The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform

Inderjit Singh - One of the best experts on this subject based on the ideXlab platform.

  • increased peroxisomal fatty Acid beta oxidation and enhanced expression of peroxisome proliferator activated receptor alpha in diabetic rat liver
    Molecular and Cellular Biochemistry, 1999
    Co-Authors: Kohtaro Asayama, Faruk Sheikh, Hidemasa Hayashibe, Takaya Nakane, Rajat Sandhir, Inderjit Singh
    Abstract:

    To determine whether the increased fatty Acid β-oxidation in the peroxisomes of diabetic rat liver is mediated by a common peroxisome proliferation mechanism, we measured the activation of long-chain (LC) and very long chain (VLC) fatty Acids catalyzed by palmitoyl CoA ligase (PAL) and lignoceryl CoA ligase and oxidation of LC (palmitic Acid) and VLC (Lignoceric Acid) fatty Acids by isotopic methods. Immunoblot analysis of acyl-CoA oxidase (ACO), and Northern blot analysis of peroxisome proliferator-activated receptor (PPAR-α), ACO, and PAL were also performed. The PAL activity increased in peroxisomes and mitochondria from the liver of diabetic rats by 2.6-fold and 2.1-fold, respectively. The lignoceroyl-CoA ligase activity increased by 2.6-fold in diabetic peroxisomes. Palmitic Acid oxidation increased in the diabetic peroxisomes and mitochondria by 2.5-fold and 2.7-fold, respectively, while Lignoceric Acid oxidation increased by 2.0-fold in the peroxisomes. Immunoreactive ACO protein increased by 2-fold in the diabetic group. The mRNA levels for PPAR-α, ACO and PAL increased 2.9-, 2.8- and 1.6-fold, respectively, in the diabetic group. These results suggest that the increased supply of fatty Acids to liver in diabetic state stimulates the expression of PPAR-α and its target genes responsible for the metabolism of fatty Acids.

  • Localization of nervonic Acid β-oxidation in human and rodent peroxisomes: impaired oxidation in Zellweger syndrome and X-linked adrenoleukodystrophy
    Journal of lipid research, 1998
    Co-Authors: Rajat Sandhir, Mushfiquddin Khan, Amarjit Chahal, Inderjit Singh
    Abstract:

    Studies with purified subcellular organelles from rat liver indicate that nervonic Acid (C24:1) is beta-oxidized preferentially in peroxisomes. Lack of effect by etomoxir, inhibitor of mitochondrial beta-oxidation, on beta-oxidation of Lignoceric Acid (C24:0), a peroxisomal function, and that of nervonic Acid (24:1) compared to the inhibition of palmitic Acid (16:0) oxidation, a mitochondrial function, supports the conclusion that nervonic Acid is oxidized in peroxisomes. Moreover, the oxidation of nervonic and Lignoceric Acids was deficient in fibroblasts from patients with defects in peroxisomal beta-oxidation [Zellweger syndrome (ZS) and X-linked adrenoleukodystrophy (X-ALD)]. Similar to Lignoceric Acid, the activation and beta-oxidation of nervonic Acid was deficient in peroxisomes isolated from X-ALD fibroblasts. Transfection of X-ALD fibroblasts with human cDNA encoding for ALDP (X-ALD gene product) restored the oxidation of both nervonic and Lignoceric Acids, demonstrating that the same molecular defect may be responsible for the abnormality in the oxidation of nervonic as well as Lignoceric Acid. Moreover, immunoprecipitation of activities for acyl-CoA ligase for both Lignoceric Acid and nervonic Acid indicate that saturated and monoenoic very long chain (VLC) fatty Acids may be activated by the same enzyme. These results clearly demonstrate that similar to saturated VLC fatty Acids (e.g., Lignoceric Acid), VLC monounsaturated fatty Acids (e.g., nervonic Acid) are oxidized preferentially in peroxisomes and that this activity is impaired in X-ALD. In view of the fact that the oxidation of unsaturated VLC fatty Acids is defective in X-ALD patients, the efficacy of dietary monoene therapy, "Lorenzo's oil," in X-ALD needs to be evaluated.

  • Therapy for X-adrenoleukodystrophy: normalization of very long chain fatty Acids and inhibition of induction of cytokines by cAMP
    Journal of lipid research, 1998
    Co-Authors: Kalipada Pahan, Mushfiquddin Khan, Inderjit Singh
    Abstract:

    X-adrenoleukodystrophy (X-ALD) is an inherited fatty Acid metabolic disorder with secondary manifestation of neuroinflammatory disease process. We report that compounds (forskolin, 8-bromo cAMP, and rolipram) that increase cAMP and activate protein kinase A (PKA) were found to stimulate the peroxisomal beta-oxidation of Lignoceric Acid (C24:0) whereas compounds (H-89 and myristoylated PKI) that decrease cAMP and PKA activity inhibited the peroxisomal beta-oxidation of Lignoceric Acid in cultured skin fibroblasts from X-ALD patients. Consistent with the stimulation of beta-oxidation of Lignoceric Acid, activators of PKA normalized the level of very long chain fatty Acids (VLCFA) in X-ALD cultured skin fibroblasts. This normalization of VLCFA in X-ALD cells with forskolin, 8-Br cAMP or with rolipram, an inhibitor of cAMP phosphodiesterase, was realized independent of expression of mRNA or protein of the ALD gene, suggesting that cAMP derivatives can correct the metabolic defect in X-ALD fibroblasts without involving the candidate gene for the disease. Because astrocytes and microglia in demyelinating lesions of X-ALD brain express proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), we examined the effect of cAMP derivatives or rolipram on lipopolysaccharide-stimulated rat primary astrocytes and microglia and found that cAMP derivatives and rolipram inhibited the induction of TNF-alpha and IL-1beta in both astrocytes and microglia. The ability of cAMP derivatives and rolipram to block the induction of TNF-alpha and IL-1beta in astrocytes and microglia and to normalize the fatty Acid pathogen in skin fibroblasts of x-adrenoleukodystrophy (X-ALD) clearly identify cAMP analogs or rolipram as candidates for potential therapy for X-ALD patients.

  • Purification of peroxisomes and subcellular distribution of enzyme activities for activation and oxidation of very-long-chain fatty Acids in rat brain.
    Biochimica et biophysica acta, 1993
    Co-Authors: Inderjit Singh, Oscar Lazo, Karl Kremser
    Abstract:

    Brain contains high amounts of very-long-chain (VLC) fatty Acids (> C22). Since mitochondria from liver and skin fibroblasts lack lignoceroyl-CoA ligase, in liver and skin fibroblasts fatty Acids are exclusively oxidized in peroxisomes. Findings by Poulos and associates [9] suggested that contrary to liver and cultured skin fibroblasts brain mitochondria contain lignoceroyl-CoA ligase and can oxidize Lignoceric Acid. The present study was undertaken to develop a procedure for the isolation of subcellular organelles of higher purity from brain and to get a better understanding of the subcellular localization of the oxidation of VLC fatty Acids in brain. The enzyme activities for activation and oxidation of palmitic and Lignoceric Acids were determined in peroxisomes, mitochondria, microsomes and a myelin fraction from rat brain and peroxisomes, mitochondria and microsomes purified from rat liver. Like in liver, brain lignoceroyl-CoA ligase activity in microsomes and peroxisomes was approx. 9 times higher than in mitochondria. In addition to palmitoyl-CoA ligase the antibodies against palmitoyl-CoA ligase inhibited the residual mitochondrial lignoceroyl-CoA ligase activity, meaning that lignoceroyl-CoA ligase activity in mitochondria was derived from palmitoyl-CoA ligase. Accordingly, in peroxisomes Lignoceric Acid was oxidized at 7 times higher rate than in mitochondria. Mitochondria were able to oxidize Lignoceric Acid efficiently when supplemented with lignoceroyl-CoA ligase activity from microsomes or myelin. These results show that in brain Lignoceric Acid is oxidized in peroxisomes and that lignoceroyl-CoA ligase activity is localized in peroxisomes and microsomes, but not in mitochondria. Peroxisomes and microsomes contain both lignoceroyl-CoA and palmitoyl-CoA ligases. Similar to peroxisomes and microsomes, the antibodies against palmitoyl-CoA ligase inhibited only the palmitoyl-CoA ligase activity in myelin but not the lignoceroyl-CoA ligase activity. These results suggest that in addition to palmitoyl-CoA ligase, myelin also contains lignoceroyl-CoA ligase.

  • Transport of fatty Acids into human and rat peroxisomes. Differential transport of palmitic and Lignoceric Acids and its implication to X-adrenoleukodystrophy.
    The Journal of biological chemistry, 1992
    Co-Authors: Inderjit Singh, Oscar Lazo, Gursev S. Dhaunsi, Miguel A. Contreras
    Abstract:

    The different topology of palmitoyl-CoA ligase (on the cytoplasmic surface) and of lignoceroyl-CoA ligase (on the luminal surface) in peroxisomal membranes suggests that these fatty Acids may be transported in different form through the peroxisomal membrane (Lazo, O., Contreras, M., and Singh, I. (1990) Biochemistry 29, 3981-3986), and this differential transport may account for deficient oxidation of Lignoceric Acid in X-adrenoleukodystrophy (X-ALD) (Singh, I., Moser, A. B., Goldfisher, S., and Moser, H. W. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 4203-4207). To define the transport mechanism for these fatty Acids through the peroxisomal membrane and its possible implication to Lignoceric Acid metabolism in X-ALD, we examined cofactors and energy requirements for the transport of palmitic and Lignoceric Acids in isolated peroxisomes from rat liver and peroxisomes isolated from X-ALD and control fibroblasts. The similar rates of transport of palmitoyl-CoA (87.6 +/- 6.3 nmol/h/mg protein) and palmitic Acid in the fatty Acid activating conditions (83.4 +/- 5.1 nmol/h/mg protein) and lack of transport of palmitic Acid (4% of palmitoyl-CoA transport) when ATP and/or CoASH were removed or substituted by alpha,beta-methyleneadenosine-5'-triphosphate (AMPCPOP) and/or desulfoCoA-agarose from assay medium clearly demonstrate that transport of palmitic Acid requires prior synthesis of palmitoyl-CoA by palmitoyl-CoA ligase on the cytoplasmic surface of peroxisomes. The 10-fold higher rate of transport of Lignoceric Acid (5.3 +/- 0.6 nmol/h/mg protein) as compared with lignoceroyl-CoA (0.41 +/- 0.11 nmol/h/mg protein) and lack of inhibition of transport of Lignoceric Acid when ATP and/or CoASH were removed or substituted with AMPCPOP or desulfoCoA-agarose suggest that Lignoceric Acid is transported through the peroxisomal membrane as such. Moreover, the lack of effect of removal of ATP or substitution with AMPOPCP (a nonhydrolyzable substrate) demonstrates that the translocation of palmitoyl-CoA and Lignoceric Acid across peroxisomal membrane does not require energy. The transport, activation, and oxidation of palmitic Acid are normal in peroxisomes from X-ALD. The deficient lignoceroyl-CoA ligase (13% of control) and oxidation of Lignoceric Acid (10% of control) as compared with normal transport of Lignoceric Acid into peroxisomes from X-ALD clearly demonstrates that pathogenomonic accumulation of very long chain fatty Acids (greater than C22) in X-ALD is due to the deficiency of peroxisomal lignoceroyl-CoA ligase activity.

Oscar Lazo - One of the best experts on this subject based on the ideXlab platform.

  • Purification of peroxisomes and subcellular distribution of enzyme activities for activation and oxidation of very-long-chain fatty Acids in rat brain.
    Biochimica et biophysica acta, 1993
    Co-Authors: Inderjit Singh, Oscar Lazo, Karl Kremser
    Abstract:

    Brain contains high amounts of very-long-chain (VLC) fatty Acids (> C22). Since mitochondria from liver and skin fibroblasts lack lignoceroyl-CoA ligase, in liver and skin fibroblasts fatty Acids are exclusively oxidized in peroxisomes. Findings by Poulos and associates [9] suggested that contrary to liver and cultured skin fibroblasts brain mitochondria contain lignoceroyl-CoA ligase and can oxidize Lignoceric Acid. The present study was undertaken to develop a procedure for the isolation of subcellular organelles of higher purity from brain and to get a better understanding of the subcellular localization of the oxidation of VLC fatty Acids in brain. The enzyme activities for activation and oxidation of palmitic and Lignoceric Acids were determined in peroxisomes, mitochondria, microsomes and a myelin fraction from rat brain and peroxisomes, mitochondria and microsomes purified from rat liver. Like in liver, brain lignoceroyl-CoA ligase activity in microsomes and peroxisomes was approx. 9 times higher than in mitochondria. In addition to palmitoyl-CoA ligase the antibodies against palmitoyl-CoA ligase inhibited the residual mitochondrial lignoceroyl-CoA ligase activity, meaning that lignoceroyl-CoA ligase activity in mitochondria was derived from palmitoyl-CoA ligase. Accordingly, in peroxisomes Lignoceric Acid was oxidized at 7 times higher rate than in mitochondria. Mitochondria were able to oxidize Lignoceric Acid efficiently when supplemented with lignoceroyl-CoA ligase activity from microsomes or myelin. These results show that in brain Lignoceric Acid is oxidized in peroxisomes and that lignoceroyl-CoA ligase activity is localized in peroxisomes and microsomes, but not in mitochondria. Peroxisomes and microsomes contain both lignoceroyl-CoA and palmitoyl-CoA ligases. Similar to peroxisomes and microsomes, the antibodies against palmitoyl-CoA ligase inhibited only the palmitoyl-CoA ligase activity in myelin but not the lignoceroyl-CoA ligase activity. These results suggest that in addition to palmitoyl-CoA ligase, myelin also contains lignoceroyl-CoA ligase.

  • Transport of fatty Acids into human and rat peroxisomes. Differential transport of palmitic and Lignoceric Acids and its implication to X-adrenoleukodystrophy.
    The Journal of biological chemistry, 1992
    Co-Authors: Inderjit Singh, Oscar Lazo, Gursev S. Dhaunsi, Miguel A. Contreras
    Abstract:

    The different topology of palmitoyl-CoA ligase (on the cytoplasmic surface) and of lignoceroyl-CoA ligase (on the luminal surface) in peroxisomal membranes suggests that these fatty Acids may be transported in different form through the peroxisomal membrane (Lazo, O., Contreras, M., and Singh, I. (1990) Biochemistry 29, 3981-3986), and this differential transport may account for deficient oxidation of Lignoceric Acid in X-adrenoleukodystrophy (X-ALD) (Singh, I., Moser, A. B., Goldfisher, S., and Moser, H. W. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 4203-4207). To define the transport mechanism for these fatty Acids through the peroxisomal membrane and its possible implication to Lignoceric Acid metabolism in X-ALD, we examined cofactors and energy requirements for the transport of palmitic and Lignoceric Acids in isolated peroxisomes from rat liver and peroxisomes isolated from X-ALD and control fibroblasts. The similar rates of transport of palmitoyl-CoA (87.6 +/- 6.3 nmol/h/mg protein) and palmitic Acid in the fatty Acid activating conditions (83.4 +/- 5.1 nmol/h/mg protein) and lack of transport of palmitic Acid (4% of palmitoyl-CoA transport) when ATP and/or CoASH were removed or substituted by alpha,beta-methyleneadenosine-5'-triphosphate (AMPCPOP) and/or desulfoCoA-agarose from assay medium clearly demonstrate that transport of palmitic Acid requires prior synthesis of palmitoyl-CoA by palmitoyl-CoA ligase on the cytoplasmic surface of peroxisomes. The 10-fold higher rate of transport of Lignoceric Acid (5.3 +/- 0.6 nmol/h/mg protein) as compared with lignoceroyl-CoA (0.41 +/- 0.11 nmol/h/mg protein) and lack of inhibition of transport of Lignoceric Acid when ATP and/or CoASH were removed or substituted with AMPCPOP or desulfoCoA-agarose suggest that Lignoceric Acid is transported through the peroxisomal membrane as such. Moreover, the lack of effect of removal of ATP or substitution with AMPOPCP (a nonhydrolyzable substrate) demonstrates that the translocation of palmitoyl-CoA and Lignoceric Acid across peroxisomal membrane does not require energy. The transport, activation, and oxidation of palmitic Acid are normal in peroxisomes from X-ALD. The deficient lignoceroyl-CoA ligase (13% of control) and oxidation of Lignoceric Acid (10% of control) as compared with normal transport of Lignoceric Acid into peroxisomes from X-ALD clearly demonstrates that pathogenomonic accumulation of very long chain fatty Acids (greater than C22) in X-ALD is due to the deficiency of peroxisomal lignoceroyl-CoA ligase activity.

  • Effect of ciprofibrate on the activation and oxidation of very long chain fatty Acids
    Molecular and Cellular Biochemistry, 1991
    Co-Authors: Oscar Lazo, Miguel Contreras, Inderjit Singh
    Abstract:

    The effect of ciprofibrate, a hypolipidemic drug, was examined in the metabolism of palmitic (C_16:0) and Lignoceric (C_24:0) Acids in rat liver. Ciprofibrate is a peroxisomal proliferating drug which increases the number of peroxisomes. The palmitoyl-CoA ligase activity in peroxisomes, mitochondria and microsomes from ciprofibrate treated liver was 3.2, 1.9 and 1.5-fold higher respectively and the activity for oxidation of palmitic Acid in peroxisomes and mitochondria was 8.5 and 2.3-fold higher respectively. Similarly, ciprofibrate had a higher effect on the metabolism of Lignoceric Acid. Treatment with ciprofibrate increased lignoceroyl-CoA ligase activity in peroxisomes, mitochondria and microsomes by 5.3, 3.3 and 2.3-fold respectively and that of oxidation of Lignoceric Acid was increased in peroxisomes and mitochondria by 13.4 and 2.3-fold respectively. The peroxisomal rates of oxidation of palmitic Acid (8.5-fold) and Lignoceric Acid (13.4-fold) were increased to a different degree by ciprofibrate treatment. This differential effect of ciprofibrate suggests that different enzymes may be responsible for the oxidation of fatty Acids of different chain length, at least at one or more step(s) of the peroxisomal fatty Acid β-oxidation pathway.

  • Postnatal development and isolation of peroxisomes from brain.
    Journal of neurochemistry, 1991
    Co-Authors: Oscar Lazo, Avtar K. Singh, Inderjit Singh
    Abstract:

    We analyzed the postnatal peroxisome development in rat brain by measuring the enzyme activities of catalase and acyl-CoA oxidase and beta-oxidation of [1-14C]Lignoceric Acid. These enzyme activities were higher between 10 and 16 days of postnatal life and then decreased. We developed and compared two different methods for isolation of enriched peroxisomes from 10-day-old rat brain by using a combination of differential and density gradient centrifugation techniques. Peroxisomes in Percoll (self-generating gradient) banded at a density of 1.036 +/- 0.012 g/ml and in Nycodenz continuous gradient at 1.125 +/- 0.014 g/ml. Acyl-CoA oxidase, D-amino Acid oxidase, L-pipecolic Acid oxidase, and dihydroxyacetone phosphate acyltransferase activities and activities for the oxidation of very long chain fatty Acid (Lignoceric Acid) were almost exclusively associated with catalase activity (a marker enzyme for peroxisomes) in the gradient. The postnatal increase in peroxisomal activity with the onset of myelination and the presence of enzyme for the biosynthesis of plasmalogens and oxidation of very long chain fatty Acid (both predominant constituents of myelin) suggest that brain peroxisomes may play an important role in the assembly and turnover of myelin.

Rajat Sandhir - One of the best experts on this subject based on the ideXlab platform.

  • increased peroxisomal fatty Acid beta oxidation and enhanced expression of peroxisome proliferator activated receptor alpha in diabetic rat liver
    Molecular and Cellular Biochemistry, 1999
    Co-Authors: Kohtaro Asayama, Faruk Sheikh, Hidemasa Hayashibe, Takaya Nakane, Rajat Sandhir, Inderjit Singh
    Abstract:

    To determine whether the increased fatty Acid β-oxidation in the peroxisomes of diabetic rat liver is mediated by a common peroxisome proliferation mechanism, we measured the activation of long-chain (LC) and very long chain (VLC) fatty Acids catalyzed by palmitoyl CoA ligase (PAL) and lignoceryl CoA ligase and oxidation of LC (palmitic Acid) and VLC (Lignoceric Acid) fatty Acids by isotopic methods. Immunoblot analysis of acyl-CoA oxidase (ACO), and Northern blot analysis of peroxisome proliferator-activated receptor (PPAR-α), ACO, and PAL were also performed. The PAL activity increased in peroxisomes and mitochondria from the liver of diabetic rats by 2.6-fold and 2.1-fold, respectively. The lignoceroyl-CoA ligase activity increased by 2.6-fold in diabetic peroxisomes. Palmitic Acid oxidation increased in the diabetic peroxisomes and mitochondria by 2.5-fold and 2.7-fold, respectively, while Lignoceric Acid oxidation increased by 2.0-fold in the peroxisomes. Immunoreactive ACO protein increased by 2-fold in the diabetic group. The mRNA levels for PPAR-α, ACO and PAL increased 2.9-, 2.8- and 1.6-fold, respectively, in the diabetic group. These results suggest that the increased supply of fatty Acids to liver in diabetic state stimulates the expression of PPAR-α and its target genes responsible for the metabolism of fatty Acids.

  • Increased peroxisomal fatty Acid beta-oxidation and enhanced expression of peroxisome proliferator-activated receptor-alpha in diabetic rat liver.
    Molecular and cellular biochemistry, 1999
    Co-Authors: Kohtaro Asayama, Hidemasa Hayashibe, Takaya Nakane, Rajat Sandhir, F G Sheikh, I Singh
    Abstract:

    To determine whether the increased fatty Acid beta-oxidation in the peroxisomes of diabetic rat liver is mediated by a common peroxisome proliferation mechanism, we measured the activation of long-chain (LC) and very long chain (VLC) fatty Acids catalyzed by palmitoyl CoA ligase (PAL) and lignoceryl CoA ligase and oxidation of LC (palmitic Acid) and VLC (Lignoceric Acid) fatty Acids by isotopic methods. Immunoblot analysis of acyl-CoA oxidase (ACO), and Northern blot analysis of peroxisome proliferator-activated receptor (PPAR-alpha), ACO, and PAL were also performed. The PAL activity increased in peroxisomes and mitochondria from the liver of diabetic rats by 2.6-fold and 2.1 -fold, respectively. The lignoceroyl-CoA ligase activity increased by 2.6-fold in diabetic peroxisomes. Palmitic Acid oxidation increased in the diabetic peroxisomes and mitochondria by 2.5-fold and 2.7-fold, respectively, while Lignoceric Acid oxidation increased by 2.0-fold in the peroxisomes. Immunoreactive ACO protein increased by 2-fold in the diabetic group. The mRNA levels for PPAR-alpha, ACO and PAL increased 2.9-, 2.8- and 1.6-fold, respectively, in the diabetic group. These results suggest that the increased supply of fatty Acids to liver in diabetic state stimulates the expression of PPAR-alpha and its target genes responsible for the metabolism of fatty Acids.

  • Localization of nervonic Acid β-oxidation in human and rodent peroxisomes: impaired oxidation in Zellweger syndrome and X-linked adrenoleukodystrophy
    Journal of lipid research, 1998
    Co-Authors: Rajat Sandhir, Mushfiquddin Khan, Amarjit Chahal, Inderjit Singh
    Abstract:

    Studies with purified subcellular organelles from rat liver indicate that nervonic Acid (C24:1) is beta-oxidized preferentially in peroxisomes. Lack of effect by etomoxir, inhibitor of mitochondrial beta-oxidation, on beta-oxidation of Lignoceric Acid (C24:0), a peroxisomal function, and that of nervonic Acid (24:1) compared to the inhibition of palmitic Acid (16:0) oxidation, a mitochondrial function, supports the conclusion that nervonic Acid is oxidized in peroxisomes. Moreover, the oxidation of nervonic and Lignoceric Acids was deficient in fibroblasts from patients with defects in peroxisomal beta-oxidation [Zellweger syndrome (ZS) and X-linked adrenoleukodystrophy (X-ALD)]. Similar to Lignoceric Acid, the activation and beta-oxidation of nervonic Acid was deficient in peroxisomes isolated from X-ALD fibroblasts. Transfection of X-ALD fibroblasts with human cDNA encoding for ALDP (X-ALD gene product) restored the oxidation of both nervonic and Lignoceric Acids, demonstrating that the same molecular defect may be responsible for the abnormality in the oxidation of nervonic as well as Lignoceric Acid. Moreover, immunoprecipitation of activities for acyl-CoA ligase for both Lignoceric Acid and nervonic Acid indicate that saturated and monoenoic very long chain (VLC) fatty Acids may be activated by the same enzyme. These results clearly demonstrate that similar to saturated VLC fatty Acids (e.g., Lignoceric Acid), VLC monounsaturated fatty Acids (e.g., nervonic Acid) are oxidized preferentially in peroxisomes and that this activity is impaired in X-ALD. In view of the fact that the oxidation of unsaturated VLC fatty Acids is defective in X-ALD patients, the efficacy of dietary monoene therapy, "Lorenzo's oil," in X-ALD needs to be evaluated.

D. Fessas - One of the best experts on this subject based on the ideXlab platform.

  • Thermogenic flux induced by Lignoceric Acid in peroxisomes isolated from HepG2 cells and from X-adrenoleukodystrophy and control fibroblasts.
    Journal of cellular physiology, 2019
    Co-Authors: A. Petroni, R. Paroni, A.m. Aloisi, M. Blasevich, N. Haman, D. Fessas
    Abstract:

    This work analyzes the thermogenic flux induced by the very long-chain fatty Acid (VLCFA) Lignoceric Acid (C24:0) in isolated peroxisomes. Specific metabolic alterations of peroxisomes are related to a variety of disorders, the most frequent one being the neurodegenerative inherited disease X-linked adrenoleukodystrophy (X-ALD). A peroxisomal transport protein is mutated in this disorder. Due to reduced catabolism and enhanced fatty Acid (FA) elongation, VLCFA accumulates in plasma and in all tissues, contributing to the clinical manifestations of this disorder. During peroxisomal metabolism, heat is produced but it is considered lost. Instead, it is a form of energy that could play a role in molecular mechanisms of this pathology and other neurodegenerative disorders. The thermogenic flux induced by Lignoceric Acid (C24:0) was estimated by isothermal titration calorimetry in peroxisomes isolated from HepG2 cells and from fibroblasts obtained from patients with X-ALD and healthy subjects. Heat flux induced by Lignoceric Acid in HepG2 peroxisomes was exothermic, indicating normal peroxisomal metabolism. In X-ALD peroxisomes the heat flux was endothermic, indicating the requirement of heat/energy, possibly for cellular metabolism. In fibroblasts from healthy subjects, the effect was less pronounced than in HepG2, a kind of cell known to have greater FA metabolism than fibroblasts. Our hypothesis is that heat is not lost but it could act as an activator, for example on the heat-sensitive pathway related to TRVP2 receptors. To investigate this hypothesis we focused on peroxisomal metabolism, considering that impaired heat generation could contribute to the development of peroxisomal neurodegenerative disorders.

  • Thermogenic flux induced by Lignoceric Acid in peroxisomes isolated from HepG2 cells and from X- adrenoleukodystrophy and control fibroblasts
    'Wiley', 2019
    Co-Authors: A. Petroni, R. Paroni, A.m. Aloisi, M. Blasevich, N. Haman, D. Fessas
    Abstract:

    This work analyzes the thermogenic flux induced by the very long-chain fatty Acid (VLCFA) Lignoceric Acid (C24:0) in isolated peroxisomes. Specific metabolic alterations of peroxisomes are related to a variety of disorders, the most frequent one being the neurodegenerative inherited disease X-linked adrenoleukodystrophy (X-ALD). A peroxisomal transport protein is mutated in this disorder. Due to reduced catabolism and enhanced fatty Acid elongation, VLCFA accumulate in plasma and in all tissues, contributing to the clinical manifestations of this disorder. During peroxisomal metabolism, heat is produced but it is considered lost. Instead, it is a form of energy that could play a role in molecular mechanisms of this pathology and other neurodegenerative disorders. The thermogenic flux induced by Lignoceric Acid (C24:0) was estimated by isothermal titration calorimetry in peroxisomes isolated from HepG2 cells and from fibroblasts obtained from X-linked adrenoleukodystrophy patients and healthy subjects. Heat flux induced by Lignoceric Acid in HepG2 peroxisomes was exothermic, indicating normal peroxisomal metabolism. In X-ALD peroxisomes the heat flux was endothermic, indicating the requirement of heat/energy, possibly for cellular metabolism. In fibroblasts from healthy subjects the effect was less pronounced than in HepG2, a kind of cell known to have greater FA metabolism than fibroblasts. Our hypothesis is that heat is not lost but it could act a s an activator, for example on the heat-sensitive pathway related to TRVP2 receptors. To investigate this hypothesis we focused on peroxisomal metabolism, considering that impaired heat generation could contribute to the development of peroxisomal neurodegenerative disorders

Harmeet Singh - One of the best experts on this subject based on the ideXlab platform.

  • metabolism of trideuterated iso Lignoceric Acid in rats in vivo and in human fibroblasts in culture
    Lipids, 1999
    Co-Authors: Alfred Poulos, Peter C. Stockham, David W. Johnson, Barbara C. Paton, K. Beckman, Harmeet Singh
    Abstract:

    Saturated very long chain fatty Acids (fatty Acids with greater than 22 carbon atoms; VLCFA) accumulate in peroxisomal disorders, but there is little information on their turnover in patients. To determine the suitability of using stable isotope-labeled VLCFA in patients with these disorders, the metabolism of 22-methyl[23,23,23-2H3]tricosanoic (iso-Lignoceric) Acid was studied in rats in vivo and in human skin fibroblasts in culture. The deuterated iso-VLCFA was degraded to the corresponding 16- and 18-carbon iso-fatty Acids by rats in vivo and by normal human skin fibroblasts in culture, but there was little or no degradation in peroxisome-deficient (Zellweger’s syndrome) fibroblasts, indicating that its oxidation was peroxisomal. Neither the 14-, 20-, and 22-carbon iso-fatty Acids nor the corresponding odd-chain metabolites could be detected. In the rat, the organ containing most of the iso-Lignoceric Acid, and its breakdown products, was the liver, whereas negligible amounts were detected in the brain, suggesting that little of the fatty Acid crossed the blood-brain barrier. Our data indicate that VLCFA labeled with deuterium at the ω-position of the carbon chain are suitable derivatives for the in vivo investigation of patients with defects in peroxisomal β-oxidation because they are metabolized by the same pathways as the corresponding n-VLCFA. Moreover, as iso-VLCFA and their β-oxidation products are readily separated from the corresponding n-fatty Acids by normal chromatographic procedures, the turnover of VLCFA can be more precisely measured.

  • Metabolism of trideuterated iso-Lignoceric Acid in rats in vivo and in human fibroblasts in culture.
    Lipids, 1999
    Co-Authors: Alfred Poulos, Peter C. Stockham, David W. Johnson, Barbara C. Paton, K. Beckman, Harmeet Singh
    Abstract:

    Saturated very long chain fatty Acids (fatty Acids with greater than 22 carbon atoms; VLCFA) accumulate in peroxisomal disorders, but there is little information on their turnover in patients. To determine the suitability of using stable isotope-labeled VLCFA in patients with these disorders, the metabolism of 22-methyl[23,23,23-2H3]tricosanoic (iso-Lignoceric) Acid was studied in rats in vivo and in human skin fibroblasts in culture. The deuterated iso-VLCFA was degraded to the corresponding 16- and 18-carbon iso-fatty Acids by rats in vivo and by normal human skin fibroblasts in culture, but there was little or no degradation in peroxisome-deficient (Zellweger's syndrome) fibroblasts, indicating that its oxidation was peroxisomal. Neither the 14-, 20-, and 22-carbon iso-fatty Acids nor the corresponding odd-chain metabolites could be detected. In the rat, the organ containing most of the iso-Lignoceric Acid, and its breakdown products, was the liver, whereas negligible amounts were detected in the brain, suggesting that little of the fatty Acid crossed the blood-brain barrier. Our data indicate that VLCFA labeled with deuterium at the omega-position of the carbon chain are suitable derivatives for the in vivo investigation of patients with defects in peroxisomal beta-oxidation because they are metabolized by the same pathways as the corresponding n-VLCFA. Moreover, as iso-VLCFA and their beta-oxidation products are readily separated from the corresponding n-fatty Acids by normal chromatographic procedures, the turnover of VLCFA can be more precisely measured.

  • 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