Plasma membrane Ca2+-ATPase in the cilia of olfactory receptor neurons:: Possible role in Ca2+ clearance
Plasma membrane Ca2+-ATPase in the cilia of olfactory receptor neurons:: Possible role in Ca2+ clearance
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DOI：
10.1111/j.1460-9568.2007.05863.x
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发表时间：
2007-11-01
影响因子：
3.4
通讯作者：
Bacigalupo, Juan
中科院分区：
文献类型：
--
作者：
Castillo, Karen;Delgado, Ricardo;Bacigalupo, Juan
嗅觉感觉神经元对增加其化学感觉纤毛中的Ca 2+浓度的气味剂作出反应。钙通过cAMP门控通道进入纤毛，激活Ca 2+依赖性氯或钾通道。钙在气味适应、调节cAMP周转率和环核苷酸门控通道对cAMP的亲和力中也具有重要作用。已经表明，Na+/Ca 2+交换器（NCX）从纤毛中挤出Ca 2+。在这里，我们确认以前的证据表明，嗅纤毛也表达质膜Ca 2 +-ATP酶（PMCA），并显示第一个证据支持在Ca 2+清除的作用。这两种转运蛋白通过纯化的嗅纤毛膜的免疫印迹检测。免疫细胞化学和免疫组织化学也显示了泵。内翻纤毛膜囊泡转运Ca 2+在ATP依赖的方式。PMCA活性通过管腔Ca 2+（K-0.5 = 670 nM）增强，并通过钙调蛋白（CaM; K-0.5 = 31 nM）增强。羧化肌球蛋白（CE）和calimidazolium减少钙离子转运，预期钙调素调制的PMCA。Ca 2+依赖性Cl-电流的弛豫时间常数（tau）（272 +/- 78 ms），指示管腔Ca 2+下降，通过CE（2181 +/- 437 ms），通过省略ATP（666 +/- 49 ms）和通过升高pH（725 +/- 65 ms）增加，表明泵对Ca 2+清除的作用。用Li+替代外部Na+具有类似的效果（tau = 442 +/- 8 ms），证实了NCX参与Ca 2+挤出。证据表明，这两个Ca 2+转运蛋白有助于重建休息Ca 2+水平的纤毛嗅觉反应。
Olfactory sensory neurons respond to odorants increasing Ca2+ concentrations in their chemosensory cilia. Calcium enters the cilia through cAMP-gated channels, activating Ca2+-dependent chloride or potassium channels. Calcium also has a fundamental role in odour adaptation, regulating cAMP turnover rate and the affinity of the cyclic nucleotide-gated channels for cAMP. It has been shown that a Na+/Ca2+ exchanger (NCX) extrudes Ca2+ from the cilia. Here we confirm previous evidence that olfactory cilia also express plasma membrane Ca2+-ATPase (PMCA), and show the first evidence supporting a role in Ca2+ removal. Both transporters were detected by immunoblot of purified olfactory cilia membranes. The pump was also revealed by immunocytochemistry and immunohistochemistry. Inside-out cilia membrane vesicles transported Ca2+ in an ATP-dependent fashion. PMCA activity was potentiated by luminal Ca2+ (K-0.5 = 670 nM) and enhanced by calmodulin (CaM; K-0.5 = 31 nM). Both carboxyeosin (CE) and calmidazolium reduced Ca2+ transport, as expected for a CaM-modulated PMCA. The relaxation time constant (tau) of the Ca2+-dependent Cl- current (272 +/- 78 ms), indicative of luminal Ca2+ decline, was increased by CE (2181 +/- 437 ms), by omitting ATP (666 +/- 49 ms) and by raising pH (725 +/- 65 ms), suggesting a role of the pump on Ca2+ clearance. Replacement of external Na+ by Li+ had a similar effect (tau = 442 +/- 8 ms), confirming the NCX involvement in Ca2+ extrusion. The evidence suggests that both Ca2+ transporters contribute to re-establish resting Ca2+ levels in the cilia following olfactory responses.