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Pike B, Zhao J, Hicks JA, Wang F, Hagen R, Liu HC, Odle J, Lin X. Intestinal Carnitine Status and Fatty Acid Oxidation in Response to Clofibrate and Medium-Chain Triglyceride Supplementation in Newborn Pigs. Int J Mol Sci 2023; 24:ijms24076066. [PMID: 37047049 PMCID: PMC10094207 DOI: 10.3390/ijms24076066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/13/2023] [Accepted: 03/15/2023] [Indexed: 04/14/2023] Open
Abstract
To investigate the role of peroxisome proliferator-activated receptor alpha (PPARα) in carnitine status and intestinal fatty acid oxidation in neonates, a total of 72 suckled newborn piglets were assigned into 8 dietary treatments following a 2 (±0.35% clofibrate) × 4 (diets with: succinate+glycerol (Succ), tri-valerate (TC5), tri-hexanoate (TC6), or tri-2-methylpentanoate (TMPA)) factorial design. All pigs received experimental milk diets with isocaloric energy for 5 days. Carnitine statuses were evaluated, and fatty acid oxidation was measured in vitro using [1-14C]-palmitic acid (1 mM) as a substrate in absence or presence of L659699 (1.6 µM), iodoacetamide (50 µM), and carnitine (1 mM). Clofibrate increased concentrations of free (41%) and/or acyl-carnitine (44% and 15%) in liver and plasma but had no effects in the intestine. The effects on carnitine status were associated with the expression of genes involved in carnitine biosynthesis, absorption, and transportation. TC5 and TMPA stimulated the increased fatty acid oxidation rate induced by clofibrate, while TC6 had no effect on the increased fatty acid oxidation induced by clofibrate (p > 0.05). These results suggest that dietary clofibrate improved carnitine status and increased fatty acid oxidation. Propionyl-CoA, generated from TC5 and TMPA, could stimulate the increased fatty acid oxidation rate induced by clofibrate as anaplerotic carbon sources.
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Affiliation(s)
- Brandon Pike
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Jinan Zhao
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Julie A Hicks
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Feng Wang
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Rachel Hagen
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Hsiao-Ching Liu
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Jack Odle
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Xi Lin
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
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Lamhonwah AM, Ackerley C, Onizuka R, Tilups A, Lamhonwah D, Chung C, Tao KS, Tellier R, Tein I. Epitope shared by functional variant of organic cation/carnitine transporter, OCTN1, Campylobacter jejuni and Mycobacterium paratuberculosis may underlie susceptibility to Crohn’s disease at 5q31. Biochem Biophys Res Commun 2005; 337:1165-75. [PMID: 16246312 DOI: 10.1016/j.bbrc.2005.09.170] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Accepted: 09/27/2005] [Indexed: 12/19/2022]
Abstract
Campylobacter jejuni and Mycobacterium paratuberculosis have been implicated in the pathogenesis of Crohn's disease. The presence of bacterial metabolites in the colonic lumen causing a specific breakdown of fatty acid oxidation in colonic epithelial cells has been suggested as an initiating event in inflammatory bowel disease (IBD). l-Carnitine is a small highly polar zwitterion that plays an essential role in fatty acid oxidation and ATP generation in intestinal bioenergetic metabolism. The organic cation/carnitine transporters, OCTN1 and OCTN2, function primarily in the transport of l-carnitine and elimination of cationic drugs in the intestine. High-resolution linkage disequilibrium mapping has identified a region of about 250kb in size at 5q31 (IBD5) encompassing the OCTN1 and -2 genes, to confer susceptibility to Crohn's disease. Recently, two variants in the OCTN1 and OCTN2 genes have been shown to form a haplotype which is associated with susceptibility to Crohn's. We show that OCTN1 and OCTN2 are strongly expressed in target areas for IBD such as ileum and colon. Further, we have now identified a nine amino acid epitope shared by this functional variant of OCTN1 (Leu503Phe) (which decreases the efficiency of carnitine transport), and by C. jejuni (9 aa) and M. paratuberculosis (6 aa). The prevalence of this variant of OCTN1 (Phe503:Leu503) is 3-fold lower in unaffected individuals of Jewish origin (1:3.44) compared to unaffected individuals of non-Jewish origin (1:1). We hypothesize that a specific antibody raised to this epitope during C. jejuni or M. paratuberculosis enterocolitis would cross-react with the intestinal epithelial cell functional variant of OCTN1, an already less efficient carnitine transporter, leading to an impairment of mitochondrial beta-oxidation which may then serve as an initiating event in IBD. This impairment of l-carnitine transport by OCTN1 may respond to high-dose l-carnitine therapy.
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Affiliation(s)
- Anne-Marie Lamhonwah
- Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Ont., Canada
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3
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Lamhonwah AM, Ackerley CA, Tilups A, Edwards VD, Wanders RJ, Tein I. OCTN3 is a mammalian peroxisomal membrane carnitine transporter. Biochem Biophys Res Commun 2005; 338:1966-72. [PMID: 16288981 DOI: 10.1016/j.bbrc.2005.10.170] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2005] [Accepted: 10/25/2005] [Indexed: 11/29/2022]
Abstract
Carnitine is a zwitterion essential for the beta-oxidation of fatty acids. The role of the carnitine system is to maintain homeostasis in the acyl-CoA pools of the cell, keeping the acyl-CoA/CoA pool constant even under conditions of very high acyl-CoA turnover, thereby providing cells with a critical source of free CoA. Carnitine derivatives can be moved across intracellular barriers providing a shuttle mechanism between mitochondria, peroxisomes, and microsomes. We now demonstrate expression and colocalization of mOctn3, the intermediate-affinity carnitine transporter (Km 20 microM), and catalase in murine liver peroxisomes by TEM using immunogold labelled anti-mOctn3 and anti-catalase antibodies. We further demonstrate expression of hOCTN3 in control human cultured skin fibroblasts both by Western blotting and immunostaining analysis using our specific anti-mOctn3 antibody. In contrast with two peroxisomal biogenesis disorders, we show reduced expression of hOCTN3 in human PEX 1 deficient Zellweger fibroblasts in which the uptake of peroxisomal matrix enzymes is impaired but the biosynthesis of peroxisomal membrane proteins is normal, versus a complete absence of hOCTN3 in human PEX 19 deficient Zellweger fibroblasts in which both the uptake of peroxisomal matrix enzymes as well as peroxisomal membranes are deficient. This supports the localization of hOCTN3 to the peroxisomal membrane. Given the impermeability of the peroxisomal membrane and the key role of carnitine in the transport of different chain-shortened products out of peroxisomes, there appears to be a critical need for the intermediate-affinity carnitine/organic cation transporter, OCTN3, on peroxisomal membranes now shown to be expressed in both human and murine peroxisomes. This Octn3 localization is in keeping with the essential role of carnitine in peroxisomal lipid metabolism.
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Affiliation(s)
- Anne-Marie Lamhonwah
- Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Canada
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4
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Lamhonwah AM, Skaug J, Scherer SW, Tein I. A third human carnitine/organic cation transporter (OCTN3) as a candidate for the 5q31 Crohn's disease locus (IBD5). Biochem Biophys Res Commun 2003; 301:98-101. [PMID: 12535646 DOI: 10.1016/s0006-291x(02)02946-7] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Organic cation transporters function primarily in the elimination of cationic drugs in kidney, intestine, and liver. The murine organic cation/carnitine (Octn) transporter family, Octn1, Octn2, and Octn3 is clustered on mouse chromosome 11 (NCBI Accession No. NW_000039). The human OCTN1 and OCTN2 orthologs map to the syntenic IBD5 locus at 5q31, which has been shown to confer susceptibility to Crohn's disease. We show that the human OCTN3 protein, whose corresponding gene is not yet cloned or annotated in the human reference DNA sequence, does indeed exist and is uniquely involved in carnitine-dependent transport in peroxisomes. Its functional properties and inferred chromosomal location implicate it for involvement in Crohn's disease.
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Affiliation(s)
- Anne-Marie Lamhonwah
- Department of Pediatrics, Division of Neurology, The Hospital for Sick Children, University of Toronto, 555 University Ave., Toronto, Ont, Canada M5G 1X8
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5
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Jørgensen J, Mortensen PB. Substrate utilization by intestinal mucosal tissue strips from patients with inflammatory bowel disease. Am J Physiol Gastrointest Liver Physiol 2001; 281:G405-11. [PMID: 11447021 DOI: 10.1152/ajpgi.2001.281.2.g405] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A primary metabolic disorder may be present in the colonic mucosa of patients with ulcerative colitis. Preserving the epithelium in situ, we evaluated the metabolism of the colonic mucosa of control patients and patients with ulcerative colitis and Crohn's disease. Colonic mucosal strips (approximately 500 mg) were incubated with partially 14C-labeled acetate (C2), butyrate (C4), hexanoate (C6), octanoate (C8), and glucose, and the production of CO2 and ketone bodies was quantitated. Metabolism by small intestinal mucosal strips was also evaluated. Compared with controls, no decrease in either CO2 or ketone body production by colonic strips from patients with either ulcerative colitis or Crohn's disease was observed for any substrate. The CO2 production from each of the C2-C8 fatty acids was the same for colonic and small intestinal strips, whereas CO2 production from glucose was higher in small intestinal strips than in colonic strips. The production of ketone bodies was low in small intestinal strips. A primary metabolic disorder in the colonic mucosa of patients with inflammatory bowel disease was not found.
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Affiliation(s)
- J Jørgensen
- Department of Medicine CA2121, Section of Gastroenterology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark.
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6
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Miliar A, Serra D, Casaroli R, Vilaró S, Asins G, Hegardt FG. Developmental Changes in Carnitine Octanoyltransferase Gene Expression in Intestine and Liver of Suckling Rats. Arch Biochem Biophys 2001; 385:283-9. [PMID: 11368009 DOI: 10.1006/abbi.2000.2155] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carnitine octanoyltransferase (COT), which facilitates the transport of shortened fatty acyl-CoAs from peroxisomes to mitochondria, is expressed in the intestinal mucosa of suckling rats; its mRNA levels increase rapidly after birth, remain steady until day 15, and decrease until weaning, when basal, adult values are established, which remain unchanged thereafter. The process seems to be controlled at the transcriptional level since the developmental pattern of mRNA coincides with that of pre-mRNA values. Dam's milk may influence the intestinal expression of COT, since mRNA levels at birth are low and increase after the first lactation. Moreover, mRNA levels decrease in rats weaned on day 18 or 21. COT is also expressed in the liver of suckling rats. Hepatic COT mRNA is maximal at day 3, remains constant until day 9, and decreases thereafter; this pattern is also similar to that of pre-mRNA values. The profile of expression of COT in intestine and liver strongly resembles that of mitochondrial 3-hydroxy 3-methylglutaryl-coenzyme A synthase and carnitine palmitoyltransferase I, suggesting that analogous transcription factors modulate ketogenesis and mitochondrial and peroxisomal fatty acid oxidation.
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Affiliation(s)
- A Miliar
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Barcelona, Spain
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7
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Abstract
Considerable progress has been made over the last decade in the understanding of mechanisms responsible for the ontogenetic changes of mammalian intestine. This review presents the current knowledge about the development of intestinal transport function in the context of intestinal mucosa ontogeny. The review predominantly focuses on signals that trigger and/or modulate the developmental changes of intestinal transport. After an overview of the proliferation and differentiation of intestinal mucosa, data about the bidirectional traffic (absorption and secretion) across the developing intestinal epithelium are presented. The largest part of the review is devoted to the description of developmental patterns concerning the absorption of nutrients, ions, water, vitamins, trace elements, and milk-borne biologically active substances. Furthermore, the review examines the development of intestinal secretion that has a variety of functions including maintenance of the fluidity of the intestinal content, lubrication of mucosal surface, and mucosal protection. The age-dependent shifts of absorption and secretion are the subject of integrated regulatory mechanisms, and hence, the input of hormonal, nervous, immune, and dietary signals is reviewed. Finally, the utilization of energy for transport processes in the developing intestine is highlighted, and the interactions between various sources of energy are discussed. The review ends with suggestions concerning possible directions of future research.
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Affiliation(s)
- J Pácha
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
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8
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Thumelin S, Kohl C, Girard J, Pégorier JP. Atypical expression of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase in subcutaneous adipose tissue of male rats. J Lipid Res 1999. [DOI: 10.1016/s0022-2275(20)33511-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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9
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Arias G, Asins G, Hegardt FG, Serra D. The effect of dexamethasone treatment on the expression of the regulatory genes of ketogenesis in intestine and liver of suckling rats. Mol Cell Biochem 1998; 178:325-33. [PMID: 9546617 DOI: 10.1023/a:1006875716407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The influence of the injection of dexamethasone on ketogenesis in 12 day old suckling rats was studied in intestine and liver by determining mRNA levels and enzyme activity of the two genes responsible for regulation of ketogenesis: carnitine palmitoyl transferase I (CPT I) and mitochondrial HMG-CoA synthase. Dexamethasone produced a 2 fold increase in mRNA and activity of CPT I in intestine, but led to a decrease in mit. HMG-CoA synthase. In liver the mRNA levels and activity of both CPT I and mit. HMG-CoA synthase decreased. Comparison of these values with the ketogenic rate of both tissues following dexamethasone treatment suggests that mit. HMG-CoA synthase could be the main gene responsible for the regulation of ketogenesis in suckling rats. The changes produced in serum ketone bodies by dexamethasone, with a profile that is more similar to the ketogenic rate in the liver than that in the intestine, indicate that liver contributes more to ketone body synthesis in suckling rats. Two day treatment with dexamethasone produced no change in mRNA or activity levels for CPT I in liver or intestine. While mRNA levels for mit. HMG-CoA synthase changed little, the enzyme activity is decreased in both tissues.
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Affiliation(s)
- G Arias
- Department of Biochemistry, School of Pharmacy, University of Barcelona, Spain
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10
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Adams SH, Alho CS, Asins G, Hegardt FG, Marrero PF. Gene expression of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase in a poorly ketogenic mammal: effect of starvation during the neonatal period of the piglet. Biochem J 1997; 324 ( Pt 1):65-73. [PMID: 9164842 PMCID: PMC1218402 DOI: 10.1042/bj3240065] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The low ketogenic capacity of pigs correlates with a low activity of mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase. To identify the molecular mechanism controlling such activity, we isolated the pig cDNA encoding this enzyme and analysed changes in mRNA levels and mitochondrial specific activity induced during development and starvation. Pig mitochondrial synthase showed a tissue-specific expression pattern. As with rat and human, the gene is expressed in liver and large intestine; however, the pig differs in that mRNA was not detected in testis, kidney or small intestine. During development, pig mitochondrial HMG-CoA synthase gene expression showed interesting differences from that in the rat: (1) there was a 2-3 week lag in the postnatal induction; (2) the mRNA levels remained relatively abundant through the suckling-weaning transition and at maturity, in contrast with the fall observed in rats at similar stages of development; and (3) the gene expression was highly induced by fasting during the suckling, whereas no such change in mitochondrial HMG-CoA synthase mRNA levels has been observed in rat. The enzyme activity of mitochondrial HMG-CoA synthase increased 27-fold during starvation in piglets, but remained one order of magnitude lower than rats. These results indicate that post-transcriptional mechanism(s) and/or intrinsic differences in the encoded enzyme are responsible for the low activity of pig HMG-CoA synthase observed throughout development or after fasting.
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Affiliation(s)
- S H Adams
- Unit of Biochemistry, School of Pharmacy, University of Barcelona, Avda. Diagonal, 643, 08028 Barcelona, Spain
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11
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Arias G, Asins G, Hegardt FG, Serra D. The effect of fasting/refeeding and insulin treatment on the expression of the regulatory genes of ketogenesis in intestine and liver of suckling rats. Arch Biochem Biophys 1997; 340:287-98. [PMID: 9143333 DOI: 10.1006/abbi.1997.9911] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The influence of fasting/refeeding and insulin treatment on ketogenesis in 12-day-old suckling rats was studied in intestine and liver by determining mRNA levels and enzyme activity of the two genes responsible for regulation of ketogenesis: carnitine palmitoyl transferase I (CPT I) and mitochondrial HMG-CoA synthase. Fasting produced hardly any change in mRNA or activity of CPT 1 in intestine, but led to a decrease in mitochondrial (mit.) HMG-CoA synthase. In liver, while mRNA levels and activity for CPT I increased, neither parameter was changed in HMG-CoA synthase. The comparison of these values with the ketogenic rate of both tissues under the fasting/refeeding treatment shows that HMG-CoA synthase could be the main gene responsible for regulation of ketogenesis in suckling rats. The small changes produced in serum ketone bodies in fasting/refeeding, with a profile similar to the ketogenic rate of the liver, indicate that liver contributes most to ketone body synthesis in suckling rats under these experimental conditions. Short-term insulin treatment produced increases in mRNA levels and activity in CPT I in intestine, but it also decreased both parameters in mit. HMG-CoA synthase. In liver, graphs of mRNA and activity were nearly identical in both genes. There was a marked decrease in mRNA levels and activity, resembling those values observed in adult rats. As in fasting/refeeding, the ketogenic rate correlated better to mit. HMG-CoA synthase than CPT I, and liver was the main organ regulating ketogenesis after insulin treatment. Serum ketone body concentrations were decreased by insulin but recovered after the second hour. Long-term insulin treatment had little effect on the mRNA levels for CPT I or mit. HMG-CoA synthase, but both the expressed and total activities of mit. HMG-CoA synthase were reduced by half in both intestine and liver. The ketogenic rate of both organs was decreased to 40% by long-term insulin treatment. The different effects of refeeding and insulin treatment on the expression of both genes, on the ketogenic rate, and on ketone body concentrations are discussed.
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Affiliation(s)
- G Arias
- Department of Biochemistry, School of Pharmacy, University of Barcelona, Spain
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12
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Serra D, Bellido D, Asins G, Arias G, Vilaró S, Hegardt FG. The expression of mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme-A synthase in neonatal rat intestine and liver is under transcriptional control. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 237:16-24. [PMID: 8620869 DOI: 10.1111/j.1432-1033.1996.0016n.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HOMeGlt-CoA) synthase regulates ketogenesis in the liver of adult rat and in the intestine and liver of neonatal animals but whose mechanisms of regulation have not been fully defined. To investigate transcriptional control of this gene in intestine and liver of suckling rats a quantitative PCR amplification of the pre-mRNA (heteronuclear RNA), compose of part of the first exon and of the first intron, was carried out. Results show that the intestinal pre-mRNA for mitochondrial HOMeGlt-CoA synthase from suckling rats follows a pattern that is nearly identical to that of mature mRNA, with maximum levels on the ninth postnatal day then decreasing smoothly so that at weaning there is no transcriptional activity. Mitochondrial HOMeGlt-CoA synthase protein follows a pattern that is identical to the pre-mRNA and mature mRNA, suggesting no translational regulation. The changes in transcriptional activity are not produced by the presence of an alternative promoter, since the transcription-initiation site is identical in several tissues assayed, including intestine and liver. Enterocytes are the only intestinal cells that express this ketogenic enzyme, as deduced from immunolocalization experiments. The mature intestinal protein is located in mitochondria and not in the cytosol, which coincides with what is found in liver. By using analogous techniques we conclude that hepatic pre-mRNA of mitochondrial HOMeGlt-CoA synthase from suckling rats follows a pattern of expression identical to that of mature hepatic mRNA, which also suggests a transcriptional modulation of this gene in the liver of neonatal rats.
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Affiliation(s)
- D Serra
- Unit of Biochemistry, School of Pharmacy, University of Barcelona, Spain
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13
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Asins G, Serra D, Arias G, Hegardt FG. Developmental changes in carnitine palmitoyltransferases I and II gene expression in intestine and liver of suckling rats. Biochem J 1995; 306 ( Pt 2):379-84. [PMID: 7887892 PMCID: PMC1136532 DOI: 10.1042/bj3060379] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Carnitine palmitoyltransferase (CPT) I is expressed in the intestine of suckling rats; its mRNA increases very rapidly after birth, remains on a plateau until day 18 and decreases until weaning, when basal (adult) values are reached, which remain unchanged thereafter. CPT II mRNA values do not show any appreciable change in this period. CPT I and CPT II are expressed mainly in mucosa and, to a lesser extent, in the muscular part of the intestine. Intestinal expression of CPT I is maximal in duodenum and jejunum, whereas CPT II is expressed in a similar pattern throughout the whole intestine. Dam's milk may influence the intestinal expression of CPT I, since mRNA levels at birth are low but increase after the first lactation. Moreover, rats weaned at either day 18 or 21 decrease their mRNA levels. Apparently, CPT II gene expression is not influenced by the mother's milk. CPT I and CPT II are also expressed in the liver of suckling rats. Hepatic CPT I is maximal at day 3, and levels of CPT II mRNA do not change, in a similar fashion to that in intestine. The profile of expression of CPT I in liver and intestine strongly resembles that previously reported for mitochondrial 3-hydroxy-3-methyl-glutaryl-CoA synthase.
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Affiliation(s)
- G Asins
- Unit of Biochemistry, School of Pharmacy, University of Barcelona, Spain
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14
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Thumelin S, Forestier M, Girard J, Pegorier JP. Developmental changes in mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene expression in rat liver, intestine and kidney. Biochem J 1993; 292 ( Pt 2):493-6. [PMID: 8099282 PMCID: PMC1134236 DOI: 10.1042/bj2920493] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The tissue-specific expression of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase gene was studied in 15-day-old suckling rats. The mRNA and protein were present in liver, intestine and kidney, but were absent from brain, heart, skeletal muscles, brown and white adipose tissues. Kidney-cortex mitochondria from suckling rats were able to produce low amounts of ketone bodies from oleate. Hepatic, intestinal and renal HMG-CoA synthase mRNA levels increased slowly during foetal life and markedly after birth. The postnatal increase in liver HMG-CoA synthase mRNA could be due to the increase in plasma glucagon levels, since it rapidly induced the accumulation of HMG-CoA synthase mRNA in cultured foetal hepatocytes. Hepatic, intestinal and renal HMG-CoA synthase mRNA levels remained elevated throughout the suckling period or in rats weaned on to a high-fat carbohydrate-free diet (HF), but decreased by 50% in the liver and totally disappeared from the intestine and the kidney of rats weaned on to a high-carbohydrate low-fat diet (HC). When HC-weaned rats were fed on a HF-diet for a week, HMG-CoA synthase mRNA was re-induced in the intestine and the kidney. The role of hormones and nutrients in the regulation of HMG-CoA synthase gene expression is discussed.
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Affiliation(s)
- S Thumelin
- Centre de Recherche sur l'Endocrinologie Moléculaire et le Développement, CNRS, Meudon-Bellevue, France
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Royo T, Pedragosa MJ, Ayté J, Gil-Gómez G, Vilaró S, Hegardt FG. Testis and ovary express the gene for the ketogenic mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase. J Lipid Res 1993. [DOI: 10.1016/s0022-2275(20)39673-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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16
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Quant PA, Robin D, Robin P, Girard J, Brand MD. A top-down control analysis in isolated rat liver mitochondria: can the 3-hydroxy-3-methylglutaryl-CoA pathway be rate-controlling for ketogenesis? BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1156:135-43. [PMID: 8427872 DOI: 10.1016/0304-4165(93)90128-u] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We incubated isolated liver mitochondria with palmitoyl-CoA, 2,4-dinitrophenol and malonate. Under these conditions all the flux of carbon from palmitoyl-CoA was directed towards acetoacetate synthesis. We measured the rate of acetyl-CoA formation from palmitoyl-CoA (by measuring the rate of oxygen consumption) and the rate of acetoacetate production from acetyl-CoA at three different acetyl-CoA/CoA ratios. Using the top-down approach of metabolic control analysis we calculated the control over ketogenesis exerted by (a) the conversion of extramitochondrial palmitoyl-CoA to intramitochondrial acetyl-CoA and by (b) the conversion of acetyl-CoA to acetoacetate (the 'HMG-CoA pathway'). The overall flux control coefficients of the groups of enzymes involved in (a) and (b) over ketogenesis were 0.28 and 0.72, respectively. Our results show that it is possible for significant control to be exerted over ketogenesis by the enzymes of the HMG-CoA pathway.
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Affiliation(s)
- P A Quant
- Centre de Recherche sur l'Endocrinologie Moléculaire et le Développement, Centre National de la Recherche Scientifique, Meudon-Bellevue, France
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