Spatial distribution of inositol 1,4,5-trisphosphate receptor isoforms shapes Ca2+ waves
Spatial distribution of inositol 1,4,5-trisphosphate receptor isoforms shapes Ca2+ waves
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DOI：
10.1074/jbc.m700746200
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发表时间：
2007-03-30
影响因子：
4.8
通讯作者：
Nathanson, Michael H.
中科院分区：
文献类型：
--
作者：
Hernandez, Erick;Leite, M. Fatima;Nathanson, Michael H.
胞质Ca2+是一种多功能的第二信使，可以同时调节多种细胞过程。这部分是通过Ca2+波和Ca2+信号的其他空间模式来完成的。为了研究Ca2+波形成的机制，我们研究了肌醇1,4,5-三磷酸受体（InsP3R）异构体在Ca2+波形成中的作用。在以极化方式表达I型和II型InsP3R的肝细胞和AR4-2J细胞中检测了Ca2+信号，AR4-2J细胞是一种非极化细胞系，以与肝细胞相似的比例表达I型和II型InsP3R，但在整个细胞中均匀分布。在腺病毒传递系统中，I型或II型InsP3R的表达被异构体特异性DNA反义选择性抑制，该系统在培养中传递给AR4-2J细胞，并在体内传递给肝细胞。在AR4-2J细胞中，两种异构体的缺失对Ca2+信号的抑制程度相似。相反，基底外侧I型InsP3R的缺失降低了肝细胞对抗利尿激素的敏感性，但对肝细胞内Ca2+波的启动或传播几乎没有影响。顶端II型异构体的缺失导致肝细胞对抗利尿激素的敏感性更大的下降，并导致Ca2+波的发生更慢和延迟。这些发现提供了证据，证明II型InsP3Rs的顶点浓度对肝细胞中Ca2+波的形成至关重要。InsP3R亚型的亚细胞分布可能决定Ca2+信号的空间模式。
Cytosolic Ca2+ is a versatile second messenger that can regulate multiple cellular processes simultaneously. This is accomplished in part through Ca2+ waves and other spatial patterns of Ca2+ signals. To investigate the mechanism responsible for the formation of Ca2+ waves, we examined the role of inositol 1,4,5-trisphosphate receptor (InsP3R) isoforms in Ca2+ wave formation. Ca2+ signals were examined in hepatocytes, which express the type I and II InsP3R in a polarized fashion, and in AR4-2J cells, a nonpolarized cell line that expresses type I and II InsP3R in a ratio similar to what is found in hepatocytes but homogeneously throughout the cell. Expression of type I or II InsP3R was selectively suppressed by isoform-specific DNA antisense in an adenoviral delivery system, which was delivered to AR4-2J cells in culture and to hepatocytes in vivo. Loss of either isoform inhibited Ca2+ signals to a similar extent in AR4-2J cells. In contrast, loss of the basolateral type I InsP3R decreased the sensitivity of hepatocytes to vasopressin but had little effect on the initiation or spread of Ca2+ waves across hepatocytes. Loss of the apical type II isoform caused an even greater decrease in the sensitivity of hepatocytes to vasopressin and resulted in Ca2+ waves that were much slower and delayed in onset. These findings provide evidence that the apical concentration of type II InsP3Rs is essential for the formation of Ca2+ waves in hepatocytes. The subcellular distribution of InsP3R isoforms may critically determine the repertoire of spatial patterns of Ca2+ signals.