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Ronald J A Wanders - One of the best experts on this subject based on the ideXlab platform.

  • Identification and diagnostic value of phytanoyl- and pristanoyl-carnitine in plasma from patients with peroxisomal disorders.
    Molecular Genetics and Metabolism, 2017
    Co-Authors: Katharina Herzog, Hans R Waterham, Ronald J A Wanders, Henk Van Lenthe, Frédéric M. Vaz, Sacha Ferdinandusse
    Abstract:

    Phytanic Acid is a Branched-Chain Fatty Acid, the level of which is elevated in patients with a variety of peroxisomal disorders, including Refsum disease, and Rhizomelic chondrodysplasia punctata type 1 and 5. Elevated levels of both phytanic and pristanic Acid are found in patients with Zellweger Spectrum Disorders, and pristanic Acid is elevated in patients with α-methylacyl-CoA racemase deficiency. For the diagnosis of peroxisomal disorders, a variety of metabolites can be measured in blood samples from suspected patients, including very long-chain Fatty Acids, phytanic and pristanic Acid. Based on the fact that very long-chain Fatty acylcarnitines are elevated in tissues and plasma from patients with certain peroxisomal disorders, we investigated whether phytanoyl- and pristanoyl-carnitine are also present in plasma from patients with different peroxisomal disorders. Our study shows that phytanoyl- and pristanoyl-carnitine are indeed present in plasma samples from patients with different types of peroxisomal disorders, but only when the total plasma levels of their corresponding Fatty Acids, phytanic Acid and pristanic Acid, are markedly elevated. We conclude that the measurement of phytanoyl- and pristanoyl-carnitine is not sensitive and specific enough to use these acylcarnitines as conclusive diagnostic markers for peroxisomal disorders.

  • Inhibition of hepatic Carnitine Palmitoyl-Transferase I (CPT IA) by Valproyl–CoA as a possible mechanism of Valproate-induced steatosis
    Biochemical Pharmacology, 2009
    Co-Authors: Caroline Cotrin Aires, Femke Stet, Carina Prip-buus, Isabel Tavares De Almeida, Marinus Duran, Ronald J A Wanders, Lodewijk Ijlst, Margarida F.b. Silva
    Abstract:

    Carnitine palmitoyl-transferase I (CPT I) catalyses the synthesis of long-chain(LC)-acylcarnitines from LC-acyl-CoA esters. It is the rate-limiting enzyme of mitochondrial Fatty Acid β–oxidation (FAO) pathway and its activity is regulated by malonyl-CoA. The antiepileptic drug valproic Acid (VPA) is a branched chain Fatty Acid that is activated to the respective CoA ester in the intra- and extra-mitochondrial compartments. This drug has been associated with a clear inhibition of mitochondrial FAO, which motivated our study on its potential effect on hepatic CPT I.

  • Ataxia with loss of Purkinje cells in a mouse model for Refsum disease.
    Proceedings of the National Academy of Sciences of the United States of America, 2008
    Co-Authors: Anna W. M. Zomer, Jasper C. Komen, Ronald J A Wanders, Paul T. Van Der Saag, Bwee Tien Poll-the, Christina E. Van Den Brink, Melissa Thanos, Frank P. T. Hamers, Pedro Brites
    Abstract:

    Refsum disease is caused by a deficiency of phytanoyl-CoA hydroxylase (PHYH), the first enzyme of the peroxisomal alpha-oxidation system, resulting in the accumulation of the Branched-Chain Fatty Acid phytanic Acid. The main clinical symptoms are polyneuropathy, cerebellar ataxia, and retinitis pigmentosa. To study the pathogenesis of Refsum disease, we generated and characterized a Phyh knockout mouse. We studied the pathological effects of phytanic Acid accumulation in Phyh(-/-) mice fed a diet supplemented with phytol, the precursor of phytanic Acid. Phytanic Acid accumulation caused a reduction in body weight, hepatic steatosis, and testicular atrophy with loss of spermatogonia. Phenotype assessment using the SHIRPA protocol and subsequent automated gait analysis using the CatWalk system revealed unsteady gait with strongly reduced paw print area for both fore- and hindpaws and reduced base of support for the hindpaws. Histochemical analyses in the CNS showed astrocytosis and up-regulation of calcium-binding proteins. In addition, a loss of Purkinje cells in the cerebellum was observed. No demyelination was present in the CNS. Motor nerve conduction velocity measurements revealed a peripheral neuropathy. Our results show that, in the mouse, high phytanic Acid levels cause a peripheral neuropathy and ataxia with loss of Purkinje cells. These findings provide important insights in the pathophysiology of Refsum disease.

  • Peroxisomal branched chain Fatty Acid beta-oxidation pathway is upregulated in prostate cancer.
    The Prostate, 2005
    Co-Authors: Shan Zha, Ronald J A Wanders, Simone Denis, Sacha Ferdinandusse, Jessica Hicks, Thomas A. Dunn, Jun Luo, Angelo M. De Marzo, William B. Isaacs
    Abstract:

    Overexpression of alpha-methylacyl-CoA racemase (AMACR), an enzyme involved in branched chain Fatty Acid beta-oxidation, in prostate cancer has been reported. Here, we report that an enzyme downstream from AMACR in the peroxisomal branched chain Fatty Acid beta-oxidation pathway-D-bifunctional protein (DBP)-is also upregulated in prostate cancer at both mRNA and protein levels, accompanied by increased enzymatic activity. Furthermore, our data suggest that pristanoyl-CoA oxidase (ACOX3), which is expressed at extremely low level in other human organs studied including the liver, might contribute significantly to peroxisomal branched chain Fatty Acid beta-oxidation in human prostate tissue and some prostate cancer cell lines. In contrast to these results for peroxisomal enzymes, no significant expression changes of mitochondrial Fatty Acid beta-oxidation enzymes were observed in prostate cancer tissues through comprehensive quantitative RT-PCR screening. These data for the first time provide evidence for the selective over-activation of peroxisomal branched chain Fatty Acid beta-oxidation in prostate cancer, emphasizing a new metabolic change during prostate oncogenesis.

  • Molecular basis of Refsum disease: sequence variations in phytanoyl-CoA hydroxylase (PHYH) and the PTS2 receptor (PEX7).
    Human mutation, 2004
    Co-Authors: G A Jansen, Hans R Waterham, Ronald J A Wanders
    Abstract:

    Refsum disease has long been known to be an inherited disorder of lipid metabolism characterized by the accumulation of phytanic Acid (3,7,11,15-tetramethylhexadecanoic Acid) caused by an alpha-oxidation deficiency of this branched chain Fatty Acid in peroxisomes. The mechanism of phytanic Acid alpha-oxidation and the enzymes involved had long remained mysterious, but they have been resolved in recent years. This has led to the resolution of the molecular basis of Refsum disease. Interestingly, Refsum disease is genetically heterogeneous; two genes, PHYH (also named PAHX) and PEX7, have been identified to cause Refsum disease, as reviewed in this work.

Stephanie J. Mihalik - One of the best experts on this subject based on the ideXlab platform.

  • Human very-long-chain acyl-CoA synthetase: cloning, topography, and relevance to Branched-Chain Fatty Acid metabolism.
    Biochemical and biophysical research communications, 1999
    Co-Authors: Steven J. Steinberg, Stephanie J. Mihalik, Susan J. Wang, G. Kim, Paul A. Watkins
    Abstract:

    Abstract Very-long-chain acyl-CoA synthetases (VLCS) activate very-long-chain Fatty Acids (VLCFA) containing 22 or more carbons to their CoA derivatives. We cloned the human ortholog (hVLCS) of the gene encoding the rat liver enzyme (rVLCS). Both hVLCS and rVLCS contain 620 amino Acids, are expressed primarily in liver and kidney, and have a potential peroxisome targeting signal 1 (-LKL) at their carboxy termini. When expressed in COS-1 cells, hVLCS activated the VLCFA lignoceric Acid (C24:0), a long-chain Fatty Acid (C16:0), and two Branched-Chain Fatty Acids, phytanic Acid and pristanic Acid. Immunofluorescence and immunoblot studies localized hVLCS to both peroxisomes and endoplasmic reticulum. In peroxisomes of HepG2 cells, hVLCS was topographically oriented facing the matrix and not the cytoplasm. This orientation, coupled with the observation that hVLCS activates Branched-Chain Fatty Acids, suggests that hVLCS could play a role in the intraperoxisomal reactivation of pristanic Acid produced via α-oxidation of phytanic Acid.

  • Phytanoyl-CoA Hydroxylase Is Present in Human Liver, Located in Peroxisomes, and Deficient in Zellweger Syndrome: Direct, Unequivocal Evidence for the New, Revised Pathway of Phytanic Acid α-Oxidation in Humans
    Biochemical and biophysical research communications, 1996
    Co-Authors: G A Jansen, Simone Denis, Paul A. Watkins, Stephanie J. Mihalik, Hugo W. Moser, C.a.j.m. Jakobs, Ronald J A Wanders
    Abstract:

    Phytanic Acid (3,7,11,15-tetramethylhexadecanoic Acid) is a Branched-Chain Fatty Acid which accumulates in a number of inherited diseases in human. Because beta-oxidation is blocked by the methyl group at C-3, phytanic Acid first undergoes decarboxylation via an alpha-oxidation mechanism. The structure and subcellular localization of the phytanic Acid alpha-oxidation pathway have remained enigmatic through the years, although they have generally been assumed to involve phytanic Acid and not its CoA-ester. This view has recently been challenged by the findings that in rat liver phytanic Acid first has to be activated to its CoA-ester before alpha-oxidation and by the discovery of a new enzyme, phytanoyl-CoA hydroxylase, which converts phytanoyl-CoA to 2-hydroxyphytanoyl-CoA. We now show that this newly discovered enzyme is also present in human liver. Furthermore, we show that this enzyme is located in peroxisomes and deficient in liver from Zellweger patients who lack morphologically distinguishable peroxisomes, which provides an explanation for the long-known deficient oxidation of phytanic Acid in these patients. These results suggest that phytanic Acid alpha-oxidation is peroxisomal and that it utilizes the coenzyme A derivative as substrate, thus giving further support in favour of the new, revised pathway of phytanic Acid alpha-oxidation.

  • Phytanic Acid activation in rat liver peroxisomes is catalyzed by long-chain acyl-CoA synthetase.
    Journal of lipid research, 1996
    Co-Authors: Paul A. Watkins, A E Howard, S J Gould, J Avigan, Stephanie J. Mihalik
    Abstract:

    In Refsum disease, disorders of peroxisome biogen- esis, and rhizomelic chondrodysplasia punctata, pathological accumulation of phytanic Acid results from impaired a-oxida- tion of this Branched-Chain Fatty Acid. Previous studies from this laboratory indicated that activation of phytanic Acid to its CoA derivative precedes its a-oxidation in peroxisomes. It was reported that this reaction is catalyzed by a unique phytanoyl- CoA synthetase in human peroxisomes. We wanted to deter- mine whether phytanic Acid activation in rats required long- chain acyl-CoA synthetase (LCS) , very long-chain acyl-CoA synthetase (VLCS), or a different enzyme. To test directly whether LCS could activate phytanic Acid, rat liver cDNA en- coding this enzyme was transcribed and translated in vitro. The expressed enzyme had both LCS activity (assayed with palmitic Acid, C16: 0) and phytanoyl-CoA synthetase activity; VLCS activity (assayed with lignoceric Acid, C24:O) was not detectable. The ratio of phytanoyl-CoA synthetase activity to palmitoyl-CoA synthetase activity for LCS synthetized in vitro (-20%) was higher than that ohsewed in peroxisomes iso- lated from rat liver (5-lo%), suggesting that the expressed enzyme contained sufficient phytanoyl-CoA synthetase activity to account for all activity observed in intact peroxisomes. Fur- ther experiments were carried out to verify that phytanic Acid was activated by LCS in rat liver peroxisomes. Attempts to sep arate LCS from phytanoyl-CoA synthetase by chromatography on several matrices were unsuccessful. Preparative isoelectric focusing revealed that phytanoyl-CoA synthetase and LCS had indistinguishable isoelectric points. Phytanoyl-CoA synthetase activity was inhibited by unlabeled palmitic Acid but not by lignoceric Acid. Heat treatment inactivated both phytanoyl- CoA and palmitoyl-CoA synthetase activities at similar rates. 5,8,11,14-Eicosatetraynoic Acid inhibited activation of phy- tanic Acid and palmitic Acid in a parallel dosedependent man- ner, whereas activation of lignoceric Acid was not affected.W These data support our conclusion that rat liver LCS, an en- zyme known to be present in peroxisomal membranes, has phytanoyl-CoA synthetase activity.-Watkins, P. A, A. E. How- ard, S. J. Gould, J. Avigan, and S. J. Mihalik. Phytanic Acid activation in rat liver peroxisomes is catalyzed by long-chain acyl-CoA synthetase. ,/. Lipid Rrc. 1996. 37: 2288-2295.

  • Phytanic Acid activation in rat liver peroxisomes is catalyzed by long-chain acyl-CoA synthetase.
    Journal of lipid research, 1996
    Co-Authors: Paul A. Watkins, A E Howard, S J Gould, J Avigan, Stephanie J. Mihalik
    Abstract:

    In Refsum disease, disorders of peroxisome biogenesis, and rhizomelic chondrodysplasia punctata, pathological accumulation of phytanic Acid results from impaired alpha-oxidation of this Branched-Chain Fatty Acid. Previous studies from this laboratory indicated that activation of phytanic Acid to its CoA derivative precedes its alpha-oxidation in peroxisomes. It was reported that this reaction is catalyzed by a unique phytanoyl-CoA synthetase in human peroxisomes. We wanted to determine whether phytanic Acid activation in rats required long-chain acyl-CoA synthetase (LCS), very long-chain acyl-CoA synthetase (VLCS), or a different enzyme. To test directly whether LCS could activate phytanic Acid, rat liver cDNA encoding this enzyme was transcribed and translated in vitro. The expressed enzyme had both LCS activity (assayed with palmitic Acid, C16: 0) and phytanoyl-CoA synthetase activity; VLCS activity (assayed with lignoceric Acid, C24: 0) was not detectable. The ratio of phytanoyl-CoA synthetized activity to palmitoyl-CoA synthetase activity for LCS synthetized in vitro (approximately 205) was higher than that observed in peroxisomes isolated from rat liver (5-10%), suggesting that the expressed enzyme contained sufficient phytanoyl-Coa synthetase activity to account for all activity observed in intact peroxisomes. Further experiments were carried out to verify that phytanic Acid was activated by LCS in rat liver peroxisomes. Attempts to separate LCS from phytanoyl-CoA synthetase by chromatography on several matrices were unsuccessful. Preparative isoelectric focusing revealed that phytanoyl-CoA synthetase and LCS had indistinguishable isoelectric points. Phytanoyl-CoA synthetase activity was inhibited by unlabeled palmitic Acid but not by lignoceric Acid. Heat treatment inactivated both phytanoyl-CoA and palmitoyl-CoA synthetase activities at similar rates. 5,8,11,14-Eicosatetraynoic Acid inhibited activation of phytanic Acid and palmitic Acid in a parallel dose-dependent manner, whereas activation of lignoceric Acid was not affected. These data support our conclusion that rat liver LCS, an enzyme known to be present in peroxisomal membranes, has phytanoyl-CoA synthetase activity.

  • Phytanic Acid must be activated to phytanoyl-CoA prior to its α-oxidation in rat liver peroxisomes
    Biochimica et biophysica acta, 1994
    Co-Authors: Paul A. Watkins, A E Howard, Stephanie J. Mihalik
    Abstract:

    alpha-Oxidation of the Branched-Chain Fatty Acid, phytanic Acid, is defective in patients with Refsum's disease, the disorders of peroxisome biogenesis (e.g., Zellweger syndrome), and in rhizomelic chondrodysplasia punctata. 3H-Release from [2,3-3H]phytanic Acid, which is impaired in cultured skin fibroblasts from these patients, was investigated in rat liver peroxisomes. Cofactors necessary for optimal 3H-release, ATP, Mg2+, and coenzyme A, were also necessary for optimal acyl-CoA synthetase activity, suggesting that the substrate for 3H-release might be phytanoyl-CoA. 5,8,11,14-Eicosatetraynoic Acid (ETYA), an inhibitor of long-chain acyl-CoA synthetase activity, blocked phytanoyl-CoA synthesis as well as 3H-release from [2,3-3H]phytanic Acid in a dose-dependent manner. However, this inhibitor had little effect on 3H-release from [2,3-3H]phytanoyl-CoA. Tetradecylglycidic Acid (TDGA) inhibited 3H-release from [2,3-3H]phytanic Acid in peroxisomal but not in mitochondrial fractions from rat liver. This agent inhibited 3H-release from [2,3-3H]phytanic Acid and [2,3-3H]phytanoyl-CoA equally. In contrast to ETYA, which appeared to decrease 3H-release as a consequence of synthetase inhibition, TDGA appeared to act directly on the enzyme catalyzing 3H-release. This enzyme was partially purified from rat liver. The purified enzyme, which did not possess phytanoyl-CoA synthetase activity, catalyzed tritium release from [2,3-3H]phytanoyl-CoA. This enzyme catalyzed 3H-release from [2,3-3H]phytanic Acid only if a source of phytanoyl-CoA synthetase was present. We conclude that in rat liver peroxisomes, phytanic Acid must be activated to its coenzyme A derivative prior to subsequent alpha-oxidation.

Paul A. Watkins - One of the best experts on this subject based on the ideXlab platform.

  • Human very-long-chain acyl-CoA synthetase: cloning, topography, and relevance to Branched-Chain Fatty Acid metabolism.
    Biochemical and biophysical research communications, 1999
    Co-Authors: Steven J. Steinberg, Stephanie J. Mihalik, Susan J. Wang, G. Kim, Paul A. Watkins
    Abstract:

    Abstract Very-long-chain acyl-CoA synthetases (VLCS) activate very-long-chain Fatty Acids (VLCFA) containing 22 or more carbons to their CoA derivatives. We cloned the human ortholog (hVLCS) of the gene encoding the rat liver enzyme (rVLCS). Both hVLCS and rVLCS contain 620 amino Acids, are expressed primarily in liver and kidney, and have a potential peroxisome targeting signal 1 (-LKL) at their carboxy termini. When expressed in COS-1 cells, hVLCS activated the VLCFA lignoceric Acid (C24:0), a long-chain Fatty Acid (C16:0), and two Branched-Chain Fatty Acids, phytanic Acid and pristanic Acid. Immunofluorescence and immunoblot studies localized hVLCS to both peroxisomes and endoplasmic reticulum. In peroxisomes of HepG2 cells, hVLCS was topographically oriented facing the matrix and not the cytoplasm. This orientation, coupled with the observation that hVLCS activates Branched-Chain Fatty Acids, suggests that hVLCS could play a role in the intraperoxisomal reactivation of pristanic Acid produced via α-oxidation of phytanic Acid.

  • Phytanoyl-CoA Hydroxylase Is Present in Human Liver, Located in Peroxisomes, and Deficient in Zellweger Syndrome: Direct, Unequivocal Evidence for the New, Revised Pathway of Phytanic Acid α-Oxidation in Humans
    Biochemical and biophysical research communications, 1996
    Co-Authors: G A Jansen, Simone Denis, Paul A. Watkins, Stephanie J. Mihalik, Hugo W. Moser, C.a.j.m. Jakobs, Ronald J A Wanders
    Abstract:

    Phytanic Acid (3,7,11,15-tetramethylhexadecanoic Acid) is a Branched-Chain Fatty Acid which accumulates in a number of inherited diseases in human. Because beta-oxidation is blocked by the methyl group at C-3, phytanic Acid first undergoes decarboxylation via an alpha-oxidation mechanism. The structure and subcellular localization of the phytanic Acid alpha-oxidation pathway have remained enigmatic through the years, although they have generally been assumed to involve phytanic Acid and not its CoA-ester. This view has recently been challenged by the findings that in rat liver phytanic Acid first has to be activated to its CoA-ester before alpha-oxidation and by the discovery of a new enzyme, phytanoyl-CoA hydroxylase, which converts phytanoyl-CoA to 2-hydroxyphytanoyl-CoA. We now show that this newly discovered enzyme is also present in human liver. Furthermore, we show that this enzyme is located in peroxisomes and deficient in liver from Zellweger patients who lack morphologically distinguishable peroxisomes, which provides an explanation for the long-known deficient oxidation of phytanic Acid in these patients. These results suggest that phytanic Acid alpha-oxidation is peroxisomal and that it utilizes the coenzyme A derivative as substrate, thus giving further support in favour of the new, revised pathway of phytanic Acid alpha-oxidation.

  • Phytanic Acid activation in rat liver peroxisomes is catalyzed by long-chain acyl-CoA synthetase.
    Journal of lipid research, 1996
    Co-Authors: Paul A. Watkins, A E Howard, S J Gould, J Avigan, Stephanie J. Mihalik
    Abstract:

    In Refsum disease, disorders of peroxisome biogen- esis, and rhizomelic chondrodysplasia punctata, pathological accumulation of phytanic Acid results from impaired a-oxida- tion of this Branched-Chain Fatty Acid. Previous studies from this laboratory indicated that activation of phytanic Acid to its CoA derivative precedes its a-oxidation in peroxisomes. It was reported that this reaction is catalyzed by a unique phytanoyl- CoA synthetase in human peroxisomes. We wanted to deter- mine whether phytanic Acid activation in rats required long- chain acyl-CoA synthetase (LCS) , very long-chain acyl-CoA synthetase (VLCS), or a different enzyme. To test directly whether LCS could activate phytanic Acid, rat liver cDNA en- coding this enzyme was transcribed and translated in vitro. The expressed enzyme had both LCS activity (assayed with palmitic Acid, C16: 0) and phytanoyl-CoA synthetase activity; VLCS activity (assayed with lignoceric Acid, C24:O) was not detectable. The ratio of phytanoyl-CoA synthetase activity to palmitoyl-CoA synthetase activity for LCS synthetized in vitro (-20%) was higher than that ohsewed in peroxisomes iso- lated from rat liver (5-lo%), suggesting that the expressed enzyme contained sufficient phytanoyl-CoA synthetase activity to account for all activity observed in intact peroxisomes. Fur- ther experiments were carried out to verify that phytanic Acid was activated by LCS in rat liver peroxisomes. Attempts to sep arate LCS from phytanoyl-CoA synthetase by chromatography on several matrices were unsuccessful. Preparative isoelectric focusing revealed that phytanoyl-CoA synthetase and LCS had indistinguishable isoelectric points. Phytanoyl-CoA synthetase activity was inhibited by unlabeled palmitic Acid but not by lignoceric Acid. Heat treatment inactivated both phytanoyl- CoA and palmitoyl-CoA synthetase activities at similar rates. 5,8,11,14-Eicosatetraynoic Acid inhibited activation of phy- tanic Acid and palmitic Acid in a parallel dosedependent man- ner, whereas activation of lignoceric Acid was not affected.W These data support our conclusion that rat liver LCS, an en- zyme known to be present in peroxisomal membranes, has phytanoyl-CoA synthetase activity.-Watkins, P. A, A. E. How- ard, S. J. Gould, J. Avigan, and S. J. Mihalik. Phytanic Acid activation in rat liver peroxisomes is catalyzed by long-chain acyl-CoA synthetase. ,/. Lipid Rrc. 1996. 37: 2288-2295.

  • Phytanic Acid activation in rat liver peroxisomes is catalyzed by long-chain acyl-CoA synthetase.
    Journal of lipid research, 1996
    Co-Authors: Paul A. Watkins, A E Howard, S J Gould, J Avigan, Stephanie J. Mihalik
    Abstract:

    In Refsum disease, disorders of peroxisome biogenesis, and rhizomelic chondrodysplasia punctata, pathological accumulation of phytanic Acid results from impaired alpha-oxidation of this Branched-Chain Fatty Acid. Previous studies from this laboratory indicated that activation of phytanic Acid to its CoA derivative precedes its alpha-oxidation in peroxisomes. It was reported that this reaction is catalyzed by a unique phytanoyl-CoA synthetase in human peroxisomes. We wanted to determine whether phytanic Acid activation in rats required long-chain acyl-CoA synthetase (LCS), very long-chain acyl-CoA synthetase (VLCS), or a different enzyme. To test directly whether LCS could activate phytanic Acid, rat liver cDNA encoding this enzyme was transcribed and translated in vitro. The expressed enzyme had both LCS activity (assayed with palmitic Acid, C16: 0) and phytanoyl-CoA synthetase activity; VLCS activity (assayed with lignoceric Acid, C24: 0) was not detectable. The ratio of phytanoyl-CoA synthetized activity to palmitoyl-CoA synthetase activity for LCS synthetized in vitro (approximately 205) was higher than that observed in peroxisomes isolated from rat liver (5-10%), suggesting that the expressed enzyme contained sufficient phytanoyl-Coa synthetase activity to account for all activity observed in intact peroxisomes. Further experiments were carried out to verify that phytanic Acid was activated by LCS in rat liver peroxisomes. Attempts to separate LCS from phytanoyl-CoA synthetase by chromatography on several matrices were unsuccessful. Preparative isoelectric focusing revealed that phytanoyl-CoA synthetase and LCS had indistinguishable isoelectric points. Phytanoyl-CoA synthetase activity was inhibited by unlabeled palmitic Acid but not by lignoceric Acid. Heat treatment inactivated both phytanoyl-CoA and palmitoyl-CoA synthetase activities at similar rates. 5,8,11,14-Eicosatetraynoic Acid inhibited activation of phytanic Acid and palmitic Acid in a parallel dose-dependent manner, whereas activation of lignoceric Acid was not affected. These data support our conclusion that rat liver LCS, an enzyme known to be present in peroxisomal membranes, has phytanoyl-CoA synthetase activity.

  • Phytanic Acid must be activated to phytanoyl-CoA prior to its α-oxidation in rat liver peroxisomes
    Biochimica et biophysica acta, 1994
    Co-Authors: Paul A. Watkins, A E Howard, Stephanie J. Mihalik
    Abstract:

    alpha-Oxidation of the Branched-Chain Fatty Acid, phytanic Acid, is defective in patients with Refsum's disease, the disorders of peroxisome biogenesis (e.g., Zellweger syndrome), and in rhizomelic chondrodysplasia punctata. 3H-Release from [2,3-3H]phytanic Acid, which is impaired in cultured skin fibroblasts from these patients, was investigated in rat liver peroxisomes. Cofactors necessary for optimal 3H-release, ATP, Mg2+, and coenzyme A, were also necessary for optimal acyl-CoA synthetase activity, suggesting that the substrate for 3H-release might be phytanoyl-CoA. 5,8,11,14-Eicosatetraynoic Acid (ETYA), an inhibitor of long-chain acyl-CoA synthetase activity, blocked phytanoyl-CoA synthesis as well as 3H-release from [2,3-3H]phytanic Acid in a dose-dependent manner. However, this inhibitor had little effect on 3H-release from [2,3-3H]phytanoyl-CoA. Tetradecylglycidic Acid (TDGA) inhibited 3H-release from [2,3-3H]phytanic Acid in peroxisomal but not in mitochondrial fractions from rat liver. This agent inhibited 3H-release from [2,3-3H]phytanic Acid and [2,3-3H]phytanoyl-CoA equally. In contrast to ETYA, which appeared to decrease 3H-release as a consequence of synthetase inhibition, TDGA appeared to act directly on the enzyme catalyzing 3H-release. This enzyme was partially purified from rat liver. The purified enzyme, which did not possess phytanoyl-CoA synthetase activity, catalyzed tritium release from [2,3-3H]phytanoyl-CoA. This enzyme catalyzed 3H-release from [2,3-3H]phytanic Acid only if a source of phytanoyl-CoA synthetase was present. We conclude that in rat liver peroxisomes, phytanic Acid must be activated to its coenzyme A derivative prior to subsequent alpha-oxidation.

G A Jansen - One of the best experts on this subject based on the ideXlab platform.

  • Molecular basis of Refsum disease: sequence variations in phytanoyl-CoA hydroxylase (PHYH) and the PTS2 receptor (PEX7).
    Human mutation, 2004
    Co-Authors: G A Jansen, Hans R Waterham, Ronald J A Wanders
    Abstract:

    Refsum disease has long been known to be an inherited disorder of lipid metabolism characterized by the accumulation of phytanic Acid (3,7,11,15-tetramethylhexadecanoic Acid) caused by an alpha-oxidation deficiency of this branched chain Fatty Acid in peroxisomes. The mechanism of phytanic Acid alpha-oxidation and the enzymes involved had long remained mysterious, but they have been resolved in recent years. This has led to the resolution of the molecular basis of Refsum disease. Interestingly, Refsum disease is genetically heterogeneous; two genes, PHYH (also named PAHX) and PEX7, have been identified to cause Refsum disease, as reviewed in this work.

  • Phytanoyl‐CoA hydroxylase activity is induced by phytanic Acid
    European journal of biochemistry, 2000
    Co-Authors: Anna W. M. Zomer, G A Jansen, Ronald J A Wanders, Bart Van Der Burg, Paul T. Van Der Saag, Bwee Tien Poll-the
    Abstract:

    Phytanic Acid (3,7,11,15-tetramethylhexadecanoic Acid) is a Branched-Chain Fatty Acid present in various dietary products such as milk, cheese and fish. In patients with Refsum disease, accumulation of phytanic Acid occurs due to a deficiency of phytanoyl-CoA hydroxylase, a peroxisomal enzyme containing a peroxisomal targeting signal 2. Recently, phytanoyl-CoA hydroxylase cDNA has been isolated and functional mutations have been identified. As it has been shown that phytanic Acid activates the nuclear hormone receptors peroxisome proliferator-activated receptor (PPAR)α and all three retinoid X receptors (RXRs), the intracellular concentration of this Fatty Acid should be tightly regulated. When various cell lines were grown in the presence of phytanic Acid, the activity of phytanoyl-CoA hydroxylase increased up to four times, depending on the particular cell type. In one cell line, HepG2, no induction of phytanoyl-CoA hydroxylase activity was observed. After addition of phytanic Acid to COS-1 cells, an increase in phytanoyl-CoA hydroxylase activity was observed within 2 h, indicating a quick cell response. No stimulation of phytanoyl-CoA hydroxylase was observed when COS-1 cells were grown in the presence of clofibric Acid, 9-cis-retinoic Acid or both ligands together. This indicates that the activation of phytanoyl-CoA hydroxylase is not regulated via PPARα or RXR. However, stimulation of PPARα and all RXRs by clofibric Acid and 9-cis-retinoic Acid was observed in transient transfection assays. These results suggest that the induction of phytanoyl-CoA hydroxylase by phytanic Acid does not proceed via one of the nuclear hormone receptors, RXR or PPARα.

  • Refsum disease is caused by mutations in the phytanoyl-CoA hydroxylase gene.
    Nature genetics, 1997
    Co-Authors: G A Jansen, Rob Ofman, Lodewijk Ijlst, Anton O. Muijsers, O. H. Skjeldal, Oddvar Stokke, G. T. N. Besley, James E. Wraith
    Abstract:

    Refsum disease is an autosomal-recessively inherited disorder characterized clinically by a tetrad of abnormalities: retinitis pigmentosa, peripheral neuropathy, cerebellar ataxia and elevated protein levels in the cerebrospinal fluid (CSF) without an increase in the number of cells in the CSF. All patients exhibit accumulation of an unusual Branched-Chain Fatty Acid, phytanic Acid (3,7,11,15-tetramethylhexadecanoic Acid), in blood and tissues. Biochemically, the disease is caused by the deficiency of phytanoyl-CoA hydroxylase (PhyH), a peroxisomal protein catalyzing the first step in the α-oxidation of phytanic Acid. We have purified PhyH from rat-liver peroxisomes and determined the N-terminal amino-Acid sequence, as well as an additional internal amino-Acid sequence obtained after Lys-C digestion of the purified protein. A search of the EST database with these partial amino-Acid sequences led to the identification of the full-length human cDNA sequence encoding PhyH: the open reading frame encodes a 41.2-kD protein of 338 amino Acids, which contains a cleavable peroxisomal targeting signal type 2 (PTS2). Sequence analysis of PHYH fibroblast cDNA from five patients with Refsum disease revealed distinct mutations, including a one-nucleotide deletion, a 111-nucleotide deletion and a point mutation. This analysis confirms our finding that Refsum disease is caused by a deficiency of PhyH.

  • Phytanoyl-CoA Hydroxylase Is Present in Human Liver, Located in Peroxisomes, and Deficient in Zellweger Syndrome: Direct, Unequivocal Evidence for the New, Revised Pathway of Phytanic Acid α-Oxidation in Humans
    Biochemical and biophysical research communications, 1996
    Co-Authors: G A Jansen, Simone Denis, Paul A. Watkins, Stephanie J. Mihalik, Hugo W. Moser, C.a.j.m. Jakobs, Ronald J A Wanders
    Abstract:

    Phytanic Acid (3,7,11,15-tetramethylhexadecanoic Acid) is a Branched-Chain Fatty Acid which accumulates in a number of inherited diseases in human. Because beta-oxidation is blocked by the methyl group at C-3, phytanic Acid first undergoes decarboxylation via an alpha-oxidation mechanism. The structure and subcellular localization of the phytanic Acid alpha-oxidation pathway have remained enigmatic through the years, although they have generally been assumed to involve phytanic Acid and not its CoA-ester. This view has recently been challenged by the findings that in rat liver phytanic Acid first has to be activated to its CoA-ester before alpha-oxidation and by the discovery of a new enzyme, phytanoyl-CoA hydroxylase, which converts phytanoyl-CoA to 2-hydroxyphytanoyl-CoA. We now show that this newly discovered enzyme is also present in human liver. Furthermore, we show that this enzyme is located in peroxisomes and deficient in liver from Zellweger patients who lack morphologically distinguishable peroxisomes, which provides an explanation for the long-known deficient oxidation of phytanic Acid in these patients. These results suggest that phytanic Acid alpha-oxidation is peroxisomal and that it utilizes the coenzyme A derivative as substrate, thus giving further support in favour of the new, revised pathway of phytanic Acid alpha-oxidation.

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  • Peroxisomal beta-oxidation of branched chain Fatty Acids in rat liver. Evidence that carnitine palmitoyltransferase I prevents transport of branched chain Fatty Acids into mitochondria.
    Journal of Biological Chemistry, 1994
    Co-Authors: Harmeet Singh, K Beckman, Alf Poulos
    Abstract:

    Abstract Fatty Acid beta-oxidation was investigated in highly purified mitochondrial and peroxisomal preparations from rat liver. Under isotonic conditions, pristanic and homophytanic Acid beta-oxidation in purified peroxisomes was severalfold greater compared to the oxidation in purified mitochondria. Branched chain Fatty Acid beta-oxidation in purified mitochondria was very low, and the oxidation was not stimulated by exogenous L-carnitine or L-malate. In contrast, stearic Acid beta-oxidation by purified mitochondria depended upon exogenous L-carnitine, and the oxidation was stimulated by L-malate. Both mitochondrial and peroxisomal beta-oxidation of branched chain Fatty Acids was strongly inhibited by Fatty Acid-free bovine serum albumin, whereas stearic Acid oxidation was either unaffected or slightly inhibited by bovine serum albumin. The results presented clearly indicate that branched chain Fatty Acids are mainly degraded in peroxisomes in rat liver. Branched chain Fatty Acids were efficiently converted to coenzyme A thioesters by purified mitochondria, peroxisomes, and microsomes. Although pristanic and phytanic Acids were rapidly converted to pristanoyl-CoA and phytanoyl-CoA, respectively, they were not converted to carnitine esters by mitochondrial outer membranes. The results indicate that acyl-CoA synthetase and carnitine acyltransferase located at the mitochondrial outer membranes regulate entry of branched chain Fatty Acids into mitochondria. Mitochondrial carnitine acyltransferase I appears to be highly specific for straight chain Fatty Acids and restricts entry of branched chain Fatty Acids into mitochondria. Thus, branched chain Fatty Acids which cannot be transported across the mitochondrial membranes via the carnitine acyltransferase system are directed to peroxisomes for beta-oxidation. The results reported indicate that phytanic Acid, the Fatty Acid which can be initially degraded by alpha-oxidation due to the presence of a beta-methyl group in the molecule, cannot be transported across the mitochondrial membranes. The data presented strongly suggest that phytanic Acid alpha-oxidation occurs in organelles other than mitochondria and possibly in peroxisomes.

  • Peroxisomal beta-oxidation of branched chain Fatty Acids in human skin fibroblasts.
    Journal of lipid research, 1992
    Co-Authors: Harmeet Singh, David W. Johnson, Michael Brogan, Alf Poulos
    Abstract:

    Human skin fibroblasts in suspension are able to de- grade (1-'4C)-labeled a- and y-methyl branched chain Fatty Acids such as pristanic and homophytanic Acid. Pristanic Acid was converted to propionyl-CoA, whereas homophytanic Acid was @-oxidized to acetyl-coA. Incubation of skin fibroblasts with (l-i4C)-labeled Fatty Acids for longer periods produced radiolabeled carbon dioxide, presumably by further degradation of acetyl-coA or propionyl-CoA generated by @-oxidation. Under the same conditions similar products were produced from very long chain Fatty Acids, such as lignoceric Acid. Inclusion of digitonin ( > 10 pg/ml) in the incubations strongly inhibited car- bon dioxide production but stimulated acetyl-coA or propionyl- CoA production from Fatty Acids. ATP, Mg2+, coenzyme A, NAD' and L-carnitine stimulated acetyl-coA or propionyl-CoA production from (l-'4C)-labeled Fatty Acids in skin fibroblast sus- pensions. Branched chain Fatty Acid @-oxidation was reduced in peroxisome-deficient cells (Zellweger syndrome and infantile Refsum's disease) but they were @-oxidized normally in cells from patients with X-linked adrenoleukodystmphy (ALD). Under the same conditions, lignoceric Acid @-oxidation was im- paired in the above three peroxisomal disease states. I These