1
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Udupa P, Kumar A, Parit R, Ghosh DK. Acyl-CoA binding protein regulates nutrient-dependent autophagy. Metabolism 2022:155338. [PMID: 36280213 DOI: 10.1016/j.metabol.2022.155338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 12/15/2022]
Abstract
BACKGROUND Homeostasis of autophagy under normal conditions and nutrient stress is maintained by adaptive activation of regulatory proteins. However, the protein-lipid crosstalk that modulates the switch from suppression to activation of autophagy initiation is largely unknown. RESULTS Here, we show that human diazepam-binding inhibitor (DBI), also known as acyl-CoA binding protein (ACBP), binds to phosphatidylethanolamine of the phagophore membrane under nutrient-rich growth conditions, leading to inhibition of LC3 lipidation and suppression of autophagy initiation. Specific residues, including the conserved tyrosine residues of DBI, interact with phosphatidylethanolamine to stabilize the later molecule in the acyl-CoA binding cavity of the protein. Under starvation, phosphorylation of serine-21 of DBI mediated by the AMP-activated protein kinase results in a drastic reduction in the affinity of the protein for phosphatidylethanolamine. The release of serine-21 phosphorylated DBI from the phagophore upon nutrient starvation restores the high LC3 lipidation flux and maturation of the phagophore to autophagosome. CONCLUSION DBI acts as a strategic barrier against overactivation of phagophore maturation under nutrient-rich conditions, while triggering autophagy under nutrient-deficient conditions.
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Affiliation(s)
- Prajna Udupa
- Departmentof Medical Genetics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Abhishek Kumar
- School of Medicine, University of California, San Francisco, United States of America
| | - Rahul Parit
- Departmentof Medical Genetics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Debasish Kumar Ghosh
- Departmentof Medical Genetics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India.
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2
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Xu C, Li H, Tang CK. Sterol carrier protein 2 in lipid metabolism and non-alcoholic fatty liver disease: Pathophysiology, molecular biology, and potential clinical implications. Metabolism 2022; 131:155180. [PMID: 35311663 DOI: 10.1016/j.metabol.2022.155180] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/03/2022] [Accepted: 03/13/2022] [Indexed: 11/29/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is considered as the most common chronic liver disease and has become a rapidly global public health problem. Sterol carrier protein 2 (SCP-2), also called non-specific lipid-transfer protein, is predominantly expressed by the liver. SCP-2 plays a key role in intracellular lipid transport and metabolism. SCP-2 has been closely implicated in the development of NAFLD-related metabolic disorders, such as obesity, atherosclerosis, Type 2 diabetes mellitus (T2DM), and gallstones. Recent studies indicate that SCP-2 plays a beneficial role in NAFLD by regulating cholesterol-, endocannabinoid-, and fatty acid-related aspects of lipid metabolism. Hence, in this paper, we summarize the latest findings about the roles of SCP-2 in hepatic steatosis and further describe its molecular function in the pathogenesis of NAFLD.
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Affiliation(s)
- Can Xu
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, The First Affiliated Hospital of University of South China, Department of Cardiology, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, PR China
| | - Heng Li
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, The First Affiliated Hospital of University of South China, Department of Cardiology, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, PR China.
| | - Chao-Ke Tang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, The First Affiliated Hospital of University of South China, Department of Cardiology, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, PR China.
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3
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Alquier T, Christian-Hinman CA, Alfonso J, Færgeman NJ. From benzodiazepines to fatty acids and beyond: revisiting the role of ACBP/DBI. Trends Endocrinol Metab 2021; 32:890-903. [PMID: 34565656 PMCID: PMC8785413 DOI: 10.1016/j.tem.2021.08.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/29/2021] [Accepted: 08/30/2021] [Indexed: 01/19/2023]
Abstract
Four decades ago Costa and colleagues identified a small, secreted polypeptide in the brain that can displace the benzodiazepine diazepam from the GABAA receptor, and was thus termed diazepam binding inhibitor (DBI). Shortly after, an identical polypeptide was identified in liver by its ability to induce termination of fatty acid synthesis, and was named acyl-CoA binding protein (ACBP). Since then, ACBP/DBI has been studied in parallel without a clear and integrated understanding of its dual roles. The first genetic loss-of-function models have revived the field, allowing targeted approaches to better understand the physiological roles of ACBP/DBI in vivo. We discuss the roles of ACBP/DBI in central and tissue-specific functions in mammals, with an emphasis on metabolism and mechanisms of action.
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Affiliation(s)
- Thierry Alquier
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal Diabetes Research Center, and Departments of Medicine, Pharmacology and Physiology, Biochemistry, and Neurosciences, Université de Montréal, Montreal, QC, Canada.
| | - Catherine A Christian-Hinman
- Department of Molecular and Integrative Physiology, Neuroscience Program, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Julieta Alfonso
- Department of Clinical Neurobiology, University Hospital Heidelberg and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Nils J Færgeman
- Department of Biochemistry and Molecular Biology, Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
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4
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Milligan S, Martin GG, Landrock D, McIntosh AL, Mackie JT, Schroeder F, Kier AB. Ablating both Fabp1 and Scp2/Scpx (TKO) induces hepatic phospholipid and cholesterol accumulation in high fat-fed mice. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:323-338. [PMID: 29307784 DOI: 10.1016/j.bbalip.2017.12.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 12/13/2017] [Accepted: 12/31/2017] [Indexed: 01/16/2023]
Abstract
Although singly ablating Fabp1 or Scp2/Scpx genes may exacerbate the impact of high fat diet (HFD) on whole body phenotype and non-alcoholic fatty liver disease (NAFLD), concomitant upregulation of the non-ablated gene, preference for ad libitum fed HFD, and sex differences complicate interpretation. Therefore, these issues were addressed in male and female mice ablated in both genes (Fabp1/Scp2/Scpx null or TKO) and pair-fed HFD. Wild-type (WT) males gained more body weight as fat tissue mass (FTM) and exhibited higher hepatic lipid accumulation than WT females. The greater hepatic lipid accumulation in WT males was associated with higher hepatic expression of enzymes in glyceride synthesis, higher hepatic bile acids, and upregulation of transporters involved in hepatic reuptake of serum bile acids. While TKO had little effect on whole body phenotype and hepatic bile acid accumulation in either sex, TKO increased hepatic accumulation of lipids in both, specifically phospholipid and cholesteryl esters in males and females and free cholesterol in females. TKO-induced increases in glycerides were attributed not only to complete loss of FABP1, SCP2 and SCPx, but also in part to sex-dependent upregulation of hepatic lipogenic enzymes. These data with WT and TKO mice pair-fed HFD indicate that: i) Sex significantly impacted the ability of HFD to increase body weight, induce hepatic lipid accumulation and increase hepatic bile acids; and ii) TKO exacerbated the HFD ability to induce hepatic lipid accumulation, regardless of sex, but did not significantly alter whole body phenotype in either sex.
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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 Physiology/Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466, 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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5
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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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6
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Gallego SF, Sprenger RR, Neess D, Pauling JK, Færgeman NJ, Ejsing CS. Quantitative lipidomics reveals age-dependent perturbations of whole-body lipid metabolism in ACBP deficient mice. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:145-155. [DOI: 10.1016/j.bbalip.2016.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/06/2016] [Accepted: 10/28/2016] [Indexed: 01/08/2023]
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7
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Huang H, McIntosh AL, Martin GG, Landrock D, Chung S, Landrock KK, Dangott LJ, Li S, Kier AB, Schroeder F. FABP1: A Novel Hepatic Endocannabinoid and Cannabinoid Binding Protein. Biochemistry 2016; 55:5243-55. [PMID: 27552286 DOI: 10.1021/acs.biochem.6b00446] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Endocannabinoids (ECs) and cannabinoids are very lipophilic molecules requiring the presence of cytosolic binding proteins that chaperone these molecules to intracellular targets. While three different fatty acid binding proteins (FABP3, -5, and -7) serve this function in brain, relatively little is known about how such hydrophobic ECs and cannabinoids are transported within the liver. The most prominent hepatic FABP, liver fatty acid binding protein (FABP1 or L-FABP), has high affinity for arachidonic acid (ARA) and ARA-CoA, suggesting that FABP1 may also bind ARA-derived ECs (AEA and 2-AG). Indeed, FABP1 bound ECs with high affinity as shown by displacement of FABP1-bound fluorescent ligands and by quenching of FABP1 intrinsic tyrosine fluorescence. FABP1 also had high affinity for most non-ARA-containing ECs, FABP1 inhibitors, EC uptake/hydrolysis inhibitors, and phytocannabinoids and less so for synthetic cannabinoid receptor (CBR) agonists and antagonists. The physiological impact was examined with liver from wild-type (WT) versus FABP1 gene-ablated (LKO) male mice. As shown by liquid chromatography and mass spectrometry, FABP1 gene ablation significantly increased hepatic levels of AEA, 2-AG, and 2-OG. These increases were not due to increased protein levels of EC synthetic enzymes (NAPEPLD and DAGL) or a decreased level of EC degradative enzyme (FAAH) but correlated with complete loss of FABP1, a decreased level of SCP2 (8-fold less prevalent than FABP1, but also binds ECs), and a decreased level of degradative enzymes (NAAA and MAGL). These data indicated that FABP1 not only is the most prominent endocannabinoid and cannabinoid binding protein but also impacts hepatic endocannabinoid levels.
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Affiliation(s)
| | | | | | | | | | | | | | - Shengrong Li
- Avanti Polar Lipids , 700 Industrial Park Drive, Alabaster, Alabama 35007-9105, United States
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8
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Martin GG, Chung S, Landrock D, Landrock KK, Dangott LJ, Peng X, Kaczocha M, Murphy EJ, Kier AB, Schroeder F. Female Mice are Resistant to Fabp1 Gene Ablation-Induced Alterations in Brain Endocannabinoid Levels. Lipids 2016; 51:1007-20. [PMID: 27450559 PMCID: PMC5418128 DOI: 10.1007/s11745-016-4175-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 07/14/2016] [Indexed: 10/21/2022]
Abstract
Although liver fatty acid binding protein (FABP1, L-FABP) is not detectable in the brain, Fabp1 gene ablation (LKO) markedly increases endocannabinoids (EC) in brains of male mice. Since the brain EC system of females differs significantly from that of males, it was important to determine if LKO differently impacted the brain EC system. LKO did not alter brain levels of arachidonic acid (ARA)-containing EC, i.e. arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG), but decreased non-ARA-containing N-acylethanolamides (OEA, PEA) and 2-oleoylglycerol (2-OG) that potentiate the actions of AEA and 2-AG. These changes in brain potentiating EC levels were not associated with: (1) a net decrease in levels of brain membrane proteins associated with fatty acid uptake and EC synthesis; (2) a net increase in brain protein levels of cytosolic EC chaperones and enzymes in EC degradation; or (3) increased brain protein levels of EC receptors (CB1, TRVP1). Instead, the reduced or opposite responsiveness of female brain EC levels to loss of FABP1 (LKO) correlated with intrinsically lower FABP1 level in livers of WT females than males. These data show that female mouse brain endocannabinoid levels were unchanged (AEA, 2-AG) or decreased (OEA, PEA, 2-OG) by complete loss of FABP1 (LKO).
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Affiliation(s)
- Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, 4466 TAMU, College Station, TX, 77843-4466, USA
| | - Sarah Chung
- Department of Pathobiology, Texas A&M University, College Station, TX, 77843-4466, USA
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, College Station, TX, 77843-4466, USA
| | - Kerstin K Landrock
- Department of Physiology and Pharmacology, Texas A&M University, 4466 TAMU, College Station, TX, 77843-4466, USA
| | - Lawrence J Dangott
- Protein Chemistry Laboratory, Texas A&M University, College Station, TX, 77843-2128, USA
| | - Xiaoxue Peng
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Martin Kaczocha
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Eric J Murphy
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58202-9037, USA
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University, College Station, TX, 77843-4466, USA
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, 4466 TAMU, College Station, TX, 77843-4466, USA.
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Lung SC, Chye ML. Deciphering the roles of acyl-CoA-binding proteins in plant cells. PROTOPLASMA 2016; 253:1177-95. [PMID: 26340904 DOI: 10.1007/s00709-015-0882-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 08/21/2015] [Indexed: 05/18/2023]
Abstract
Lipid trafficking is vital for metabolite exchange and signal communications between organelles and endomembranes. Acyl-CoA-binding proteins (ACBPs) are involved in the intracellular transport, protection, and pool formation of acyl-CoA esters, which are important intermediates and regulators in lipid metabolism and cellular signaling. In this review, we highlight recent advances in our understanding of plant ACBP families from a cellular and developmental perspective. Plant ACBPs have been extensively studied in Arabidopsis thaliana (a dicot) and to a lesser extent in Oryza sativa (a monocot). Thus far, they have been detected in the plasma membrane, vesicles, endoplasmic reticulum, Golgi apparatus, apoplast, cytosol, nuclear periphery, and peroxisomes. In combination with biochemical and molecular genetic tools, the widespread subcellular distribution of respective ACBP members has been explicitly linked to their functions in lipid metabolism during development and in response to stresses. At the cellular level, strong expression of specific ACBP homologs in specialized cells, such as embryos, stem epidermis, guard cells, male gametophytes, and phloem sap, is of relevance to their corresponding distinct roles in organ development and stress responses. Other interesting patterns in their subcellular localization and spatial expression that prompt new directions in future investigations are discussed.
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Affiliation(s)
- Shiu-Cheung Lung
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Mee-Len Chye
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
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10
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Martin GG, Chung S, Landrock D, Landrock KK, Huang H, Dangott LJ, Peng X, Kaczocha M, Seeger DR, Murphy EJ, Golovko MY, Kier AB, Schroeder F. FABP-1 gene ablation impacts brain endocannabinoid system in male mice. J Neurochem 2016; 138:407-22. [PMID: 27167970 PMCID: PMC4961623 DOI: 10.1111/jnc.13664] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 04/14/2016] [Accepted: 04/26/2016] [Indexed: 12/15/2022]
Abstract
Liver fatty acid-binding protein (FABP1, L-FABP) has high affinity for and enhances uptake of arachidonic acid (ARA, C20:4, n-6) which, when esterified to phospholipids, is the requisite precursor for synthesis of endocannabinoids (EC) such as arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG). The brain derives most of its ARA from plasma, taking up ARA and transporting it intracellularly via cytosolic fatty acid-binding proteins (FABPs 3,5, and 7) localized within the brain. In contrast, the much more prevalent cytosolic FABP1 is not detectable in the brain but is instead highly expressed in the liver. Therefore, the possibility that FABP1 outside the central nervous system may regulate brain AEA and 2-AG was examined in wild-type (WT) and FABP1 null (LKO) male mice. LKO increased brain levels of AA-containing EC (AEA, 2-AG), correlating with increased free and total ARA in brain and serum. LKO also increased brain levels of non-ARA that contain potentiating endocannabinoids (EC*) such as oleoyl ethanolamide (OEA), PEA, 2-OG, and 2-PG. Concomitantly, LKO decreased serum total ARA-containing EC, but not non-ARA endocannabinoids. LKO did not elicit these changes in the brain EC and EC* as a result of compensatory up-regulation of brain protein levels of enzymes in EC synthesis (NAPEPLD, DAGLα) or cytosolic EC chaperone proteins (FABPs 3, 5, 7, SCP-2, HSP70), or cannabinoid receptors (CB1, TRVP1). These data show for the first time that the non-CNS fatty acid-binding protein FABP1 markedly affected brain levels of both ARA-containing endocannabinoids (AEA, 2-AG) as well as their non-ARA potentiating endocannabinoids. Fatty acid-binding protein-1 (FABP-1) is not detectable in brain but instead is highly expressed in liver. The possibility that FABP1 outside the central nervous system may regulate brain endocannabinoids arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG) was examined in wild-type (WT) and FABP-1 null (LKO) male mice. LKO increased brain levels of arachidonic acid-containing endocannabinoids (AEA, 2-AG), correlating with increased free and total arachidonic acid in brain and serum. Read the Editorial Highlight for this article on page 371.
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Affiliation(s)
- Gregory G. Martin
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466
| | - Sarah Chung
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467
| | - Kerstin K. Landrock
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467
| | - Huan Huang
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466
| | - Lawrence J. Dangott
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2128
| | - Xiaoxue Peng
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY 11794
| | - Martin Kaczocha
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY 11794
| | - Drew R. Seeger
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58202-9037 USA
| | - Eric J. Murphy
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58202-9037 USA
| | - Mikhail Y. Golovko
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58202-9037 USA
| | - Ann B. Kier
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466
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11
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Plant acyl-CoA-binding proteins: An emerging family involved in plant development and stress responses. Prog Lipid Res 2016; 63:165-81. [DOI: 10.1016/j.plipres.2016.06.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 06/25/2016] [Accepted: 06/26/2016] [Indexed: 01/22/2023]
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12
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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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13
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Majerowicz D, Hannibal-Bach HK, Castro RSC, Bozaquel-Morais BL, Alves-Bezerra M, Grillo LAM, Masuda CA, Færgeman NJ, Knudsen J, Gondim KC. The ACBP gene family in Rhodnius prolixus: Expression, characterization and function of RpACBP-1. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 72:41-52. [PMID: 27001070 DOI: 10.1016/j.ibmb.2016.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 03/04/2016] [Accepted: 03/16/2016] [Indexed: 06/05/2023]
Abstract
The acyl-CoA-binding proteins (ACBP) constitute a family of conserved proteins that bind acyl-CoA with high affinity and protect it from hydrolysis. Thus, ACBPs may have essential roles in basal cellular lipid metabolism. The genome of the insect Rhodnius prolixus encodes five ACBP genes similar to those described for other insect species. The qPCR analysis revealed that these genes have characteristic expression profiles in insect organs, suggesting that they have specific roles in insect physiology. Recombinant RpACBP-1 was able to bind acyl-CoA in an in vitro gel-shift assay. Moreover, heterologous RpACBP-1 expression in acb1Δ mutant yeast rescued the multi-lobed vacuole phenotype, indicating that RpACBP-1 acts as a bona fide acyl-CoA-binding protein. RpACBP-1 knockdown using RNAi caused triacylglycerol accumulation in the insect posterior midgut and a reduction in the number of deposited eggs. The amount of stored triacylglycerol was reduced in flight muscle, and the incorporation of fatty acids in cholesteryl esters was increased in the fat body. These results showed that RpACBP-1 participates in several lipid metabolism steps in R. prolixus.
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Affiliation(s)
- David Majerowicz
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Institut for Biokemi og Molekylær Biologi, Syddansk Universitet, Odense, Denmark
| | - Hans K Hannibal-Bach
- Institut for Biokemi og Molekylær Biologi, Syddansk Universitet, Odense, Denmark
| | - Rodolfo S C Castro
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Bruno L Bozaquel-Morais
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Michele Alves-Bezerra
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luciano A M Grillo
- Escola de Enfermagem e Farmácia, Universidade Federal de Alagoas, Maceió, Brazil
| | - Claudio A Masuda
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nils J Færgeman
- Institut for Biokemi og Molekylær Biologi, Syddansk Universitet, Odense, Denmark
| | - Jens Knudsen
- Institut for Biokemi og Molekylær Biologi, Syddansk Universitet, Odense, Denmark
| | - Katia C Gondim
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Brazil.
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14
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Soupene E, Kao J, Cheng DH, Wang D, Greninger AL, Knudsen GM, DeRisi JL, Kuypers FA. Association of NMT2 with the acyl-CoA carrier ACBD6 protects the N-myristoyltransferase reaction from palmitoyl-CoA. J Lipid Res 2016; 57:288-98. [PMID: 26621918 PMCID: PMC4727424 DOI: 10.1194/jlr.m065003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Indexed: 01/13/2023] Open
Abstract
The covalent attachment of a 14-carbon aliphatic tail on a glycine residue of nascent translated peptide chains is catalyzed in human cells by two N-myristoyltransferase (NMT) enzymes using the rare myristoyl-CoA (C(14)-CoA) molecule as fatty acid donor. Although, NMT enzymes can only transfer a myristate group, they lack specificity for C(14)-CoA and can also bind the far more abundant palmitoyl-CoA (C(16)-CoA) molecule. We determined that the acyl-CoA binding protein, acyl-CoA binding domain (ACBD)6, stimulated the NMT reaction of NMT2. This stimulatory effect required interaction between ACBD6 and NMT2, and was enhanced by binding of ACBD6 to its ligand, C(18:2)-CoA. ACBD6 also interacted with the second human NMT enzyme, NMT1. The presence of ACBD6 prevented competition of the NMT reaction by C(16)-CoA. Mutants of ACBD6 that were either deficient in ligand binding to the N-terminal ACBD or unable to interact with NMT2 did not stimulate activity of NMT2, nor could they protect the enzyme from utilizing the competitor C(16)-CoA. These results indicate that ACBD6 can locally sequester C(16)-CoA and prevent its access to the enzyme binding site via interaction with NMT2. Thus, the ligand binding properties of the NMT/ACBD6 complex can explain how the NMT reaction can proceed in the presence of the very abundant competitive substrate, C(16)-CoA.
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Affiliation(s)
- Eric Soupene
- Children's Hospital Oakland Research Institute, Oakland, CA
| | - Joseph Kao
- Children's Hospital Oakland Research Institute, Oakland, CA
| | - Daniel H Cheng
- Children's Hospital Oakland Research Institute, Oakland, CA
| | - Derek Wang
- Children's Hospital Oakland Research Institute, Oakland, CA
| | - Alexander L Greninger
- Department of Biochemistry and Biophysics, University of California at San Francisco and Howard Hughes Medical Institute, San Francisco, CA
| | - Giselle M Knudsen
- Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, CA
| | - Joseph L DeRisi
- Department of Biochemistry and Biophysics, University of California at San Francisco and Howard Hughes Medical Institute, San Francisco, CA
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15
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Abstract
Acyl-CoA-binding proteins (ACBPs) play a pivotal role in fatty acid metabolism because they can transport medium- and long-chain acyl-CoA esters. In eukaryotic cells, ACBPs are involved in intracellular trafficking of acyl-CoA esters and formation of a cytosolic acyl-CoA pool. In addition to these ubiquitous functions, more specific non-redundant roles of plant ACBP subclasses are implicated by the existence of multigene families with variable molecular masses, ligand specificities, functional domains (e.g. protein-protein interaction domains), subcellular locations and gene expression patterns. In this chapter, recent progress in the characterization of ACBPs from the model dicot plant, Arabidopsis thaliana, and the model monocot, Oryza sativa, and their emerging roles in plant growth and development are discussed. The functional significance of respective members of the plant ACBP families in various developmental and physiological processes such as seed development and germination, stem cuticle formation, pollen development, leaf senescence, peroxisomal fatty acid β-oxidation and phloem-mediated lipid transport is highlighted.
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Affiliation(s)
- Shiu-Cheung Lung
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Mee-Len Chye
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
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16
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Martin GG, Landrock D, Landrock KK, Howles PN, Atshaves BP, Kier AB, Schroeder F. Relative contributions of L-FABP, SCP-2/SCP-x, or both to hepatic biliary phenotype of female mice. Arch Biochem Biophys 2015; 588:25-32. [PMID: 26541319 PMCID: PMC4683591 DOI: 10.1016/j.abb.2015.10.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 10/20/2015] [Accepted: 10/28/2015] [Indexed: 01/01/2023]
Abstract
Both sterol carrier protein-2/sterol carrier protein-x (SCP-2/SCP-x) and liver fatty acid binding protein (L-FABP) have been proposed to function in hepatobiliary bile acid metabolism/accumulation. To begin to address this issue, the impact of ablating L-FABP (LKO) or SCP-2/SCP-x (DKO) individually or both together (TKO) was examined in female mice. Biliary bile acid levels were decreased in LKO, DKO, and TKO mice; however, hepatic bile acid concentration was decreased in LKO mice only. In contrast, biliary phospholipid level was decreased only in TKO mice, while biliary cholesterol levels were unaltered regardless of phenotype. The loss of either or both genes increased hepatic expression of the major bile acid synthetic enzymes (CYP7A1 and/or CYP27A1). Loss of L-FABP and/or SCP-2/SCP-x genes significantly altered the molecular composition of biliary bile acids, but not the proportion of conjugated/unconjugated bile acids or overall bile acid hydrophobicity index. These data suggested that L-FABP was more important in hepatic retention of bile acids, while SCP-2/SCP-x more broadly affected biliary bile acid and phospholipid levels.
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Affiliation(s)
- Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466, USA
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467, USA
| | - Kerstin K Landrock
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466, USA
| | - Philip N Howles
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45219, 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, College Station, TX 77843-4467, USA
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466, USA.
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17
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Klipsic D, Landrock D, Martin GG, McIntosh AL, Landrock KK, Mackie JT, Schroeder F, Kier AB. Impact of SCP-2/SCP-x gene ablation and dietary cholesterol on hepatic lipid accumulation. Am J Physiol Gastrointest Liver Physiol 2015; 309:G387-99. [PMID: 26113298 PMCID: PMC4556946 DOI: 10.1152/ajpgi.00460.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 06/22/2015] [Indexed: 01/31/2023]
Abstract
While a high-cholesterol diet induces hepatic steatosis, the role of intracellular sterol carrier protein-2/sterol carrier protein-x (SCP-2/SCP-x) proteins is unknown. We hypothesized that ablating SCP-2/SCP-x [double knockout (DKO)] would impact hepatic lipids (cholesterol and cholesteryl ester), especially in high-cholesterol-fed mice. DKO did not alter food consumption, and body weight (BW) gain decreased especially in females, concomitant with hepatic steatosis in females and less so in males. DKO-induced steatosis in control-fed wild-type (WT) mice was associated with 1) loss of SCP-2; 2) upregulation of liver fatty acid binding protein (L-FABP); 3) increased mRNA and/or protein levels of sterol regulatory element binding proteins (SREBP1 and SREBP2) as well as increased expression of target genes of cholesterol synthesis (Hmgcs1 and Hmgcr) and fatty acid synthesis (Acc1 and Fas); and 4) cholesteryl ester accumulation was also associated with increased acyl-CoA cholesterol acyltransferase-2 (ACAT2) in males. DKO exacerbated the high-cholesterol diet-induced hepatic cholesterol and glyceride accumulation, without further increasing SREBP1, SREBP2, or target genes. This exacerbation was associated both with loss of SCP-2 and concomitant downregulation of Ceh/Hsl, apolipoprotein B (ApoB), MTP, and/or L-FABP protein expression. DKO diminished the ability to secrete excess cholesterol into bile and oxidize cholesterol to bile acid for biliary excretion, especially in females. This suggested that SCP-2/SCP-x affects cholesterol transport to particular intracellular compartments, with ablation resulting in less to the endoplasmic reticulum for SREBP regulation, making more available for cholesteryl ester synthesis, for cholesteryl-ester storage in lipid droplets, and for bile salt synthesis and/or secretion. These alterations are significant findings, since they affect key processes in regulation of sterol metabolism.
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Affiliation(s)
- Devon Klipsic
- Department of Pathobiology, Texas A&M University, College Station, Texas; and
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, College Station, Texas; and
| | - Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | - Avery L McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | - Kerstin K Landrock
- Department of Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | - John T Mackie
- Department of Pathobiology, Texas A&M University, College Station, Texas; and
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University, College Station, Texas; and
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18
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Bek S, Neess D, Dixen K, Bloksgaard M, Marcher AB, Chemnitz J, Færgeman NJ, Mandrup S. Compromised epidermal barrier stimulates Harderian gland activity and hypertrophy in ACBP-/- mice. J Lipid Res 2015; 56:1738-46. [PMID: 26142722 DOI: 10.1194/jlr.m060780] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Indexed: 11/20/2022] Open
Abstract
Acyl-CoA binding protein (ACBP) is a small, ubiquitously expressed intracellular protein that binds C14-C22 acyl-CoA esters with very high affinity and specificity. We have recently shown that targeted disruption of the Acbp gene leads to a compromised epidermal barrier and that this causes delayed adaptation to weaning, including the induction of the hepatic lipogenic and cholesterogenic gene programs. Here we show that ACBP is highly expressed in the Harderian gland, a gland that is located behind the eyeball of rodents and involved in the production of fur lipids and lipids used for lubrication of the eye lid. We show that disruption of the Acbp gene leads to a significant enlargement of this gland with hypertrophy of the acinar cells and increased de novo synthesis of monoalkyl diacylglycerol, the main lipid species produced by the gland. Mice with conditional targeting of the Acbp gene in the epidermis recapitulate this phenotype, whereas generation of an artificial epidermal barrier during gland development reverses the phenotype. Our findings indicate that the Harderian gland is activated by the compromised epidermal barrier as an adaptive and protective mechanism to overcome the barrier defect.
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Affiliation(s)
- Signe Bek
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Ditte Neess
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Karen Dixen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Maria Bloksgaard
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Ann-Britt Marcher
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - John Chemnitz
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Nils J Færgeman
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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19
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Martin GG, Atshaves BP, Landrock KK, Landrock D, Schroeder F, Kier AB. Loss of L-FABP, SCP-2/SCP-x, or both induces hepatic lipid accumulation in female mice. Arch Biochem Biophys 2015; 580:41-9. [PMID: 26116377 DOI: 10.1016/j.abb.2015.06.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Revised: 06/08/2015] [Accepted: 06/17/2015] [Indexed: 02/06/2023]
Abstract
Although roles for both sterol carrier protein-2/sterol carrier protein-x (SCP-2/SCP-x) and liver fatty acid binding protein (L-FABP) have been proposed in hepatic lipid accumulation, individually ablating these genes has been complicated by concomitant alterations in the other gene product(s). For example, ablating SCP2/SCP-x induces upregulation of L-FABP in female mice. Therefore, the impact of ablating SCP-2/SCP-x (DKO) or L-FABP (LKO) individually or both together (TKO) was examined in female mice. Loss of SCP-2/SCP-x (DKO, TKO) more so than loss of L-FABP alone (LKO) increased hepatic total lipid and total cholesterol content, especially cholesteryl ester. Hepatic accumulation of nonesterified long chain fatty acids (LCFA) and phospholipids occurred only in DKO and TKO mice. Loss of SCP-2/SCP-x (DKO, TKO) increased serum total lipid primarily by increasing triglycerides. Altered hepatic level of proteins involved in cholesterol uptake, efflux, and/or secretion was observed, but did not compensate for the loss of L-FABP, SCP-2/SCP-x or both. However, synergistic responses were not seen with the combinatorial knock out animals-suggesting that inhibiting SCP-2/SCP-x is more correlative with hepatic dysfunction than L-FABP. The DKO- and TKO-induced hepatic accumulation of cholesterol and long chain fatty acids shared significant phenotypic similarities with non-alcoholic fatty liver disease (NAFLD).
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Affiliation(s)
- Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466, United States
| | - Barbara P Atshaves
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States
| | - Kerstin K Landrock
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467, United States
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467, United States
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466, United States
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467, United States.
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20
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Neess D, Bek S, Engelsby H, Gallego SF, Færgeman NJ. Long-chain acyl-CoA esters in metabolism and signaling: Role of acyl-CoA binding proteins. Prog Lipid Res 2015; 59:1-25. [PMID: 25898985 DOI: 10.1016/j.plipres.2015.04.001] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/11/2015] [Accepted: 04/09/2015] [Indexed: 02/03/2023]
Abstract
Long-chain fatty acyl-CoA esters are key intermediates in numerous lipid metabolic pathways, and recognized as important cellular signaling molecules. The intracellular flux and regulatory properties of acyl-CoA esters have been proposed to be coordinated by acyl-CoA-binding domain containing proteins (ACBDs). The ACBDs, which comprise a highly conserved multigene family of intracellular lipid-binding proteins, are found in all eukaryotes and ubiquitously expressed in all metazoan tissues, with distinct expression patterns for individual ACBDs. The ACBDs are involved in numerous intracellular processes including fatty acid-, glycerolipid- and glycerophospholipid biosynthesis, β-oxidation, cellular differentiation and proliferation as well as in the regulation of numerous enzyme activities. Little is known about the specific roles of the ACBDs in the regulation of these processes, however, recent studies have gained further insights into their in vivo functions and provided further evidence for ACBD-specific functions in cellular signaling and lipid metabolic pathways. This review summarizes the structural and functional properties of the various ACBDs, with special emphasis on the function of ACBD1, commonly known as ACBP.
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Affiliation(s)
- Ditte Neess
- Villum Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Signe Bek
- Villum Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Hanne Engelsby
- Villum Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Sandra F Gallego
- Villum Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Nils J Færgeman
- Villum Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
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21
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Bouyakdan K, Taïb B, Budry L, Zhao S, Rodaros D, Neess D, Mandrup S, Faergeman NJ, Alquier T. A novel role for central ACBP/DBI as a regulator of long-chain fatty acid metabolism in astrocytes. J Neurochem 2015; 133:253-65. [PMID: 25598214 DOI: 10.1111/jnc.13035] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 12/15/2014] [Accepted: 01/08/2015] [Indexed: 12/29/2022]
Abstract
Acyl-CoA-binding protein (ACBP) is a ubiquitously expressed protein that binds intracellular acyl-CoA esters. Several studies have suggested that ACBP acts as an acyl-CoA pool former and regulates long-chain fatty acids (LCFA) metabolism in peripheral tissues. In the brain, ACBP is known as Diazepam-Binding Inhibitor, a secreted peptide acting as an allosteric modulator of the GABAA receptor. However, its role in central LCFA metabolism remains unknown. In the present study, we investigated ACBP cellular expression, ACBP regulation of LCFA intracellular metabolism, FA profile, and FA metabolism-related gene expression using ACBP-deficient and control mice. ACBP was mainly found in astrocytes with high expression levels in the mediobasal hypothalamus. We demonstrate that ACBP deficiency alters the central LCFA-CoA profile and impairs unsaturated (oleate, linolenate) but not saturated (palmitate, stearate) LCFA metabolic fluxes in hypothalamic slices and astrocyte cultures. In addition, lack of ACBP differently affects the expression of genes involved in FA metabolism in cortical versus hypothalamic astrocytes. Finally, ACBP deficiency increases FA content and impairs their release in response to palmitate in hypothalamic astrocytes. Collectively, these findings reveal for the first time that central ACBP acts as a regulator of LCFA intracellular metabolism in astrocytes. Acyl-CoA-binding protein (ACBP) or diazepam-binding inhibitor is a secreted peptide acting centrally as a GABAA allosteric modulator. Using brain slices, cortical, and hypothalamic astrocyte cultures from ACBP KO mice, we demonstrate that ACBP mainly localizes in astrocytes and regulates unsaturated but not saturated long-chain fatty acids (LCFA) metabolism. In addition, ACBP deficiency alters FA metabolism-related genes and results in intracellular FA accumulation while affecting their release. Our results support a novel role for ACBP in brain lipid metabolism. FA, fatty acids; KO, knockout; PL, phospholipids; TAG, triacylglycerol.
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Affiliation(s)
- Khalil Bouyakdan
- Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Universite de Montreal (CRCHUM), Montreal, Quebec, Canada; Department of Biochemistry, University of Montreal, Montreal, Quebec, Canada
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22
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McIntosh AL, Huang H, Storey SM, Landrock KK, Landrock D, Petrescu AD, Gupta S, Atshaves BP, Kier AB, Schroeder F. Human FABP1 T94A variant impacts fatty acid metabolism and PPAR-α activation in cultured human female hepatocytes. Am J Physiol Gastrointest Liver Physiol 2014; 307:G164-76. [PMID: 24875102 PMCID: PMC4101680 DOI: 10.1152/ajpgi.00369.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 05/27/2014] [Indexed: 02/07/2023]
Abstract
Although human liver fatty acid-binding protein (FABP1) T94A variant has been associated with nonalcoholic fatty liver disease and reduced ability of fenofibrate to lower serum triglycerides (TG) to target levels, molecular events leading to this phenotype are poorly understood. Cultured primary hepatocytes from female human subjects expressing the FABP1 T94A variant exhibited increased neutral lipid (TG, cholesteryl ester) accumulation associated with (1) upregulation of total FABP1, a key protein stimulating mitochondrial glycerol-3-phosphate acyltransferase (GPAM), the rate-limiting enzyme in lipogenesis; (2) increased mRNA expression of key enzymes in lipogenesis (GPAM, LPIN2) in heterozygotes; (3) decreased mRNA expression of microsomal triglyceride transfer protein; (4) increased secretion of ApoB100 but not TG; (5) decreased long-chain fatty acid (LCFA) β-oxidation. TG accumulation was not due to any increase in LCFA uptake, de novo lipogenesis, or the alternate monoacylglycerol O-acyltransferase pathway in lipogenesis. Despite increased expression of total FABP1 mRNA and protein, fenofibrate-mediated FABP1 redistribution to nuclei and ligand-induced peroxisome proliferator-activated receptor (PPAR-α) transcription of LCFA β-oxidative enzymes (carnitine palmitoyltransferase 1A, carnitine palmitoyltransferase 2, and acyl-coenzyme A oxidase 1, palmitoyl) were attenuated in FABP1 T94A hepatocytes. Although the phenotype of FABP1 T94A variant human hepatocytes exhibits some similarities to that of FABP1-null or PPAR-α-null hepatocytes and mice, expression of FABP1 T94A variant did not abolish or reduce ligand binding. Thus the FABP1 T94A variant represents an altered/reduced function mutation resulting in TG accumulation.
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Affiliation(s)
| | - Huan Huang
- Departments of Physiology and Pharmacology, and
| | | | | | - Danilo Landrock
- Pathobiology, Texas A & M University, College Station, Texas
| | | | - Shipra Gupta
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Barbara P Atshaves
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Ann B Kier
- Pathobiology, Texas A & M University, College Station, Texas
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23
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Huang H, McIntosh AL, Martin GG, Landrock KK, Landrock D, Gupta S, Atshaves BP, Kier AB, Schroeder F. Structural and functional interaction of fatty acids with human liver fatty acid-binding protein (L-FABP) T94A variant. FEBS J 2014; 281:2266-83. [PMID: 24628888 DOI: 10.1111/febs.12780] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 02/17/2014] [Accepted: 03/11/2014] [Indexed: 12/13/2022]
Abstract
The human liver fatty acid-binding protein (L-FABP) T94A variant, the most common in the FABP family, has been associated with elevated liver triglyceride levels. How this amino acid substitution elicits these effects is not known. This issue was addressed using human recombinant wild-type (WT) and T94A variant L-FABP proteins as well as cultured primary human hepatocytes expressing the respective proteins (genotyped as TT, TC and CC). The T94A substitution did not alter or only slightly altered L-FABP binding affinities for saturated, monounsaturated or polyunsaturated long chain fatty acids, nor did it change the affinity for intermediates of triglyceride synthesis. Nevertheless, the T94A substitution markedly altered the secondary structural response of L-FABP induced by binding long chain fatty acids or intermediates of triglyceride synthesis. Finally, the T94A substitution markedly decreased the levels of induction of peroxisome proliferator-activated receptor α-regulated proteins such as L-FABP, fatty acid transport protein 5 and peroxisome proliferator-activated receptor α itself meditated by the polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid in cultured primary human hepatocytes. Thus, although the T94A substitution did not alter the affinity of human L-FABP for long chain fatty acids, it significantly altered human L-FABP structure and stability, as well as the conformational and functional response to these ligands.
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Affiliation(s)
- Huan Huang
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, USA
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Bloksgaard M, Neess D, Færgeman NJ, Mandrup S. Acyl-CoA binding protein and epidermal barrier function. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:369-76. [DOI: 10.1016/j.bbalip.2013.09.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/20/2013] [Accepted: 09/23/2013] [Indexed: 11/29/2022]
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Martin GG, McIntosh AL, Huang H, Gupta S, Atshaves BP, Landrock KK, Landrock D, Kier AB, Schroeder F. The human liver fatty acid binding protein T94A variant alters the structure, stability, and interaction with fibrates. Biochemistry 2013; 52:9347-57. [PMID: 24299557 PMCID: PMC3930105 DOI: 10.1021/bi401014k] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Although the human liver fatty acid binding protein (L-FABP) T94A variant arises from the most commonly occurring single-nucleotide polymorphism in the entire FABP family, there is a complete lack of understanding regarding the role of this polymorphism in human disease. It has been hypothesized that the T94A substitution results in the complete loss of ligand binding ability and function analogous to that seen with L-FABP gene ablation. This possibility was addressed using the recombinant human wild-type (WT) T94T and T94A variant L-FABP and cultured primary human hepatocytes. Nonconservative replacement of the medium-sized, polar, uncharged T residue with a smaller, nonpolar, aliphatic A residue at position 94 of the human L-FABP significantly increased the L-FABP α-helical structure content at the expense of β-sheet content and concomitantly decreased the thermal stability. T94A did not alter the binding affinities for peroxisome proliferator-activated receptor α (PPARα) agonist ligands (phytanic acid, fenofibrate, and fenofibric acid). While T94A did not alter the impact of phytanic acid and only slightly altered that of fenofibrate on the human L-FABP secondary structure, the active metabolite fenofibric acid altered the T94A secondary structure much more than that of the WT T94T L-FABP. Finally, in cultured primary human hepatocytes, the T94A variant exhibited a significantly reduced extent of fibrate-mediated induction of PPARα-regulated proteins such as L-FABP, FATP5, and PPARα itself. Thus, while the T94A substitution did not alter the affinity of the human L-FABP for PPARα agonist ligands, it significantly altered the human L-FABP structure, stability, and conformational and functional response to fibrate.
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Affiliation(s)
- Gregory G. Martin
- Department of Physiology and Pharmacology, Texas A&M University, TVMC College Station, TX 77843-4466
| | - Avery L. McIntosh
- Department of Physiology and Pharmacology, Texas A&M University, TVMC College Station, TX 77843-4466
| | - Huan Huang
- Department of Physiology and Pharmacology, Texas A&M University, TVMC College Station, TX 77843-4466
| | - Shipra Gupta
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824
| | - Barbara P. Atshaves
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824
| | - Kerstin K. Landrock
- Department of Pathobiology, Texas A&M University, TVMC College Station, TX 77843-4467
| | - Danilo Landrock
- 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 77843-4466
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Delayed Hepatic Adaptation to Weaning in ACBP−/− Mice Is Caused by Disruption of the Epidermal Barrier. Cell Rep 2013; 5:1403-12. [DOI: 10.1016/j.celrep.2013.11.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 10/24/2013] [Accepted: 11/04/2013] [Indexed: 11/24/2022] Open
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Dixon JL, Kim YK, Brinker A, Quadro L. Loss of β-carotene 15,15'-oxygenase in developing mouse tissues alters esterification of retinol, cholesterol and diacylglycerols. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:34-43. [PMID: 23988655 DOI: 10.1016/j.bbalip.2013.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 08/11/2013] [Accepted: 08/13/2013] [Indexed: 11/20/2022]
Abstract
We provide novel insights into the function(s) of β-carotene-15,15'-oxygenase (CMOI) during embryogenesis. By performing in vivo and in vitro experiments, we showed that CMOI influences not only lecithin:retinol acyltransferase but also acyl CoA:retinol acyltransferase reaction in the developing tissues at mid-gestation. In addition, LC/MS lipidomics analysis of the CMOI-/- embryos showed reduced levels of four phosphatidylcholine and three phosphatidylethanolamine acyl chain species, and of eight triacylglycerol species with four or more unsaturations and fifty-two or more carbons in the acyl chains. Cholesteryl esters of arachidonate, palmitate, linoleate, and DHA were also reduced to less than 30% of control. Analysis of the fatty acyl CoA species ruled out a loss in fatty acyl CoA synthetase capability. Comparison of acyl species suggested significantly decreased 18:2, 18:3, 20:1, 20:4, or 22:6 acyl chains within the above lipids in CMOI-null embryos. Furthermore, LCAT, ACAT1 and DGAT2 mRNA levels were also downregulated in CMOI-/- embryos. These data strongly support the notion that, in addition to cleaving β-carotene to generate retinoids, CMOI serves an additional function(s) in retinoid and lipid metabolism and point to its role in the formation of specific lipids, possibly for use in nervous system tissue.
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Affiliation(s)
- Joseph L Dixon
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901, USA; Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
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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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Dunner S, Sevane N, García D, Cortés O, Valentini A, Williams J, Mangin B, Cañón J, Levéziel H. Association of genes involved in carcass and meat quality traits in 15 European bovine breeds. Livest Sci 2013. [DOI: 10.1016/j.livsci.2013.02.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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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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31
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Bloksgaard M, Bek S, Marcher AB, Neess D, Brewer J, Hannibal-Bach HK, Helledie T, Fenger C, Due M, Berzina Z, Neubert R, Chemnitz J, Finsen B, Clemmensen A, Wilbertz J, Saxtorph H, Knudsen J, Bagatolli L, Mandrup S. The acyl-CoA binding protein is required for normal epidermal barrier function in mice. J Lipid Res 2012; 53:2162-2174. [PMID: 22829653 DOI: 10.1194/jlr.m029553] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The acyl-CoA binding protein (ACBP) is a 10 kDa intracellular protein expressed in all eukaryotic species. Mice with targeted disruption of Acbp (ACBP(-/-) mice) are viable and fertile but present a visible skin and fur phenotype characterized by greasy fur and development of alopecia and scaling with age. Morphology and development of skin and appendages are normal in ACBP(-/-) mice; however, the stratum corneum display altered biophysical properties with reduced proton activity and decreased water content. Mass spectrometry analyses of lipids from epidermis and stratum corneum of ACBP(+/+) and ACBP(-/-) mice showed very similar composition, except for a significant and specific decrease in the very long chain free fatty acids (VLC-FFA) in stratum corneum of ACBP(-/-) mice. This finding indicates that ACBP is critically involved in the processes that lead to production of stratum corneum VLC-FFAs via complex phospholipids in the lamellar bodies. Importantly, we show that ACBP(-/-) mice display a ∼50% increased transepidermal water loss compared with ACBP(+/+) mice. Furthermore, skin and fur sebum monoalkyl diacylglycerol (MADAG) levels are significantly increased, suggesting that ACBP limits MADAG synthesis in sebaceous glands. In summary, our study shows that ACBP is required for production of VLC-FFA for stratum corneum and for maintaining normal epidermal barrier function.
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Affiliation(s)
- Maria Bloksgaard
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark; MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Signe Bek
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Ann-Britt Marcher
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Ditte Neess
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Jonathan Brewer
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark; MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense, Denmark
| | | | - Torben Helledie
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Christina Fenger
- Institute of Molecular Medicine, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Marianne Due
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Zane Berzina
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Reinhard Neubert
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
| | - John Chemnitz
- Institute of Molecular Medicine, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Bente Finsen
- Institute of Molecular Medicine, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Anders Clemmensen
- Department of Dermatology, Odense University Hospital, Odense, Denmark; and
| | - Johannes Wilbertz
- Department of Dermatology, Karolinska Center of Transgene Technologies, Stockholm, Sweden
| | - Henrik Saxtorph
- Laboratory Animal Science and Comparative Medicine, University of Southern Denmark, DK-5230 Odense, Denmark and
| | - Jens Knudsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Luis Bagatolli
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark; MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense, Denmark; Danish Molecular Biomedical Imaging Center (DaMBIC), University of Southern Denmark, DK-5230 Odense, Denmark.
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark.
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32
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Host acyl coenzyme A binding protein regulates replication complex assembly and activity of a positive-strand RNA virus. J Virol 2012; 86:5110-21. [PMID: 22345450 DOI: 10.1128/jvi.06701-11] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
All positive-strand RNA viruses reorganize host intracellular membranes to assemble their replication complexes. Similarly, brome mosaic virus (BMV) induces two alternate forms of membrane-bound RNA replication complexes: vesicular spherules and stacks of appressed double-membrane layers. The mechanisms by which these membrane rearrangements are induced, however, remain unclear. We report here that host ACB1-encoded acyl coenzyme A (acyl-CoA) binding protein (ACBP) is required for the assembly and activity of both BMV RNA replication complexes. ACBP is highly conserved among eukaryotes, specifically binds to long-chain fatty acyl-CoA, and promotes general lipid synthesis. Deleting ACB1 inhibited BMV RNA replication up to 30-fold and resulted in formation of spherules that were ∼50% smaller but ∼4-fold more abundant than those in wild-type (wt) cells, consistent with the idea that BMV 1a invaginates and maintains viral spherules by coating the inner spherule membrane. Furthermore, smaller and more frequent spherules were preferentially formed under conditions that induce layer formation in wt cells. Conversely, cellular karmella structures, which are arrays of endoplasmic reticulum (ER) membranes formed upon overexpression of certain cellular ER membrane proteins, were formed normally, indicating a selective inhibition of 1a-induced membrane rearrangements. Restoring altered lipid composition largely complemented the BMV RNA replication defect, suggesting that ACBP was required for maintaining lipid homeostasis. Smaller and more frequent spherules are also induced by 1a mutants with specific substitutions in a membrane-anchoring amphipathic α-helix, implying that the 1a-lipid interactions play critical roles in viral replication complex assembly.
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33
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Differentially expressed genes in human peripheral blood as potential markers for statin response. J Mol Med (Berl) 2011; 90:201-11. [PMID: 21947165 DOI: 10.1007/s00109-011-0818-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 08/25/2011] [Accepted: 09/12/2011] [Indexed: 10/17/2022]
Abstract
There is a considerable inter-individual variation in response to statin therapy and one third of patients do not meet their treatment goals. We aimed to identify differentially expressed genes that might be involved in the effects of statin treatment and to suggest potential markers to guide statin therapy. Forty-six healthy Korean subjects received atorvastatin; their whole-genome expression profiles in peripheral blood were analyzed before and after atorvastatin administration in relation with changes in lipid profiles. The expression patterns of the differentially expressed genes were also compared with the data of familial hypercholesterolemia (FH) patients and controls. Pairwise comparison analyses revealed differentially expressed genes involved in diverse biological processes and molecular functions related with immune responses. Atorvastain mainly affected antigen binding, immune or inflammatory response including interleukin pathways. Similar expression patterns of the genes were observed in patients with FH and controls. The Charcol-Leyden crystal (CLC), CCR2, CX3CR1, LRRN3, FOS, LDLR, HLA-DRB1, ERMN, and TCN1 genes were significantly associated with cholesterol levels or statin response. Interestingly, the CLC gene, which was significantly altered by atorvastatin administration and differentially expressed between FH patients and controls, showed much bigger change in high-responsive group than in low-responsive group. We identified differentially expressed genes that might be involved in mechanisms underlying the known pleiotropic effects of atorvastatin, baseline cholesterol levels, and drug response. Our findings suggest CLC as a new candidate marker for statin response, and further validation is needed.
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Neess D, Bloksgaard M, Bek S, Marcher AB, Elle IC, Helledie T, Due M, Pagmantidis V, Finsen B, Wilbertz J, Kruhøffer M, Færgeman N, Mandrup S. Disruption of the acyl-CoA-binding protein gene delays hepatic adaptation to metabolic changes at weaning. J Biol Chem 2010; 286:3460-72. [PMID: 21106527 DOI: 10.1074/jbc.m110.161109] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The acyl-CoA-binding protein (ACBP)/diazepam binding inhibitor is an intracellular protein that binds C(14)-C(22) acyl-CoA esters and is thought to act as an acyl-CoA transporter. In vitro analyses have indicated that ACBP can transport acyl-CoA esters between different enzymatic systems; however, little is known about the in vivo function in mammalian cells. We have generated mice with targeted disruption of ACBP (ACBP(-/-)). These mice are viable and fertile and develop normally. However, around weaning, the ACBP(-/-) mice go through a crisis with overall weakness and a slightly decreased growth rate. Using microarray analysis, we show that the liver of ACBP(-/-) mice displays a significantly delayed adaptation to weaning with late induction of target genes of the sterol regulatory element-binding protein (SREBP) family. As a result, hepatic de novo cholesterogenesis is decreased at weaning. The delayed induction of SREBP target genes around weaning is caused by a compromised processing and decreased expression of SREBP precursors, leading to reduced binding of SREBP to target sites in chromatin. In conclusion, lack of ACBP interferes with the normal metabolic adaptation to weaning and leads to delayed induction of the lipogenic gene program in the liver.
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Affiliation(s)
- Ditte Neess
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
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Yurchenko OP, Weselake RJ. Involvement of low molecular mass soluble acyl-CoA-binding protein in seed oil biosynthesis. N Biotechnol 2010; 28:97-109. [PMID: 20933624 DOI: 10.1016/j.nbt.2010.09.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Revised: 09/11/2010] [Accepted: 09/29/2010] [Indexed: 01/03/2023]
Abstract
Acyl-CoA-binding protein (ACBP), a low molecular mass (m) (∼ 10 kDa) soluble protein ubiquitous in eukaryotes, plays an important housekeeping role in lipid metabolism by maintaining the intracellular acyl-CoA pool. ACBP is involved in lipid biosynthesis and transport, gene expression, and membrane biogenesis. In plants, low m ACBP and high m ACBPs participate in response mechanisms to biotic and abiotic factors, acyl-CoA transport in phloem, and biosynthesis of structural and storage lipids. In light of current research on the modification of seed oil, insight into mechanisms of substrate trafficking within lipid biosynthetic pathways is crucial for developing rational strategies for the production of specialty oils with the desired alterations in fatty acid composition. In this review, we summarize our knowledge of plant ACBPs with emphasis on the role of low m ACBP in seed oil biosynthesis, based on in vitro studies and analyses of transgenic plants. Future prospects and possible applications of low m ACBP in seed oil modification are discussed.
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Affiliation(s)
- Olga P Yurchenko
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Agriculture/Forestry Centre, Edmonton, Alberta, Canada
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36
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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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Leon CG, Locke JA, Adomat HH, Etinger SL, Twiddy AL, Neumann RD, Nelson CC, Guns ES, Wasan KM. Alterations in cholesterol regulation contribute to the production of intratumoral androgens during progression to castration-resistant prostate cancer in a mouse xenograft model. Prostate 2010; 70:390-400. [PMID: 19866465 DOI: 10.1002/pros.21072] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Emerging evidence suggests that androgens and the androgen receptor (AR) are important mediators of castration-resistant prostate cancer (CRPC) progression. Increased expression of several enzymes responsible for cholesterol synthesis and conversion into downstream androgens has been documented in human CRPC tumors in comparison to primary tumors. Based on these observations it is hypothesized that cholesterol and its overall regulation within the cell are altered, thus modifying precursor levels for de novo androgen synthesis within the castrate tumoral environment. METHODS Tumoral steroid levels were assessed by LC-MS. Free and esterified cholesterol was quantified by LC-MS and a fluorescent assay. Gene and protein expression were assessed by RT-PCR and immunoblotting. RESULTS Herein, using a prostate cancer xenograft mouse model it is demonstrated by Western blot analysis that proteins responsible for cholesterol regulation (LDL-r, SR-B1, HMG-CoA reductase, ACAT1,2, ABCA1) are altered during disease progression to increase influx and synthesis of cholesterol as well as free cholesterol formation from cholesteryl ester stores. In turn this can provide increased amounts of precursor for intratumoral steroidogenesis after castration. Androgens- testosterone and dihydrotestosterone- coincidently increase at CRPC to physiologically relevant levels leading to the induction of AR expression and PSA production. Furthermore, cellular cholesterol homeostasis is maintained by increased cholesterol efflux at CRPC so that excess free cholesterol does not cause toxicity to the tumor cells. CONCLUSIONS Cellular cholesterol regulation processes are altered during progression to CRPC. Free cholesterol from increased biosynthesis or uptake is likely a precursor for intratumoral de novo androgen synthesis.
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Affiliation(s)
- Carlos G Leon
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada.
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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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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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Atshaves BP, McIntosh AL, Martin GG, Landrock D, Payne HR, Bhuvanendran S, Landrock KK, Lyuksyutova OI, Johnson JD, Macfarlane RD, Kier AB, Schroeder F. Overexpression of sterol carrier protein-2 differentially alters hepatic cholesterol accumulation in cholesterol-fed mice. J Lipid Res 2009; 50:1429-47. [PMID: 19289417 DOI: 10.1194/jlr.m900020-jlr200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Although in vitro studies suggest a role for sterol carrier protein-2 (SCP-2) in cholesterol trafficking and metabolism, the physiological significance of these observations remains unclear. This issue was addressed by examining the response of mice overexpressing physiologically relevant levels of SCP-2 to a cholesterol-rich diet. While neither SCP-2 overexpression nor cholesterol-rich diet altered food consumption, increased weight gain, hepatic lipid, and bile acid accumulation were observed in wild-type mice fed the cholesterol-rich diet. SCP-2 overexpression further exacerbated hepatic lipid accumulation in cholesterol-fed females (cholesterol/cholesteryl esters) and males (cholesterol/cholesteryl esters and triacyglycerol). Primarily in female mice, hepatic cholesterol accumulation induced by SCP-2 overexpression was associated with increased levels of LDL-receptor, HDL-receptor scavenger receptor-B1 (SR-B1) (as well as PDZK1 and/or membrane-associated protein 17 kDa), SCP-2, liver fatty acid binding protein (L-FABP), and 3alpha-hydroxysteroid dehydrogenase, without alteration of other proteins involved in cholesterol uptake (caveolin), esterification (ACAT2), efflux (ATP binding cassette A-1 receptor, ABCG5/8, and apolipoprotein A1), or oxidation/transport of bile salts (cholesterol 7alpha-hydroxylase, sterol 27alpha-hydroxylase, Na(+)/taurocholate cotransporter, Oatp1a1, and Oatp1a4). The effects of SCP-2 overexpression and cholesterol-rich diet was downregulation of proteins involved in cholesterol transport (L-FABP and SR-B1), cholesterol synthesis (related to sterol regulatory element binding protein 2 and HMG-CoA reductase), and bile acid oxidation/transport (via Oapt1a1, Oatp1a4, and SCP-x). Levels of serum and hepatic bile acids were decreased in cholesterol-fed SCP-2 overexpression mice, especially in females, while the total bile acid pool was minimally affected. Taken together, these findings support an important role for SCP-2 in hepatic cholesterol homeostasis.
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Affiliation(s)
- Barbara P Atshaves
- Department of Physiology and Pharmacology, Texas A&M University, Texas Veterinary Medical Center, College Station, TX 77843-4466, USA
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Petrescu AD, Vespa A, Huang H, McIntosh AL, Schroeder F, Kier AB. Fluorescent sterols monitor cell penetrating peptide Pep-1 mediated uptake and intracellular targeting of cargo protein in living cells. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1788:425-41. [PMID: 18992218 PMCID: PMC2680736 DOI: 10.1016/j.bbamem.2008.09.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 08/25/2008] [Accepted: 09/24/2008] [Indexed: 12/15/2022]
Abstract
Although cell-penetrating peptides (CPP) facilitate endocytic uptake of proteins, little is known regarding the extent to which CPPs facilitate protein cargo exit from endocytic vesicles for targeting to other intracellular sites. Since the plasma membrane and less so intracellular membranes contain cholesterol, the fluorescent sterol analogues dansyl-cholestanol (DChol) and dehydroergosterol (DHE) were used to monitor the uptake and intracellular distribution of fluorescent-tagged acyl coenzyme A binding protein (ACBP) into COS-7 cells and rat hepatoma cells. Confocal microscopy colocalized DChol and Texas Red-ACBP (TR-ACBP) with markers for the major endocytosis pathways, especially fluorescent-labeled cholera toxin (marker of ganglioside GM1 in plasma membrane lipid rafts) and dextran (macropinocytosis marker), but less so with transferrin (clathrin-mediated endocytosis marker). These findings were confirmed by multiphoton laser scanning microscopy colocalization of TR-ACBP with DHE (naturally-fluorescent sterol) and by double immunofluorescence labeling of native endogenous ACBP. Serum greatly and Pep-1 further 2.4-fold facilitated uptake of TR-ACBP, but neither altered the relative proportion of TR-ACBP colocalized with membranes/organelles (nearly 80%) vs cytoplasm and/or nucleoplasm (20%). Interestingly, Pep-1 selectively increased TR-ACBP associated with mitochondria while concomitantly decreasing that in endoplasmic reticulum. In summary, fluorescent sterols (DChol, DHE) were useful markers for comparing the distributions of both transported and endogenous proteins. Pep-1 modestly enhanced the translocation and altered the intracellular targeting of exogenous-delivered (TR-ACBP) in living cells.
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Affiliation(s)
- Anca D. Petrescu
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Aude Vespa
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Huan Huang
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Avery L. McIntosh
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Friedhelm Schroeder
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Ann B. Kier
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4467
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Acyl-CoA-binding protein (ACBP) localizes to the endoplasmic reticulum and Golgi in a ligand-dependent manner in mammalian cells. Biochem J 2008; 410:463-72. [PMID: 17953517 DOI: 10.1042/bj20070559] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present study, we microinjected fluorescently labelled liver bovine ACBP (acyl-CoA-binding protein) [FACI-50 (fluorescent acyl-CoA indicator-50)] into HeLa and BMGE (bovine mammary gland epithelial) cell lines to characterize the localization and dynamics of ACBP in living cells. Results showed that ACBP targeted to the ER (endoplasmic reticulum) and Golgi in a ligand-binding-dependent manner. A variant Y28F/K32A-FACI-50, which is unable to bind acyl-CoA, did no longer show association with the ER and became segregated from the Golgi, as analysed by intensity correlation calculations. Depletion of fatty acids from cells by addition of FAFBSA (fatty-acid-free BSA) significantly decreased FACI-50 association with the Golgi, whereas fatty acid overloading increased Golgi association, strongly supporting that ACBP associates with the Golgi in a ligand-dependent manner. FRAP (fluorescence recovery after photobleaching) showed that the fatty-acid-induced targeting of FACI-50 to the Golgi resulted in a 5-fold reduction in FACI-50 mobility. We suggest that ACBP is targeted to the ER and Golgi in a ligand-binding-dependent manner in living cells and propose that ACBP may be involved in vesicular trafficking.
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Soupene E, Serikov V, Kuypers FA. Characterization of an acyl-coenzyme A binding protein predominantly expressed in human primitive progenitor cells. J Lipid Res 2008; 49:1103-12. [PMID: 18268358 DOI: 10.1194/jlr.m800007-jlr200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Human acyl-coenzyme A binding domain-containing member 6 (ACBD6) is a modular protein that carries an acyl-CoA binding domain at its N terminus and two ankyrin motifs at its C terminus. ACBD6 binds long-chain acyl-CoAs with a strong preference for unsaturated, C18:1-CoA and C20:4-CoA, over saturated, C16:0-CoA, acyl species. Deletion of the C terminus, which is not conserved among the members of this family, did not affect the binding capacity or the substrate specificity of the protein. ACBD6 is not a ubiquitous protein, and its expression is restricted to tissues and progenitor cells with functions in blood and vessel development. ACBD6 was detected in bone marrow, spleen, placenta, cord blood, circulating CD34+ progenitors, and embryonic-like stem cells derived from placenta. In placenta, the protein was only detected in CD34+ progenitor cells present in blood and in CD31+ endothelial cells surrounding the blood vessels. These cells were also positive for the marker CD133, and they probably constitute hemangiogenic stem cells, precursors of both blood and vessels. We propose that human ACBD6 represents a cellular marker for primitive progenitor cells with functions in hematopoiesis and vascular endothelium development.
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Affiliation(s)
- Eric Soupene
- Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA.
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Structural and functional characterization of a new recombinant histidine-tagged acyl coenzyme A binding protein (ACBP) from mouse. Protein Expr Purif 2007; 58:184-93. [PMID: 18178100 DOI: 10.1016/j.pep.2007.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 11/19/2007] [Accepted: 11/20/2007] [Indexed: 10/22/2022]
Abstract
Acyl coenzyme A binding protein (ACBP) has been proposed to transport fatty acyl CoAs intracellularly, facilitating their metabolism. In this study, a new mouse recombinant ACBP was produced by insertion of a histidine (his) tag at the C-terminus to allow efficient purification by Ni-affinity chromatography. The his-tag was inserted at the C-terminus since ACBP is a small molecular size (10 kDa) protein whose structure and activity are sensitive to amino acid substitutions in the N-terminus. The his-tag had no or little effect on ACBP structure or ligand binding affinity and specificity. His-ACBP bound the naturally occurring fluorescent cis-parinaroyl-CoA with very high affinity (K(d)=2.15 nM), but exhibited no affinity for non-esterified cis-parinaric acid. To determine if the presence of the C-terminal his-tag altered ACBP interactions with other proteins, direct binding to hepatocyte nuclear factor-4alpha (HNF-4alpha), a nuclear receptor regulating transcription of genes involved in lipid metabolism, was examined. His-ACBP and HNF-4alpha were labeled with Cy5 and Cy3, respectively, and direct interaction was determined by a novel fluorescence resonance energy transfer (FRET) binding assay. FRET analysis showed that his-ACBP directly interacted with HNF-4alpha (intermolecular distance of 73 A) at high affinity (K(d)=64-111 nM) similar to native ACBP. The his-tag also had no effect on ACBPs ability to interact with and stimulate microsomal enzymes utilizing or forming fatty acyl CoA. Thus, C-terminal his-tagged-ACBP maintained very similar structural and functional features of the untagged native protein and can be used in further in vitro experiments that require pure recombinant ACBP.
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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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Faergeman NJ, Wadum M, Feddersen S, Burton M, Kragelund BB, Knudsen J. Acyl-CoA binding proteins; structural and functional conservation over 2000 MYA. Mol Cell Biochem 2007; 299:55-65. [PMID: 17013545 DOI: 10.1007/s11010-005-9040-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Besides serving as essential substrates for beta-oxidation and synthesis of triacylglycerols and more complex lipids like sphingolipids and sterol esters, long-chain fatty acyl-CoA esters are increasingly being recognized as important regulators of enzyme activities and gene transcription. Acyl-CoA binding protein, ACBP, has been proposed to play a pivotal role in the intracellular trafficking and utilization of long-chain fatty acyl-CoA esters. Depletion of acyl-CoA binding protein in yeast results in aberrant organelle morphology incl. fragmented vacuoles, multi-layered plasma membranes and accumulation of vesicles of variable sizes. In contrast to synthesis and turn-over of glycerolipids, the levels of very-long-chain fatty acids, long-chain bases and ceramide are severely affected by Acb1p depletion, suggesting that Acb1p, rather than playing a general role, serves specific roles in cellular lipid metabolism.
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Affiliation(s)
- Nils J Faergeman
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark.
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Taskinen JP, van Aalten DM, Knudsen J, Wierenga RK. High resolution crystal structures of unliganded and liganded human liver ACBP reveal a new mode of binding for the acyl-CoA ligand. Proteins 2007; 66:229-38. [PMID: 17044054 DOI: 10.1002/prot.21124] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The acyl-CoA binding protein (ACBP) is essential for the fatty acid metabolism, membrane structure, membrane fusion, and ceramide synthesis. Here high resolution crystal structures of human cytosolic liver ACBP, unliganded and liganded with a physiological ligand, myristoyl-CoA are described. The binding of the acyl-CoA molecule induces only few structural differences near the binding pocket. The crystal form of the liganded ACBP, which has two ACBP molecules in the asymmetric unit, shows that in human ACBP the same acyl-CoA binding pocket is present as previously described for the bovine and Plasmodium falciparum ACBP and the mode of binding of the 3'-phosphate-AMP moiety is conserved. Unexpectedly, in one of the acyl-CoA binding pockets the acyl moiety is bound in a reversed mode as compared with the bovine and P. falciparum structures. In this binding mode, the myristoyl-CoA molecule is fully ordered and bound across the two ACBP molecules of the crystallographic asymmetric unit: the 3'-phosphate-AMP moiety is bound in the binding pocket of one ACBP molecule and the acyl chain is bound in the pocket of the other ACBP molecule. The remaining binding pocket cavities of these two ACBP molecules are filled by other ligand fragments. This novel binding mode shows that the acyl moiety can flip out of its classical binding pocket and bind elsewhere, suggesting a mechanism for the acyl-CoA transfer between ACBP and the active site of a target enzyme. This mechanism is of possible relevance for the in vivo function of ACBP.
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Affiliation(s)
- Jukka P Taskinen
- Biocenter Oulu and Department of Biochemistry, University of Oulu, FIN-90014, Finland
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Schønberg SA, Lundemo AG, Fladvad T, Holmgren K, Bremseth H, Nilsen A, Gederaas O, Tvedt KE, Egeberg KW, Krokan HE. Closely related colon cancer cell lines display different sensitivity to polyunsaturated fatty acids, accumulate different lipid classes and downregulate sterol regulatory element-binding protein 1. FEBS J 2006; 273:2749-65. [PMID: 16817902 DOI: 10.1111/j.1742-4658.2006.05292.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
N-6 polyunsaturated fatty acids (PUFAs) may be associated with increased risk of colon cancer, whereas n-3 PUFAs may have a protective effect. We examined the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid and arachidonic acid on the colon carcinoma cell lines SW480 derived from a primary tumour, and SW620 derived from a metastasis of the same tumour. DHA had the strongest growth-inhibitory effect on both cell lines. SW620 was relatively more growth-inhibited than SW480, but SW620 also had the highest growth rate in the absence of PUFAs. Flow cytometry revealed an increase in the fraction of cells in the G2/M phase of the cell cycle, particularly for SW620 cells. Growth inhibition was apparently not caused by increased lipid peroxidation, reduced glutathione or low activity of glutathione peroxidase. Transmission electron microscopy revealed formation of cytoplasmic lipid droplets after DHA treatment. In SW620 cells an eightfold increase in total cholesteryl esters and a 190-fold increase in DHA-containing cholesteryl esters were observed after DHA treatment. In contrast, SW480 cells accumulated DHA-enriched triglycerides. Arachidonic acid accumulated in a similar manner, whereas the nontoxic oleic acid was mainly incorporated in triglycerides in both cell lines. Interestingly, nuclear sterol regulatory element-binding protein 1 (nSREBP1), recently associated with cell growth regulation, was downregulated after DHA treatment in both cell lines. Our results demonstrate cell-specific mechanisms for the processing and storage of cytotoxic PUFAs in closely related cell lines, and suggest downregulation of nSREBP1 as a possible contributor to the growth inhibitory effect of DHA.
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Affiliation(s)
- Svanhild A Schønberg
- Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, Trondheim, Norway.
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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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Milis DG, Moore MK, Atshaves BP, Schroeder F, Jefferson JR. Sterol carrier protein-2 expression alters sphingolipid metabolism in transfected mouse L-cell fibroblasts. Mol Cell Biochem 2006; 283:57-66. [PMID: 16444586 DOI: 10.1007/s11010-006-2270-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 08/18/2005] [Indexed: 10/25/2022]
Abstract
The influence of sterol carrier protein-2 (SCP-2) on the cellular metabolism of sphingolipids was examined in control mouse L-cells and stably transfected clones expressing the protein SCP-2. Three approaches were used to examine for differences; (1) compositional analysis of endogenous sphingolipid classes, (2) metabolism of NBD-ceramide, and (3) live cell labelling via endocytic uptake of BODIPY-sphingomyelin. SCP-2 over expression significantly altered the endogenous levels of both neutral and acidic sphingolipid classes. Among the neutral sphingolipids, expression of SCP-2 induced a 1.7-fold increase in the level of lactosylceramide (LacCer, p < 0.05) and a similar fold decrease in the level of the higher-order neutral glycosylceramides (p < 0.05). Among the acidic sphingolipids, SCP-2 resulted in a 5.2-fold decrease in the endogenous plasma membrane level of ganglioside GM1 (p < 0.03). Incubation of both control and transfected cell lines with NBD-ceramide resulted in the rapid establishment of a steady-state distribution of NBD-labelled sphingomyelin (NBD-SM) and glucosylceramide (NBD-GlcCer). In the SCP-2 expressing clones the conversion of NBD-Cer to NBD-GlcCer was 30% lower during incubation periods between 5 and 30 min (p < 0.025). Inspection of the cells by fluorescence microscopy after incubation with BODIPY labelled sphingomyelin (BODIPY-SM) revealed similar punctuated patterns with no distinguishable differences between the cell types. These results imply that SCP-2 plays a role in modulating enzymatic steps involved in metabolism of sphingolipid homeostasis.
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Affiliation(s)
- Daniel G Milis
- Department of Chemistry, Luther College, Decorah, Iowa, 52101-1045, USA
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