Co-localization and polarized distribution of Na,K-ATPase alpha 3 and beta 2 subunits in photoreceptor cells.

Schneider, Barbara; Shyjan, Andrew W.; Levenson, Robert

doi:10.1177/39.4.1848572

Cited by 38 publications

(22 citation statements)

References 38 publications

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“…This contrasts with the situation in rodents, where the ␣1 subunit is the only isoform that appears to be expressed (Shyjan and Levenson 1989). In mammals, the ␣3 gene is expressed predominantly within neurons (Cameron et al 1994) and in retinal photoreceptors (Schneider et al 1991). Both of the zebrafish ␣3 orthologs show expression in brain and eye.…”

Section: Cshlporg Downloaded Frommentioning

confidence: 43%

The Repertoire of Na,K-ATPase α and β Subunit Genes Expressed in the Zebrafish, Danio rerio

Rajarao¹,

Canfield²,

Mohideen³

et al. 2001

Genome Res.

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We have identified a cohort of zebrafish expressed sequence tags encoding eight Na,K-ATPase ␣ subunits and five ␤ subunits. Sequence comparisons and phylogenetic analysis indicate that five of the zebrafish ␣ subunit genes comprise an ␣1-like gene subfamily and two are orthologs of the mammalian ␣3 subunit gene. The remaining ␣ subunit clone is most similar to the mammalian ␣2 subunit. Among the five ␤ subunit genes, two are orthologs of the mammalian ␤1 isoform, one represents a ␤2 ortholog, and two are orthologous to the mammalian ␤3 subunit. Using zebrafish radiation hybrid and meiotic mapping panels, we determined linkage assignments for each ␣ and ␤ subunit gene. Na,K-ATPase genes are dispersed in the zebrafish genome with the exception of four of the ␣1-like genes, which are tightly clustered on linkage group 1. Comparative mapping studies indicate that most of the zebrafish Na,K-ATPase genes localize to regions of conserved synteny between zebrafish and humans. The expression patterns of Na,K-ATPase ␣ and ␤ subunit genes in zebrafish are quite distinctive. No two ␣ or ␤ subunit genes exhibit the same expression profile. Together, our data imply a very high degree of Na,K-ATPase isoenzyme heterogeneity in zebrafish, with the potential for 40 structurally distinct ␣/␤ subunit combinations. Differences in expression patterns of ␣ and ␤ subunits suggest that many of the isoenzymes are also likely to exhibit differences in functional properties within specific cell and tissue types. Our studies form a framework for analyzing structure function relationships for sodium pump isoforms using reverse genetic approaches.

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Section: Cshlporg Downloaded Frommentioning

confidence: 43%

The Repertoire of Na,K-ATPase α and β Subunit Genes Expressed in the Zebrafish, Danio rerio

Rajarao¹,

Canfield²,

Mohideen³

et al. 2001

Genome Res.

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“…The distribution of syntaxin 3 closely paralleled that of the β2 subunit of Na,K-ATPase, a marker for the RIS PM (Schneider et al, 1991), suggesting that they were present in the same membrane (Fig. 1M).…”

Section: Resultsmentioning

confidence: 86%

Syntaxin 3 and SNAP-25 pairing, regulated by omega-3 docosahexaenoic acid, controls the delivery of rhodopsin for the biogenesis of cilia-derived sensory organelles, the rod outer segments

Mazelova

Ransom

Astuto-Gribble

et al. 2009

Journal of Cell Science

118

108

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The biogenesis of cilia-derived sensory organelles, the photoreceptor rod outer segments (ROS), is mediated by rhodopsin transport carriers (RTCs). The small GTPase Rab8 regulates ciliary targeting of RTCs, but their specific fusion sites have not been characterized. Here, we report that the Sec6/8 complex, or exocyst, is a candidate effector for Rab8. We also show that the Qa-SNARE syntaxin 3 is present in the rod inner segment (RIS) plasma membrane at the base of the cilium and displays a microtubule-dependent concentration gradient, whereas the Qbc-SNARE SNAP-25 is uniformly distributed in the RIS plasma membrane and the synapse. Treatment with omega-3 docosahexaenoic acid [DHA, 22:6(n-3)] causes increased co-immunoprecipitation and colocalization of SNAP-25 and syntaxin 3 at the base of the cilium, which results in the increased delivery of membrane to the ROS. This is particularly evident in propranolol-treated retinas, in which the DHA-mediated increase in SNARE pairing overcomes the tethering block, including dissociation of Sec8 into the cytosol. Together, our data indicate that the Sec6/8 complex, syntaxin 3 and SNAP-25 regulate rhodopsin delivery, probably by mediating docking and fusion of RTCs. We show further that DHA, an essential polyunsaturated fatty acid of the ROS, increases pairing of syntaxin 3 and SNAP-25 to regulate expansion of the ciliary membrane and ROS biogenesis.

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“…The C3 isoform has been localized to rat photoreceptors, horizontal cells, and bipolar cells (4)(5)(6). Photoreceptors predominantly express the a3 mRNA (-85%), a small amount of a1 mRNA (-15%), and almost no detectable CY2 mRNA (.0.4%).…”

mentioning

confidence: 99%

“…Photoreceptors predominantly express the a3 mRNA (-85%), a small amount of a1 mRNA (-15%), and almost no detectable CY2 mRNA (.0.4%). Electron microscopic immunocytochemistry studies reveal that the a3 isoform is localized exclusively to the plasma membrane of the inner segments (5,6). The photoreceptor Na+,K+-pump operates near Vmax in the darkadapted or depolarized state, due to the constant entry of Na+ into the cell and the leakage of K+ from the cell, and is slowed during maintained rod-saturating illumination in response to a decrease in the intracellular Na+ concentration (7,8).…”

mentioning

confidence: 99%

Dopamine inhibits mammalian photoreceptor Na+,K+-ATPase activity via a selective effect on the alpha3 isozyme.

Shulman

Fox

1996

Proc. Natl. Acad. Sci. U.S.A.

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The rat retina contains dopaminergic interplexiform cells that send processes to the outer plexiform layer where dopamine is released in a light-dependent manner. We report herein that physiologically relevant concentrations of dopamine inhibited ouabain-sensitive photoreceptor oxygen consumption in dark-and light-adapted rat retinas and inhibited Na+,K+-ATPase specific activity (EC 3.6.1.37) in a rat rod outer-inner segment preparation. Experiments with the selective Dt agonist fenoldopam or D2 agonist quinpirole and experiments with dopamine plus either the Di antagonist SCH23390 or D2/D4 antagonist clozapine showed that the inhibition of oxygen consumption and enzyme activity were mediated by D2/D4-like receptors. The amphetamineinduced release of dopamine, monitored by the inhibition of oxygen consumption, was blocked by L-2-amino-4-phosphonobutyric acid and kynurenic acid. Pharmacological and biochemical experiments determined that the IC50 values of ouabain for the cvl-low and a3-high ouabain affinity isozymes of photoreceptor Na+,K+-ATPase were -10-5 and _10-7 M, respectively, and that the D2/D4-like mediated inhibition of Na+,K+-ATPase was exclusively selective for the a3 isozyme. The dopamine-mediated inhibition of a3 first occurred at 5 nM, was maximal at 100 ,uM (-47%), had an IC50 value of 382 + 23 nM, and exhibited negative cooperativity (Hill coefficient, 0.27). Prior homogenization of the rod outer-inner segment completely prevented the long-lasting inhibition, suggesting that the effect was coupled to a second messenger. Although the physiological significance of our findings to photoreceptor function is unknown, we hypothesize that these results may have relevance for the temporal tuning properties of rods.

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Co-localization and polarized distribution of Na,K-ATPase alpha 3 and beta 2 subunits in photoreceptor cells.

Cited by 38 publications

References 38 publications

The Repertoire of Na,K-ATPase α and β Subunit Genes Expressed in the Zebrafish, Danio rerio

The Repertoire of Na,K-ATPase α and β Subunit Genes Expressed in the Zebrafish, Danio rerio

Syntaxin 3 and SNAP-25 pairing, regulated by omega-3 docosahexaenoic acid, controls the delivery of rhodopsin for the biogenesis of cilia-derived sensory organelles, the rod outer segments

Dopamine inhibits mammalian photoreceptor Na+,K+-ATPase activity via a selective effect on the alpha3 isozyme.

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