cAMP controls cytosolic Ca2+ levels in Dictyostelium discoideum.
cAMP controls cytosolic Ca2+ levels in Dictyostelium discoideum.
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DOI：
10.1186/1471-2121-6-12
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发表时间：
2005-03-07
期刊：
影响因子：
--
通讯作者：
Schlatterer C
中科院分区：
文献类型：
--
作者：
Lusche DF;Bezares-Roder K;Happle K;Schlatterer C
分化中的盘基网柄藻对cAMP刺激的反应是细胞内游离Ca 2+浓度（[Ca 2 +]i）的增加，其由储存的Ca 2+的释放和细胞外Ca 2+内流组成。在这项研究中，我们研究了细胞内cAMP是否参与[Ca 2 +]i的控制。我们分析了Ca 2+通量的突变体是缺乏主要的cAMP-磷酸二酯酶（PDE）RegA和显示改变cAMP代谢。与野生型相比，在发育细胞的悬浮液中，cAMP激活的细胞外Ca 2+流入减少。然而，regA-阿米巴原虫的单细胞[Ca 2 +] i成像显示cAMP诱导的[Ca 2 +]i增加，即使在细胞外Ca 2+不存在的情况下。cAMP PDE抑制剂3-异丁基-1-甲基黄嘌呤（IBMX）的胞质存在诱导升高的基础[Ca 2 +]i在突变体和野生型细胞。在此条件下，野生型细胞在名义上无Ca 2+的培养基中也显示cAMP激活的[Ca 2 +] i-瞬变。在突变株中，光散射振荡和伴随的cAMP振荡的振幅强烈降低到几乎基础水平。此外，EGTA孵育改变了cAMP填充玻璃毛细管激发期间的趋化性能。细胞比野生型对EGTA处理更敏感：已经在2 mM EGTA下，仅小伪足延伸，趋化速度降低。我们的结论是，有第二信使cAMP和Ca 2+之间的联系。cAMP依赖性蛋白激酶（PKA）可以提供这种联系，因为膜渗透性PKA激活剂也增加regA-细胞的基础[Ca 2 +]i。细胞内cAMP水平通过调节钙库的钙流来控制[Ca 2 +]i，而钙库的钙流又影响钙内流、光散射振荡和趋化性能。
Differentiating Dictyostelium discoideum amoebae respond upon cAMP-stimulation with an increase in the cytosolic free Ca2+ concentration ([Ca2+]i) that is composed of liberation of stored Ca2+ and extracellular Ca2+-influx. In this study we investigated whether intracellular cAMP is involved in the control of [Ca2+]i. We analyzed Ca2+-fluxes in a mutant that is devoid of the main cAMP-phosphodiesterase (PDE) RegA and displays an altered cAMP metabolism. In suspensions of developing cells cAMP-activated influx of extracellular Ca2+ was reduced as compared to wild type. Yet, single cell [Ca2+]i-imaging of regA- amoebae revealed a cAMP-induced [Ca2+]i increase even in the absence of extracellular Ca2+. The cytosolic presence of the cAMP PDE inhibitor 3-isobutyl-1-methylxanthine (IBMX) induced elevated basal [Ca2+]i in both, mutant and wild type cells. Under this condition wild type cells displayed cAMP-activated [Ca2+]i-transients also in nominally Ca2+-free medium. In the mutant strain the amplitude of light scattering oscillations and of accompanying cAMP oscillations were strongly reduced to almost basal levels. In addition, chemotactic performance during challenge with a cAMP-filled glass capillary was altered by EGTA-incubation. Cells were more sensitive to EGTA treatment than wild type: already at 2 mM EGTA only small pseudopods were extended and chemotactic speed was reduced. We conclude that there is a link between the second messengers cAMP and Ca2+. cAMP-dependent protein kinase (PKA) could provide for this link as a membrane-permeable PKA-activator also increased basal [Ca2+]i of regA- cells. Intracellular cAMP levels control [Ca2+]i by regulating Ca2+-fluxes of stores which in turn affect Ca2+-influx, light scattering oscillations and chemotactic performance.
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影响因子：
11.4
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Thomason, PA;Traynor, D;Kay, RR
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