Neary J T, McCarthy M, Kang Y, Zuniga S
Department of Pathology, University of Miami School of Medicine, FL 33125, USA.
Neurosci Lett. 1998 Feb 20;242(3):159-62. doi: 10.1016/s0304-3940(98)00067-6.
To investigate potential trophic actions of extracellular ATP in human astrocytes, we have examined mitogenic signaling by purinergic receptors in cultures prepared from first trimester rostral central nervous system tissue. We found that ATP and ATPgammaS, a hydrolysis-resistant analog, stimulated DNA synthesis, thereby indicating that P2 purinergic receptors can stimulate mitogenic signaling in these cells. In addition, ATP activated a mitogen-activated protein kinase (MAPK) termed ERK (extracellular signal-regulated protein kinase), a key component of signal transduction pathways involved in cellular proliferation and differentiation. The activation of MAPK was mediated at least in part by P2 purinergic receptors, because a P2 purinoceptor antagonist, suramin, inhibited the ATP-evoked stimulation by 50%, whereas a P1 purinergic-receptor antagonist, 8-(para-sulfonphenyl)-theophylline, was without effect. In contrast to rat astrocytes, adenosine/P1 purinergic-receptor agonists, 2-chloroadenosine and 5'-N-ethylcarboxyamidoadenosine, stimulated MAPK activity and DNA synthesis in human astrocytes. A selective inhibitor of protein kinase C, Ro 31-8220, blocked the ability of ATP and adenosine analogs to stimulate MAPK, thereby indicating that protein kinase C is upstream of MAPK in both P2- and P1-receptor signaling pathways. An inhibitor of the MAPK activator MEK, PD 098059, effectively blocked ATP- and 2-chloroadenosine-induced DNA synthesis, thereby indicating that the ERK/MAPK cascade mediates mitogenic signaling by P2 and P1 purinergic receptors in human fetal astrocytes. These findings suggest a role for P1 and P2 purinergic receptors in the proliferation of human fetal astrocytes.
为了研究细胞外ATP对人星形胶质细胞的潜在营养作用，我们检测了从孕早期延髓中枢神经系统组织制备的培养物中嘌呤能受体介导的有丝分裂信号。我们发现ATP和ATPγS（一种抗水解类似物）可刺激DNA合成，这表明P2嘌呤能受体可在这些细胞中刺激有丝分裂信号。此外，ATP激活了一种名为ERK（细胞外信号调节蛋白激酶）的丝裂原激活蛋白激酶，它是参与细胞增殖和分化的信号转导途径的关键组成部分。MAPK的激活至少部分由P2嘌呤能受体介导，因为P2嘌呤受体拮抗剂苏拉明可抑制ATP诱发的刺激达50%，而P1嘌呤能受体拮抗剂8-（对磺苯基）茶碱则无此作用。与大鼠星形胶质细胞不同，腺苷/P1嘌呤能受体激动剂2-氯腺苷和5'-N-乙基羧酰胺腺苷可刺激人星形胶质细胞中的MAPK活性和DNA合成。蛋白激酶C的选择性抑制剂Ro 31-8220可阻断ATP和腺苷类似物刺激MAPK的能力，这表明蛋白激酶C在P2和P1受体信号通路中均位于MAPK的上游。MAPK激活剂MEK的抑制剂PD 098059可有效阻断ATP和2-氯腺苷诱导的DNA合成，这表明ERK/MAPK级联在人胎儿星形胶质细胞中介导P2和P1嘌呤能受体的有丝分裂信号。这些发现提示P1和P2嘌呤能受体在人胎儿星形胶质细胞增殖中发挥作用。
