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Morito K, Ali H, Kishino S, Tanaka T. Fatty Acid Metabolism in Peroxisomes and Related Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024. [PMID: 38811487 DOI: 10.1007/5584_2024_802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
One of the functions of peroxisomes is the oxidation of fatty acids (FAs). The importance of this function in our lives is evidenced by the presence of peroxisomal disorders caused by the genetic deletion of proteins involved in these processes. Unlike mitochondrial oxidation, peroxisomal oxidation is not directly linked to ATP production. What is the role of FA oxidation in peroxisomes? Recent studies have revealed that peroxisomes supply the building blocks for lipid synthesis in the endoplasmic reticulum and facilitate intracellular carbon recycling for membrane quality control. Accumulation of very long-chain fatty acids (VLCFAs), which are peroxisomal substrates, is a diagnostic marker in many types of peroxisomal disorders. However, the relationship between VLCFA accumulation and various symptoms of these disorders remains unclear. Recently, we developed a method for solubilizing VLCFAs in aqueous media and found that VLCFA toxicity could be mitigated by oleic acid replenishment. In this chapter, we present the physiological role of peroxisomal FA oxidation and the knowledge obtained from VLCFA-accumulating peroxisome-deficient cells.
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Affiliation(s)
- Katsuya Morito
- Laboratory of Environmental Biochemistry, Division of Biological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Hanif Ali
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Japan
| | | | - Tamotsu Tanaka
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Japan.
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2
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Tan T, Luo Y, Sun W, Li X. Effects of Branched-Chain Fatty Acids Derived from Yak Ghee on Lipid Metabolism and the Gut Microbiota in Normal-Fat Diet-Fed Mice. Molecules 2023; 28:7222. [PMID: 37894700 PMCID: PMC10609089 DOI: 10.3390/molecules28207222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/10/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023] Open
Abstract
Branched-chain fatty acids (BCFAs) are natural components with a variety of biological activities. However, the regulation of lipid metabolism by BCFAs is unknown. It was dedicated to examining the impacts of BCFAs inferred from yak ghee on the expression of qualities related to lipid metabolism, natural pathways, and intestinal microbiota in mice. The treatment group (purified BCFAs from yak ghee) exhibited a decrease in cholesterol levels; a decrease in HMGCR levels; downregulation of FADS1, FADS2, ACC-α, FAS, GAPT4, GPAM, ACSL1, THRSP, A-FABP, and PPARα gene expression; and upregulation of SCD1, ACSS1, FABP1, CPT1, and DGAT-1 gene expression. Gut microbiota 16S rDNA sequencing analysis showed that the treatment group improved the gut microbiota by increasing the relative abundances and increasing the short-chain fatty acid levels produced by the genera Akkermansia, Clostridium, Lachnospiraceae, Lactobacillus, Anaerotaenia, and Prevotella. After adding BCFAs to cultured breast cancer cells, pathways that were downregulated were found to be related to fatty acid degradation and fatty acid metabolism, while 20 other pathways were upregulated. Our results suggest that BCFAs reduce body fat in mice by modulating intestinal flora and lipid metabolism and modulating fatty acid metabolism in breast cancer cells.
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Affiliation(s)
| | - Yihao Luo
- Animal Science Department, College of Agriculture and Animal Husbandry, Qinghai University, Ning Da Road 251, Xining 810016, China; (T.T.); (W.S.); (X.L.)
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Muthusamy G, Liu CC, Johnston AN. Deletion of PGAM5 Downregulates FABP1 and Attenuates Long-Chain Fatty Acid Uptake in Hepatocellular Carcinoma. Cancers (Basel) 2023; 15:4796. [PMID: 37835490 PMCID: PMC10571733 DOI: 10.3390/cancers15194796] [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: 07/30/2023] [Revised: 09/14/2023] [Accepted: 09/22/2023] [Indexed: 10/15/2023] Open
Abstract
Phosphoglycerate mutase 5 (PGAM5) is a Ser/His/Thr phosphatase responsible for regulating mitochondrial homeostasis. Overexpression of PGAM5 is correlated with a poor prognosis in hepatocellular carcinoma, colon cancer, and melanoma. In hepatocellular carcinoma, silencing of PGAM5 reduces growth, which has been attributed to decreased mitophagy and enhanced apoptosis. Yet in colon cancer, PGAM5's pro-tumor survival effect is correlated to lipid metabolism. We sought to identify whether deletion of PGAM5 modulated lipid droplet accrual in hepatocellular carcinoma. HepG2 and Huh7 PGAM5 knockout cell lines generated using CRISPR/Cas9 technology were used to measure cell growth, cellular ATP, and long-chain fatty acid uptake. Expression of hepatocellular fatty acid transporters, cluster of differentiation 36 (CD36), solute carrier family 27 member 2 (SLC27A2), solute carrier family 27 member 5 (SLC27A5), and fatty acid binding protein 1 (FABP1) was measured by quantitative PCR and Western blot. We found that deletion of PGAM5 attenuates hepatocellular carcinoma cell growth and ATP production. Further, PGAM5 knockout ameliorates palmitate-induced steatosis and reduces expression of FABP1 in HepG2 and Huh7 cell lines. PGAM5's role in hepatocellular carcinoma includes regulation of fatty acid metabolism, which may be related to expression of the fatty acid transporter, FABP1.
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Affiliation(s)
| | | | - Andrea N. Johnston
- Louisiana State University School of Veterinary Medicine, Baton Rouge, LA 70803, USA; (G.M.); (C.-C.L.)
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Gozdzik P, Magkos F, Sledzinski T, Mika A. Monomethyl branched-chain fatty acids: Health effects and biological mechanisms. Prog Lipid Res 2023; 90:101226. [PMID: 37094753 DOI: 10.1016/j.plipres.2023.101226] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/19/2023] [Accepted: 04/20/2023] [Indexed: 04/26/2023]
Abstract
Branched-chain fatty acids (BCFA) are a group of lipids that are widely present in various organisms; they take part in numerous biochemical processes and affect multiple signaling pathways. However, BCFA are not well explored in terms of their effects on human health. Recently, they have been gaining interest, especially in relation to various human diseases. This review describes the occurrence of BCFA, their dietary sources, their potential health effects, and the current state of knowledge concerning their mechanism(s) of action. Many studies have been conducted so far in cellular and animal models, which reveal potent anti-cancer, lipid lowering, anti-inflammatory and neuroprotective actions. Research in humans is scarce. Therefore, further studies on animals and humans should be performed to confirm and expand these findings, and improve our understanding of the potential relevance of BCFA to human health and disease.
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Affiliation(s)
- Paulina Gozdzik
- Department of Pharmaceutical Biochemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
| | - Faidon Magkos
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Frederiksberg C, Denmark
| | - Tomasz Sledzinski
- Department of Pharmaceutical Biochemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland.
| | - Adriana Mika
- Department of Pharmaceutical Biochemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland; Department of Environmental Analytics, Faculty of Chemistry, University of Gdansk, Gdansk, Poland
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5
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Zhao CS, Wei W, Luo SW, Yang P, Ren YH, Liu Y, Wang WN. FABP regulates fatty acid metabolism and oxidative response via PPARα/RXR signaling in Litopenaeus vannamei following environmental exposure of clofibric acid. ECOTOXICOLOGY (LONDON, ENGLAND) 2021; 30:954-965. [PMID: 33864550 DOI: 10.1007/s10646-021-02408-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/28/2021] [Indexed: 06/12/2023]
Abstract
Clofibric acid (CFA), a drug and personal care product, has been identified as ubiquitous in the aquatic system and surface water, causing pollution to the environment. In this study, after environmental (4 µg/L) levels of CFA challenge, the LvFABP, LvACS gene expressions, total haemocyte count (THC), relative enzymes (SOD1 and GST) activities in Litopenaeus vannamei were observed to decrease. In the meantime LvFATP, LvRXR expression and the level of NEFA were upregulated in L. vannamei body. LvFABP expression in vivo was knocked down by dsRNA-mediated RNA interference (RNAi), which led to significantly decreased levels of PPARα (including LvFATP, LvRXR and LvACS). When exposed to environmental CFA after 4 days, LvFABP knocked down group had a sharp upregulation of LvFATP, LvRXR, LvACS expression, GST activity and NEFA amount, following decreased THC and SOD1 activity. These results suggested that environmental concentration CFA may have some toxicological effect on L. vannamei, following fatty acids metabolism and oxidative stress responses by LvFABP via the PPARα/RXR signaling pathway, including LvFATP, LvRXR and LvACS.
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Affiliation(s)
- Chang-Sheng Zhao
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou, 510631, PR China
| | - Wei Wei
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou, 510631, PR China
| | - Sheng-Wei Luo
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou, 510631, PR China
| | - Ping Yang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou, 510631, PR China
| | - Ying-Hao Ren
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou, 510631, PR China
| | - Yuan Liu
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou, 510631, PR China
| | - Wei-Na Wang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou, 510631, PR China.
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Yang S, Chen R, Zhang L, Sun Q, Li R, Gu W, Zhong M, Liu Y, Chen LC, Sun Q, Liu C. Lipid metabolic adaption to long-term ambient PM 2.5 exposure in mice. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 269:116193. [PMID: 33302088 DOI: 10.1016/j.envpol.2020.116193] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/22/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Emerging evidence has demonstrated that exposure to fine particulate matter (PM2.5) is a risk factor for lipid metabolic disorders in the liver. However, the effects of PM2.5 exposure time duration on hepatic lipid metabolism remain unknown. In this study, C57BL/6 mice were randomly divided into ambient PM2.5 (PM) or filtered air (FA) exposure chamber for short-term (4 weeks) or long-term (24 weeks) exposure via a whole body exposure system. We measured hepatic triglyceride and free fatty acid levels and analyzed the alteration of lipometabolism-related molecules in the liver. We found that triglyceride levels were significantly elevated in both short-term and long-term PM2.5-exposed mice and free fatty acid levels were increased after long-term PM2.5 exposure. Besides, enzymes for lipolysis and fatty acid oxidation in the liver were inhibited after short-term PM2.5 exposure but adaptively enhanced after long-term PM2.5 exposure. Furthermore, molecules for fatty acid uptake were down-regulated in the short-term PM2.5-exposed mice whereas molecules for lipid export were induced after long-term PM2.5 exposure. Therefore, ambient PM2.5 exposure disturbed hepatic lipid metabolism and the effects varied in different exposure duration. These findings in mice provide new insight into the biological basis of PM2.5-induced human metabolic dysfunction and specific strategies may be applied based on different exposure time periods.
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Affiliation(s)
- Sijia Yang
- School of Basic Medical Sciences and Public Health, Joint China-US Research Center for Environment and Pulmonary Diseases, Zhejiang Chinese Medical University, Hangzhou, China
| | - Rucheng Chen
- School of Basic Medical Sciences and Public Health, Joint China-US Research Center for Environment and Pulmonary Diseases, Zhejiang Chinese Medical University, Hangzhou, China
| | - Lu Zhang
- School of Basic Medical Sciences and Public Health, Joint China-US Research Center for Environment and Pulmonary Diseases, Zhejiang Chinese Medical University, Hangzhou, China
| | - Qing Sun
- School of Basic Medical Sciences and Public Health, Joint China-US Research Center for Environment and Pulmonary Diseases, Zhejiang Chinese Medical University, Hangzhou, China
| | - Ran Li
- School of Basic Medical Sciences and Public Health, Joint China-US Research Center for Environment and Pulmonary Diseases, Zhejiang Chinese Medical University, Hangzhou, China
| | - Weijia Gu
- School of Basic Medical Sciences and Public Health, Joint China-US Research Center for Environment and Pulmonary Diseases, Zhejiang Chinese Medical University, Hangzhou, China
| | - Mianhua Zhong
- Department of Environmental Medicine, New York University of School of Medicine, New York, USA
| | - Ying Liu
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety & CAS Center for Excellence in Nanoscience & Beijing Key Laboratory of Ambient Particles Health Effects and Prevention Techniques, National Center for Nanoscience and Technology of China and University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Lung-Chi Chen
- Department of Environmental Medicine, New York University of School of Medicine, New York, USA
| | - Qinghua Sun
- College of Public Health, The Ohio State University, Columbus, OH, USA
| | - Cuiqing Liu
- School of Basic Medical Sciences and Public Health, Joint China-US Research Center for Environment and Pulmonary Diseases, Zhejiang Chinese Medical University, Hangzhou, China.
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Martin GG, Landrock D, McIntosh AL, Milligan S, Landrock KK, Kier AB, Mackie J, Schroeder F. High Glucose and Liver Fatty Acid Binding Protein Gene Ablation Differentially Impact Whole Body and Liver Phenotype in High-Fat Pair-Fed Mice. Lipids 2020; 55:309-327. [PMID: 32314395 DOI: 10.1002/lipd.12238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 03/12/2020] [Accepted: 03/30/2020] [Indexed: 12/14/2022]
Abstract
Ad libitum-fed diets high in fat and carbohydrate (especially fructose) induce weight gain, obesity, and nonalcoholic fatty liver disease (NAFLD) in humans and animal models. However, interpretation is complicated since ad libitum feeding of such diets induces hyperphagia and upregulates expression of liver fatty acid binding protein (L-FABP)-a protein intimately involved in fatty acid and glucose regulation of lipid metabolism. Wild-type (WT) and L-fabp gene ablated (LKO) mice were pair-fed either high-fat diet (HFD) or high-fat/high-glucose diet (HFGD) wherein total carbohydrate was maintained constant but the proportion of glucose was increased at the expense of fructose. In LKO mice, the pair-fed HFD increased body weight and lean tissue mass (LTM) but had no effect on fat tissue mass (FTM) or hepatic fatty vacuolation as compared to pair-fed WT counterparts. These LKO mice exhibited upregulation of hepatic proteins in fatty acid uptake and cytosolic transport (caveolin and sterol carrier protein-2), but lower hepatic fatty acid oxidation (decreased serum β-hydroxybutyrate). LKO mice pair-fed HFGD also exhibited increased body weight; however, these mice had increased FTM, not LTM, and increased hepatic fatty vacuolation as compared to pair-fed WT counterparts. These LKO mice also exhibited upregulation of hepatic proteins in fatty acid uptake and cytosolic transport (caveolin and acyl-CoA binding protein, but not sterol carrier protein-2), but there was no change in hepatic fatty acid oxidation (serum β-hydroxybutyrate) as compared to pair-fed WT counterparts.
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Affiliation(s)
- Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843, USA
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX, 77843, USA
| | - Avery L McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843, USA
| | - Sherrelle Milligan
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX, 77843, USA
| | - Kerstin K Landrock
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843, USA
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX, 77843, USA
| | - John Mackie
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX, 77843, USA
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843, USA
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Nerstedt A, Kurhe Y, Cansby E, Caputo M, Gao L, Vorontsov E, Ståhlman M, Nuñez-Durán E, Borén J, Marschall HU, Mashek DG, Saunders DN, Sihlbom C, Hoy AJ, Mahlapuu M. Lipid droplet-associated kinase STK25 regulates peroxisomal activity and metabolic stress response in steatotic liver. J Lipid Res 2019; 61:178-191. [PMID: 31857389 DOI: 10.1194/jlr.ra119000316] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/05/2019] [Indexed: 12/18/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are emerging as leading causes of liver disease worldwide and have been recognized as one of the major unmet medical needs of the 21st century. Our recent translational studies in mouse models, human cell lines, and well-characterized patient cohorts have identified serine/threonine kinase (STK)25 as a protein that coats intrahepatocellular lipid droplets (LDs) and critically regulates liver lipid homeostasis and progression of NAFLD/NASH. Here, we studied the mechanism-of-action of STK25 in steatotic liver by relative quantification of the hepatic LD-associated phosphoproteome from high-fat diet-fed Stk25 knockout mice compared with their wild-type littermates. We observed a total of 131 proteins and 60 phosphoproteins that were differentially represented in STK25-deficient livers. Most notably, a number of proteins involved in peroxisomal function, ubiquitination-mediated proteolysis, and antioxidant defense were coordinately regulated in Stk25 -/- versus wild-type livers. We confirmed attenuated peroxisomal biogenesis and protection against oxidative and ER stress in STK25-deficient human liver cells, demonstrating the hepatocyte-autonomous manner of STK25's action. In summary, our results suggest that regulation of peroxisomal function and metabolic stress response may be important molecular mechanisms by which STK25 controls the development and progression of NAFLD/NASH.
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Affiliation(s)
- Annika Nerstedt
- Departments of Chemistry and Molecular Biology University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Yeshwant Kurhe
- Departments of Chemistry and Molecular Biology University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Emmelie Cansby
- Departments of Chemistry and Molecular Biology University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Mara Caputo
- Departments of Chemistry and Molecular Biology University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Lei Gao
- Departments of Chemistry and Molecular Biology University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Egor Vorontsov
- Proteomics Core Facility, University of Gothenburg, Gothenburg, Sweden
| | - Marcus Ståhlman
- Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Esther Nuñez-Durán
- Departments of Chemistry and Molecular Biology University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jan Borén
- Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Hanns-Ulrich Marschall
- Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Douglas G Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN
| | - Darren N Saunders
- School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Carina Sihlbom
- Proteomics Core Facility, University of Gothenburg, Gothenburg, Sweden
| | - Andrew J Hoy
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Margit Mahlapuu
- Departments of Chemistry and Molecular Biology University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
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McIntosh AL, Atshaves BP, Martin GG, Landrock D, Milligan S, Landrock KK, Huang H, Storey SM, Mackie J, Schroeder F, Kier AB. Effect of liver fatty acid binding protein (L-FABP) gene ablation on lipid metabolism in high glucose diet (HGD) pair-fed mice. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:985-1004. [PMID: 30910689 DOI: 10.1016/j.bbalip.2019.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 03/02/2019] [Accepted: 03/21/2019] [Indexed: 01/06/2023]
Abstract
Liver fatty acid binding protein (L-FABP) is the major fatty acid binding/"chaperone" protein in hepatic cytosol. Although fatty acids can be derived from the breakdown of dietary fat and glucose, relatively little is known regarding the impact of L-FABP on phenotype in the context of high dietary glucose. Potential impact was examined in wild-type (WT) and Lfabp gene ablated (LKO) female mice fed either a control or pair-fed high glucose diet (HGD). WT mice fed HGD alone exhibited decreased whole body weight gain and weight gain/kcal food consumed-both as reduced lean tissue mass (LTM) and fat tissue mass (FTM). Conversely, LKO alone increased weight gain, lean tissue mass, and fat tissue mass while decreasing serum β-hydroxybutyrate (indicative of hepatic fatty acid oxidation)-regardless of diet. Both LKO alone and HGD alone significantly altered the serum lipoprotein profile and increased triacylglycerol (TG), but in HGD mice the LKO did not further exacerbate serum TG content. HGD had little effect on hepatic lipid composition in WT mice, but prevented the LKO-induced selective increase in hepatic phospholipid, free-cholesterol and cholesteryl-ester. Taken together, these findings suggest that high glucose diet diminished the effects of LKO on the whole body and lipid phenotype of these mice.
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Affiliation(s)
- Avery L McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - Barbara P Atshaves
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, United States of America
| | - Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - Sherrelle Milligan
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - Kerstin K Landrock
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - Huan Huang
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - Stephen M Storey
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - John Mackie
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843, United States of America
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843, United States of America.
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McIntosh AL, Martin GG, Huang H, Landrock D, Kier AB, Schroeder F. Δ 9-Tetrahydrocannabinol induces endocannabinoid accumulation in mouse hepatocytes: antagonism by Fabp1 gene ablation. J Lipid Res 2018; 59:646-657. [PMID: 29414765 PMCID: PMC5880504 DOI: 10.1194/jlr.m082644] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/03/2018] [Indexed: 01/06/2023] Open
Abstract
Phytocannabinoids, such as Δ9-tetrahydrocannabinol (THC), bind and activate cannabinoid (CB) receptors, thereby "piggy-backing" on the same pathway's endogenous endocannabinoids (ECs). The recent discovery that liver fatty acid binding protein-1 (FABP1) is the major cytosolic "chaperone" protein with high affinity for both Δ9-THC and ECs suggests that Δ9-THC may alter hepatic EC levels. Therefore, the impact of Δ9-THC or EC treatment on the levels of endogenous ECs, such as N-arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG), was examined in cultured primary mouse hepatocytes from WT and Fabp1 gene-ablated (LKO) mice. Δ9-THC alone or 2-AG alone significantly increased AEA and especially 2-AG levels in WT hepatocytes. LKO alone markedly increased AEA and 2-AG levels. However, LKO blocked/diminished the ability of Δ9-THC to further increase both AEA and 2-AG. In contrast, LKO potentiated the ability of exogenous 2-AG to increase the hepatocyte level of AEA and 2-AG. These and other data suggest that Δ9-THC increases hepatocyte EC levels, at least in part, by upregulating endogenous AEA and 2-AG levels. This may arise from Δ9-THC competing with AEA and 2-AG binding to FABP1, thereby decreasing targeting of bound AEA and 2-AG to the degradative enzymes, fatty acid amide hydrolase and monoacylglyceride lipase, to decrease hydrolysis within hepatocytes.
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Affiliation(s)
- Avery L McIntosh
- Departments of Physiology and Pharmacology Texas A&M University, College Station, TX 77843
| | - Gregory G Martin
- Departments of Physiology and Pharmacology Texas A&M University, College Station, TX 77843
| | - Huan Huang
- Departments of Physiology and Pharmacology Texas A&M University, College Station, TX 77843
| | - Danilo Landrock
- Departments of Pathobiology, Texas A&M University, College Station, TX 77843
| | - Ann B Kier
- Departments of Pathobiology, Texas A&M University, College Station, TX 77843
| | - Friedhelm Schroeder
- Departments of Physiology and Pharmacology Texas A&M University, College Station, TX 77843.
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11
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McIntosh AL, Storey SM, Huang H, Kier AB, Schroeder F. Sex-dependent impact of Scp-2/Scp-x gene ablation on hepatic phytol metabolism. Arch Biochem Biophys 2017; 635:17-26. [PMID: 29051070 DOI: 10.1016/j.abb.2017.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/10/2017] [Accepted: 10/14/2017] [Indexed: 12/19/2022]
Abstract
While prior studies focusing on male mice suggest a role for sterol carrier protein-2/sterol carrier protein-x (SCP-2/SCP-x; DKO) on hepatic phytol metabolism, its role in females is unresolved. This issue was addressed using female and male wild-type (WT) and DKO mice fed a phytoestrogen-free diet without or with 0.5% phytol. GC/MS showed that hepatic: i) phytol was absent and its branched-chain fatty acid (BCFA) metabolites were barely detectable in WT control-fed mice; ii) accumulation of phytol as well as its peroxisomal metabolite BCFAs (phytanic acid » pristanic and 2,3-pristenic acids) was increased by dietary phytol in WT females, but only slightly in WT males; iii) accumulation of phytol and BCFA was further increased by DKO in phytol-fed females, but much more markedly in males. Livers of phytol-fed WT female mice as well as phytol-fed DKO female and male mice also accumulated increased proportion of saturated straight-chain fatty acids (LCFA) at the expense of unsaturated LCFA. Liver phytol accumulation was not due to increased SCP-2 binding/transport of phytol since SCP-2 bound phytanic acid, but not its precursor phytol. Thus, the loss of Scp-2/Scp-x contributed to a sex-dependent hepatic accumulation of dietary phytol and BCFA.
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Affiliation(s)
- Avery L McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, United States
| | - Stephen M Storey
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, United States
| | - Huan Huang
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, United States
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467, United States
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, United States.
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12
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Landrock D, Milligan S, Martin GG, McIntosh AL, Landrock KK, Schroeder F, Kier AB. Effect of Fabp1/Scp-2/Scp-x Ablation on Whole Body and Hepatic Phenotype of Phytol-Fed Male Mice. Lipids 2017; 52:385-397. [PMID: 28382456 PMCID: PMC5500168 DOI: 10.1007/s11745-017-4249-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/28/2017] [Indexed: 11/29/2022]
Abstract
Liver fatty acid binding protein (Fabp1) and sterol carrier protein-2/sterol carrier protein-x (SCP-2/SCP-x) genes encode proteins that enhance hepatic uptake, cytosolic transport, and peroxisomal oxidation of toxic branched-chain fatty acids derived from dietary phytol. Since male wild-type (WT) mice express markedly higher levels of these proteins than females, the impact of ablating both genes (TKO) was examined in phytol-fed males. In WT males, high phytol diet alone had little impact on whole body weight and did not alter the proportion of lean tissue mass (LTM) versus fat tissue mass (FTM). TKO conferred on dietary phytol the ability to induce weight loss as well as reduce liver weight, FTM, and even more so LTM. Concomitantly TKO induced hepatic lipid accumulation, preferentially threefold increased phospholipid (PL) at the expense of decreased triacylglycerol (TG) and total cholesterol. Increased PL was associated with upregulation of membrane fatty acid transport/translocase proteins (FATP 2,4), cytosolic fatty acid/fatty acyl-CoA binding proteins (FABP2, ACBP), and the rate limiting enzyme in PL synthesis (Gpam). Decreased TG and cholesterol levels were not attributable to altered levels in respective synthetic enzymes or nuclear receptors. These data suggest that the higher level of Fabp1 and Scp2/Scpx gene products in WT males was protective against deleterious effects of dietary phytol, but TKO significantly exacerbated phytol effects in males.
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Affiliation(s)
- Danilo Landrock
- Department of Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, TVMC, College Station, TX, 77843-4467, USA
| | - Sherrelle Milligan
- Department of Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, TVMC, College Station, TX, 77843-4467, USA
| | - Gregory G Martin
- Department of Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843-4466, USA
| | - Avery L McIntosh
- Department of Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843-4466, USA
| | - Kerstin K Landrock
- Department of Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, TVMC, College Station, TX, 77843-4467, USA
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843-4466, USA
| | - Ann B Kier
- Department of Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, TVMC, College Station, TX, 77843-4467, USA.
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13
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Storey SM, Huang H, McIntosh AL, Martin GG, Kier AB, Schroeder F. Impact of Fabp1/Scp-2/Scp-x gene ablation (TKO) on hepatic phytol metabolism in mice. J Lipid Res 2017; 58:1153-1165. [PMID: 28411199 DOI: 10.1194/jlr.m075457] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/07/2017] [Indexed: 01/19/2023] Open
Abstract
Studies in vitro have suggested that both sterol carrier protein-2/sterol carrier protein-x (Scp-2/Scp-x) and liver fatty acid binding protein [Fabp1 (L-FABP)] gene products facilitate hepatic uptake and metabolism of lipotoxic dietary phytol. However, interpretation of physiological function in mice singly gene ablated in the Scp-2/Scp-x has been complicated by concomitant upregulation of FABP1. The work presented herein provides several novel insights: i) An 8-anilino-1-naphthalenesulfonic acid displacement assay showed that neither SCP-2 nor L-FABP bound phytol, but both had high affinity for its metabolite, phytanic acid; ii) GC-MS studies with phytol-fed WT and Fabp1/Scp-2/SCP-x gene ablated [triple KO (TKO)] mice showed that TKO exacerbated hepatic accumulation of phytol metabolites in vivo in females and less so in males. Concomitantly, dietary phytol increased hepatic levels of total long-chain fatty acids (LCFAs) in both male and female WT and TKO mice. Moreover, in both WT and TKO female mice, dietary phytol increased hepatic ratios of saturated/unsaturated and polyunsaturated/monounsaturated LCFAs, while decreasing the peroxidizability index. However, in male mice, dietary phytol selectively increased the saturated/unsaturated ratio only in TKO mice, while decreasing the peroxidizability index in both WT and TKO mice. These findings suggested that: 1) SCP-2 and FABP1 both facilitated phytol metabolism after its conversion to phytanic acid; and 2) SCP-2/SCP-x had a greater impact on hepatic phytol metabolism than FABP1.
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Affiliation(s)
- Stephen M Storey
- Departments of Physiology and Pharmacology Texas A&M Veterinary Medical Center, Texas A&M University, College Station, TX 77843
| | - Huan Huang
- Departments of Physiology and Pharmacology Texas A&M Veterinary Medical Center, Texas A&M University, College Station, TX 77843
| | - Avery L McIntosh
- Departments of Physiology and Pharmacology Texas A&M Veterinary Medical Center, Texas A&M University, College Station, TX 77843
| | - Gregory G Martin
- Departments of Physiology and Pharmacology Texas A&M Veterinary Medical Center, Texas A&M University, College Station, TX 77843
| | - Ann B Kier
- Pathobiology, Texas A&M Veterinary Medical Center, Texas A&M University, College Station, TX 77843
| | - Friedhelm Schroeder
- Departments of Physiology and Pharmacology Texas A&M Veterinary Medical Center, Texas A&M University, College Station, TX 77843
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14
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Quinlivan VH, Wilson MH, Ruzicka J, Farber SA. An HPLC-CAD/fluorescence lipidomics platform using fluorescent fatty acids as metabolic tracers. J Lipid Res 2017; 58:1008-1020. [PMID: 28280113 DOI: 10.1194/jlr.d072918] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 03/07/2017] [Indexed: 11/20/2022] Open
Abstract
Fluorescent lipids are important tools for live imaging in cell culture and animal models, yet their metabolism has not been well-characterized. Here we describe a novel combined HPLC and LC-MS/MS method developed to characterize both total lipid profiles and the products of fluorescently labeled lipids. Using this approach, we found that lipids labeled with the fluorescent tags, 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY FL), 4,4-difluoro-5-(2-thienyl)-4-bora-3a,4a-diaza-s-indacene [BODIPY(558/568)], and dipyrrometheneboron difluoride undecanoic acid (TopFluor) are all metabolized into varying arrays of polar and nonpolar fluorescent lipid products when they are fed to larval zebrafish. Quantitative metabolic labeling experiments performed in this system revealed significant effects of total dietary lipid composition on fluorescent lipid partitioning. We provide evidence that cholesterol metabolism in the intestine is important in determining the metabolic fates of dietary FAs. Using this method, we found that inhibitors of dietary cholesterol absorption and esterification both decreased incorporation of dietary fluorescent FAs into cholesterol esters (CEs), suggesting that CE synthesis in enterocytes is primarily responsive to the availability of dietary cholesterol. These results are the first to comprehensively characterize fluorescent FA metabolism and to demonstrate their utility as metabolic labeling reagents, effectively coupling quantitative biochemistry with live imaging studies.
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Affiliation(s)
- Vanessa H Quinlivan
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218.,Department of Biology, Johns Hopkins University, Baltimore, MD 21218; and
| | - Meredith H Wilson
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218
| | | | - Steven A Farber
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218; .,Department of Biology, Johns Hopkins University, Baltimore, MD 21218; and
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15
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Milligan S, Martin GG, Landrock D, McIntosh AL, Mackie JT, Schroeder F, Kier AB. Impact of dietary phytol on lipid metabolism in SCP2/SCPX/L-FABP null mice. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:291-304. [PMID: 27940000 PMCID: PMC5266609 DOI: 10.1016/j.bbalip.2016.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/15/2016] [Accepted: 12/04/2016] [Indexed: 12/20/2022]
Abstract
In vitro studies suggest that liver fatty acid binding protein (L-FABP) and sterol carrier protein-2/sterol carrier protein-x (SCP2/SCPx) gene products facilitate uptake and metabolism and detoxification of dietary-derived phytol in mammals. However, concomitant upregulation of L-FABP in SCP2/SCPx null mice complicates interpretation of their physiological phenotype. Therefore, the impact of ablating both the L-FABP gene and SCP2/SCPx gene (L-FABP/SCP2/SCPx null or TKO) was examined in phytol-fed female wild-type (WT) and TKO mice. TKO increased hepatic total lipid accumulation, primarily phospholipid, by mechanisms involving increased hepatic levels of proteins in the phospholipid synthetic pathway. Concomitantly, TKO reduced expression of proteins in targeting fatty acids towards the triacylglycerol synthetic pathway. Increased hepatic lipid accumulation was not associated with any concomitant upregulation of membrane fatty acid transport/translocase proteins involved in fatty acid uptake (FATP2, FATP4, FATP5 or GOT) or cytosolic proteins involved in fatty acid intracellular targeting (ACBP). In addition, TKO exacerbated dietary phytol-induced whole body weight loss, especially lean tissue mass. Since individually ablating SCPx or SCP2/SCPx elicited concomitant upregulation of L-FABP, these findings with TKO mice help to resolve the contributions of SCP2/SCPx gene ablation on dietary phytol-induced whole body and hepatic lipid phenotype independent of concomitant upregulation of L-FABP.
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Affiliation(s)
- Sherrelle Milligan
- Department of Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA
| | - Gregory G Martin
- Department of Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA
| | - Danilo Landrock
- Department of Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA
| | - Avery L McIntosh
- Department of Physiology/Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466, USA
| | - John T Mackie
- Department of Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA
| | - Friedhelm Schroeder
- Department of Physiology/Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466, USA
| | - Ann B Kier
- Department of Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA.
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16
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Schroeder F, McIntosh AL, Martin GG, Huang H, Landrock D, Chung S, Landrock KK, Dangott LJ, Li S, Kaczocha M, Murphy EJ, Atshaves BP, Kier AB. Fatty Acid Binding Protein-1 (FABP1) and the Human FABP1 T94A Variant: Roles in the Endocannabinoid System and Dyslipidemias. Lipids 2016; 51:655-76. [PMID: 27117865 PMCID: PMC5408584 DOI: 10.1007/s11745-016-4155-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 04/11/2016] [Indexed: 01/01/2023]
Abstract
The first discovered member of the mammalian FABP family, liver fatty acid binding protein (FABP1, L-FABP), occurs at high cytosolic concentration in liver, intestine, and in the case of humans also in kidney. While the rat FABP1 is well studied, the extent these findings translate to human FABP1 is not clear-especially in view of recent studies showing that endocannabinoids and cannabinoids represent novel rat FABP1 ligands and FABP1 gene ablation impacts the hepatic endocannabinoid system, known to be involved in non-alcoholic fatty liver (NAFLD) development. Although not detectable in brain, FABP1 ablation nevertheless also impacts brain endocannabinoids. Despite overall tertiary structure similarity, human FABP1 differs significantly from rat FABP1 in secondary structure, much larger ligand binding cavity, and affinities/specificities for some ligands. Moreover, while both mouse and human FABP1 mediate ligand induction of peroxisome proliferator activated receptor-α (PPARα), they differ markedly in pattern of genes induced. This is critically important because a highly prevalent human single nucleotide polymorphism (SNP) (26-38 % minor allele frequency and 8.3 ± 1.9 % homozygous) results in a FABP1 T94A substitution that further accentuates these species differences. The human FABP1 T94A variant is associated with altered body mass index (BMI), clinical dyslipidemias (elevated plasma triglycerides and LDL cholesterol), atherothrombotic cerebral infarction, and non-alcoholic fatty liver disease (NAFLD). Resolving human FABP1 and the T94A variant's impact on the endocannabinoid and cannabinoid system is an exciting challenge due to the importance of this system in hepatic lipid accumulation as well as behavior, pain, inflammation, and satiety.
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Affiliation(s)
- Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA.
| | - Avery L McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
| | - Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
| | - Huan Huang
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
| | - Sarah Chung
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
| | - Kerstin K Landrock
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
| | - Lawrence J Dangott
- Department of Biochemistry and Biophysics, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
| | - Shengrong Li
- Avanti Polar Lipids, 700 Industrial Park Dr., Alabaster, AL, 35007-9105, USA
| | - Martin Kaczocha
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Eric J Murphy
- Department of Pharmacology, Physiology, and Therapeutics and Chemistry, University of North Dakota, Grand Forks, ND, 58202-9037, USA
| | - Barbara P Atshaves
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
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17
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Wang G, Bonkovsky HL, de Lemos A, Burczynski FJ. Recent insights into the biological functions of liver fatty acid binding protein 1. J Lipid Res 2015; 56:2238-47. [PMID: 26443794 DOI: 10.1194/jlr.r056705] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Indexed: 12/18/2022] Open
Abstract
Over four decades have passed since liver fatty acid binding protein (FABP)1 was first isolated. There are few protein families for which most of the complete tertiary structures, binding properties, and tissue occurrences are described in such detail and yet new functions are being uncovered for this protein. FABP1 is known to be critical for fatty acid uptake and intracellular transport and also has an important role in regulating lipid metabolism and cellular signaling pathways. FABP1 is an important endogenous cytoprotectant, minimizing hepatocyte oxidative damage and interfering with ischemia-reperfusion and other hepatic injuries. The protein may be targeted for metabolic activation through the cross-talk among many transcriptional factors and their activating ligands. Deficiency or malfunction of FABP1 has been reported in several diseases. FABP1 also influences cell proliferation during liver regeneration and may be considered as a prognostic factor for hepatic surgery. FABP1 binds and modulates the action of many molecules such as fatty acids, heme, and other metalloporphyrins. The ability to bind heme is another cytoprotective property and one that deserves closer investigation. The role of FABP1 in substrate availability and in protection from oxidative stress suggests that FABP1 plays a pivotal role during intracellular bacterial/viral infections by reducing inflammation and the adverse effects of starvation (energy deficiency).
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Affiliation(s)
- GuQi Wang
- Jiangxi Normal University, Nanchang, Jiangxi, People's Republic of China Department of Biology, University of North Carolina at Charlotte, Charlotte, NC Carolinas HealthCare System, Charlotte, NC
| | - Herbert L Bonkovsky
- Department of Biology, University of North Carolina at Charlotte, Charlotte, NC Carolinas HealthCare System, Charlotte, NC Wake Forest Baptist Medical Center, Winston-Salem, NC
| | - Andrew de Lemos
- Carolinas HealthCare System, Charlotte, NC Wake Forest Baptist Medical Center, Winston-Salem, NC
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18
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Maximin E, Langelier B, Aïoun J, Al-Gubory KH, Bordat C, Lavialle M, Heberden C. Fatty acid binding protein 7 and n-3 poly unsaturated fatty acid supply in early rat brain development. Dev Neurobiol 2015; 76:287-97. [DOI: 10.1002/dneu.22314] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 05/26/2015] [Accepted: 05/30/2015] [Indexed: 01/01/2023]
Affiliation(s)
- Elise Maximin
- Département Alimentation Humaine; INRA, Unité De Nutrition Et Régulation Lipidique Des Fonctions Cérébrales (UR 909); F-78352 Jouy-en-Josas Cedex France
| | - Bénédicte Langelier
- Département Alimentation Humaine; INRA, Unité De Nutrition Et Régulation Lipidique Des Fonctions Cérébrales (UR 909); F-78352 Jouy-en-Josas Cedex France
| | - Josiane Aïoun
- Département Alimentation Humaine; INRA, Unité De Nutrition Et Régulation Lipidique Des Fonctions Cérébrales (UR 909); F-78352 Jouy-en-Josas Cedex France
| | - Kaïs H. Al-Gubory
- Département Physiologie Animale; Unité De Biologie Du Développement Et De La Reproduction (UMR 1198); F-78352 Jouy-en-Josas Cedex France
| | - Christian Bordat
- Département Alimentation Humaine; INRA, Unité De Nutrition Et Régulation Lipidique Des Fonctions Cérébrales (UR 909); F-78352 Jouy-en-Josas Cedex France
| | - Monique Lavialle
- Département Alimentation Humaine; INRA, Unité De Nutrition Et Régulation Lipidique Des Fonctions Cérébrales (UR 909); F-78352 Jouy-en-Josas Cedex France
| | - Christine Heberden
- Département Alimentation Humaine; INRA, Unité De Nutrition Et Régulation Lipidique Des Fonctions Cérébrales (UR 909); F-78352 Jouy-en-Josas Cedex France
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19
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Liao CC, Ou TT, Huang HP, Wang CJ. The inhibition of oleic acid induced hepatic lipogenesis and the promotion of lipolysis by caffeic acid via up-regulation of AMP-activated kinase. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2014; 94:1154-1162. [PMID: 24027117 DOI: 10.1002/jsfa.6386] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 08/15/2013] [Accepted: 09/11/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Caffeic acid (CA) can inhibit toxin-induced liver injury. In this study, CA is assessed for its lipid lowering potential when oleic acid is used to induce non-alcoholic fatty liver disease in human HepG2 cells. RESULTS The results showed that both the triglyceride and cholesterol content are decreased in the HepG2 cells by using the enzymatic colorimetric method. CA enhances the phosphorylation of AMP-activated protein kinase (AMPK) and its primary downstream targeting enzyme, acetyl-CoA carboxylase. CA down-regulates the lipogenesis gene expression of sterol regulatory element-binding protein-1 and its target genes, fatty acid synthase in the presence of oleic acid. In addition, CA significantly decreases cholesterol and triglyceride production via inhibition the expression of both 3-hydroxy-3-methyglutary coenzyme A reductase and glycerol-3-phosphate acyltransferase. These effects are eliminated by pretreatment with compound C, an AMPK inhibitor. CONCLUSIONS These results demonstrate that CA inhibits oleic acid induced hepatic lipogenesis and the promotion of lipolysis via up-regulation of AMP-activated kinase.
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Affiliation(s)
- Chung-Chia Liao
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Cheng-Ching Hospital, Taichung, Taiwan; Institute of Biochemistry and Biotechnology, College of Medicine, Chung Shan Medical University, Taichung, Taiwan
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20
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High glucose potentiates L-FABP mediated fibrate induction of PPARα in mouse hepatocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1412-25. [PMID: 23747828 DOI: 10.1016/j.bbalip.2013.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 05/17/2013] [Accepted: 05/30/2013] [Indexed: 01/22/2023]
Abstract
Although liver fatty acid binding protein (L-FABP) binds fibrates and PPARα in vitro and enhances fibrate induction of PPARα in transformed cells, the functional significance of these findings is unclear, especially in normal hepatocytes. Studies with cultured primary mouse hepatocytes show that: 1) At physiological (6mM) glucose, fibrates (bezafibrate, fenofibrate) only weakly activated PPARα transcription of genes in LCFA β-oxidation; 2) High (11-20mM) glucose, but not maltose (osmotic control), significantly potentiated fibrate-induction of mRNA of these and other PPARα target genes to increase LCFA β-oxidation. These effects were associated with fibrate-mediated redistribution of L-FABP into nuclei-an effect prolonged by high glucose-but not with increased de novo fatty acid synthesis from glucose; 3) Potentiation of bezafibrate action by high glucose required an intact L-FABP/PPARα signaling pathway as shown with L-FABP null, PPARα null, PPARα inhibitor-treated WT, or PPARα-specific fenofibrate-treated WT hepatocytes. High glucose alone in the absence of fibrate was ineffective. Thus, high glucose potentiation of PPARα occurred through FABP/PPARα rather than indirectly through other PPARs or glucose induced signaling pathways. These data indicated L-FABP's importance in fibrate-induction of hepatic PPARα LCFA β-oxidative genes, especially in the context of high glucose levels.
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21
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McIntosh AL, Atshaves BP, Landrock D, Landrock KK, Martin GG, Storey SM, Kier AB, Schroeder F. Liver fatty acid binding protein gene-ablation exacerbates weight gain in high-fat fed female mice. Lipids 2013; 48:435-48. [PMID: 23539345 DOI: 10.1007/s11745-013-3777-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 02/19/2013] [Indexed: 12/30/2022]
Abstract
Loss of liver fatty acid binding protein (L-FABP) decreases long chain fatty acid uptake and oxidation in primary hepatocytes and in vivo. On this basis, L-FABP gene ablation would potentiate high-fat diet-induced weight gain and weight gain/energy intake. While this was indeed the case when L-FABP null (-/-) mice on the C57BL/6NCr background were pair-fed a high-fat diet, whether this would also be observed under high-fat diet fed ad libitum was not known. Therefore, this possibility was examined in female L-FABP (-/-) mice on the same background. L-FABP (-/-) mice consumed equal amounts of defined high-fat or isocaloric control diets fed ad libitum. However, on the ad libitum-fed high-fat diet the L-FABP (-/-) mice exhibited: (1) decreased hepatic long chain fatty acid (LCFA) β-oxidation as indicated by lower serum β-hydroxybutyrate level; (2) decreased hepatic protein levels of key enzymes mitochondrial (rate limiting carnitine palmitoyl acyltransferase A1, CPT1A; HMG-CoA synthase) and peroxisomal (acyl CoA oxidase 1, ACOX1) LCFA β-oxidation; (3) increased fat tissue mass (FTM) and FTM/energy intake to the greatest extent; and (4) exacerbated body weight gain, weight gain/energy intake, liver weight, and liver weight/body weight to the greatest extent. Taken together, these findings showed that L-FABP gene-ablation exacerbated diet-induced weight gain and fat tissue mass gain in mice fed high-fat diet ad libitum--consistent with the known biochemistry and cell biology of L-FABP.
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Affiliation(s)
- Avery L McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, USA
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Storey SM, McIntosh AL, Huang H, Martin GG, Landrock KK, Landrock D, Payne HR, Kier AB, Schroeder F. Loss of intracellular lipid binding proteins differentially impacts saturated fatty acid uptake and nuclear targeting in mouse hepatocytes. Am J Physiol Gastrointest Liver Physiol 2012; 303:G837-50. [PMID: 22859366 PMCID: PMC3469595 DOI: 10.1152/ajpgi.00489.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The liver expresses high levels of two proteins with high affinity for long-chain fatty acids (LCFAs): liver fatty acid binding protein (L-FABP) and sterol carrier protein-2 (SCP-2). Real-time confocal microscopy of cultured primary hepatocytes from gene-ablated (L-FABP, SCP-2/SCP-x, and L-FABP/SCP-2/SCP-x null) mice showed that the loss of L-FABP reduced cellular uptake of 12-N-methyl-(7-nitrobenz-2-oxa-1,3-diazo)-aminostearic acid (a fluorescent-saturated LCFA analog) by ∼50%. Importantly, nuclear targeting of the LCFA was enhanced when L-FABP was upregulated (SCP-2/SCP-x null) but was significantly reduced when L-FABP was ablated (L-FABP null), thus impacting LCFA nuclear targeting. These effects were not associated with a net decrease in expression of key membrane proteins involved in LCFA or glucose transport. Since hepatic LCFA uptake and metabolism are closely linked to glucose uptake, the effect of glucose on L-FABP-mediated LCFA uptake and nuclear targeting was examined. Increasing concentrations of glucose decreased cellular LCFA uptake and even more extensively decreased LCFA nuclear targeting. Loss of L-FABP exacerbated the decrease in LCFA nuclear targeting, while loss of SCP-2 reduced the glucose effect, resulting in enhanced LCFA nuclear targeting compared with control. Simply, ablation of L-FABP decreases LCFA uptake and even more extensively decreases its nuclear targeting.
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Affiliation(s)
- Stephen M. Storey
- 1Department of Physiology and Pharmacology, Texas A & M University, College Station, Texas; and
| | - Avery L. McIntosh
- 1Department of Physiology and Pharmacology, Texas A & M University, College Station, Texas; and
| | - Huan Huang
- 1Department of Physiology and Pharmacology, Texas A & M University, College Station, Texas; and
| | - Gregory G. Martin
- 1Department of Physiology and Pharmacology, Texas A & M University, College Station, Texas; and
| | - Kerstin K. Landrock
- 1Department of Physiology and Pharmacology, Texas A & M University, College Station, Texas; and
| | - Danilo Landrock
- 2Department of Pathobiology, Texas A & M University, College Station, Texas
| | - H. Ross Payne
- 2Department of Pathobiology, Texas A & M University, College Station, Texas
| | - Ann B. Kier
- 2Department of Pathobiology, Texas A & M University, College Station, Texas
| | - Friedhelm Schroeder
- 1Department of Physiology and Pharmacology, Texas A & M University, College Station, Texas; and
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23
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McIntosh AL, Atshaves BP, Storey SM, Landrock KK, Landrock D, Martin GG, Kier AB, Schroeder F. Loss of liver FA binding protein significantly alters hepatocyte plasma membrane microdomains. J Lipid Res 2012; 53:467-480. [PMID: 22223861 PMCID: PMC3276470 DOI: 10.1194/jlr.m019919] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 12/21/2011] [Indexed: 12/13/2022] Open
Abstract
Although lipid-rich microdomains of hepatocyte plasma membranes serve as the major scaffolding regions for cholesterol transport proteins important in cholesterol disposition, little is known regarding intracellular factors regulating cholesterol distribution therein. On the basis of its ability to bind cholesterol and alter hepatic cholesterol accumulation, the cytosolic liver type FA binding protein (L-FABP) was hypothesized to be a candidate protein regulating these microdomains. Compared with wild-type hepatocyte plasma membranes, L-FABP gene ablation significantly increased the proportion of cholesterol-rich microdomains. Lack of L-FABP selectively increased cholesterol, phospholipid (especially phosphatidylcholine), and branched-chain FA accumulation in the cholesterol-rich microdomains. These cholesterol-rich microdomains are important, owing to enrichment therein of significant amounts of key transport proteins involved in uptake of cholesterol [SR-B1, ABCA-1, P-glycoprotein (P-gp), sterol carrier binding protein (SCP-2)], FA transport protein (FATP), and glucose transporters 1 and 2 (GLUT1, GLUT2) insulin receptor. L-FABP gene ablation enhanced the concentration of SCP-2, SR-B1, FATP4, and GLUT1 in the cholesterol-poor microdomains, with functional implications in HDL-mediated uptake and efflux of cholesterol. Thus L-FABP gene ablation significantly impacted the proportion of cholesterol-rich versus -poor microdomains in the hepatocyte plasma membrane and altered the distribution of lipids and proteins involved in cholesterol uptake therein.
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Affiliation(s)
- Avery L McIntosh
- Department of Physiology and Pharmacology, Texas A&M University Texas Veterinary Medical Center, College Station, TX 77843; and
| | - Barbara P Atshaves
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824
| | - Stephen M Storey
- Department of Physiology and Pharmacology, Texas A&M University Texas Veterinary Medical Center, College Station, TX 77843; and
| | - Kerstin K Landrock
- Department of Physiology and Pharmacology, Texas A&M University Texas Veterinary Medical Center, College Station, TX 77843; and
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University Texas Veterinary Medical Center, College Station, TX 77843; and
| | - Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University Texas Veterinary Medical Center, College Station, TX 77843; and
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University Texas Veterinary Medical Center, College Station, TX 77843; and
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University Texas Veterinary Medical Center, College Station, TX 77843; and.
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24
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Carten JD, Bradford MK, Farber SA. Visualizing digestive organ morphology and function using differential fatty acid metabolism in live zebrafish. Dev Biol 2011; 360:276-85. [PMID: 21968100 DOI: 10.1016/j.ydbio.2011.09.010] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/13/2011] [Accepted: 09/13/2011] [Indexed: 01/05/2023]
Abstract
Lipids are essential for cellular function as sources of fuel, critical signaling molecules and membrane components. Deficiencies in lipid processing and transport underlie many metabolic diseases. To better understand metabolic function as it relates to disease etiology, a whole animal approach is advantageous, one in which multiple organs and cell types can be assessed simultaneously in vivo. Towards this end, we have developed an assay to visualize fatty acid (FA) metabolism in larval zebrafish (Danio rerio). The method utilizes egg yolk liposomes to deliver different chain length FA analogs (BODIPY-FL) to six day-old larvae. Following liposome incubation, larvae accumulate the analogs throughout their digestive organs, providing a comprehensive readout of organ structure and physiology. Using this assay we have observed that different chain length FAs are differentially transported and metabolized by the larval digestive system. We show that this assay can also reveal structural and metabolic defects in digestive mutants. Because this labeling technique can be used to investigate digestive organ morphology and function, we foresee its application in diverse studies of organ development and physiology.
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Affiliation(s)
- Juliana Debrito Carten
- The Johns Hopkins University, Department of Biology, 3400 North Charles Street, Baltimore, MD 21218, USA.
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25
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Hostetler HA, Lupas D, Tan Y, Dai J, Kelzer MS, Martin GG, Woldegiorgis G, Kier AB, Schroeder F. Acyl-CoA binding proteins interact with the acyl-CoA binding domain of mitochondrial carnitine palmitoyl transferase I. Mol Cell Biochem 2011; 355:135-48. [PMID: 21541677 DOI: 10.1007/s11010-011-0847-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 04/20/2011] [Indexed: 12/16/2022]
Abstract
Although the rate limiting step in mitochondrial fatty acid oxidation, catalyzed by carnitine palmitoyl transferase I (CPTI), utilizes long-chain fatty acyl-CoAs (LCFA-CoA) as a substrate, how LCFA-CoA is transferred to CPTI remains elusive. Based on secondary structural predictions and conserved tryptophan residues, the cytoplasmic C-terminal domain was hypothesized to be the LCFA-CoA binding site and important for interaction with cytoplasmic LCFA-CoA binding/transport proteins to provide a potential route for LCFA-CoA transfer. To begin to address this question, the cytoplasmic C-terminal region of liver CPTI (L-CPTI) was recombinantly expressed and purified. Data herein showed for the first time that the L-CPTI C-terminal 89 residues were sufficient for high affinity binding of LCFA-CoA (K (d) = 2-10 nM) and direct interaction with several cytoplasmic LCFA-CoA binding proteins (K (d) < 10 nM), leading to enhanced CPTI activity. Furthermore, alanine substitutions for tryptophan in L-CPTI (W391A and W452A) altered secondary structure, decreased binding affinity for LCFA-CoA, and almost completely abolished L-CPTI activity, suggesting that these amino acids may be important for ligand stabilization necessary for L-CPTI activity. Moreover, while decreased activity of the W452A mutant could be explained by decreased binding of lipid binding proteins, W391 itself seems to be important for activity. These data suggest that both interactions with lipid binding proteins and the peptide itself are important for optimal enzyme activity.
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Affiliation(s)
- Heather A Hostetler
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, USA
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26
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Atshaves B, Martin G, Hostetler H, McIntosh A, Kier A, Schroeder F. Liver fatty acid-binding protein and obesity. J Nutr Biochem 2010; 21:1015-32. [PMID: 20537520 PMCID: PMC2939181 DOI: 10.1016/j.jnutbio.2010.01.005] [Citation(s) in RCA: 159] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 01/11/2010] [Accepted: 01/12/2010] [Indexed: 12/17/2022]
Abstract
While low levels of unesterified long chain fatty acids (LCFAs) are normal metabolic intermediates of dietary and endogenous fat, LCFAs are also potent regulators of key receptors/enzymes and at high levels become toxic detergents within the cell. Elevated levels of LCFAs are associated with diabetes, obesity and metabolic syndrome. Consequently, mammals evolved fatty acid-binding proteins (FABPs) that bind/sequester these potentially toxic free fatty acids in the cytosol and present them for rapid removal in oxidative (mitochondria, peroxisomes) or storage (endoplasmic reticulum, lipid droplets) organelles. Mammals have a large (15-member) family of FABPs with multiple members occurring within a single cell type. The first described FABP, liver-FABP (L-FABP or FABP1), is expressed in very high levels (2-5% of cytosolic protein) in liver as well as in intestine and kidney. Since L-FABP facilitates uptake and metabolism of LCFAs in vitro and in cultured cells, it was expected that abnormal function or loss of L-FABP would reduce hepatic LCFA uptake/oxidation and thereby increase LCFAs available for oxidation in muscle and/or storage in adipose. This prediction was confirmed in vitro with isolated liver slices and cultured primary hepatocytes from L-FABP gene-ablated mice. Despite unaltered food consumption when fed a control diet ad libitum, the L-FABP null mice exhibited age- and sex-dependent weight gain and increased fat tissue mass. The obese phenotype was exacerbated in L-FABP null mice pair fed a high-fat diet. Taken together with other findings, these data suggest that L-FABP could have an important role in preventing age- or diet-induced obesity.
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Affiliation(s)
- B.P. Atshaves
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466
| | - G.G. Martin
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466
| | - H.A. Hostetler
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466
| | - A.L. McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466
| | - A.B. Kier
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - F. Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466
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27
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McIntosh AL, Huang H, Atshaves BP, Wellberg E, Kuklev DV, Smith WL, Kier AB, Schroeder F. Fluorescent n-3 and n-6 very long chain polyunsaturated fatty acids: three-photon imaging in living cells expressing liver fatty acid-binding protein. J Biol Chem 2010; 285:18693-708. [PMID: 20382741 PMCID: PMC2881794 DOI: 10.1074/jbc.m109.079897] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 03/10/2010] [Indexed: 01/24/2023] Open
Abstract
Despite the considerable beneficial effects of n-3 and n-6 very long chain polyunsaturated fatty acids (VLC-PUFAs), very little is known about the factors that regulate their uptake and intracellular distribution in living cells. This issue was addressed in cells expressing liver-type fatty acid-binding protein (L-FABP) by real time multiphoton laser scanning microscopy of novel fluorescent VLC-PUFAs containing a conjugated tetraene fluorophore near the carboxyl group and natural methylene-interrupted n-3 or n-6 grouping. The fluorescent VLC-PUFAs mimicked many properties of their native nonfluorescent counterparts, including uptake, distribution, and metabolism in living cells. The unesterified fluorescent VLC-PUFAs distributed either equally in nuclei versus cytoplasm (22-carbon n-3 VLC-PUFA) or preferentially to cytoplasm (20-carbon n-3 and n-6 VLC-PUFAs). L-FABP bound fluorescent VLC-PUFA with affinity and specificity similar to their nonfluorescent natural counterparts. Regarding n-3 and n-6 VLC-PUFA, L-FABP expression enhanced uptake into the cell and cytoplasm, selectively altered the pattern of fluorescent n-6 and n-3 VLC-PUFA distribution in cytoplasm versus nuclei, and preferentially distributed fluorescent VLC-PUFA into nucleoplasm versus nuclear envelope, especially for the 22-carbon n-3 VLC-PUFA, correlating with its high binding by L-FABP. Multiphoton laser scanning microscopy data showed for the first time VLC-PUFA in nuclei of living cells and suggested a model, whereby L-FABP facilitated VLC-PUFA targeting to nuclei by enhancing VLC-PUFA uptake and distribution into the cytoplasm and nucleoplasm.
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Affiliation(s)
| | - Huan Huang
- From the Departments of Physiology and Pharmacology and
| | - Barbara P. Atshaves
- the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, and
| | | | - Dmitry V. Kuklev
- the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - William L. Smith
- the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Ann B. Kier
- Pathobiology, Texas A & M University, Texas Veterinary Medical Center, College Station, Texas 77843-4466
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28
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PPAR/RXR Regulation of Fatty Acid Metabolism and Fatty Acid omega-Hydroxylase (CYP4) Isozymes: Implications for Prevention of Lipotoxicity in Fatty Liver Disease. PPAR Res 2010; 2009:952734. [PMID: 20300478 PMCID: PMC2840373 DOI: 10.1155/2009/952734] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Accepted: 12/30/2009] [Indexed: 02/08/2023] Open
Abstract
Fatty liver disease is a common lipid metabolism disorder influenced by the combination of individual genetic makeup, drug exposure, and life-style choices that are frequently associated with metabolic syndrome, which encompasses obesity, dyslipidemia, hypertension, hypertriglyceridemia, and insulin resistant diabetes. Common to obesity related dyslipidemia is the excessive storage of hepatic fatty acids (steatosis), due to a decrease in mitochondria β-oxidation with an increase in both peroxisomal β-oxidation, and microsomal ω-oxidation of fatty acids through peroxisome proliferator activated receptors (PPARs). How steatosis increases PPARα activated gene expression of fatty acid transport proteins, peroxisomal and mitochondrial fatty acid β-oxidation and ω-oxidation of fatty acids genes regardless of whether dietary fatty acids are polyunsaturated (PUFA), monounsaturated (MUFA), or saturated (SFA) may be determined by the interplay of PPARs and HNF4α with the fatty acid transport proteins L-FABP and ACBP. In hepatic steatosis and steatohepatitis, the ω-oxidation cytochrome P450 CYP4A gene expression is increased even with reduced hepatic levels of PPARα. Although numerous studies have suggested the role ethanol-inducible CYP2E1 in contributing to increased oxidative stress, Cyp2e1-null mice still develop steatohepatitis with a dramatic increase in CYP4A gene expression. This strongly implies that CYP4A fatty acid ω-hydroxylase P450s may play an important role in the development of steatohepatitis. In this review and tutorial, we briefly describe how fatty acids are partitioned by fatty acid transport proteins to either anabolic or catabolic pathways regulated by PPARs, and we explore how medium-chain fatty acid (MCFA) CYP4A and long-chain fatty acid (LCFA) CYP4Fω-hydroxylase genes are regulated in fatty liver. We finally propose a hypothesis that increased CYP4A expression with a decrease in CYP4F genes may promote the progression of steatosis to steatohepatitis.
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29
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Atshaves BP, McIntosh AL, Storey SM, Landrock KK, Kier AB, Schroeder F. High dietary fat exacerbates weight gain and obesity in female liver fatty acid binding protein gene-ablated mice. Lipids 2009; 45:97-110. [PMID: 20035485 DOI: 10.1007/s11745-009-3379-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 11/24/2009] [Indexed: 01/01/2023]
Abstract
Since liver fatty acid binding protein (L-FABP) facilitates uptake/oxidation of long-chain fatty acids in cultured transfected cells and primary hepatocytes, loss of L-FABP was expected to exacerbate weight gain and/or obesity in response to high dietary fat. Male and female wild-type (WT) and L-FABP gene-ablated mice, pair-fed a defined isocaloric control or high fat diet for 12 weeks, consumed equal amounts of food by weight and kcal. Male WT mice gained weight faster than their female WT counterparts regardless of diet. L-FABP gene ablation enhanced weight gain more in female than male mice-an effect exacerbated by high fat diet. Dual emission X-ray absorptiometry revealed high-fat fed male and female WT mice gained mostly fat tissue mass (FTM). L-FABP gene ablation increased FTM in female, but not male, mice-an effect also exacerbated by high fat diet. Concomitantly, L-FABP gene ablation decreased serum beta-hydroxybutyrate in male and female mice fed the control diet and, even more so, on the high-fat diet. Thus, L-FABP gene ablation decreased fat oxidation and sensitized all mice to weight gain as whole body FTM and LTM-with the most gain observed in FTM of control vs high-fat fed female L-FABP null mice. Taken together, these results indicate loss of L-FABP exacerbates weight gain and/or obesity in response to high dietary fat.
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Affiliation(s)
- Barbara P Atshaves
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, 77843-4466, USA
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30
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Martin GG, Atshaves BP, Huang H, McIntosh AL, Williams BJ, Pai PJ, Russell DH, Kier AB, Schroeder F. Hepatic phenotype of liver fatty acid binding protein gene-ablated mice. Am J Physiol Gastrointest Liver Physiol 2009; 297:G1053-65. [PMID: 19815623 PMCID: PMC2850096 DOI: 10.1152/ajpgi.00116.2009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 10/06/2009] [Indexed: 01/31/2023]
Abstract
Although the function of liver fatty acid binding protein in hepatic fatty acid metabolism has been extensively studied, its potential role in hepatic cholesterol homeostasis is less clear. Although hepatic cholesterol accumulation was initially reported in L-FABP-null female mice, that study was performed with early N2 backcross generation mice. To resolve whether the hepatic cholesterol phenotype in these L-FABP(-/-) mice was attributable to genetic inhomogeneity, these L-FABP(-/-) mice were further backcrossed to C57Bl/6 mice up to the N10 (99.9% homogeneity) generation. Hepatic total cholesterol accumulation was observed in female, but not male, L-FABP(-/-) mice at all (N2, N4, N6, N10) backcross generations examined. The greater total cholesterol was due to increased hepatic levels of both unesterified (free) cholesterol and esterified cholesterol. Altered hepatic cholesterol accumulation correlated directly with L-FABP's ability to bind cholesterol with high affinity as shown by direct L-FABP binding of fluorescent cholesterol analogs (NBD-cholesterol, dansyl-cholesterol), a photoactivatable cholesterol analog [free cholesterol benzophenone (FCBP)], and free cholesterol (circular dichroism, isothermal titration microcalorimetry). One mole of fluorescent sterol was bound per mole of L-FABP. This was confirmed by photo-cross-linking studies with the photoactivatable cholesterol analog FCBP and by isothermal titration calorimetry with free cholesterol, which showed that L-FABP bound only one sterol molecule per L-FABP molecule. In contrast, the hepatic phenotype of male, but not female, L-FABP(-/-) mice was characterized by decreased hepatic triacylglycerol levels at all backcross generations examined. Taken together, these data support the hypothesis that L-FABP plays a role in physiological regulation of not only hepatic fatty acid metabolism, but also that of hepatic cholesterol.
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Affiliation(s)
- Gregory G Martin
- Dept. of Physiology & Pharmacology, Texas A&M Univ., College Station, 77843-4466, USA
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31
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McIntosh AL, Atshaves BP, Hostetler HA, Huang H, Davis J, Lyuksyutova OI, Landrock D, Kier AB, Schroeder F. Liver type fatty acid binding protein (L-FABP) gene ablation reduces nuclear ligand distribution and peroxisome proliferator-activated receptor-alpha activity in cultured primary hepatocytes. Arch Biochem Biophys 2009; 485:160-73. [PMID: 19285478 DOI: 10.1016/j.abb.2009.03.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 03/03/2009] [Accepted: 03/05/2009] [Indexed: 11/29/2022]
Abstract
The effect of liver type fatty acid binding protein (L-FABP) gene ablation on the uptake and distribution of long chain fatty acids (LCFA) to the nucleus by real-time laser scanning confocal imaging and peroxisome proliferator-activated receptor-alpha (PPARalpha) activity was examined in cultured primary hepatocytes from livers wild-type L-FABP+/+ and gene ablated L-FABP-/- mice. Cultured primary hepatocytes from livers of L-FABP-/- mice exhibited: (i) reduced oxidation of palmitic acid, a common dietary long chain fatty acid (LCFA); (ii) reduced expression of fatty acid oxidative enzymes-proteins transcriptionally regulated by PPARalpha; (iii) reduced palmitic acid-induced PPARalpha co-immunoprecipitation with coactivator SRC-1 concomitant with increased PPARalpha co-immunoprecipitation with coinhibitor N-CoR; (iv) reduced palmitic acid-induced PPARalpha. Diminished PPARalpha activation in L-FABP null hepatocytes was associated with lower uptake of common dietary LCFA (palmitic acid as well as its fluorescent derivative BODIPY FL C(16)), reduced level of total unesterified LCFA, and real-time redistribution of BODIPY FL C(16) from the central nucleoplasm to the nuclear envelope. Taken together, these studies support the hypothesis that L-FABP may facilitate ligand (LCFA)-activated PPARalpha transcriptional activity at least in part by increasing total LCFA ligand available to PPARalpha for inducing PPARalpha-mediated transcription of proteins involved in LCFA metabolism.
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Affiliation(s)
- Avery L McIntosh
- Department of Physiology and Pharmacology, TVMC College Station, TX 77843-4466, USA
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32
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Martin GG, Atshaves BP, McIntosh AL, Payne HR, Mackie JT, Kier AB, Schroeder F. Liver fatty acid binding protein gene ablation enhances age-dependent weight gain in male mice. Mol Cell Biochem 2008; 324:101-15. [PMID: 19104910 DOI: 10.1007/s11010-008-9989-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 12/11/2008] [Indexed: 01/02/2023]
Abstract
Although studies performed in vitro and with transfected cells in culture suggest a role for liver fatty acid binding protein (L-FABP) in regulating fatty acid oxidation and fat deposition, the physiological significance of this possibility is not completely clear. To begin to address this question, the effect of L-FABP gene ablation on phenotype of standard rodent chow-fed male mice was examined with increasing age up to 18 months. While young (2-3 months old) L-FABP null mice displayed no visually obvious phenotype, with increasing age >9 months the L-FABP null mice were visibly larger, exhibiting increased body weight due to increased fat and lean tissue mass. Liver lipid concentrations were unaffected by L-FABP gene ablation with the exception of triacylglycerol, which was decreased by 74% in the livers of 3-month-old mice. Likewise, serum lipid levels were not altered in L-FABP null mice with the exception of triacylglycerol, which was increased in the serum of 18-month-old mice. Increased body weight, fat tissue mass, and lean tissue mass in 18-month-old L-FABP null mice were accompanied by increased hepatic levels of low-density lipoprotein (LDL) receptor, peroxisome proliferator-activated receptor (PPAR) alpha, and PPARalpha-regulated proteins such as fatty acid transport protein (FATP), fatty acid translocase (FAT/CD36), carnitine palmitoyl transferase I (CPT I), and lipoprotein lipase (LPL). A key enzyme in cholesterol biosynthesis, 3-hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) reductase, was down-regulated in L-FABP null mice. These findings were consistent with a proposed role for L-FABP as an important physiological regulator of PPARalpha.
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Affiliation(s)
- Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, USA.
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33
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Martin GG, Atshaves BP, McIntosh AL, Mackie JT, Kier AB, Schroeder F. Liver fatty acid-binding protein gene-ablated female mice exhibit increased age-dependent obesity. J Nutr 2008; 138:1859-65. [PMID: 18806093 PMCID: PMC2835297 DOI: 10.1093/jn/138.10.1859] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Previous work conducted in our laboratory suggested a role for liver fatty acid-binding protein (L-FABP) in obesity that develops in aging female L-FABP gene-ablated (-/-) mice. To examine this possibility in more detail, cohorts of wild-type (+/+) and L-FABP (-/-) female mice were fed a standard, low-fat, nonpurified rodent diet for up to 18 mo. Various obesity-related parameters were examined, including body weight and fat and lean tissue mass. Obesity in (-/-) mice was associated with increased expression of nuclear receptors that induce PPARalpha (e.g. hepatocyte nuclear factor 1alpha, genotype effect) and of PPARalpha-regulated proteins involved in uptake of free (lipoprotein lipase and fatty acid transport protein, genotype, and/or age effect) and esterified (scavenger receptor class B type 1, genotype effect) long-chain fatty acids (LCFA). Hepatic total lipid and neutral lipid levels were not affected by age or genotype, consistent with absence of gross and histologic steatosis. There was increased mRNA expression of liver proteins involved in LCFA oxidation [mitochondrial 3-oxoacyl-CoA thiolase (genotype effect) and butyryl-CoA dehydrogenase (genotype and/or age effect)], increased expression of LCFA esterification enzymes [glycerol-3-phosphate acyltransferase (age x genotype effect) and acyl-CoA:cholesterol acyltransferase-2 (genotype and/or age effect)], and increased expression of proteins involved in intracellular transfer and secretion of esterified LCFA [liver microsomal triacylglycerol transfer protein (genotype effect), serum apolipoprotein (apo) B (genotype or age effect), and liver apoB (age and age x genotype effect)]. The data support a working model in which obesity development in these mice results from shifts toward reduced energy expenditure and/or more efficient energy uptake in the gut.
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Affiliation(s)
- Gregory G. Martin
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Barbara P. Atshaves
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Avery L. McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - John T. Mackie
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Ann B. Kier
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4467,To whom correspondence should be addressed: Department of Physiology & Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466. Phone: 979-862-1433, Fax: 979-862-4929,
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Schroeder F, Petrescu AD, Huang H, Atshaves BP, McIntosh AL, Martin GG, Hostetler HA, Vespa A, Landrock D, Landrock KK, Payne HR, Kier AB. Role of fatty acid binding proteins and long chain fatty acids in modulating nuclear receptors and gene transcription. Lipids 2007; 43:1-17. [PMID: 17882463 DOI: 10.1007/s11745-007-3111-z] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Accepted: 07/26/2007] [Indexed: 12/16/2022]
Abstract
Abnormal energy regulation may significantly contribute to the pathogenesis of obesity, diabetes mellitus, cardiovascular disease, and cancer. For rapid control of energy homeostasis, allosteric and posttranslational events activate or alter activity of key metabolic enzymes. For longer impact, transcriptional regulation is more effective, especially in response to nutrients such as long chain fatty acids (LCFA). Recent advances provide insights into how poorly water-soluble lipid nutrients [LCFA; retinoic acid (RA)] and their metabolites (long chain fatty acyl Coenzyme A, LCFA-CoA) reach nuclei, bind their cognate ligand-activated receptors, and regulate transcription for signaling lipid and glucose catabolism or storage: (i) while serum and cytoplasmic LCFA levels are in the 200 mircroM-mM range, real-time imaging recently revealed that LCFA and LCFA-CoA are also located within nuclei (nM range); (ii) sensitive fluorescence binding assays show that LCFA-activated nuclear receptors [peroxisome proliferator-activated receptor-alpha (PPARalpha) and hepatocyte nuclear factor 4alpha (HNF4alpha)] exhibit high affinity (low nM KdS) for LCFA (PPARalpha) and/or LCFA-CoA (PPARalpha, HNF4alpha)-in the same range as nuclear levels of these ligands; (iii) live and fixed cell immunolabeling and imaging revealed that some cytoplasmic lipid binding proteins [liver fatty acid binding protein (L-FABP), acyl CoA binding protein (ACBP), cellular retinoic acid binding protein-2 (CRABP-2)] enter nuclei, bind nuclear receptors (PPARalpha, HNF4alpha, CRABP-2), and activate transcription of genes in fatty acid and glucose metabolism; and (iv) studies with gene ablated mice provided physiological relevance of LCFA and LCFA-CoA binding proteins in nuclear signaling. This led to the hypothesis that cytoplasmic lipid binding proteins transfer and channel lipidic ligands into nuclei for initiating nuclear receptor transcriptional activity to provide new lipid nutrient signaling pathways that affect lipid and glucose catabolism and storage.
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Affiliation(s)
- Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, USA.
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Schroeder F, Atshaves BP, McIntosh AL, Gallegos AM, Storey SM, Parr RD, Jefferson JR, Ball JM, Kier AB. Sterol carrier protein-2: new roles in regulating lipid rafts and signaling. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1771:700-18. [PMID: 17543577 PMCID: PMC1989133 DOI: 10.1016/j.bbalip.2007.04.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 03/28/2007] [Accepted: 04/03/2007] [Indexed: 12/31/2022]
Abstract
Sterol carrier protein-2 (SCP-2) was independently discovered as a soluble protein that binds and transfers cholesterol as well as phospholipids (nonspecific lipid transfer protein, nsLTP) in vitro. Physiological functions of this protein are only now beginning to be resolved. The gene encoding SCP-2 also encodes sterol carrier protein-x (SCP-x) arising from an alternate transcription site. In vitro and in vivo SCP-x serves as a peroxisomal 3-ketoacyl-CoA thiolase in oxidation of branched-chain lipids (cholesterol to form bile acids; branched-chain fatty acid for detoxification). While peroxisomal SCP-2 facilitates branched-chain lipid oxidation, the role(s) of extraperoxisomal (up to 50% of total) are less clear. Studies using transfected fibroblasts overexpressing SCP-2 and hepatocytes from SCP-2/SCP-x gene-ablated mice reveal that SCP-2 selectively remodels the lipid composition, structure, and function of lipid rafts/caveolae. Studies of purified SCP-2 and in cells show that SCP-2 has high affinity for and selectively transfers many lipid species involved in intracellular signaling: fatty acids, fatty acyl CoAs, lysophosphatidic acid, phosphatidylinositols, and sphingolipids (sphingomyelin, ceramide, mono-di-and multi-hexosylceramides, gangliosides). SCP-2 selectively redistributes these signaling lipids between lipid rafts/caveolae and intracellular sites. These findings suggest SCP-2 serves not only in cholesterol and phospholipid transfer, but also in regulating multiple lipid signaling pathways in lipid raft/caveolae microdomains of the plasma membrane.
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Affiliation(s)
- Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, USA.
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Kamijo-Ikemori A, Sugaya T, Kimura K. Urinary fatty acid binding protein in renal disease. Clin Chim Acta 2006; 374:1-7. [PMID: 16860300 DOI: 10.1016/j.cca.2006.05.038] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Revised: 05/19/2006] [Accepted: 05/27/2006] [Indexed: 01/22/2023]
Abstract
The number of patients with end stage renal failure has been increasing throughout the world. The importance of measuring clinical parameters in renal injury has been emphasized for administering appropriate treatment and preventing a worsening of the disease. However, there are no clinically useful markers in predicting and monitoring the progression of renal disease. Liver type fatty acid binding protein (L-FABP) of 14.4 kDa is expressed in human proximal tubules. In order to evaluate the clinical significance of urinary L-FABP as a biomarker in renal disease, a monoclonal antibody against human L-FABP was developed and a two step sandwich enzyme linked immunosorbent assay (ELISA) method was established for determining human L-FABP in urine. In some clinical studies, urinary excretion of L-FABP was shown to be an excellent clinical marker that can help predict and monitor the progression of renal disease. The dynamics of renal L-FABP in pathophysiological settings has been revealed in experimental studies using transgenic mice with the human L-FABP gene. This review presents recent findings on the function and pathophysiological role of L-FABP, and summarizes the clinical importance of measuring urinary L-FABP in renal disease.
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Affiliation(s)
- Atsuko Kamijo-Ikemori
- Division of Nephrology and Hypertension, Internal Medicine, St. Marianna University School of Medicine, 2-16-1 Sugao, Kawasaki, 216-8511, Tokyo, Japan
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Thornburg T, Turner AR, Chen YQ, Vitolins M, Chang B, Xu J. Phytanic acid, AMACR and prostate cancer risk. Future Oncol 2006; 2:213-23. [PMID: 16563090 DOI: 10.2217/14796694.2.2.213] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The growing body of knowledge in cancer prevention demonstrates that for many cancers, risk must be defined in terms of both environmental and genetic factors. In prostate cancer, there is increasing evidence linking risk with polymorphisms in the alpha-methylacyl-CoA racemase (AMACR) gene and branched-chain fatty acids derived from specific sources of dietary fats. We are now at the point where we can begin to conceptualize possible inter-relationships between dietary and genetic risk as applied to prostate cancer, with the goal of generating testable hypotheses amenable to coordinated examinations. A greater understanding of such relationships should provide better ways to establish overall risk, to screen for the disease and perhaps to offer specific opportunities for prevention and treatment.
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Affiliation(s)
- Todd Thornburg
- Comprehensive Cancer Center, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA
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Antonenkov V, Sormunen R, Ohlmeier S, Amery L, Fransen M, Mannaerts G, Hiltunen J. Localization of a portion of the liver isoform of fatty-acid-binding protein (L-FABP) to peroxisomes. Biochem J 2006; 394:475-84. [PMID: 16262600 PMCID: PMC1408678 DOI: 10.1042/bj20051058] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The liver isoform of fatty-acid-binding protein (L-FABP) facilitates the cellular uptake, transport and metabolism of fatty acids and is also involved in the regulation of gene expressions and cell differentiation. Consistent with these functions, L-FABP is predominantly present in the cytoplasm and to a lesser extent in the nucleus; however, a significant portion of this protein has also been detected in fractions containing different organelles. More recent observations, notably on L-FABP-deficient mice, indicated a possible direct involvement of L-FABP in the peroxisomal oxidation of long-chain fatty acids. In order to clarify the links between L-FABP and peroxisomal lipid metabolism, we reinvestigated the subcellular distribution of the protein. Analytical subcellular fractionation by a method preserving the intactness of isolated peroxisomes, two-dimensional gel electrophoresis of peroxisomal matrix proteins combined with MS analysis, and immunoelectron microscopy of liver sections demonstrate the presence of L-FABP in the matrix of peroxisomes as a soluble protein. Peroxisomal L-FABP was highly inducible by clofibrate. The induction of L-FABP was accompanied by a marked increase in the binding capacity of peroxisomal matrix proteins for oleic acid and cis-parinaric acid. The peroxisomal beta-oxidation of palmitoyl-CoA and acyl-CoA thioesterase activity were stimulated by L-FABP, indicating that the protein modulates the function of peroxisomal lipid-metabolizing enzymes. The possible role of intraperoxisomal L-FABP in lipid metabolism is discussed.
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Affiliation(s)
- Vasily D. Antonenkov
- *Department of Biochemistry, Biocenter Oulu, University of Oulu, Linnanmaa, P.O. Box 3000, FIN-90014 Oulu, Finland
- Correspondence may be addressed to either of these authors (email or )
| | - Raija T. Sormunen
- †Department of Pathology, Biocenter Oulu, University of Oulu, Linnanmaa, P.O. Box 3000, FIN-90014 Oulu, Finland
| | - Steffen Ohlmeier
- *Department of Biochemistry, Biocenter Oulu, University of Oulu, Linnanmaa, P.O. Box 3000, FIN-90014 Oulu, Finland
| | - Leen Amery
- ‡Departement Moleculaire Celbiologie, Katholieke Universiteit Leuven, Campus Gasthuisberg, Afdeling Farmakologie, Herestraat 49 (box 601), B-3000 Leuven, Belgium
| | - Marc Fransen
- ‡Departement Moleculaire Celbiologie, Katholieke Universiteit Leuven, Campus Gasthuisberg, Afdeling Farmakologie, Herestraat 49 (box 601), B-3000 Leuven, Belgium
| | - Guy P. Mannaerts
- ‡Departement Moleculaire Celbiologie, Katholieke Universiteit Leuven, Campus Gasthuisberg, Afdeling Farmakologie, Herestraat 49 (box 601), B-3000 Leuven, Belgium
| | - J. Kalervo Hiltunen
- *Department of Biochemistry, Biocenter Oulu, University of Oulu, Linnanmaa, P.O. Box 3000, FIN-90014 Oulu, Finland
- Correspondence may be addressed to either of these authors (email or )
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Hanhoff T, Benjamin S, Börchers T, Spener F. Branched-chain fatty acids as activators of peroxisome proliferator-activated receptors. EUR J LIPID SCI TECH 2005. [DOI: 10.1002/ejlt.200401076] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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40
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Atshaves BP, McIntosh AL, Payne HR, Mackie J, Kier AB, Schroeder F. Effect of branched-chain fatty acid on lipid dynamics in mice lacking liver fatty acid binding protein gene. Am J Physiol Cell Physiol 2005; 288:C543-58. [PMID: 15692150 DOI: 10.1152/ajpcell.00359.2004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although a role for liver fatty acid protein (L-FABP) in the metabolism of branched-chain fatty acids has been suggested based on data obtained with cultured cells, the physiological significance of this observation remains to be demonstrated. To address this issue, the lipid phenotype and metabolism of phytanic acid, a branched-chain fatty acid, were determined in L-FABP gene-ablated mice fed a diet with and without 1% phytol (a metabolic precursor to phytanic acid). In response to dietary phytol, L-FABP gene ablation exhibited a gender-dependent lipid phenotype. Livers of phytol-fed female L-FABP-/- mice had significantly more fatty lipid droplets than male L-FABP-/- mice, whereas in phytol-fed wild-type L-FABP+/+ mice differences between males and females were not significant. Thus L-FABP gene ablation exacerbated the accumulation of lipid droplets in phytol-fed female, but not male, mice. These results were reflected in the lipid profile, where hepatic levels of triacylglycerides in phytol-fed female L-FABP-/- mice were significantly higher than in male L-FABP-/- mice. Furthermore, livers of phytol-fed female L-FABP-/- mice exhibited more necrosis than their male counterparts, consistent with the accumulation of higher levels of phytol metabolites (phytanic acid, pristanic acid) in liver and serum, in addition to increased hepatic levels of sterol carrier protein (SCP)-x, the only known peroxisomal enzyme specifically required for branched-chain fatty acid oxidation. In summary, L-FABP gene ablation exerted a significant role, especially in female mice, in branched-chain fatty acid metabolism. These effects were only partially compensated by concomitant upregulation of SCP-x in response to L-FABP gene ablation and dietary phytol.
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Affiliation(s)
- Barbara P Atshaves
- Department of Physiology, Texas A&M University, Texas Veterinary Medical Center, College Station, TX 77843-4466, USA
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41
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Atshaves BP, McIntosh AM, Lyuksyutova OI, Zipfel W, Webb WW, Schroeder F. Liver fatty acid-binding protein gene ablation inhibits branched-chain fatty acid metabolism in cultured primary hepatocytes. J Biol Chem 2004; 279:30954-65. [PMID: 15155724 DOI: 10.1074/jbc.m313571200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Whereas the role of liver fatty acid-binding protein (L-FABP) in the uptake, transport, mitochondrial oxidation, and esterification of normal straight-chain fatty acids has been studied extensively, almost nothing is known regarding the function of L-FABP in peroxisomal oxidation and metabolism of branched-chain fatty acids. Therefore, phytanic acid (most common dietary branched-chain fatty acid) was chosen to address these issues in cultured primary hepatocytes isolated from livers of L-FABP gene-ablated (-/-) and wild type (+/+) mice. These studies provided three new insights: First, L-FABP gene ablation reduced maximal, but not initial, uptake of phytanic acid 3.2-fold. Initial uptake of phytanic acid uptake was unaltered apparently due to concomitant 5.3-, 1.6-, and 1.4-fold up-regulation of plasma membrane fatty acid transporter/translocase proteins (glutamic-oxaloacetic transaminase, fatty acid transport protein, and fatty acid translocase, respectively). Second, L-FABP gene ablation inhibited phytanic acid peroxisomal oxidation and microsomal esterification. These effects were consistent with reduced cytoplasmic fatty acid transport as evidenced by multiphoton fluorescence photobleaching recovery, where L-FABP gene ablation reduced the cytoplasmic, but not membrane, diffusional component of NBD-stearic acid movement 2-fold. Third, lipid analysis of the L-FABP gene-ablated hepatocytes revealed an altered fatty acid phenotype. Free fatty acid and triglyceride levels were decreased 1.9- and 1.6-fold, respectively. In summary, results with cultured primary hepatocytes isolated from L-FABP (+/+) and L-FABP (-/-) mice demonstrated for the first time a physiological role of L-FABP in the uptake and metabolism of branched-chain fatty acids.
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Affiliation(s)
- Barbara P Atshaves
- Department of Physiology and Pharmacology, Texas A&M University, College Station, Texas 77843-4466, USA
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42
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Atshaves BP, Payne HR, McIntosh AL, Tichy SE, Russell D, Kier AB, Schroeder F. Sexually dimorphic metabolism of branched-chain lipids in C57BL/6J mice. J Lipid Res 2004; 45:812-30. [PMID: 14993239 DOI: 10.1194/jlr.m300408-jlr200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Despite the importance of branched chain lipid oxidation in detoxification, almost nothing is known regarding factors regulating peroxisomal uptake, targeting, and metabolism. One peroxisomal protein, sterol carrier protein-x (SCP-x), is thought to catalyze a key thiolytic step in branched chain lipid oxidation. When mice with substantially lower hepatic levels of SCP-x were tested for susceptibility to dietary stress with phytol (a phytanic acid precursor and peroxisome proliferator), livers of phytol-fed female but not male mice i). accumulated phytol metabolites (phytanic acid, pristanic acid, and Delta-2,3-pristanic acid); ii). exhibited decreased fat tissue mass and increased liver mass/body mass; iii). displayed signs of histopathological lesions in the liver; and iv). demonstrated significant alterations in hepatic lipid distributions. Moreover, both male and female mice exhibited phytol-induced peroxisomal proliferation, as demonstrated by liver morphology and upregulation of the peroxisomal protein catalase. In addition, levels of liver fatty acid binding protein, along with SCP-2 and SCP-x, increased, suggesting upregulation mediated by phytanic acid, a known ligand agonist of the peroxisomal proliferator-activated receptor alpha. In summary, the present work establishes a role for SCP-x in branched chain lipid catabolism and demonstrates a sexual dimorphic response to phytol, a precursor of phytanic acid, in lipid parameters and hepatotoxicity.
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Affiliation(s)
- Barbara P Atshaves
- Departments of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466, USA
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