Daniel E E, El-Yazbi A, Cho W J
Department Of Pharmacology, University of Alberta, Edmonton, Canada.
J Cell Mol Med. 2006 Apr-Jun;10(2):529-44. doi: 10.1111/j.1582-4934.2006.tb00418.x.
Caveolae are associated with molecules crucial for calcium handling. This review considers the roles of caveolae in calcium handling for smooth muscle and interstitial cells of Cajal (ICC). Structural studies showed that the plasma membrane calcium pump (PMCA), a sodium-calcium exchanger (NCX1), and a myogenic nNOS appear to be colocalized with caveolin 1, the main constituent of these caveolae. Voltage dependent calcium channels (VDCC) are associated but not co-localized with caveolin 1, as are proteins of the peripheral sarcoplasmic reticulum (SR) such as calreticulin. Only the nNOS is absent from caveolin 1 knockout animals. Functional studies in calcium free media suggest that a source of calcium in tonic smooth muscles exists, partly sequestered from extracellular EGTA. This source supported sustained contractions to carbachol using VDCC and dependent on activity of the SERCA pump. This source is postulated to be caveolae, near peripheral SR. New evidence, presented here, suggests that a similar source exists in phasic smooth muscle of the intestine and its ICC. These results suggest that caveolae and peripheral SR are a functional unit recycling calcium through VDCC and controlling its local concentration. Calcium handling molecules associated with caveolae in smooth muscle and ICC were identified and their possible functions also reviewed.
小窝与钙处理的关键分子相关。本综述探讨了小窝在平滑肌和 Cajal 间质细胞（ICC）钙处理中的作用。结构研究表明，质膜钙泵（PMCA）、钠钙交换体（NCX1）和肌源性神经元型一氧化氮合酶（nNOS）似乎与这些小窝的主要成分小窝蛋白 1 共定位。电压依赖性钙通道（VDCC）与小窝蛋白 1 相关但不共定位，外周肌浆网（SR）的蛋白质如钙网蛋白也是如此。只有 nNOS 在小窝蛋白 1 基因敲除动物中不存在。在无钙培养基中的功能研究表明，张力性平滑肌中存在钙源，部分钙源从细胞外乙二醇双四乙酸（EGTA）中隔离。该钙源利用 VDCC 支持对卡巴胆碱的持续收缩，并依赖于肌浆网钙泵（SERCA）的活性。推测该钙源是靠近外周肌浆网的小窝。本文提供的新证据表明，在肠道及其 ICC 的相性平滑肌中也存在类似的钙源。这些结果表明，小窝和外周肌浆网是一个功能单元，通过 VDCC 循环利用钙并控制其局部浓度。鉴定了平滑肌和 ICC 中与小窝相关的钙处理分子，并对其可能的功能进行了综述。
