Disease relevance of IFT122

• Vertebrate rhodopsin couples to the Gi/o, pertussis toxin-sensitive pathway to allow modulation of G protein-gated inward rectifying potassium channels and voltage-gated Ca2+ channels [1].
• Direct evidence is not available that (1) rhodopsin-like photopigment exists in the chicken pineal and that (2) the visual pigment is responsible for the light sensitivity of the gland [2].

High impact information on IFT122

• The presence of rhodopsin-like photoreceptive pigment, transducin-like immunoreaction, and cyclic GMP-dependent cation-channel activity in the avian pinealocytes suggests that there is a similarity between retinal rod cells and pinealocytes in the phototransduction pathway [3].
• Rhodopsin-like photosensitivity of isolated chicken pineal gland [4].
• The level of rhodopsin continues to rise as the rod outer segment develops [5].
• It was found that the appearance of rhodopsin in significant levels preceded outer segment formation by at least 2 days, thus implying that rhodopsin is synthesized in the receptor cell inner segment and translocated to the outer limb when disk membrane biogenesis occurs [5].
• Correlation of rhodopsin biogenesis with ultrastructural morphogenesis in the chick retina [5].

Biological context of IFT122

• In vitro DNA binding assays and transient transfection analysis with monkey kidney cells have implicated Nrl, a member of the Maf-Nrl subfamily of bZIP transcription factors, and the Nrl response element (NRE) in the regulation of rhodopsin expression [6].
• These studies support Nrl as a regulator of rhodopsin expression in vivo, identify an additional regulatory region just upstream of the NRE, and demonstrate the utility of primary retinal cell cultures for characterizing both the cis-acting response elements and trans-acting factors that regulate photoreceptor gene expression [6].
• Characterization of the chicken rhodopsin promoter: identification of retina-specific and glass-like protein binding domains [7].
• We report the isolation and sequence of 1.8 kb of 5' flanking sequence of the chicken rhodopsin gene and analysis of DNA-binding proteins to promoter fragments by gel retardation assay [7].
• Thus in spite of the similarity in amino acid sequence, chicken green displays molecular properties required for a cone visual pigment that are clearly different from those of rhodopsin [8].

Anatomical context of IFT122

• In spite of the pure-rod morphology of the photoreceptor cells, the biochemical properties of P521 and P467 resemble those of iodopsin (the chicken red-sensitive cone visual pigment) and rhodopsin, respectively [9].
• Cone visual pigments exhibit faster regeneration from 11-cis-retinal and opsin and faster decay of physiologically active intermediate (meta II) than does the rod visual pigment, rhodopsin, as expected, due to the functional difference between rod and cone photoreceptor cells [10].
• Antibodies against visinin and GABA were used to distinguish photoreceptors from nonphotoreceptor cells, and monoclonal antibodies rhodopsin (rho) 4D2, OS-2, and COS-1 were used to distinguish subpopulations of cones and rods [11].
• Difference in molecular properties between chicken green and rhodopsin as related to the functional difference between cone and rod photoreceptor cells [12].
• In the rhodopsin cycle, retinal chromophore from bleached rod pigments is reduced to retinol and transferred to the retinal pigment epithelium (RPE) to store as all-trans retinyl ester [13].

Associations of IFT122 with chemical compounds

• The data indicate that in vivo light plays a major role in triggering rhodopsin-bound 11-cis-retinal production within 2-4 hr after darkness onset; this change likely serves as the signal for the subsequent formation of the hormonal product of the pineal gland, melatonin [14].
• With respect to their content of rhodopsin, IRBP, retinyl palmitate/stearate and unesterified retinol, (both 11-cis and all-trans isomers) no significant difference could be demonstrated between the eyes of rd and carrier chickens (3 days and 28 days post-hatching) [15].
• If a single rhodopsin-like photopigment mediates both effects of light, then vitamin A depletion and retinoid addition should affect both responses in parallel, although not proportionately [16].
• The chromophore of chloride-depleted iodopsin was easily transferred to scotopsin in the extract, resulting in formation of rhodopsin [17].
• Although chicken green was contaminated with a small amount of rhodopsin having a similar spectral shape, the maximum of its difference spectrum was located at 508 nm by taking advantage of the difference in susceptibility against hydroxylamine between these pigments [18].

Regulatory relationships of IFT122

• RT-PCR and Northern blot analysis, however, showed that rhodopsin mRNA was undetectable in both control and CNTF-treated cultures but that CNTF induced significant increases in mRNA levels for the green cone pigment [19].

Other interactions of IFT122

• Rhodopsin, violet and blue opsin expressions in the chick are highly dependent on tissue and serum conditions [20].
• We have purified and reconstituted both chicken rhodopsin and chicken iodopsin and shown them to be phosphorylated by bovine rhodopsin kinase [21].
• Green cone opsin and rhodopsin regulation by CNTF and staurosporine in cultured chick photoreceptors [19].
• RESULTS: Two candidate photosensors and/or photoisomerases were predominantly distributed within the pineal gland and retina: the retinal pigmented epithelium-derived rhodopsin homologue (peropsin, gRrh) and retinal G-protein-coupled receptor opsin (RGR opsin, gRgr) [22].
• METHODS: Neural retina RNA was obtained between embryonic day 7 (E7) and posthatch day 8 (P8) and analyzed on northern blots with cDNA probes to AANAT, HIOMT, visinin, alpha-transducin, rhodopsin, and the four cone opsins [23].

Analytical, diagnostic and therapeutic context of IFT122

• Isolation and sequence determination of the chicken rhodopsin gene [24].
• The bZIP transcription factor Nrl stimulates rhodopsin promoter activity in primary retinal cell cultures [6].
• The cultures were analyzed by immunocytochemistry with the monoclonal antibody Rho4D2, which recognizes chicken rhodopsin and green cone pigment, and by reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis to investigate visual pigment expression at the mRNA level [19].
• Here we determined the tissue and serum dependence of the expression of all photopigments in the chick by a series of distinct retinal cell cultures, analyzed by RT-PCR using specific primers for all four opsins and rhodopsin followed by quantitative scanning of the respective gel bands [20].
• By the more sensitive procedure of radioimmunoassay (RIA), rhodopsin was detected as early as day 12 (stage 37), but was undetectable in the 8 day old embryo [25].

References