Cell-type-specific tuning of Cav1.3 Ca(2+)-channels by a C-terminal automodulatory domain.
Cell-type-specific tuning of Cav1.3 Ca(2+)-channels by a C-terminal automodulatory domain.
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DOI：
10.3389/fncel.2015.00309
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发表时间：
2015
影响因子：
5.3
通讯作者：
Striessnig J
中科院分区：
文献类型：
--
作者：
Scharinger A;Eckrich S;Vandael DH;Schönig K;Koschak A;Hecker D;Kaur G;Lee A;Sah A;Bartsch D;Benedetti B;Lieb A;Schick B;Singewald N;Sinnegger-Brauns MJ;Carbone E;Engel J;Striessnig J
Cav1.3 L-型钙通道功能受C-末端自动调节结构域（CTM）调节。它影响钙调蛋白的通道结合，从而通过干扰Ca 2+和电压依赖性门控来调节通道活性。选择性剪接产生缺乏CTM的短C-末端通道变体，导致在异源表达时增强的Ca 2+依赖性失活和更强的电压敏感性。然而，这个调节结构域在其天然环境中对通道功能的作用是未知的。为了确定其在体内的功能意义，我们在突变小鼠（Cav1.3DCRDHA/HA）中用血凝素标签中断CTM。使用这些小鼠，我们提供了脑中存在长（含CTM）和短（CTM缺乏）Cav1.3 α1-亚基的生化证据。长（HA标记）Cav1.3亚型存在于耳蜗内毛细胞的所有带状突触。CTM消除受损的Ca 2+依赖性失活的Ca 2+电流的毛细胞，但增加它在嗜铬细胞，导致超极化的静息电位和减少起搏。CTM中断不影响听力阈值。我们表明，CTM的调节功能是由其在不同的细胞中的天然环境的影响，从而发生在一个细胞类型特异性的方式在体内。它稳定正常电兴奋性所需的Cav1.3通道的门控特性。
Cav1.3 L-type Ca2+-channel function is regulated by a C-terminal automodulatory domain (CTM). It affects channel binding of calmodulin and thereby tunes channel activity by interfering with Ca2+- and voltage-dependent gating. Alternative splicing generates short C-terminal channel variants lacking the CTM resulting in enhanced Ca2+-dependent inactivation and stronger voltage-sensitivity upon heterologous expression. However, the role of this modulatory domain for channel function in its native environment is unkown. To determine its functional significance in vivo, we interrupted the CTM with a hemagglutinin tag in mutant mice (Cav1.3DCRDHA/HA). Using these mice we provide biochemical evidence for the existence of long (CTM-containing) and short (CTM-deficient) Cav1.3 α1-subunits in brain. The long (HA-labeled) Cav1.3 isoform was present in all ribbon synapses of cochlear inner hair cells. CTM-elimination impaired Ca2+-dependent inactivation of Ca2+-currents in hair cells but increased it in chromaffin cells, resulting in hyperpolarized resting potentials and reduced pacemaking. CTM disruption did not affect hearing thresholds. We show that the modulatory function of the CTM is affected by its native environment in different cells and thus occurs in a cell-type specific manner in vivo. It stabilizes gating properties of Cav1.3 channels required for normal electrical excitability.