Regulation of the Phosphorylation State of Rhodopsin by Dopamine

Udovichenko, Igor P.; Newton, Alexandra C.; Williams, David S.

doi:10.1074/jbc.273.13.7181

Cited by 7 publications

(7 citation statements)

References 41 publications

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“…Numerous studies have shown that cell ± cell interactions are involved in cell fate determination during this time (Belliveau and Cepko, 1999;Belliveau et al, 2000;Cepko et al, 1996). Similarly, studies using intact frog retina indicate that the phosphorylation status of rhodopsin is in part regulated by dopamine released from the inner cell layers (Udovichenko et al, 1998). Clearly this is minor compared to the phosphorylation induced by light.…”

Section: Discussionmentioning

confidence: 95%

The proliferative and apoptotic activities of E2F1 in the mouse retina

et al. 2001

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The E2F1 transcription factor controls cell proliferation and apoptosis. E2F1 activity is negatively regulated by the retinoblastoma (RB) protein. To study how inactivation of Rb and dysregulated E2F1 a ects the developing retina, we analysed wild-type and Rb 7/7 embryonic retinas and retinal transplants and we established transgenic mice expressing human E2F1 in retinal photoreceptor cells under the regulation of the IRBP promoter (TgIRBPE2F1). A marked increase in cell proliferation and apoptosis was observed in the retinas of Rb 7/7 mice and TgIRBPE2F1 transgenic mice. In the transgenic mice, photoreceptor cells formed rosette-like arrangements at postnatal days 9 through 28. Complete loss of photoreceptors followed in the TgIRBPE2F1 mice but not in the Rb 7/7 retinal transplants. Both RBde®cient and E2F1-overexpressing photoreceptor cells expressed rhodopsin, a marker of terminal di erentiation. Loss of p53 partially reduced the apoptosis and resulted in transient hyperplasia of multiple cell types in the TgIRBPE2F1 retinas at postnatal day 6. Our ®ndings support the concept that cross-talk occurs between di erent retinal cell types and that multiple genetic pathways must become dysregulated for the full oncogenic transformation of neuronal retinal cells. Oncogene (2001) 20, 7073 ± 7084.

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Section: Discussionmentioning

confidence: 95%

The proliferative and apoptotic activities of E2F1 in the mouse retina

et al. 2001

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“…Dopamine, acting through D 4 Rs, inhibits Na + /K + ‐ATPase in rat rod photoreceptors (Shulman and Fox 1996). Dopamine increases the rate of rhodopsin dephosphorylation in frog retina (Udovichenko et al. 1998) and PKA has been shown to phosphorylate the γ‐subunit of cGMP phosphodiesterase purified from bovine rod outer segments (Xu et al.…”

Section: Discussionmentioning

confidence: 99%

Essential roles of dopamine D₄ receptors and the type 1 adenylyl cyclase in photic control of cyclic AMP in photoreceptor cells

Jackson

Chaurasia

Zhou

et al. 2009

Journal of Neurochemistry

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Dopamine is a neuromodulator that influences many physiological functions in the retina (reviewed by Witkovsky 2004). It enhances cone input signals and decreases rod input signals, uncouples horizontal cell and AII amacrine cell gap junction networks, enhances contrast sensitivity, and modulates light-and dark-adaptation. Also, it has trophic actions within the retina, affecting circadian rhythms, retinal development, and ocular growth (Witkovsky 2004). Activation of dopamine receptors, particularly the dopamine D 4 receptor (D 4 R) subtype from the D 2 family of receptors, suppresses the light-sensitive pool of cyclic AMP in dark-adapted mouse photoreceptors (Cohen and Blazynski 1990;Cohen et al. 1992). Cyclic AMP levels in photoreceptor cells are highest in darkness and reduced by light exposure. Although it is known that light and D 4 R activation regulate the same pool of cyclic AMP, they appear to do so by different mechanisms. Nir et al. (2002) showed that the effect of light is not directly dependent on D 4 R activation; however, in mice lacking D 4 Rs (Drd4)/) mice), cyclic AMP levels were significantly lower in darkness and unresponsive to light when compared with wild-type controls. These observations suggested that D 4 R activation Similarly, in mice with disruption of the gene (Drd4) encoding D 4 R, cyclic AMP levels in the dark-adapted retina are significantly lower compared to wild-type retina and are unresponsive to light. These changes in Drd4)/) mice were accompanied by significantly lower Adcy1 mRNA levels in photoreceptor cells and lower Ca 2+ /calmodulin-stimulated adenylyl cyclase activity in retinal membranes compared with wild-type controls. Reduced levels of Adcy1 mRNA were also observed in retinas of wild-type mice treated chronically with a D 4 R antagonist, L-745870. Thus, activation of D 4 R is required for normal expression of AC1 and for the regulation of its catalytic activity by light. These observations illustrate a novel mechanism for cross-talk between dopamine and photic signaling pathways regulating cyclic AMP in photoreceptor cells.

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“…The PP2A enzyme assay was optimized for phosducin dephosphorylation and may not have contained all the essential factors necessary for optimal opsin dephosphorylation. Protamine and dopamine have been shown to influence opsin dephosphorylation by PP2A (24,77). It has been suggested that, before Ser334 of opsin can be dephosphorylated, opsin must first be regenerated with 11-cis-retinal (78).…”

Section: Discussionmentioning

confidence: 99%

Light-Driven Translocation of the Protein Phosphatase 2A Complex Regulates Light/Dark Dephosphorylation of Phosducin and Rhodopsin

et al. 2002

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In steps of protein purification of bovine retinal protein phosphatase 2A (PP2A), phosducin dephosphorylation activity peaks coelute with a PP2A enzyme complex, shown by peptide sequence analysis to contain a B′ subunit, B56epsilon. Other PP2A complexes with a slightly larger (56.5 kDa) B′ subunit (sequenced to be B56alpha) or with the BR regulatory subunit have no phosducin dephosphorylation activity. Upon exposure to light, a significant increase in the immunoreactive protein level of the A, C, and B56epsilon PP2A subunits is observed in the cytosolic fraction of mouse retina, the phosducin dephosphorylation of which occurs rapidly. During dark exposure, these subunits translocate to the membrane fraction where rhodopsin is slowly dephosphorylated. This PP2A redistribution occurs in less than 1.5 min and is dependent upon light and not upon an intrinsic circadian rhythm. Forty times more of the A subunit (∼20 ng/mouse retina) and 9 times more of the C subunit (∼4 ng/mouse retina) than of the B56epsilon subunit (∼0.45 ng/mouse retina) redistribute, which suggests that the predominant form of the PP2A enzyme complex on the membrane in the dark is a dimer, consisting of only A and C subunits. We observe that the dimer favors phosphorylated opsin as a substrate, while the trimer, particularly the enzyme complex with the B56epsilon subunit, greatly prefers phosphorylated phosducin, with an activity several hundred times those of other substrates that were tested. This light-driven PP2A translocation provides a potential mechanism for efficient dephosphorylation of two critical photoreceptor transduction proteins, cytosolic phosducin and membrane-bound rhodopsin, by the same enzyme.

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Regulation of the Phosphorylation State of Rhodopsin by Dopamine

Cited by 7 publications

References 41 publications

The proliferative and apoptotic activities of E2F1 in the mouse retina

The proliferative and apoptotic activities of E2F1 in the mouse retina

Essential roles of dopamine D₄ receptors and the type 1 adenylyl cyclase in photic control of cyclic AMP in photoreceptor cells

Light-Driven Translocation of the Protein Phosphatase 2A Complex Regulates Light/Dark Dephosphorylation of Phosducin and Rhodopsin

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Regulation of the Phosphorylation State of Rhodopsin by Dopamine

Cited by 7 publications

References 41 publications

The proliferative and apoptotic activities of E2F1 in the mouse retina

The proliferative and apoptotic activities of E2F1 in the mouse retina

Essential roles of dopamine D4 receptors and the type 1 adenylyl cyclase in photic control of cyclic AMP in photoreceptor cells

Light-Driven Translocation of the Protein Phosphatase 2A Complex Regulates Light/Dark Dephosphorylation of Phosducin and Rhodopsin

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Essential roles of dopamine D₄ receptors and the type 1 adenylyl cyclase in photic control of cyclic AMP in photoreceptor cells