Vitamin A and carotenoids. The enzymic conversion of beta-carotene into retinal in hog intestinal mucosa.
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ABSTRACT:
SUBMITTER: Fidge NH
PROVIDER: S-EPMC1184953 | biostudies-other | 1969 Oct
REPOSITORIES: biostudies-other
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Project description:ObjectiveThe β-carotene oxygenase 1 (BCO1) is the enzyme responsible for the cleavage of β-carotene to retinal, the first intermediate in vitamin A formation. Preclinical studies suggest that BCO1 expression is required for dietary β-carotene to affect lipid metabolism. The goal of this study was to generate a gene therapy strategy that over-expresses BCO1 in the adipose tissue and utilizes the β-carotene stored in adipocytes to produce vitamin A and reduce obesity.MethodsWe generated a novel adipose-tissue-specific, adeno-associated vector to over-express BCO1 (AT-AAV-BCO1) in murine adipocytes. We tested this vector using a unique model to achieve β-carotene accumulation in the adipose tissue, in which Bco1-/- mice were fed β-carotene. An AT-AAV over-expressing green fluorescent protein was utilized as control. We evaluated the adequate delivery route and optimized cellular and organ specificity, dosage, and exposure of our vectors. We also employed morphometric analyses to evaluate the effect of BCO1 expression in adiposity, as well as HPLC and mass spectrometry to quantify β-carotene and retinoids in tissues, including retinoic acid.ResultsAT-AAV-BCO1 infusions in the adipose tissue of the mice resulted in the production of retinoic acid, a vitamin A metabolite with strong effects on gene regulation. AT-AAV-BCO1 treatment also reduced adipose tissue size and adipocyte area by 35% and 30%, respectively. These effects were sex-specific, highlighting the complexity of vitamin A metabolism in mammals.ConclusionsThe over-expression of BCO1 through delivery of an AT-AAV-BCO1 leads to the conversion of β-carotene to vitamin A in adipocytes, which subsequently results in reduction of adiposity. These studies highlight for the first time the potential of adipose tissue β-carotene as a target for BCO1 over-expression in the reduction of obesity.
| S-EPMC9707038 | biostudies-literature
Project description:The carboxypeptidase activity occurring in hog intestinal mucosa is apparently due to two distinct enzymes which may be responsible for the release of basic COOH-terminal amino acids from short peptides. The plasma membrane-bound carboxypeptidase activity which occurs at neutral optimum pH levels was found to be enhanced by CoCl(2) and inhibited by guanidinoethylmercaptosuccinic acid, o-phenanthroline, ethylenediamine tetraacetic acid and cadmium acetate; whereas the soluble carboxypeptidase activity which occurs at an optimum pH level of 5.0 was not activated by CoCl(2) and only slightly inhibited by o-phenanthroline, ethylenediamine tetraacetic acid, NiCl(2) and CdCl(2). The latter activity was presumably due to lysosomal cathepsin B, which is known to be present in the soluble fraction of hog intestinal mucosa. Although the membrane-bound enzyme was evenly distributed along the small intestine, it was not anchored in the phospholipidic bilayer via a glycosyl-phosphatidylinositol moiety, as carboxypeptidase M from human placenta is. The enzyme was not solubilized by phosphatidylinositol-specific phospholipase C, but was solubilized to practically the same extent by several detergents. The purified trypsin-solubilized form is a glycoprotein with a molecular mass of 200 kDa, as determined by performing SDS-PAGE and gel filtration, which differs considerably from the molecular mass of human placental carboxypeptidase M (62 kDa). It was found to cleave lysyl bonds more rapidly than arginyl bonds, which is not so in the case of carboxypeptidase M, and immunoblotting analysis provided further evidence that hog intestinal and human placental membrane-bound carboxypeptidases do not bear much resemblance to each other. Since the latter enzyme has been called carboxypeptidase M, it is suggested that the former might be carboxypeptidase D, the recently described new member of the carboxypeptide B-type family.
| S-EPMC7124209 | biostudies-literature
Project description:Atherosclerosis is characterized by the pathological accumulation of cholesterol-laden macrophages in the arterial wall. Atherosclerosis is also the main underlying cause of CVDs, and its development is largely driven by elevated plasma cholesterol. Strong epidemiological data find an inverse association between plasma β-carotene with atherosclerosis, and we recently showed that β-carotene oxygenase 1 (BCO1) activity, responsible for β-carotene cleavage to vitamin A, is associated with reduced plasma cholesterol in humans and mice. In this study, we explore whether intact β-carotene or vitamin A affects atherosclerosis progression in the atheroprone LDLR-deficient mice. Compared with control-fed Ldlr-/- mice, β-carotene-supplemented mice showed reduced atherosclerotic lesion size at the level of the aortic root and reduced plasma cholesterol levels. These changes were absent in Ldlr-/- /Bco1-/- mice despite accumulating β-carotene in plasma and atherosclerotic lesions. We discarded the implication of myeloid BCO1 in the development of atherosclerosis by performing bone marrow transplant experiments. Lipid production assays found that retinoic acid, the active form of vitamin A, reduced the secretion of newly synthetized triglyceride and cholesteryl ester in cell culture and mice. Overall, our findings provide insights into the role of BCO1 activity and vitamin A in atherosclerosis progression through the regulation of hepatic lipid metabolism.
| S-EPMC7604725 | biostudies-literature
Project description:Atherosclerosis is characterized by the pathological accumulation of cholesterol-laden macrophages in the arterial wall. Atherosclerosis is also the main underlying cause of cardiovascular diseases (CVDs), and its development is largely driven by elevated plasma cholesterol. Strong epidemiological data find an inverse association between plasma β-carotene with atherosclerosis, and we recently showed that β-carotene oxygenase 1 (BCO1) activity, responsible for β-carotene cleavage to vitamin A, is associated with reduced plasma cholesterol in humans and mice. In this study, we explore whether intact β-carotene or vitamin A affect atherosclerosis progression in the atheroprone low-density lipoprotein receptor (LDLR) - deficient mice. In comparison to control-fed Ldlr-/- mice, β-carotene-supplemented mice showed reduced atherosclerotic lesion size at the level of the aortic root and plasma cholesterol levels (P = 0.0003). These changes were absent in Ldlr-/-/Bco1-/- mice, despite accumulating β-carotene in plasma and atherosclerotic lesions. We discarded the implication of myeloid BCO1 in the development of atherosclerosis by performing bone marrow transplant experiments. Lipid production assays found that retinoic acid, the active form of vitamin A, reduced the secretion of newly synthetized triglyceride and cholesteryl ester in cell culture and mice. Overall, our findings provide insights into the role of BCO1 activity and vitamin A in atherosclerosis progression through the regulation of hepatic lipid metabolism.
2020-11-12 | GSE157972 | GEO
Project description:The uptake of dietary lipids from the small intestine is a complex process that depends on the activities of specific membrane receptors with yet unknown regulatory mechanisms. Using both mouse models and human cell lines, we show here that intestinal lipid absorption by the scavenger receptor class B type 1 (SR-BI) is subject to control by retinoid signaling. Retinoic acid via retinoic acid receptors induced expression of the intestinal transcription factor ISX. ISX then repressed the expression of SR-B1 and the carotenoid-15,15'-oxygenase Bcmo1. BCMO1 acts downstream of SR-BI and converts absorbed beta,beta-carotene to the retinoic acid precursor, retinaldehyde. Using BCMO1-knockout mice, we demonstrated increased intestinal SR-BI expression and systemic beta,beta-carotene accumulation. SR-BI-dependent accumulation of beta,beta-carotene was prevented by dietary retinoids that induced ISX expression. Thus, our study revealed a diet-responsive regulatory network that controls beta,beta-carotene absorption and vitamin A production by negative feedback regulation. The role of SR-BI in the intestinal absorption of other dietary lipids, including cholesterol, fatty acids, and tocopherols, implicates retinoid signaling in the regulation of lipid absorption more generally and has clinical implications for diseases associated with dyslipidemia.
| S-EPMC2874479 | biostudies-other
Project description:Finishing pigs (N = 224; 28.66 ± 1.90 kg bodyweight) were randomly assigned across 56 pens of either four barrows or gilts, and assigned to one of four diets: control (7,656 IU vitamin A/kg), control supplemented with vitamin A (4.36 ppm, Rovimix A 1000, DSM, Parsippany, NJ, USA), control supplemented with beta-carotene (163.28 ppm, Rovimix β-Carotene 10%, DSM, Parsippany), or control supplemented with oxidized beta-carotene (40 ppm; 10% active ingredient, Avivagen, Ottawa, ON, Canada). Pigs and feeder weights were obtained at the start of the study (d 0), and end of each phase (d 21, 42, and 63). A subset of gilts had a blood sample taken via jugular venipuncture on d 0, a blood sample and vaccinations of Lawsonia intracellularis and porcine circovirus type 2 (PCV2) on d 18, a blood sample and booster vaccination of PCV2 on d 39, a blood sample on day 60, and a final blood sample on day 63. Gilts were euthanized at the end of the study to obtain a liver (entire right lobe) and a jejunum sample (15.24 cm at 10% of length). Additionally, the second and fourth right anterior mammary were collected to assess anterior mammary tissues. Data were analyzed in SAS 9.4 (Statistical Analysis System, Cary, NC) via GLIMMIX procedure. Oxidized beta-carotene supplementation increased (P = 0.02) ADG across phases over vitamin A supplementation, although there were no differences (P = 0.18) in the body weight of pigs. There was no effect (P > 0.05) of diet on plasma or hepatic retinol, IgG or IgM levels, or immune cell presence in developing mammary tissue. Supplemented vitamin A tended (P = 0.05) to increase the mRNA abundance of retinol binding protein in the jejunum, but other mRNA abundance for genes (alcohol dehydrogenase class 1, lecithin retinol acyltransferase phosphatidylcholine-retinol O-acyltransferase, and beta-carotene oxygenase 1) were not affected (P > 0.05) by dietary treatments. A diet by time interaction (P = 0.04) was noted for the circovirus S/P ratio, where vitamin A supplementation had the best ratio compared to other diets. Analyzed titer levels for the circovirus vaccine had an interaction (P < 0.01) for diet by time, where vitamin A supplementation had the highest titer at the end of the study. Thus, pigs supplemented with oxidized beta-carotene had an improved ADG over vitamin A supplemented pigs, but pigs supplemented with vitamin A seemed to have an improved immune status.
| S-EPMC10108644 | biostudies-literature
Project description:Recent epidemiological data suggest that beta-carotene may be protective against metabolic diseases in which adipose tissue plays a key role. Adipose tissue constitutes the major beta-carotene storage tissue and its functions have been shown to be modulated in response to beta-carotene breakdown products, especially retinal produced after cleavage by beta-carotene 15,15'-monooxygenase (BCMO1), and retinoic acid arising from oxidation of retinal. However, the possibility exists that beta-carotene in its intact form can also affect adipocyte function. Development of a knock out model and identification of a loss-of-function mutation have pointed out BCMO1 as being probably the sole enzyme responsible for provitamin A conversion into retinal in mammals. The utilisation of BCMO1(-/-)mice should provide insights on beta-carotene effect on its own in the future. In humans, intervention studies have highlighted the huge interindividual variation of beta-carotene conversion efficiency, possibly due to genetic polymorphisms, which might impact on response to beta-carotene. This brief review discusses the processes involved in beta-carotene conversion and the effect of cleavage products on body fat and adipose tissue function.
| S-EPMC2745744 | biostudies-literature
Project description:Xanthophyll carotenoids, such as lutein, zeaxanthin and β-cryptoxanthin, may provide potential health benefits against chronic and degenerative diseases. Investigating pathways of xanthophyll metabolism are important to understanding their biological functions. Carotene-15,15'-monooxygenase (CMO1) has been shown to be involved in vitamin A formation, while recent studies suggest that carotene-9',10'-monooxygenase (CMO2) may have a broader substrate specificity than previously recognized. In this in vitro study, we investigated baculovirus-generated recombinant ferret CMO2 cleavage activity towards the carotenoid substrates zeaxanthin, lutein and β-cryptoxanthin. Utilizing HPLC, LC-MS and GC-MS, we identified both volatile and non-volatile apo-carotenoid products including 3-OH-β-ionone, 3-OH-α-ionone, β-ionone, 3-OH-α-apo-10'-carotenal, 3-OH-β-apo-10'-carotenal, and β-apo-10'-carotenal, indicating cleavage at both the 9,10 and 9',10' carbon-carbon double bond. Enzyme kinetic analysis indicated the xanthophylls zeaxanthin and lutein are preferentially cleaved over β-cryptoxanthin, indicating a key role of CMO2 in non-provitamin A carotenoid metabolism. Furthermore, incubation of 3-OH-β-apo-10'-carotenal with CMO2 lysate resulted in the formation of 3-OH-β-ionone. In the presence of NAD(+), in vitro incubation of 3-OH-β-apo-10'-carotenal with ferret hepatic homogenates formed 3-OH-β-apo-10'-carotenoic acid. Since apo-carotenoids serve as important signaling molecules in a variety of biological processes, enzymatic cleavage of xanthophylls by mammalian CMO2 represents a new avenue of research regarding vertebrate carotenoid metabolism and biological function.
| S-EPMC3026080 | biostudies-literature
Project description:BackgroundGolden Rice (GR) has been genetically engineered to be rich in β-carotene for use as a source of vitamin A.ObjectiveThe objective was to compare the vitamin A value of β-carotene in GR and in spinach with that of pure β-carotene in oil when consumed by children.DesignChildren (n = 68; age 6-8 y) were randomly assigned to consume GR or spinach (both grown in a nutrient solution containing 23 atom% ²H₂O) or [²H₈]β-carotene in an oil capsule. The GR and spinach β-carotene were enriched with deuterium (²H) with the highest abundance molecular mass (M) at M(β-C)+²H₁₀. [¹³C₁₀]Retinyl acetate in an oil capsule was administered as a reference dose. Serum samples collected from subjects were analyzed by using gas chromatography electron-capture negative chemical ionization mass spectrometry for the enrichments of labeled retinol: M(retinol)+4 (from [²H₈]β-carotene in oil), M(retinol)+5 (from GR or spinach [²H₁₀]β-carotene), and M(retinol)+10 (from [¹³C₁₀]retinyl acetate).ResultsUsing the response to the dose of [¹³C₁₀]retinyl acetate (0.5 mg) as a reference, our results (with the use of AUC of molar enrichment at days 1, 3, 7, 14, and 21 after the labeled doses) showed that the conversions of pure β-carotene (0.5 mg), GR β-carotene (0.6 mg), and spinach β-carotene (1.4 mg) to retinol were 2.0, 2.3, and 7.5 to 1 by weight, respectively.ConclusionsThe β-carotene in GR is as effective as pure β-carotene in oil and better than that in spinach at providing vitamin A to children. A bowl of ~100 to 150 g cooked GR (50 g dry weight) can provide ~60% of the Chinese Recommended Nutrient Intake of vitamin A for 6-8-y-old children.
| S-EPMC3417220 | biostudies-literature
Project description:Canthaxanthin is an important antioxidant with wide application prospects, and β-carotene ketolase is the key enzyme involved in the biosynthesis of canthaxanthin. However, the challenge for the soluble expression of β-carotene ketolase is that it hinders the large-scale production of carotenoids such as canthaxanthin and astaxanthin. Hence, this study employed several strategies aiming to improve the soluble expression of β-carotene ketolase and its activity, including selecting optimal expression vectors, screening induction temperatures, adding soluble expression tags, and adding a molecular chaperone. Results showed that all these strategies can improve the soluble expression and activity of β-carotene ketolase in Escherichia coli. In particular, the production of soluble β-carotene ketolase was increased 8 times, with a commercial molecular chaperon of pG-KJE8, leading to a 1.16-fold enhancement in the canthaxanthin production from β-carotene. Interestingly, pG-KJE8 could also enhance the soluble expression of β-carotene ketolase derived from eukaryotic microalgae. Further research showed that the production of canthaxanthin and echinenone was significantly improved by as many as 30.77 times when the pG-KJE8 was added, indicating the molecular chaperone performed differently among different β-carotene ketolase. This study not only laid a foundation for further research on the improvement of β-carotene ketolase activity but also provided new ideas for the improvement of carotenoid production.
| S-EPMC10891602 | biostudies-literature