Smooth muscle tissues express a major dominant negative splice variant of the type 3 Ca2+ release channel (Ryanodine receptor)
Smooth muscle tissues express a major dominant negative splice variant of the type 3 Ca2+ release channel (Ryanodine receptor)
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DOI：
10.1074/jbc.m210410200
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发表时间：
2003-02-14
影响因子：
4.8
通讯作者：
Chen, SRW
中科院分区：
文献类型：
--
作者：
Jiang, DW;Xiao, BL;Chen, SRW
众所周知，3型Ca 2+释放通道（ryanodine receptor，RyR 3）根据其所在的组织表现出显著不同的药理学和功能特性。为了研究这种组织依赖性异质性的分子基础，我们通过逆转录聚合酶链反应和DNA序列分析研究了来自各种组织的RyR 3的一级结构。检测到多达7种RyR 3的可变剪接变体。核糖核酸酶保护试验显示，这些剪接变体之一RyR 3（AS-8a），缺乏一个29个氨基酸的片段（His（4406）-Lys（4434）），包含一个预测的跨膜螺旋，在平滑肌组织中高度表达，但不在骨骼肌，心脏，或大脑。尽管RyR 3（AS-8a）剪接变体在HEK 293细胞中单独表达时不形成功能性Ca 2+释放通道，但当与野生型RyR 3共表达时，其能够形成具有降低的咖啡因敏感性的功能性异聚体通道。有趣的是，这种RyR 3剪接变体也能够与2型ryanodine受体（RyR 2）形成异聚体通道并抑制其活性。因此，RyR 3剪接变体的组织特异性表达可能解释RyR 3的一些药理学和功能异质性。这些观察结果还揭示了一种新的机制，其中一种RyR亚型（RyR 3）的剪接变体可以通过显性负效应抑制另一种RyR亚型（RyR 2）的活性。
It is well known that the type 3 Ca2+ release channel (ryanodine receptor, RyR3) exhibits strikingly different pharmacological and functional properties depending on the tissues in which it resides. To investigate the molecular basis for this tissue-dependent heterogeneity, we examined the primary structure of RyR3 from various tissues by reverse transcription polymerase chain reaction and DNA sequence analysis. As many as seven alternatively spliced variants of RyR3 were detected. Ribonuclease protection assays revealed that one of these splice variants, RyR3 (AS-8a), which lacks a 29-amino acid fragment (His(4406)-Lys(4434)) encompassing a predicted transmembrane helix, was highly expressed in smooth muscle tissues, but not in skeletal muscle, the heart, or the brain. Although the RyR3 (AS-8a) splice variant did not form a functional Ca2+ release channel when expressed alone in HEK293 cells, it was able to form functional heteromeric channels with reduced caffeine sensitivity when co-expressed with the wild type RyR3. Interestingly, this RyR3 splice variant was also able to form heteromeric channels with and suppress the activity of the type 2 ryanodine receptor (RyR2). Tissue-specific expression of RyR3 splice variants is therefore likely to account for some of the pharmacological and functional heterogeneities of RyR3. These observations also reveal a novel mechanism by which a splice variant of one RyR isoform (RyR3) can suppress the activity of another RyR isoform (RyR2) via a dominant negative effect.