title: Paradox of epithelial cell calcium homeostasis during vectorial transfer in crayfish kidney.
abstract: 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.
authors.affiliation: Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH 45435-0001, USA. michele.wheatly@wright.edu
authors.forename: Michele G
authors.initials: MG
authors.lastname: Wheatly
authors.forename: Yongping
authors.initials: Y
authors.lastname: Gao
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Gillen
mesh_terms: D000818:Animals; D003400:Astacoidea / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D007668:Kidney / Q000166:cytology* / Q000378:metabolism; D018978:Molting / Q000502:physiology
chemical_list: D002118:Calcium