Polarity in intracellular calcium signaling.
The concentration of free calcium ions (Ca(2+)) in the cytosol is precisely regulated and can be rapidly increased in response to various types of stimuli. Since Ca(2+) can be used to control different processes in the same cell, the spatial organization of cytosolic Ca(2+) signals is of considerable importance. Polarized cells have advantages for Ca(2+) studies since localized signals can be related to particular organelles. The pancreatic acinar cell is well-characterized with a clearly polarized structure and function. Since the discovery of the intracellular Ca(2+)-releasing function of inositol 1,4,5-trisphosphate (IP(3)) in the pancreas in the early 1980s, this cell has become a popular study object and is now one of the best-characterized with regard to Ca(2+) signaling properties. Stimulation of pancreatic acinar cells with the neurotransmitter acetylcholine or the hormone cholecystokinin evokes Ca(2+) signals that are either local or global, depending on the agonist concentration and the length of the stimulation period. The nature of the Ca(2+) transport events across the basal and apical plasma membranes as well as the involvement of the endoplasmic reticulum (ER), the nucleus, the mitochondria, and the secretory granules in Ca(2+) signal generation and termination have become much clearer in recent years.
Petersen
O H
OH
MRC Secretory Control Research Group, The Physiological Laboratory, University of Liverpool, Liverpool, UK. o.h.petersen@liverpool.ac.uk
Burdakov
D
D
Tepikin
A V
AV
D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D016764:Cell Polarity / Q000502:physiology*; D003594:Cytoplasmic Granules / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D010179:Pancreas / Q000166:cytology / Q000378:metabolism*