 67156阻断eNTPDases的活性导致灌流垂体细胞中ATP释放的增加和细胞外添加的ATP降解的抑制。此外，添加腺苷三磷酸双磷酸酶，可溶性外核苷酸酶，和重组小鼠eNTPDase-2的表达，增强内源性释放和外源性添加的ATP的降解。静息下丘脑细胞释放的ATP足以激活和脱敏高亲和力重组P2 X受体，而通过加入腺苷三磷酸双磷酸酶促进ATP代谢保护其脱敏。这些结果表明，下丘脑和垂体细胞质膜上ATP释放位点和外核苷酸酶活性的共定位为核苷酸作为细胞外信号分子的操作提供了有效的机制。
Hypothalamic and pituitary cells express G protein-coupled adenosine and P2Y receptors and cation-conducting P2X receptor-channels, suggesting that extracellular ATP and other nucleotides may function as autocrine and/or paracrine signaling factors in these cells. Consistent with this hypothesis, we show that cultured normal and immortalized pituitary and hypothalamic cells release ATP under resting conditions. RT-PCR analysis also revealed the presence of transcripts for ecto-nucleotidase eNTPDase 1–2 in these cells. These enzymes were functional as documented by degradation of endogenously released and exogenously added ATP. Blocking the activity of eNTPDases by ARL67156 led to an increase in ATP release in perifused pituitary cells and inhibition of degradation of extracellularly added ATP. Furthermore, the addition of apyrase, a soluble ecto-nucleotidase, and the expression of recombinant mouse eNTPDase-2, enhanced degradation of both endogenously released and exogenously added ATP. The released ATP by resting hypothalamic cells was sufficient to activate and desensitize high-affinity recombinant P2X receptors, whereas facilitation of ATP metabolism by the addition of apyrase protected their desensitization. These results indicate that colocalization of ATP release sites and ecto-nucleotidase activity at the plasma membrane of hypothalamic and pituitary cells provides an effective mechanism for the operation of nucleotides as extracellular signaling molecules.