Wheatly Michele G, Gao Yongping, Gillen Christopher M
Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH 45435-0001, USA.
Gen Comp Endocrinol. 2007 Jun-Jul;152(2-3):267-72. doi: 10.1016/j.ygcen.2007.04.006. Epub 2007 Apr 11.
The molting cycle of the freshwater crayfish, Procambarus clarkii, has been used as a model to study the cellular physiology and molecular biology of Ca "supply" proteins that effect transcellular vectorial Ca(2+) movement to achieve organismal Ca homeostasis. Specifically, periods of net Ca(2+) influx (postmolt) have been compared with periods of net Ca(2+) balance (intermolt). The broader goal is to understand the paradox facing epithelial cells of maintaining low cytosolic Ca(2+)in the face of mass Ca(2+)transit across epithelial cells. This mini-review compares mRNA and protein expression profiles for a series of proteins that are of strategic importance in effecting transcellular Ca(2+) flux in a selected epithelium, the antennal gland (kidney analog) specifically during apical to basolateral Ca(2+) conveyance. Target proteins were selected as representative of key "stages" in the transcellular transfer of Ca(2+): import (epithelial Ca(2+) channel, ECaC); storage (sarco/endoplasmic reticulum Ca(2+) ATPase, SERCA); buffering (sarcoplasmic Ca(2+) binding protein, SCP); and export (plasma membrane Ca(2+) ATPase, PMCA and Na(+)/Ca(2+) exchanger, NCX). The purpose of this review is to assess coordination of expression of these target proteins at times of high Ca(2+) demand (premolt and postmolt) compared to low Ca demand (intermolt) as a function of cellular location (apical vs. basolateral; endomembranes vs. plasma membranes) and relative abundance within different regions of the antennal gland. Understanding the spatiotemporal regulation of Ca(2+) handling proteins involved in transcellular transport is fundamental to investigating their endocrine regulation.
淡水小龙虾克氏原螯虾的蜕皮周期已被用作模型，以研究影响跨细胞向量钙（Ca(2+)）移动以实现机体钙稳态的钙“供应”蛋白的细胞生理学和分子生物学。具体而言，已将净钙（Ca(2+)）流入期（蜕皮后）与净钙（Ca(2+)）平衡期（蜕皮间期）进行了比较。更广泛的目标是了解上皮细胞在大量钙（Ca(2+)）穿过上皮细胞时维持低细胞质钙（Ca(2+)）所面临的矛盾。本综述比较了一系列蛋白质的mRNA和蛋白质表达谱，这些蛋白质在选定的上皮组织触角腺（类似肾脏）中，特别是在从顶端到基底外侧的钙（Ca(2+)）转运过程中，对影响跨细胞钙（Ca(2+)）通量具有战略重要性。选择目标蛋白作为钙（Ca(2+)）跨细胞转运关键“阶段”的代表：导入（上皮钙（Ca(2+)）通道，ECaC）；储存（肌浆/内质网钙（Ca(2+)）ATP酶，SERCA）；缓冲（肌浆钙（Ca(2+)）结合蛋白，SCP）；以及输出（质膜钙（Ca(2+)）ATP酶，PMCA和钠/钙（Ca(2+)）交换体，NCX）。本综述的目的是评估与低钙需求期（蜕皮间期）相比，在高钙需求期（蜕皮前和蜕皮后）这些目标蛋白表达的协调性，这是细胞位置（顶端与基底外侧；内膜与质膜）以及触角腺不同区域内相对丰度的函数。了解参与跨细胞运输的钙（Ca(2+)）处理蛋白的时空调节对于研究它们的内分泌调节至关重要。
