Rho-family GTPases modulate Ca2+-dependent ATP release from astrocytes
Rho-family GTPases modulate Ca2+-dependent ATP release from astrocytes
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DOI：
10.1152/ajpcell.00175.2008
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发表时间：
2008-07-01
影响因子：
5.5
通讯作者：
Dubyak, George R.
中科院分区：
文献类型：
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作者：
Blum, Andrew E.;Joseph, Sheldon M.;Dubyak, George R.
先前，我们报道了1321N1人星形细胞瘤细胞中G蛋白偶联受体（GPCR）的激活引发ATP的快速释放，该释放部分依赖于Gq/磷脂酶C (PLC)/Ca2+动员信号级联。在这项研究中，我们评估了rho家族GTPase信号作为ATP释放调节的额外途径，以响应蛋白酶激活受体-1 （PAR1）、溶血磷脂酸受体（LPAR）和m3 -毒毒碱（M3R） gpcr的激活。凝血酶（或其他PAR1肽激动剂）、LPA和carbachol在数量上触发类似的Ca2+动员反应，但只有凝血酶和LPA引起活性gtp结合的Rho的快速积累。诱导Rho激活的能力与凝血酶和LPA作为ATP分泌剂的显著更高的功效相关。艰难梭菌毒素B和肉毒梭菌C3外酶能抑制rho - gtpase，减少凝血酶和lpa刺激的ATP释放，但不减少碳甾醇刺激的释放。因此，某些gq偶联受体额外刺激rho - gtpase的能力可以强烈增强Ca2+激活的ATP释放途径。然而，Rho激酶I/II或肌球蛋白轻链激酶的药理抑制并没有减弱ATP的释放。par1诱导的ATP释放也被brefeldin治疗减少了两倍，这表明可能动员了高尔基衍生的含有ATP的分泌囊泡。在没有凝血酶引起的表明半通道门控的膜通透性改变的情况下，间隙连接通道抑制剂卡贝诺洛酮也能显著抑制ATP的释放。
Previously, we reported that activation of G protein-coupled receptors (GPCR) in 1321N1 human astrocytoma cells elicits a rapid release of ATP that is partially dependent on a Gq/phophospholipase C (PLC)/Ca2+ mobilization signaling cascade. In this study we assessed the role of Rho-family GTPase signaling as an additional pathway for the regulation of ATP release in response to activation of protease-activated receptor-1 (PAR1), lysophosphatidic acid receptor (LPAR), and M3-muscarinic (M3R) GPCRs. Thrombin (or other PAR1 peptide agonists), LPA, and carbachol triggered quantitatively similar Ca2+ mobilization responses, but only thrombin and LPA caused rapid accumulation of active GTP-bound Rho. The ability to elicit Rho activation correlated with the markedly higher efficacy of thrombin and LPA, relative to carbachol, as ATP secretagogues. Clostridium difficile toxin B and Clostridium botulinum C3 exoenzyme, which inhibit Rho-GTPases, attenuated the thrombin- and LPA-stimulated ATP release but did not decrease carbachol-stimulated release. Thus the ability of certain Gq-coupled receptors to additionally stimulate Rho-GTPases acts to strongly potentiate a Ca2+-activated ATP release pathway. However, pharmacological inhibition of Rho kinase I/II or myosin light chain kinase did not attenuate ATP release. PAR1-induced ATP release was also reduced twofold by brefeldin treatment suggesting the possible mobilization of Golgi-derived, ATP-containing secretory vesicles. ATP release was also markedly repressed by the gap junction channel inhibitor carbenoxolone in the absence of any obvious thrombin- induced change in membrane permeability indicative of hemichannel gating.