Ontogeny of plasma membrane Ca²⁺ ATPase isoforms in the neural retina of the postnatal rat

Abstract

Calcium ion~Ca 2ϩ ! signaling has been widely implicated in developmental events in the retina, but little is known about the specific mechanisms utilized by developing neurons to decrease intracellular Ca 2ϩ . Using immunocytochemistry, we determined the expression profiles of all known isoforms of a key Ca 2ϩ transporter, the plasma membrane Ca 2ϩ ATPase~PMCA!, in the rat retina. During the first postnatal week, the four PMCA isoforms were expressed in patterns that differed from their expression in the adult retina. At birth, PMCA1 was found in the ventricular zone and nascent cell processes in the distal retina as well as in ganglion and amacrine cells. After the first postnatal week, PMCA1 became restricted to photoreceptors and cone bipolar cells. By P10~by postnatal day 10!, most inner retinal PMCA consisted of PMCA2 and PMCA3. Prominent PMCA4 expression appeared after the first postnatal week and was confined primarily to the ON sublamina of the inner plexiform layer~IPL!. The four PMCA isoforms could play distinct functional roles in the development of the mammalian retina even before synaptic circuits are established. Their expression patterns are consistent with the hypothesis that inner and outer retinal neurons have different Ca 2ϩ handling needs.

Isoform-specific up-regulation of plasma membrane Ca2+ATPase expression during colon and gastric cancer cell differentiation

“…To further characterize this homeostatic matrix, in the present work we investigated the expression pattern and the function of plasma membrane Ca 2+ ATPases in various gastric and colon cancer cell lines, and studied the effect of cell differentiation on their expression and activity. Implication of PMCAs in the differentiation of various tissue/cell types has already been published [27][28][29][30][31][32][33]. Our studies, focused on gastric/colon carcinomas, indicate that the major PMCA isoform expressed in these cancer cell lines is PMCA1b, whereas PMCA4b is expressed only at a reduced level.…”

“…Modulations of PMCA expression have been observed during neuronal [27,28] and retinal [29] maturation, in myogenic [30], megakaryoblastoid [31], osteoblast-like [32] and trophoblast-like [33] differentiation models, as well as in cornea [84], in lactating mammary tissue [85] and oral and breast cancer [86,87]. In addition, marked induction of the expression of the SERCA3 endoplasmic reticulum Ca 2+ ATPases has been shown earlier during megakaryocytopoiesis [88], during cell differentiation in various leukemia [21,42] and gastric/ colon cancer cells ( [21,22,89].…”

Kinetics of Synaptic Transmission at Ribbon Synapses of Rods and Cones

“…To prevent overload and cell death, this calcium must be buffered and extruded. In the outer segment, calcium is extruded by a Na/Ca exchanger, whereas inner segment and synaptic terminal extrusion relies principally on PMCA [138,158,172,173]. PMCA are concentrated along the flanks of the terminal and appear to be absent from active zones of the ribbon synapse [135,174].…”

Scotopic Visual Signaling in the Mouse Retina Is Modulated by High-Affinity Plasma Membrane Calcium Extrusion

“…Previous studies suggested that all four PMCA isoforms are expressed in the vertebrate retina (Križaj et al, 2002(Križaj et al, , 2004Rentería et al, 2005). Quantitative real-time RT-PCR was performed to assess the abundance of PMCA transcripts in the mouse retina.…”

“…Given the prominent PMCA2 expression in retinal neurons (Križaj et al, 2002), its upregulation during retinal development (Rentería et al, 2005) and its key role in development and function of the cochlea and vestibular system (Street et al, 1998), which share a number of signaling elements with the retina (Zenisek et al, 2003;El-Amraoui and Petit, 2005), we hypothesized that PMCA2 modulates the establishment of retinal circuits in the developing retina as well as light responses at mature retinal synapses. To test this hypothesis, we analyzed retinal development and transmission of light-evoked signals in control and dfw 2J mice.…”