The study of physiological role of the splice variants of T-type calcium channel that present in human myometrial smooth muscle.

研究人类子宫肌层平滑肌中 T 型钙通道剪接变体的生理作用。

基本信息

批准号：
17591767
负责人：
INOUE Yoshihito
金额：
$ 1.82万
依托单位：
Fukuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17591767/
关键词：
human myometrial smooth muscle voltage clamp T-type calcium channel splice variant cDNA Xenopus oocyte

项目摘要

Electrophysiological characteristics were compared among four cloned human α1H isoforms transcripted by alternative splicings of exons 25B and 26 [ΔA25B/+26 (native form; α1H-a), Δ25B/Δ26 (α1H-b), +25B/Δ26, and +25B/+26] in the intracellular loop between domains III and IV (III-IV linker) of a human T-type calcium channel (Cav3.2). The native isoform Δ25B/+26 predominated in ovary and non-pregnant uterus, while isoform Δ25B/Δ26 (α1H-b) predominated in pregnant uterus and testis. Expressions of the newly identified +25B/Δ26 and +25B/+26 isoforms were greater in the uterus at gestation than in the nonpregnant uterus. When expressed in Xenopus laevis oocytes, all isoforms produced transient inward currents with low voltage-dependent activation and inactivation characterized in typical T-type Ca^<2+> currents. Each isoform possessing exon 25B (+25B/Δ26 or +25B/+26) showed current activation and inactivation at a more negative membrane potential than the respective isoform (Δ25B/Δ26 or Δ25B/+26) lacking it. Moreover, the current activation and inactivation rates were faster for the two isoforms possessing exon 25B than for the respective isoforms lacking it. By itself, exon 26 seemed not to affect any electrophysiological characteristics. Increasing the net positive charge (relative to the native form), as occurred in isoforms Δ25B/Δ26, +25B/Δ26, and +25B1+26, caused recovery from short-term inactivation to become faster. On the other hand, only Δ25B/Δ26 isoforms existed in non-pregnant myometrium with the similar electrical properties to that in pregnant myometrium. Onr results show that molecular structure variations within the III-IV linker influence the voltage-dependence and kinetics of both activation and inactivation. Although the role of T-type Ca^<2+> channels in uterine tissue remains unknown, changes in the uterine expression of these α1H isoforms may influence physiological functions during pregnancy.

在四个克隆的人α1H同工型中比较了电生理特征，该同种型通过外显子25b和26 [ΔA25b/ +26（天然形式;α1H-a），Δ25b/Δ26（α1H-B）（α1H-B）， +25b/Δ26， +25b/Δ26，以及IIIiiiii iniiiiiii iniiiiiii iniiiiiii iniiiiiii Iii iiiiiii iiiiiiii Iii iiiiiii iiiiiiii III I I IIIIV在Δ25b/ +26（Δa25b/ +26（Δ25b/ +26（ΔA25b/ +26）中）中进行了比较。人类T型钙通道（CAV3.2）的接头）。天然同工型Δ25B/+26在卵巢和非孕妇子宫中占主导地位，而同工型Δ25b/Δ26（α1H-B）占怀孕子宫和睾丸中的占主导地位。新鉴定的 +25b/δ26和 +25b/ +26同工型的表达在妊娠时的子宫比非妊娠子宫更大。当在爪蟾laevis卵母细胞中表达时，所有同工型均产生瞬时电流的瞬时向内电流，其依赖电压依赖性激活且灭活且以典型的T型Ca^<2+>电流为特征。每个具有外显子25b（+25b/Δ26或+25b/+26）的同工型显示的电流激活和灭活效率比相对同工型（Δ25B/Δ26或Δ25b/+26）更负膜电位。此外，具有外显子25B的两个同工型的当前激活和灭活率要比缺乏外显子的同工型要快。就其本身而言，26似乎不影响任何电生理特征。在同工型Δ25b/Δ26， +25b/Δ26和 +25b1 +26中增加净正电荷（相对于天然形式），导致短期失活的恢复变得更快。另一方面，在非怀孕子宫骨骼中仅存在Δ25b/Δ26同工型，其电性能与怀孕的肌层相似。 ONR结果表明，III-IV接头内的分子结构变化会影响激活和失活的电压依赖性和动力学。尽管T型Ca^<2+>通道在子宫组织中的作用尚不清楚，但这些α1H同工型的子宫表达的变化可能会影响怀孕期间的生理功能。