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  1. Article ; Online: Aster la vista: Unraveling the biochemical basis of carotenoid homeostasis in the human retina.

    Bandara, Sepalika / von Lintig, Johannes

    BioEssays : news and reviews in molecular, cellular and developmental biology

    2022  Volume 44, Issue 11, Page(s) e2200133

    Abstract: Carotenoids play pivotal roles in vision as light filters and precursor of chromophore. Many vertebrates also display the colorful pigments as ornaments in bare skin parts and feathers. Proteins involved in the transport and metabolism of these lipids ... ...

    Abstract Carotenoids play pivotal roles in vision as light filters and precursor of chromophore. Many vertebrates also display the colorful pigments as ornaments in bare skin parts and feathers. Proteins involved in the transport and metabolism of these lipids have been identified including class B scavenger receptors and carotenoid cleavage dioxygenases. Recent research implicates members of the Aster protein family, also known as GRAM domain-containing (GRAMD), in carotenoid metabolism. These multi-domain proteins facilitate the intracellular movement of carotenoids from their site of cellular uptake by scavenger receptors to the site of their metabolic processing by carotenoid cleavage dioxygenases. We provide a model how the coordinated interplay of these proteins and their differential expression establishes carotenoid distribution patterns and function in tissues, with particular emphasis on the human retina.
    MeSH term(s) Animals ; Humans ; Carotenoids/chemistry ; Dioxygenases/metabolism ; Retina ; Homeostasis ; Lipids
    Chemical Substances Carotenoids (36-88-4) ; Dioxygenases (EC 1.13.11.-) ; Lipids
    Language English
    Publishing date 2022-09-20
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 50140-2
    ISSN 1521-1878 ; 0265-9247
    ISSN (online) 1521-1878
    ISSN 0265-9247
    DOI 10.1002/bies.202200133
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Eat Your Carrots! β-Carotene and Cholesterol Homeostasis.

    von Lintig, Johannes

    The Journal of nutrition

    2020  Volume 150, Issue 8, Page(s) 2003–2005

    MeSH term(s) Cholesterol/metabolism ; Daucus carota/chemistry ; Homeostasis/drug effects ; Humans ; Lipid Metabolism/drug effects ; Retinoids/chemistry ; Retinoids/pharmacology ; beta Carotene/chemistry ; beta Carotene/metabolism ; beta Carotene/pharmacology
    Chemical Substances Retinoids ; beta Carotene (01YAE03M7J) ; Cholesterol (97C5T2UQ7J)
    Language English
    Publishing date 2020-08-01
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 218373-0
    ISSN 1541-6100 ; 0022-3166
    ISSN (online) 1541-6100
    ISSN 0022-3166
    DOI 10.1093/jn/nxaa189
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  3. Article ; Online: Unraveling the mystery of ocular retinoid turnover: Insights from albino mice and the role of STRA6.

    Ramkumar, Srinivasagan / Jastrzebska, Beata / Montenegro, Diego / Sparrow, Janet R / von Lintig, Johannes

    The Journal of biological chemistry

    2024  Volume 300, Issue 3, Page(s) 105781

    Abstract: A delicate balance between photon absorption for vision and the protection of photoreceptors from light damage is pivotal for ocular health. This equilibrium is governed by the light-absorbing 11-cis-retinylidene chromophore of visual pigments, which, ... ...

    Abstract A delicate balance between photon absorption for vision and the protection of photoreceptors from light damage is pivotal for ocular health. This equilibrium is governed by the light-absorbing 11-cis-retinylidene chromophore of visual pigments, which, upon bleaching, transforms into all-trans-retinal and undergoes regeneration through an enzymatic pathway, named the visual cycle. Chemical side reactions of retinaldehyde during the recycling process can generate by-products that may result in a depletion of retinoids. In our study, we have clarified the crucial roles played by melanin pigmentation and the retinoid transporter STRA6 in preventing this loss and preserving the integrity of the visual cycle. Our experiments initially confirmed that consecutive green and blue light bleaching of isolated bovine rhodopsin produced 9-cis and 13-cis retinal. The same unusual retinoids were found in the retinas of mice exposed to intense light, with elevated concentrations observed in albino mice. Examining the metabolic fate of these visual cycle byproducts revealed that 9-cis-retinal, but not 13-cis-retinal, was recycled back to all-trans-retinal through an intermediate called isorhodopsin. However, investigations in Stra6 knockout mice unveiled that the generation of these visual cycle byproducts correlated with a light-induced loss of ocular retinoids and visual impairment. Collectively, our findings uncover important novel aspects of visual cycle dynamics, with implications for ocular health and photoreceptor integrity.
    MeSH term(s) Animals ; Cattle ; Mice ; Diterpenes ; Mice, Knockout ; Retina/metabolism ; Retinaldehyde/metabolism ; Retinoids/metabolism ; Vision, Ocular ; Membrane Proteins/metabolism
    Chemical Substances 13-cis-retinal (472-86-6) ; Diterpenes ; Retinaldehyde (RR725D715M) ; Retinoids ; Stra6 protein, mouse ; Membrane Proteins
    Language English
    Publishing date 2024-02-21
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1016/j.jbc.2024.105781
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  4. Article ; Online: Biology of carotenoids in mammals.

    von Lintig, Johannes / Quadro, Loredana

    Biochimica et biophysica acta. Molecular and cell biology of lipids

    2020  Volume 1865, Issue 11, Page(s) 158754

    MeSH term(s) Animals ; Biology/trends ; Carotenoids/metabolism ; Mammals/metabolism
    Chemical Substances Carotenoids (36-88-4)
    Language English
    Publishing date 2020-06-05
    Publishing country Netherlands
    Document type Editorial
    ZDB-ID 60-7
    ISSN 1879-2618 ; 1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2650 ; 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
    ISSN (online) 1879-2618 ; 1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2650
    ISSN 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
    DOI 10.1016/j.bbalip.2020.158754
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: ASTER-B regulates mitochondrial carotenoid transport and homeostasis.

    Bandara, Sepalika / Moon, Jean / Ramkumar, Srinivasagan / von Lintig, Johannes

    Journal of lipid research

    2023  Volume 64, Issue 5, Page(s) 100369

    Abstract: The scavenger receptor class B type 1 (SR-B1) facilitates uptake of cholesterol and carotenoids into the plasma membrane (PM) of mammalian cells. Downstream of SR-B1, ASTER-B protein mediates the nonvesicular transport of cholesterol to mitochondria for ... ...

    Abstract The scavenger receptor class B type 1 (SR-B1) facilitates uptake of cholesterol and carotenoids into the plasma membrane (PM) of mammalian cells. Downstream of SR-B1, ASTER-B protein mediates the nonvesicular transport of cholesterol to mitochondria for steroidogenesis. Mitochondria also are the place for the processing of carotenoids into diapocarotenoids by β-carotene oxygenase-2. However, the role of these lipid transport proteins in carotenoid metabolism has not yet been established. Herein, we showed that the recombinant StART-like lipid-binding domain of ASTER-A and B preferentially binds oxygenated carotenoids such as zeaxanthin. We established a novel carotenoid uptake assay and demonstrated that ASTER-B expressing A549 cells transport zeaxanthin to mitochondria. In contrast, the pure hydrocarbon β-carotene is not transported to the organelles, consistent with its metabolic processing to vitamin A in the cytosol by β-carotene oxygenase-1. Depletion of the PM from cholesterol by methyl-β-cyclodextrin treatment enhanced zeaxanthin but not β-carotene transport to mitochondria. Loss-of-function assays by siRNA in A549 cells and the absence of zeaxanthin accumulation in mitochondria of ARPE19 cells confirmed the pivotal role of ASTER-B in this process. Together, our study in human cell lines established ASTER-B protein as key player in nonvesicular transport of zeaxanthin to mitochondria and elucidated the molecular basis of compartmentalization of the metabolism of nonprovitamin A and provitamin A carotenoids in mammalian cells.
    MeSH term(s) Animals ; Humans ; Zeaxanthins/metabolism ; Carotenoids/metabolism ; beta Carotene/metabolism ; Cholesterol ; Mitochondria/metabolism ; Homeostasis ; Mammals/metabolism
    Chemical Substances Zeaxanthins ; Carotenoids (36-88-4) ; beta Carotene (01YAE03M7J) ; Cholesterol (97C5T2UQ7J)
    Language English
    Publishing date 2023-04-06
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 80154-9
    ISSN 1539-7262 ; 0022-2275
    ISSN (online) 1539-7262
    ISSN 0022-2275
    DOI 10.1016/j.jlr.2023.100369
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  6. Article ; Online: Vitamin A deficiency compromises the barrier function of the retinal pigment epithelium.

    Moon, Jean / Zhou, Gao / Jankowsky, Eckhard / von Lintig, Johannes

    PNAS nexus

    2023  Volume 2, Issue 6, Page(s) pgad167

    Abstract: A major cause for childhood blindness worldwide is attributed to nutritional vitamin A deficiency. Surprisingly, the molecular basis of the ensuing retinal degeneration has not been well defined. Abundant expression of the retinoid transporter STRA6 in ... ...

    Abstract A major cause for childhood blindness worldwide is attributed to nutritional vitamin A deficiency. Surprisingly, the molecular basis of the ensuing retinal degeneration has not been well defined. Abundant expression of the retinoid transporter STRA6 in the retinal pigment epithelium (RPE) and homeostatic blood levels of retinol-binding protein delay vitamin A deprivation of the mouse eyes. Hence, genetic dissection of STRA6 makes mice susceptible to nutritional manipulation of ocular retinoid status. We performed RNA-seq analyses and complemented the data with tests of visual physiology, ocular morphology, and retinoid biochemistry to compare eyes with different vitamin A status. Mild ocular vitamin A deficiency decreased transcripts of photoreceptor transduction pathway-related genes and increased transcripts of oxidative stress pathways. The response was associated with impaired visual sensitivity and an accumulation of fluorescent debris in the retina. Severe vitamin A deficiency did not only impair visual perception but also decreased transcripts of genes encoding cell adhesion and cellular junction proteins. This response altered cell morphology, resulted in significant changes in transport pathways of small molecules, and compromised the barrier function of the RPE. Together, our analyses characterize the molecular events underlying nutritional blindness in a novel mouse model and indicate that breakdown of the outer blood-retinal barrier contributes to retinal degeneration and photoreceptor cell death in severe vitamin A deficiency.
    Language English
    Publishing date 2023-05-19
    Publishing country England
    Document type Journal Article
    ISSN 2752-6542
    ISSN (online) 2752-6542
    DOI 10.1093/pnasnexus/pgad167
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  7. Article ; Online: Expression and biochemical analyses of proteins involved in the transport of carotenoids and retinoids.

    Golczak, Marcin / Moise, Alexander R / von Lintig, Johannes

    Methods in enzymology

    2022  Volume 674, Page(s) 447–480

    Abstract: Animals acquire carotenoids from the diet and convert them to retinoids. These lipids must be distributed in the body to support retinoid signaling in peripheral tissues and photoreceptor function in the eyes. However, the hydrophobicity of carotenoids ... ...

    Abstract Animals acquire carotenoids from the diet and convert them to retinoids. These lipids must be distributed in the body to support retinoid signaling in peripheral tissues and photoreceptor function in the eyes. However, the hydrophobicity of carotenoids and retinoids limit their diffusion in the aqueous environment of the body. Therefore, membrane proteins and cellular binding proteins transport these lipids between extra- and intracellular compartments and facilitate their metabolism. Mutations in genes encoding these transport proteins are associated with a wide spectrum of blinding disorders. Here, we describe approaches used by our laboratories that have proven successful in expressing these proteins and examining their biochemical properties in the test tube and in cell-based assays. These assays can be utilized for screening of small molecule modulators of their activities to correct pathologies associated with retinoid metabolism.
    MeSH term(s) Animals ; Carotenoids/metabolism ; Carrier Proteins/metabolism ; Lipid Metabolism ; Lipids ; Retinoids/metabolism
    Chemical Substances Carrier Proteins ; Lipids ; Retinoids ; Carotenoids (36-88-4)
    Language English
    Publishing date 2022-06-06
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ISSN 1557-7988
    ISSN (online) 1557-7988
    DOI 10.1016/bs.mie.2022.05.004
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  8. Article ; Online: Carotenoid modifying enzymes in metazoans.

    Moise, Alexander R / Bandara, Sepalika / von Lintig, Johannes

    Methods in enzymology

    2022  Volume 674, Page(s) 405–445

    Abstract: Carotenoids constitute an essential dietary component of animals and other non-carotenogenic species which use these pigments in both their modified and unmodified forms. Animals utilize uncleaved carotenoids to mitigate light damage and oxidative stress ...

    Abstract Carotenoids constitute an essential dietary component of animals and other non-carotenogenic species which use these pigments in both their modified and unmodified forms. Animals utilize uncleaved carotenoids to mitigate light damage and oxidative stress and to signal fitness and health. Carotenoids also serve as precursors of apocarotenoids including retinol, and its retinoid metabolites, which carry out essential functions in animals by forming the visual chromophore 11-cis-retinaldehyde. Retinoids, such as all-trans-retinoic acid, can also act as ligands of nuclear hormone receptors. The fact that enzymes and biochemical pathways responsible for the metabolism of carotenoids in animals bear resemblance to the ones in plants and other carotenogenic species suggests an evolutionary relationship. We will explore some of the modes of transmission of carotenoid genes from carotenogenic species to metazoans. This apparent relationship has been successfully exploited in the past to identify and characterize new carotenoid and retinoid modifying enzymes. We will review approaches used to identify putative animal carotenoid enzymes, and we will describe methods used to functionally validate and analyze the biochemistry of carotenoid modifying enzymes encoded by animals.
    MeSH term(s) Animals ; Carotenoids/metabolism ; Plants/metabolism ; Retinaldehyde/metabolism ; Retinoids/metabolism
    Chemical Substances Retinoids ; Carotenoids (36-88-4) ; Retinaldehyde (RR725D715M)
    Language English
    Publishing date 2022-06-22
    Publishing country United States
    Document type Journal Article
    ISSN 1557-7988
    ISSN (online) 1557-7988
    DOI 10.1016/bs.mie.2022.05.005
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  9. Article ; Online: Genetic deletion of Bco2 and Isx establishes a golden mouse model for carotenoid research.

    Thomas, Linda D / Ramkumar, Srinivasagan / Golczak, Marcin / von Lintig, Johannes

    Molecular metabolism

    2023  Volume 73, Page(s) 101742

    Abstract: Objective: Low plasma levels of carotenoids are associated with mortality and chronic disease states. Genetic studies in animals revealed that the tissue accumulation of these dietary pigments is associated with the genes encoding β-carotene oxygenase 2 ...

    Abstract Objective: Low plasma levels of carotenoids are associated with mortality and chronic disease states. Genetic studies in animals revealed that the tissue accumulation of these dietary pigments is associated with the genes encoding β-carotene oxygenase 2 (BCO2) and the scavenger receptor class B type 1 (SR-B1). Here we examined in mice how BCO2 and SR-B1 affect the metabolism of the model carotenoid zeaxanthin that serves as a macular pigment in the human retina.
    Methods: We used mice with a lacZ reporter gene knock-in to determine Bco2 expression patterns in the small intestine. By genetic dissection, we studied the contribution of BCO2 and SR-B1 to zeaxanthin uptake homeostasis and tissue accumulation under different supply conditions (50 mg/kg and 250 mg/kg). We determined the metabolic profiles of zeaxanthin and its metabolites in different tissues by LC-MS using standard and chiral columns. An albino Isx
    Results: We demonstrate that BCO2 is highly expressed in enterocytes of the small intestine. Genetic deletion of Bco2 led to enhanced accumulation of zeaxanthin, indicating that the enzyme serves as a gatekeeper of zeaxanthin bioavailability. Relaxing the regulation of SR-B1 expression in enterocytes by genetic deletion of the transcription factor ISX further enhanced zeaxanthin accumulation in tissues. We observed that the absorption of zeaxanthin was dose-dependent and identified the jejunum as the major zeaxanthin-absorbing intestinal region. We further showed that zeaxanthin underwent oxidation to ε,ε-3,3'-carotene-dione in mouse tissues. We detected all three enantiomers of the zeaxanthin oxidation product whereas the parent zeaxanthin only existed as (3R, 3'R)-enantiomer in the diet. The ratio of oxidized to parent zeaxanthin varied between tissues and was dependent on the supplementation dose. We further showed in an albino Isx
    Conclusions: We established the biochemical basis of zeaxanthin metabolism in mice and showed that tissue factors and abiotic stress affect the metabolism and homeostasis of this dietary lipid.
    MeSH term(s) Animals ; Humans ; Mice ; Carotenoids/metabolism ; Dioxygenases/genetics ; Dioxygenases/metabolism ; Disease Models, Animal ; Intestines ; Retina/metabolism ; Zeaxanthins/metabolism ; Transcription Factors/genetics
    Chemical Substances Bco2 protein, mouse (EC 1.14.99.-) ; Carotenoids (36-88-4) ; Dioxygenases (EC 1.13.11.-) ; Zeaxanthins ; Isx protein, mouse ; Transcription Factors
    Language English
    Publishing date 2023-05-22
    Publishing country Germany
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2708735-9
    ISSN 2212-8778 ; 2212-8778
    ISSN (online) 2212-8778
    ISSN 2212-8778
    DOI 10.1016/j.molmet.2023.101742
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  10. Article ; Online: Genetic tuning of β-carotene oxygenase-1 activity rescues cone photoreceptor function in STRA6-deficient mice.

    Moon, Jean / Ramkumar, Srinivasagan / von Lintig, Johannes

    Human molecular genetics

    2022  Volume 32, Issue 5, Page(s) 798–809

    Abstract: Rod and cone photoreceptors in the retina mediate dim light and daylight vision, respectively. Despite their distinctive functions, rod and cone visual pigments utilize the same vitamin A-derived chromophore. To sustain vision, vitamin A precursors must ... ...

    Abstract Rod and cone photoreceptors in the retina mediate dim light and daylight vision, respectively. Despite their distinctive functions, rod and cone visual pigments utilize the same vitamin A-derived chromophore. To sustain vision, vitamin A precursors must be acquired in the gut, metabolized, and distributed to the eyes. Deficiencies in this pathway in inherited ocular disease states deplete cone photoreceptors from chromophore and eventually lead to cell death, whereas the more abundant rod photoreceptors are less affected. However, pathways that support cone function and survival under such conditions are largely unknown. Using biochemical, histological, and physiological approaches, we herein show that intervention with β-carotene in STRA6-deficient mice improved chromophore supply to cone photoreceptors. Relieving the inherent negative feedback regulation of β-carotene oxygenase-1 activity in the intestine by genetic means further bolstered cone photoreceptor functioning in the STRA6-deficient eyes. A vitamin A-rich diet, however, did not improve cone photoreceptor function in STRA6-deficiency. We provide evidence that the beneficial effect of β-carotene on cones results from favorable serum kinetics of retinyl esters in lipoproteins. The respective alterations in lipoprotein metabolism maintained a steady supply of retinoids to the STRA6-deficient eyes, which ameliorated the competition for chromophore between rod and cone photoreceptors. Together, our study elucidates a cone photoreceptor-survival pathway and unravels an unexpected metabolic connection between the gut and the retina.
    MeSH term(s) Animals ; Mice ; Retinal Cone Photoreceptor Cells/metabolism ; beta Carotene/metabolism ; Vitamin A/metabolism ; Retina/metabolism ; Oxygenases/metabolism ; Membrane Proteins/metabolism
    Chemical Substances beta Carotene (01YAE03M7J) ; Vitamin A (11103-57-4) ; Oxygenases (EC 1.13.-) ; Stra6 protein, mouse ; Membrane Proteins
    Language English
    Publishing date 2022-09-23
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1108742-0
    ISSN 1460-2083 ; 0964-6906
    ISSN (online) 1460-2083
    ISSN 0964-6906
    DOI 10.1093/hmg/ddac242
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