Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Retinaldehyde”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources
PubMed1992

Evidence that the stimulation by arginine vasopressin of the release of adrenocorticotropin from the ovine anterior pituitary involves the activation of protein kinase C.

These studies were undertaken to evaluate the role of protein kinase C (PKC) in the regulation by arginine vasopressin (AVP) of adrenocorticotropin (ACTH) secretion from the ovine anterior pituitary. AVP caused the rapid translocation of PKC from the cytosol to the cell membrane in ovine anterior pituitary cells that was maximal at 5 min. This phenomenon, which is a known concomitant of C-kinase activation, was produced to a greater extent by phorbol 12-myristate 13-acetate (PMA) but not by corticotropin-releasing factor (CRF). To determine whether AVP activated corticotrope PKC, we assessed the ability of three different PKC inhibitors (H-7, sphingosine, and retinal) to modify basal, AVP-, PMA-, and CRF-stimulated ACTH release. In addition to inhibiting the in vitro activity of purified PKC, each compound also caused in vitro inhibition of the protein kinase A (PKA) catalytic subunit, indicating that none could be considered to be a specific inhibitor of PKC and the PKA catalytic subunit. As determined by the mean IC50 values required for the in vitro inhibition of PKC and the PKA catalytic subunit, sphingosine was judged to be the most selective and H-7 the least selective PKC inhibitor. A 4 h exposure to each inhibitor caused a dose-dependent increase in basal ACTH release and attenuation of both AVP- and PMA-stimulated ACTH release. H-7 and retinal, in concentrations that caused a 20-50% inhibition of PKA, also attenuated CRF-stimulated ACTH release; however, this effect was not observed with sphingosine in concentrations that caused only a 10-20% inhibition of PKA. We conclude that: (1) AVP causes the direct activation of PKC in the ovine anterior pituitary and that C kinase activation is important in mediating the effect of AVP on ACTH release; (2) the finding that inhibition of PKC elevates ACTH suggests that basal ACTH secretion is also partly regulated by PKC; (3) since CRF does not cause PKC translocation in ovine anterior pituitary cells, it is unlikely that PKC plays a physiological role in the action of CRF on the corticotrope; (4) the finding that H-7 and retinal attenuate CRF-stimulated ACTH secretion suggests that CRF activates PKA in corticotropes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Identification of 11-cis-retinal and demonstration of its light-induced isomerization in the chicken pineal gland.

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. Therefore, the objective of this study was to test for the existence of visual pigment in the chicken pineal by means of the identification of 11-cis-retinal in this organ. 11-cis- and all-trans retinoids were extracted from light- and dark-adapted chicken pineals and analyzed by high performance liquid chromatography (HPLC) using the formaldehyde method. 11-cis-Retinal was initially identified by coelution with an authentic standard. Further characterization was carried out by collecting the retinal from the HPLC eluant, subjecting it to reduction by sodium borohydride and then identifying the derived 11-cis-retinol using HPLC. Proportions of 11-cis-retinal to total pineal retinals were also studied from decapitated heads after light and dark adaptation. Analyses of dark-adapted, pooled chicken pineals revealed equal proportions of 11-cis and all-trans retinals at 2 h after dark and at night. Two hours of light adaptation resulted in the reduction of the 11-cis proportion (from 50%) to 26% of total retinals. These observations prove that 11-cis-retinal exists in the chicken pineal and that it undergoes light-induced cis to trans isomerization in a manner similar to the visual pigment chromophores in the vertebrate retina.

Adaptation, Physiological↗
PubMed1975

Accessibility of the iodopsin chromophore.

Iodopsin can replace its chromophore (11-cis retinal) by added 9-cis retinal, resulting in the formation of isoiodopsin. NaBH4 bleaches iodopsin in the dark. In a relatively low concentration of digitonin, the scotopsin (the protein moiety of chicken rhodopsin) removes 11-cis retinal from iodopsin in the dark. These facts suggest that the linkage of the chromophore to opsin in the iodopsin molecule (presumably a Schiff-base linkage) is accessible to these reagents, which is different from the situation in rhodopsin.

Alcohol Oxidoreductases↗
PubMed1981

Activation of phosphodiesterase in frog rod outer segment by an intermediate of rhodopsin photolysis. II.

Frog (Rana catesbeiana) rod outer segment membrane contains cyclic GMP phosphodiesterase (EC 3.1.4.1). Irradiation of dark-adapted rod outer segment membrane increased the enzyme activity by 5-20-fold in the presence of GTP. The phosphodiesterase in rod outer segment membrane is also activated by mixing a photo-product of 11-cis (regenerated), 9-cis or 7-cis rhodopsin which is stable at 0 degrees C. However, neither opsin in the membrane nor all-trans retinal activates the enzyme. The phosphodiesterase in rod outer segment membrane is also activated by irradiation at -4 degrees C. Thus, we conclude that the phosphodiesterase in activated by a common photolysis intermediate of these rhodopsin isomers, perhaps before metarhodopsin II decays.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1988

Properties of retinal-oxidizing enzyme activity in rat kidney.

An enzyme activity which converts retinal to retinoic acid was found in the cytosol of rat kidney. The oxidation of retinal was pH-, temperature-, time- and protein-dependent. Under the assay conditions employed, the oxidase activity had an apparent Km of 125 microM toward all-trans retinal. n-Propylgallate, butylated hydroxytoluene and quinacrine inhibited the reaction. The inhibition caused by quinacrine can be partly reversed by FAD. p-Hydroxymercuribenzoate, a sulfhydryl cross-linking agent, was a potent inhibitor. 4'-(9-Acridinylamino)methanesulfon-anisidide, an inhibitor of aldehyde oxidase, inhibited the reaction by 77% at a concentration of 3 mM. All-trans retinal reversed the inhibition caused by acetaldehyde and 2-aminobenzaldehyde. Retinol inhibited the reaction, but retinoic acid did not. The specific activity of the enzyme was increased by vitamin A deficiency. These data indicate that retinal-oxidizing enzyme activity found in the kidney is a sulfhydryl flavoprotein and its activity is dependent on the vitamin A levels of the tissues.

Animals↗
PubMed1988

4-Hydroxyretinal, a new visual pigment chromophore found in the bioluminescent squid, Watasenia scintillans.

The bioluminescent squid, Watasenia scintillans has three visual pigments. The major pigment, based on retinal (lambda max 484 nm), is distributed over the whole retina. Another pigment based on 3-dehydroretinal (lambda max approximately 500 nm) and the third pigment (lambda max approximately 470 nm) are localized in the specific area of the ventral retina just receiving the downwelling light. Visual pigment was extracted and purified from the dissected retina. The chromophores were then extracted and analyzed with HPLC, NMR, infrared and mass spectroscopy, being compared with the synthetic 4-hydroxyretinal. A new retinal derivative, 11-cis-4-hydroxyretinal, is identified as the chromophore of the third visual pigment of the squid.

Animals↗
PubMed1990

Microsomes convert retinol and retinal into retinoic acid and interfere in the conversions catalyzed by cytosol.

Rat liver microsomes converted retinol into retinal and retinoic acid. The production of retinal was observed over a range of substrate concentrations (10-100 microM), but retinoic acid was detected only at retinol concentrations of 50 microM or higher. At 50 microM retinol, the rate of microsomal retinal production was 2-fold greater than that of cytosol, but the rate of retinoic acid synthesis was 4-fold less than that of cytosol. Retinal was also converted into retinoic acid by rat liver microsomes, but at a rate 2-5% of that catalyzed by cytosol. Microsomes also interfered with the conversion of retinol and retinal into retinoic acid by rat liver cytosol. A 50% decrease in the cytosolic rates of retinoic acid production from retinol or retinal was caused by microsomal to cytosolic protein ratios of 0.1 and 0.5, respectively. Under the incubation conditions, which included NAD in the medium, addition of microsomes to cytosol did not affect the elimination half-life of retinol or retinoic acid, but did decrease the elimination half-life of retinal by 2-fold. These data show that retinal synthesis from retinol does not necessarily reflect retinoic acid synthesis and suggest that liver microsomes sequester free retinol and convert it into retinal primarily for elimination, rather than to serve as substrate for cytosolic retinoic acid synthesis.

Animals↗
PubMed1990

Retinylidene Schiff bases in alkylammonium carboxylate reversed micelles.

All-trans-retinal, incorporated into dodecylammonium propionate, dodecylammonium 3-chloropropionate and dodecylammonium trifluoroacetate reversed micelles in cyclohexane containing different amounts of solubilized water, gave all-trans-N-retinylidene-n-dodecylamine. Formation of all-trans-N-retinylidene-n-dodecylamine was complete within a few minutes when all-trans-retinal was solubilized along with L-lysine in reversed-micellar dodecylammonium propionate in cyclohexane as compared to the several hours required for the comparable reaction to occur in the absence of lysine. In situ formed all-trans-N-retinylidene-n-dodecylamine was not protonated by the acidic moiety (i.e., propionate, 3-chloropropionate or trifluoroacetate anions) of dodecylammonium propionate, dodecylammonium 3-chloropropionate or dodecylammonium trifluoroacetate reversed micelles. Addition of propionic or 3-chloropropionic acid did not cause observable protonation of the reversed-micelle-incorporated all-trans-N-retinylidene-n-dedecylamine. Addition of strong trifluoroacetic acid to reversed micellar solutions of all-trans-N-retinylidene-n-dodecylamine caused protonation as well as hydrolysis to retinal. Retinylidene Schiff bases are protected from protonation by strongly held surfactant-ion pairs which may model proton channels whose function is controlled by protein conformational changes.

Cyclohexanes↗
PubMed1992

Identification of a rhodopsin photoreceptor in Euglena gracilis.

Visual pigments are a class of receptor proteins that absorb light and trigger sensory signals. Retinal-containing proteins are used in nature as photoreceptors mainly in animals vision. Mammalian rhodopsin is the best studied example of a light sensor which couples photon absorption to a cascade of biochemical reactions amplifying the input signal. A surprising discovery was to find rhodopsin also in Archaebacteria and in unicellular eukaryotes. On the basis of absorption microspectroscopic measurements and of inhibition experiments on pigment biosynthetic pathways, we have recently suggested that a rhodopsin could be the functional receptor of the visual process in Euglena gracilis, a flagellate which can use light directly to promote photosynthetic reactions, or as an incident flux of information to adjust its swimming orientation. We here report purification and identification of all-trans-retinal by column chromatography, HPLC and GC-MS in E. gracilis; these findings indicate with absolute certainty that rhodopsin is the photoreceptor molecule of this microorganism.

Animals↗
PubMed1996

Characteristic properties of a retinoic acid synthetic cytochrome P-450 purified from liver microsomes of 3-methylcholanthrene-induced rats.

An inducible cytochrome P-450 (P-450) catalyzing retinoic acid synthesis was purified from liver microsomes of 3-methylcholanthrene (3-MC)-treated rats, based on the activity of all-trans-retinoic acid formation from all-trans-retinal. We previously reported that the retinoic acid synthesis by microsomes was catalyzed by a cytochrome P-450-linked monooxygenase system (Tomita et al. (1993) Int. J. Biochem. 25, 1775-1784). This microsomal retinoic acid synthesis in rat liver was induced more than 8-fold by 3-MC. The purified P-450 electophoretically gave a single protein band and its minimum molecular weight was estimated to be 57.2 kDa on SDS-PAGE. The optical spectrum of the oxidized P-450 without retinal revealed it was the low-spin form, and the CO-complex exhibited a maximum peak at 447 nm. The specific activity of the reconstituted P-450-linked monooxygenase system was 29.5 nmol/min per nmol P-450 at pH 7.6 and 37 degrees C. The K(m) and Vmax values for all-trans-retinal were 11.6 microM and 38.5 nmol/min per nmol P-450, respectively. The amino-acid sequence of the N-terminal region of the P-450 was identical to that of rat P-450 1A1 (CYP 1A1). Xenobiotic activities, such as 7-ethoxycoumarin O-deethylase (7-ECOD) and 7-ethoxyresorufin O-deethylase (7-EROD) activities, of the P-450-linked monooxygenase system were specific to the P-450 1A1. The retinoic acid formation in the reconstituted monooxygenase system was specifically inhibited by alpha-naphthoflavone (alpha-NF), which is a P-450 1A1-specific inhibitor, citral, which is a retinoid analogue structurally, and an anti-rat P-450 1A1 antibody. These results further support that the purified P-450 is P-450 1A1. This paper describes that P-450 1A1 was purified and characterized as a retinoic acid synthetic P-450.

Acyclic Monoterpenes↗
PubMed1991

Effects of retinoic acid on bone formation and resorption in cultured mouse calvaria.

1. The effects of retinoids on bone metabolism were examined in newborn mouse calvaria. 2. Incubation of calvaria with 0.01-1 microM retinoic acid for 4 days decreased their alkaline phosphatase (ALP) activity, mineral content and collagen content in a concentration-dependent fashion. 3. With treatment for 2 days, retinoic acid (1 microM) decreased the ALP activity and collagen content, but not the mineral content. 4. All these inhibitory effects were observed in calvaria from 0-day-old mice, but no inhibition of ALP activity was observed in calvaria from 14-day-old mice. 5. 1-Hydroxyethylidene-1,1-bisphosphonate (HEBP, 1 mM), which inhibits bone resorption, prevented the effect of retinoic acid (1 microM) on the bone mineral content, but not the effects on ALP and collagen (synthesized by osteoblasts). HEBP (1 mM) alone had no effect on the calvarial mineral and collagen contents. 6. These findings indicate that retinoic acid both stimulates bone resorption and inhibits osteoblastic activity by different mechanisms, and that stimulation of bone resorption by retinoic acid is inhibited by HEBP.

Alkaline Phosphatase↗
PubMed1985

Distribution of retinoids in different compartments of the posterior segment of the rabbit eye.

Using high-performance liquid chromatography, the amounts of all-trans retinol, retinal and retinyl palmitate were measured in the following ocular tissues and fluid of the light (LA) and dark adapted (DA) rabbit: cytosol and membrane fractions of the retina (R/C and R/M), cytosol and membrane fractions of the retinal pigment epithelium (RPE/C and RPE/M), subretinal fluid collected from the inter-photoreceptor matrix (S/R) and the matrix between apical microvilli of the RPE (S/RPE). The total amount of all-trans retinol extracted from LA eyes, 2.74 nmol per eye, was ten times greater than the amount extracted from DA eyes. In the LA eye, most of the all-trans retinol was extracted from the membrane fraction of the retina (67%); in the DA eye, most of the retinol was extracted from the cytosol fraction of the retina (58%). In contrast, the DA eye yielded more all-trans retinal (9.84 nmol) than the LA eye (5.80 nmol) and most of this retinoid was recovered from the cytosol and membrane fractions of the retina. A higher amount of all-trans retinyl palmitate was recovered from the LA eye (5.88 nmol) than the DA eye (2.02 nmol). Although most of this retinyl palmitate was extracted from the cytosol fraction of the RPE (45%, LA eye), appreciable amounts were found in all other ocular compartments. The amount of retinyl palmitate in the LA eye exceeded that of the DA eye in every compartment examined in the present study, suggesting a possible important role of retinyl esters in the visual cycle.

Animals↗
PubMed1994

The primary structure of mantid opsin.

The sequence encoding opsin from the mantid Sphodromantis sp. has been determined by dideoxynucleotide sequencing of PCR products from a cDNA derived from eye cup tissue. The 376-amino-acid (aa) residues show approx. 56% identity and 85% similarity to known insect opsins (Drosophila melanogaster and Calliphora erythrocephala). The predicted protein structure, based on the hydropathy profile and placement of key aa residues, reveals a seven-transmembrane structure typical of a rhodopsin. Unlike the previously characterised insect visual pigments which have 3-hydroxy retinal in their binding sites, mantid rhodopsin contains 11-cis retinal. Comparison of transmembrane sequences from the opsin family was performed in order to identify any specific aa substitutions which are able to account for the selection of retinal or its 3-hydroxy derivative by insect opsins.

Amino Acid Sequence↗
PubMed1994

Cloning and sequencing of a rat heart cDNA encoding a G-protein beta subunit related to the human retinal beta 3 subunit.

A cDNA (pJ5) encoding a protein with significant sequence identity to the previously known beta 1, beta 2, beta 3 and beta 4 subunits of guanine-nucleotide-binding proteins (G proteins) has been cloned from a 8-12-week-old rat heart cDNA library. Its predicted amino acid (aa) sequence of 340 aa most closely resembles that of the human beta 3 subunit, showing 96% identity. Northern blot analysis revealed that the major mRNA corresponding to the rat pJ5 cDNA is 2.0 kb in length. It is expressed at a high level in the heart and at a much lower level in the brain.

Amino Acid Sequence↗
PubMed1995

Cloning of a cDNA encoding rat aldehyde dehydrogenase with high activity for retinal oxidation.

Retinoic acid (RA), an important regulator of cell differentiation, is biosynthesized from retinol via retinal by a two-step oxidation process. We previously reported the purification and partial amino acid (aa) sequence of a rat kidney aldehyde dehydrogenase (ALDH) isozyme that catalyzed the oxidation of 9-cis and all-trans retinal to corresponding RA with high efficiency [Labrecque et al. Biochem. J. 305 (1995) 681-684]. A rat kidney cDNA library was screened using a 291-bp PCR product generated from total kidney RNA using a pair of oligodeoxyribonucleotide primers matched with the aa sequence. The full-length rat kidney ALDH cDNA contains a 2315-bp (501 aa) open reading frame (ORF). The aa sequence of rat kidney ALDH is 89, 96 and 87% identical to that of the rat cytosolic ALDH, the mouse cytosolic ALDH and human cytosolic ALDH, respectively. Northern blot and RT-PCR-mediated analysis demonstrated that rat kidney ALDH is strongly expressed in kidney, lung, testis, intestine, stomach and trachea, but weakly in the liver.

Aldehyde Dehydrogenase↗
PubMed1996

Analytical applications of retinoid-cyclodextrin inclusion complexes. 1. Characterization of a retinal-beta-cyclodextrin complex.

In studies in these laboratories on the supramolecular chemistry of the retinoids, it has been recently confirmed that inclusion of these substances within the cavity of cyclodextrins protects their excited states, thus improving their photochemical stability. In the present paper, the isolation is described of a crystalline stable complex between retinal and beta-cyclodextrin, which has been characterized by means of several techniques including atomic force microscopy (AFM). The complex shows distinct spectroscopic differences from both retinal and beta-cyclodextrin. Thus, it absorbs at lambda(max) = 380 nm in water whereas retinal is insoluble; it shows room-temperature luminescence, which retinal does not; finally, it give 1H-NMR and 13C-NMR spectra in d6-DMSO with clear differences in chemical shifts with respect to those of beta-cyclodextrin. Besides these studies in solution, the behaviour of the complex in the solid state has been compared with that of physical mixtures of retinal and beta-cyclodextrin. IR spectroscopy shows clear differences, particularly a shift in the retinal carbonyl absorption (1644-1672 cm-1). AFM studies reveal the existence of aggregates; X-ray diffractometry also supports the formation of a cyclodextrin-retinal complex.

Cyclodextrins↗