Author/Editor     Križaj, David; Demarco, Steven J; Johnson, Juliette; Strehler, Emanuel E; Copenhagen, David R
Title     Cell-specific expression of plasma membrane calcium ATPase isoforms in retinal neurons
Type     članek
Source     J Comp Neurol
Vol. and No.     Letnik 451, št. 1
Publication year     2002
Volume     str. 1-21
Language     eng
Abstract     Ca(2+) extrusion by high-affinity plasma membrane calcium ATPases (PMCAs) is a principal mechanism for the clearance of Ca(2+) from the cytosol. The PMCA family consists of four isoforms (PMCA1-4). Little is known about the selective expression of these isoforms in brain tissues or about the physiological function conferred upon neurons by any given isoform. We investigated the cellular and subcellular distribution of PMCA isoforms in a mammalian retina. Mouse photoreceptors, cone bipolar cells and horizontal cells, which respond to light with a graded polarization, express isoform 1 (PMCA1) of the PMCA family. PMCA2 is localized to rod bipolar cells, horizontal cells, amacrine cells, and ganglion cells, and PMCA3 is predominantly expressed in spiking neurons, including both amacrine and ganglion cells but is also found in horizontal cells. PMCA4 was found to be selectively expressed in both synaptic layers. Optical measurements of Ca(2+) clearance showed that PMCAs mediate Ca(2+) extrusion in both rod and cone bipolar cells. In addition, we found that rod bipolar cells, but not cone bipolar cells possess a prominent Na(+)/Ca(2+) exchange mechanism. We conclude that PMCA isoforms are selectively expressed in retinal neurons and that processes of Ca(2+) clearance are different in rod and cone bipolar cells.
Descriptors     ANIMALS
CELL MEMBRANE
MAMMALS
MICE
MICE, INBRED C57BL
RETINA
RETINAL GANGLION CELLS