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The conversion of exogenous retinol and related compounds into retinyl phosphate mannose by adult Brugia pahangi in vitro.

ABSTRACT: Adult Brugia pahangi took up and incorporated beta-carotene and free retinol in vitro. The uptake of retinol was 50 times greater than that of beta-carotene under similar incubation conditions. beta-Carotene was almost entirely metabolized, primarily to retinol. The metabolism of retinol by B. pahangi in vitro was less extensive, with a variety of retinoids tentatively identified, including retinyl phosphate (Ret-P), retinyl phosphate mannose (Ret-P-Man) and anhydroretinol as minor metabolites. B. pahangi microsomes were also shown to biosynthesize Ret-P-Man from exogenous Ret-P and GDP-mannose, but not from endogenous lipid acceptors alone. In this circumstance an unidentified lipid appeared to be mannosylated by B. pahangi. The rate of mannose transfer to exogenous Ret-P by B. pahangi microsomes was 150 pmol X min -1. (mg of protein) -1. Ret-P-Man synthetase activity from both B. pahangi and rat liver microsomes had an absolute requirement for bovine serum albumin and MnCl2, and occurred in the absence of detergent. The results suggest a biochemical role for vitamin A in B. pahangi, possibly in filarial glycoprotein synthesis.

SUBMITTER: Comley JC

PROVIDER: S-EPMC1152257 | biostudies-other | 1983 Aug

REPOSITORIES: biostudies-other

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Synthesis of retinyl phosphate mannose in vitro. Non-enzymic breakdown and reversibility.

Project description:Hamster liver microsomal membranes catalyse the synthesis of retinyl phosphate mannose (Ret-P-Man) from GDP-mannose and exogenous retinyl phosphate (Ret-P). We have previously shown that maximal Ret-P-Man synthesis occurs in vitro at 20-30 min, followed by a subsequent loss of mannose from Ret-P-Man, suggestive of an intermediary function of Ret-P-Man and/or Ret-P-Man breakdown [Shidoji, Silverman-Jones & De Luca (1982) Biochem. J. 208, 865-868; Creek, Morre, Silverman-Jones, Shidoji & De Luca (1983) Biochem. J. 210, 541-547). To monitor Ret-P-Man synthesis and breakdown carefully, we developed a chromatographic system in which mannose, Ret-P-Man, mannose phosphate and GDP-mannose are separated in a single analysis on a Mono Q column eluted with a gradient of NaCl. Using this chromatographic system, we have determined that 80-90% of the Ret-P-Man made in vitro by hamster liver membranes in 30 min is recovered with the membranes upon centrifugation. Subsequent incubation of Ret-P-Man-loaded membranes at 37 degrees C results in a non-enzymic breakdown of Ret-P-Man to beta-mannopyranosyl phosphate and anhydroretinol. However, incubation of the Ret-P-Man-loaded hamster liver membranes with GDP, but not GMP, ADP, CDP or UDP, results in a loss of mannose from Ret-P-Man and the formation of GDP-mannose and Ret-P. These results demonstrate that Ret-P-Man synthesized in vitro is subject to non-enzymic breakdown to beta-mannopyranosyl phosphate and anhydroretinol and that the GDP-mannose:retinyl phosphate mannosyltransferase reaction is reversible.

| S-EPMC1144895 | biostudies-other

Subcellular localization of the enzyme that forms mannosyl retinyl phosphate from guanosine diphosphate [14C]mannose and retinyl phosphate.

Project description:The subcellular distribution of the enzyme catalysing the conversion of retinyl phosphate and GDP-[14C]mannose into [14C]mannosyl retinyl phosphate was determined by using subcellular fractions of rat liver. Purity of fractions, as determined by marker enzymes, was 80% or better. The amount of mannosyl retinyl phosphate formed (pmol/min per mg of protein) for each fraction was: rough endoplasmic reticulum 0.48 +/- 0.09 (mean +/- S.D.); smooth membranes (consisting of 60% smooth endoplasmic reticulum and 40% Golgi apparatus), 0.18 +/- 0.03; Golgi apparatus, 0.13 +/- 0.03; and plasma membrane 0.02.

| S-EPMC1161080 | biostudies-other

Retinyl phosphate mannose synthesis in rat liver membranes. Phospholipase sensitivity and phospholipid requirement.

Project description:A remarkable and immediate decrease in GDP-mannose:retinyl phosphate mannosyltransferase activity was found on pre-incubation of rat liver postnuclear membranes with phospholipase A2 or phospholipase C. Under the same conditions of pre-incubation (1 min at 37 degrees C) trypsin did not affect the enzyme activity, whereas pre-incubation for 30 min with trypsin and Pronase abolished enzyme activity. The lipid extract of untreated rat liver membranes partially restored enzyme activity after phospholipase treatment. Sphingomyelin was as active as the endogenous lipids. Other phospholipids were less active in the following order: phosphatidylcholine greater than phosphatidylethanolamine greater than phosphatidylinositol = phosphatidylserine. Dolichyl phosphate mannose synthesis was inhibited less (33%) by phospholipase C than was Ret-P-Man synthesis (98.5%) under identical conditions of incubation, which included 0.025% Triton. However, retinyl phosphate mannose synthesis by purified endoplasmic reticulum was found to be resistant to phospholipase C. Mixing experiments failed to demonstrate an inhibitory effect of the phospholipase-treated postnuclear membrane fraction on the synthetic activity of the endoplasmic reticulum, thus excluding the release of an inhibitory factor from the postnuclear membranes.

| S-EPMC1152568 | biostudies-other

Retinyl esters are elevated in progeny of retinol dehydrogenase 11 deficient dams.

Project description:Retinol dehydrogenase 11 (RDH11) is an NADPH-dependent retinaldehyde reductase that was previously reported to function in the visual cycle. Recently, we have shown that RDH11 contributes to the maintenance of retinol levels in extraocular tissues under conditions of vitamin A deficiency or reduced vitamin A availability. RDH11 is also expressed in the embryo. Rdh11 knockout animals do not display embryonic defects and appear to develop normally to the adult stage, but the exact function of RDH11 during development is not yet known. In contrast to RDH11-null mice, animals that lack dehydrogenase/reductase 3 (DHRS3), the enzyme that functions as a retinaldehyde reductase and is essential for the maintenance of retinoid homeostasis during embryogenesis, rarely survive until birth. Here, we investigated whether inactivation of RDH11 together with DHRS3 exacerbates the severity of retinoid homeostasis disruption in embryos that lack both enzymes compared to DHRS3-null mice. The results of this study indicate that in vitamin A sufficient animals, the loss of RDH11 in addition to DHRS3 does not appear to significantly impact the total levels of retinoic acid, free retinol, or retinyl esters in Rdh11-/-/Dhrs3-/-embryos in comparison to Dhrs3-/- embryos. Surprisingly, Rdh11-/- single gene knockout embryos obtained from breeding of Rdh11-/- dams display elevated levels of embryonic retinyl esters compared to wild type embryos. The mechanism of the maternal effect of Rdh11 status on fetal retinoid stores remains to be elucidated.

| S-EPMC6506212 | biostudies-literature

Clinical outcomes in an adult patient with mannose phosphate isomerase-congenital disorder of glycosylation who discontinued mannose therapy.

Project description:The mannose phosphate isomerase-congenital disorder of glycosylation (MPI-CDG) is caused by phosphomannose isomerase deficiency. Clinical features include hyperinsulinaemic hypoglycaemia, protein losing enteropathy, hepatomegaly and hepatic fibrosis, digestive symptoms and coagulation abnormalities. The condition is treated with mannose supplementation. Long-term outcomes in adults are not well described. We present a case of an adult female patient who discontinued mannose therapy in her adolescence. In adulthood she developed gastrointestinal problems, chronic anaemia and osteophytes in her knees.

| S-EPMC7490551 | biostudies-literature

Transcriptomic comparison of the vitamin A ester retinyl propionate and retinol in human keratinocytes

Project description:Retinoids are potent skin care actives used to treat a number of common clinical and cosmetic skin conditions, including skin aging. Here, we compare the effects of retinyl proprionate and retinol on gene expression in immortalized human keratinocytes.

2021-09-09 | GSE155789 | GEO

The Effect of In Vitro Cultivation on the Transcriptome of Adult Brugia malayi.

Project description:BACKGROUND:Filarial nematodes cause serious and debilitating infections in human populations of tropical countries, contributing to an entrenched cycle of poverty. Only one human filarial parasite, Brugia malayi, can be maintained in rodents in the laboratory setting. It has been a widely used model organism in experiments that employ culture systems, the impact of which on the worms is unknown. METHODOLOGY/PRINCIPAL FINDINGS:Using Illumina RNA sequencing, we characterized changes in gene expression upon in vitro maintenance of adult B. malayi female worms at four time points: immediately upon removal from the host, immediately after receipt following shipment, and after 48 h and 5 days in liquid culture media. The dramatic environmental change and the 24 h time lapse between removal from the host and establishment in culture caused a globally dysregulated gene expression profile. We found a maximum of 562 differentially expressed genes based on pairwise comparison between time points. After an initial shock upon removal from the host and shipping, a few stress fingerprints remained after 48 h in culture and until the experiment was stopped. This was best illustrated by a strong and persistent up-regulation of several genes encoding cuticle collagens, as well as serpins. CONCLUSIONS/SIGNIFICANCE:These findings suggest that B. malayi can be maintained in culture as a valid system for pharmacological and biological studies, at least for several days after removal from the host and adaptation to the new environment. However, genes encoding several stress indicators remained dysregulated until the experiment was stopped.

| S-EPMC4699822 | biostudies-literature

Retinol metabolism in the mollusk Osilinus lineatus indicates an ancient origin for retinyl ester storage capacity.

Project description:Although retinoids have been reported to be present and active in vertebrates and invertebrates, the presence of mechanisms for retinoid storage in the form of retinyl esters, a key feature to maintain whole-organism retinoid homeostasis, have been considered to date a vertebrate innovation. Here we demonstrate for the first time the presence of retinol and retinyl esters in an invertebrate lophotrochozoan species, the gastropod mollusk Osilinus lineatus. Furthermore, through a pharmacological approach consisting of intramuscular injections of different retinoid precursors, we also demonstrate that the retinol esterification pathway is active in vivo in this species. Interestingly, retinol and retinyl esters were only detected in males, suggesting a gender-specific role for these compounds in the testis. Females, although lacking detectable levels of retinol or retinyl esters, also have the biochemical capacity to esterify retinol, but at a lower rate than males. The occurrence of retinyl ester storage capacity, together with the presence in males and females of active retinoids, i.e., retinoic acid isomers, indicates that O. lineatus has a well developed retinoid system. Hence, the present data strongly suggest that the capacity to maintain retinoid homeostasis has arisen earlier in Bilateria evolution than previously thought.

| S-EPMC3320870 | biostudies-literature

Retinyl ester formation by lecithin: retinol acyltransferase is a key regulator of retinoid homeostasis in mouse embryogenesis.

Project description:The developing mammalian embryo is entirely dependent on the maternal circulation for its supply of retinoids (vitamin A and its metabolites). The mechanisms through which mammalian developing tissues maintain adequate retinoid levels in the face of suboptimal or excessive maternal dietary vitamin A intake have not been established. We investigated the role of retinyl ester formation catalyzed by lecithin:retinol acyltransferase (LRAT) in regulating retinoid homeostasis during embryogenesis. Dams lacking both LRAT and retinol-binding protein (RBP), the sole specific carrier for retinol in serum, were maintained on diets containing different amounts of vitamin A during pregnancy. We hypothesized that the lack of both proteins would make the embryo more vulnerable to changes in maternal dietary vitamin A intake. Our data demonstrate that maternal dietary vitamin A deprivation during pregnancy generates a severe retinoid-deficient phenotype of the embryo due to the severe retinoid-deficient status of the double mutant dams rather than to the lack of LRAT in the developing tissues. Moreover, in the case of excessive maternal dietary vitamin A intake, LRAT acts together with Cyp26A1, one of the enzymes that catalyze the degradation of retinoic acid, and possibly with STRA6, the recently identified cell surface receptor for retinol-RBP, in maintaining adequate levels of retinoids in embryonic and extraembryonic tissues. In contrast, the pathway of retinoic acid synthesis does not contribute significantly to regulating retinoid homeostasis during mammalian development except under conditions of severe maternal retinoid deficiency.

| S-EPMC3771510 | biostudies-literature

Identification of a fourth mannose 6-phosphate binding site in the cation-independent mannose 6-phosphate receptor.

Project description:The 300 kDa cation-independent mannose 6-phosphate receptor (CI-MPR) plays an essential role in lysosome biogenesis by targeting ? 60 different phosphomannosyl-containing acid hydrolases to the lysosome. This type I membrane glycoprotein has a large extracellular region comprised of 15 homologous domains. Two mannose 6-phosphate (M6P) binding sites have been mapped to domains 3 and 9, whereas domain 5 binds preferentially to the phosphodiester, M6P-N-acetylglucosamine (GlcNAc). A structure-based sequence alignment predicts that the C-terminal domain 15 contains three out of the four conserved residues identified as essential for carbohydrate recognition by domains 3, 5 and 9 of the CI-MPR, but lacks two cysteine residues that are predicted to form a disulfide bond. To determine whether domain 15 of the CI-MPR has lectin activity and to probe its carbohydrate-binding specificity, truncated forms of the CI-MPR were tested for binding to acid hydrolases with defined N-glycans in surface plasmon resonance analyses, and used to interrogate a phosphorylated glycan microarray. The results show that a construct encoding domains 14-15 binds both M6P and M6P-GlcNAc with similar affinity (Kd = 13 and 17 ?M, respectively). Site-directed mutagenesis studies demonstrate the essential role of the conserved Tyr residue in domain 15 for phosphomannosyl binding. A structural model of domain 15 was generated that predicted an Arg residue to be in the binding pocket and mutagenesis studies confirmed its important role in carbohydrate binding. Together, these results show that the CI-MPR contains a fourth carbohydrate-recognition site capable of binding both phosphomonoesters and phosphodiesters.

| S-EPMC4410830 | biostudies-literature

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