Institute of Physiology, Otto-von-Guericke University Magdeburg, Germany.
PLoS One. 2011;6(12):e27474. doi: 10.1371/journal.pone.0027474. Epub 2011 Dec 2.
Neuronal high-voltage-activated (HVA) Ca(2+) channels are rapidly inactivated by a mechanism that is termed Ca(2+)-dependent inactivation (CDI). In this study we have shown that β-adrenergic receptor (βAR) stimulation inhibits CDI in rat thalamocortical (TC) relay neurons. This effect can be blocked by inhibition of cAMP-dependent protein kinase (PKA) with a cell-permeable inhibitor (myristoylated protein kinase inhibitor-(14-22)-amide) or A-kinase anchor protein (AKAP) St-Ht31 inhibitory peptide, suggesting a critical role of these molecules downstream of the receptor. Moreover, inhibition of protein phosphatases (PP) with okadaic acid revealed the involvement of phosphorylation events in modulation of CDI after βAR stimulation. Double fluorescence immunocytochemistry and pull down experiments further support the idea that modulation of CDI in TC neurons via βAR stimulation requires a protein complex consisting of Ca(V)1.2, PKA and proteins from the AKAP family. All together our data suggest that AKAPs mediate targeting of PKA to L-type Ca(2+) channels allowing their phosphorylation and thereby modulation of CDI.
神经元高电压激活 (HVA) Ca(2+) 通道通过一种称为 Ca(2+) 依赖性失活 (CDI) 的机制快速失活。在这项研究中,我们已经表明,β-肾上腺素能受体 (βAR) 刺激抑制大鼠丘脑皮质 (TC) 中继神经元中的 CDI。这种效应可以通过用细胞通透抑制剂 (豆蔻酰化蛋白激酶抑制剂-(14-22)-酰胺) 或 A-激酶锚蛋白 (AKAP) St-Ht31 抑制肽抑制 cAMP 依赖性蛋白激酶 (PKA) 来阻断,表明这些分子在受体下游发挥关键作用。此外,用 okadaic 酸抑制蛋白磷酸酶 (PP) 表明在 βAR 刺激后 CDI 调节中磷酸化事件的参与。双重荧光免疫细胞化学和下拉实验进一步支持这样一种观点,即通过 βAR 刺激调节 TC 神经元中的 CDI 需要包含 Ca(V)1.2、PKA 和 AKAP 家族蛋白的蛋白质复合物。总的来说,我们的数据表明,AKAP 介导 PKA 靶向 L 型 Ca(2+) 通道,允许其磷酸化,从而调节 CDI。