1
|
Agellon LB. Importance of fatty acid binding proteins in cellular function and organismal metabolism. J Cell Mol Med 2023; 28:e17703. [PMID: 36876733 PMCID: PMC10902576 DOI: 10.1111/jcmm.17703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/25/2023] [Accepted: 02/14/2023] [Indexed: 03/07/2023] Open
Abstract
Fatty acid binding proteins (Fabps) are small soluble proteins that are abundant in the cytosol. These proteins are known to bind a myriad of small hydrophobic molecules and have been postulated to serve a variety of roles, yet their precise functions have remained an enigma over half a century of study. Here, we consider recent findings, along with the cumulative findings contributed by many laboratories working on Fabps over the last half century, to synthesize a new outlook for what functions Fabps serve in cells and organisms. Collectively, the findings illustrate that Fabps function as versatile multi-purpose devices serving as sensors, conveyors and modulators to enable cells to detect and handle a specific class of metabolites, and to adjust their metabolic capacity and efficiency.
Collapse
Affiliation(s)
- Luis B Agellon
- School of Human Nutrition, McGill University, Ste. Anne de Bellevue, Quebec, Canada
| |
Collapse
|
2
|
Wiarda JE, Becker SR, Sivasankaran SK, Loving CL. Regional epithelial cell diversity in the small intestine of pigs. J Anim Sci 2023; 101:skac318. [PMID: 36183288 PMCID: PMC9831138 DOI: 10.1093/jas/skac318] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 09/28/2022] [Indexed: 01/13/2023] Open
Abstract
Understanding regional distribution and specialization of small intestinal epithelial cells is crucial for developing methods to control appetite, stress, and nutrient uptake in swine. To establish a better understanding of specific epithelial cells found across different regions of the small intestine in pigs, we utilized single-cell RNA sequencing (scRNA-seq) to recover and analyze epithelial cells from duodenum, jejunum, and ileum. Cells identified included crypt cells, enterocytes, BEST4 enterocytes, goblet cells, and enteroendocrine (EE) cells. EE cells were divided into two subsets based on the level of expression of the EE lineage commitment gene, NEUROD1. NEUROD1hi EE cells had minimal expression of hormone-encoding genes and were dissimilar to EE cells in humans and mice, indicating a subset of EE cells unique to pigs. Recently discovered BEST4 enterocytes were detected in both crypts and villi throughout the small intestine via in situ staining, unlike in humans, where BEST4 enterocytes are found only in small intestinal villi. Proximal-to-distal gradients of expression were noted for hormone-encoding genes in EE cells and nutrient transport genes in enterocytes via scRNA-seq, demonstrating regional specialization. Regional gene expression in EE cells and enterocytes was validated via quantitative PCR (qPCR) analysis of RNA isolated from epithelial cells of different small intestinal locations. Though many genes had similar patterns of regional expression when assessed by qPCR of total epithelial cells, some regional expression was only detected via scRNA-seq, highlighting advantages of scRNA-seq to deconvolute cell type-specific regional gene expression when compared to analysis of bulk samples. Overall, results provide new information on regional localization and transcriptional profiles of epithelial cells in the pig small intestine.
Collapse
Affiliation(s)
- Jayne E Wiarda
- Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA, USA
- Immunobiology Graduate Program, Iowa State University, Ames, IA, USA
- Department of Veterinary Microbiology and Preventative Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
- Oak Ridge Institute for Science and Education, Agricultural Research Service Participation Program, Oak Ridge, TN, USA
| | - Sage R Becker
- Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA, USA
- Immunobiology Graduate Program, Iowa State University, Ames, IA, USA
- Department of Veterinary Microbiology and Preventative Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Sathesh K Sivasankaran
- Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA, USA
- Genome Informatics Facility, Iowa State University, Ames, IA, USA
| | - Crystal L Loving
- Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA, USA
- Immunobiology Graduate Program, Iowa State University, Ames, IA, USA
| |
Collapse
|
3
|
Chen Y, Agellon LB. Distinct Alteration of Gene Expression Programs in the Small Intestine of Male and Female Mice in Response to Ablation of Intestinal Fabp Genes. Genes (Basel) 2020; 11:genes11080943. [PMID: 32824144 PMCID: PMC7465894 DOI: 10.3390/genes11080943] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/02/2020] [Accepted: 08/13/2020] [Indexed: 02/07/2023] Open
Abstract
Fatty acid-binding proteins (Fabps) make up a family of widely distributed cytoplasmic lipid-binding proteins. The small intestine contains three predominant Fabp species, Fabp1, Fabp2, and Fabp6. Our previous studies showed that Fabp2 and Fabp6 gene-disrupted mice exhibited sexually dimorphic phenotypes. In this study, we carried out a systematic comparative analysis of the small intestinal transcriptomes of 10 week-old wild-type (WT) and Fabp gene-disrupted male and female mice. We found that the small intestinal transcriptome of male and female mice showed key differences in the gene expression profiles that affect major biological processes. The deletion of specific Fabp genes induced unique and sex-specific changes in the gene expression program, although some differentially expressed genes in certain genotypes were common to both sexes. Functional annotation and interaction network analyses revealed that the number and type of affected pathways, as well as the sets of interacting nodes in each of the Fabp genotypes, are partitioned by sex. To our knowledge, this is the first time that sex differences were identified and categorized at the transcriptome level in mice lacking different intestinal Fabps. The distinctive transcriptome profiles of WT male and female small intestine may predetermine the nature of transcriptional reprogramming that manifests as sexually dimorphic responses to the ablation of intestinal Fabp genes.
Collapse
|
4
|
Jung J, Wang J, Groenendyk J, Lee D, Michalak M, Agellon LB. Fatty acid binding protein (Fabp) 5 interacts with the calnexin cytoplasmic domain at the endoplasmic reticulum. Biochem Biophys Res Commun 2017; 493:202-206. [PMID: 28911862 DOI: 10.1016/j.bbrc.2017.09.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 09/09/2017] [Indexed: 10/18/2022]
Abstract
Calnexin is a type 1 integral endoplasmic reticulum membrane molecular chaperone with an endoplasmic reticulum luminal chaperone domain and a highly conserved C-terminal domain oriented to the cytoplasm. Fabp5 is a cytoplasmic protein that binds long-chain fatty acids and other lipophilic ligands. Using a yeast two-hybrid screen, immunoprecipitation, microscale thermophoresis analysis and cellular fractionation, we discovered that Fabp5 interacts with the calnexin cytoplasmic C-tail domain at the endoplasmic reticulum. These observations identify Fabp5 as a previously unrecognized calnexin binding partner.
Collapse
Affiliation(s)
- Joanna Jung
- Departments of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Jessica Wang
- Departments of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Jody Groenendyk
- Departments of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Dukgyu Lee
- School of Human Nutrition, McGill University, Ste. Anne de Bellevue, Quebec, H9X 3V9, Canada
| | - Marek Michalak
- Departments of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Luis B Agellon
- School of Human Nutrition, McGill University, Ste. Anne de Bellevue, Quebec, H9X 3V9, Canada.
| |
Collapse
|
5
|
Duggavathi R, Siddappa D, Schuermann Y, Pansera M, Menard IJ, Praslickova D, Agellon LB. The fatty acid binding protein 6 gene (Fabp6) is expressed in murine granulosa cells and is involved in ovulatory response to superstimulation. J Reprod Dev 2015; 61:237-40. [PMID: 25754072 PMCID: PMC4498371 DOI: 10.1262/jrd.2014-139] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The fatty acid binding protein 6 (Fabp6) is commonly regarded as a bile acid binding protein found in the distal portion of the small intestine and has been shown to be important in maintaining bile acid homeostasis. Previous studies have also reported the presence of Fabp6 in human, rat and fish ovaries, but the significance of Fabp6 in this organ is largely unknown. Therefore, we surveyed murine ovaries for Fabp6 gene expression and evaluated its role in ovarian function using mice with whole body Fabp6 deficiency. Here we show that the Fabp6 gene is expressed in granulosa and luteal cells of the mouse ovary. Treatment with gonadotropins stimulated Fabp6 gene expression in large antral follicles. The ovulation rate in response to superovulatory treatment in Fabp6-deficient mice was markedly decreased compared to wildtype (C57BL/6) mice. The results of this study suggest that expression of Fabp6 gene in
granulosa cells serves an important and previously unrecognized function in fertility.
Collapse
Affiliation(s)
- Raj Duggavathi
- Department of Animal Sciences, McGill University, Quebec H9X 3V9, Canada
| | | | | | | | | | | | | |
Collapse
|
6
|
Dawson PA, Karpen SJ. Intestinal transport and metabolism of bile acids. J Lipid Res 2014; 56:1085-99. [PMID: 25210150 DOI: 10.1194/jlr.r054114] [Citation(s) in RCA: 335] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Indexed: 12/17/2022] Open
Abstract
In addition to their classical roles as detergents to aid in the process of digestion, bile acids have been identified as important signaling molecules that function through various nuclear and G protein-coupled receptors to regulate a myriad of cellular and molecular functions across both metabolic and nonmetabolic pathways. Signaling via these pathways will vary depending on the tissue and the concentration and chemical structure of the bile acid species. Important determinants of the size and composition of the bile acid pool are their efficient enterohepatic recirculation, their host and microbial metabolism, and the homeostatic feedback mechanisms connecting hepatocytes, enterocytes, and the luminal microbiota. This review focuses on the mammalian intestine, discussing the physiology of bile acid transport, the metabolism of bile acids in the gut, and new developments in our understanding of how intestinal metabolism, particularly by the gut microbiota, affects bile acid signaling.
Collapse
Affiliation(s)
- Paul A Dawson
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Emory University, Atlanta, GA 30322
| | - Saul J Karpen
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Emory University, Atlanta, GA 30322
| |
Collapse
|
7
|
Hemmerling J, Heller K, Hörmannsperger G, Bazanella M, Clavel T, Kollias G, Haller D. Fetal exposure to maternal inflammation does not affect postnatal development of genetically-driven ileitis and colitis. PLoS One 2014; 9:e98237. [PMID: 24849654 PMCID: PMC4029898 DOI: 10.1371/journal.pone.0098237] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 04/29/2014] [Indexed: 12/19/2022] Open
Abstract
Background: Chronic inflammatory disorders have been increasing in incidence over the past decades following geographical patterns of industrialization. Fetal exposure to maternal inflammation may alter organ functions and the offspring's disease risk. We studied the development of genetically-driven ileitis and colitis in response to maternal inflammation using mouse models. Methods: Disease susceptible (TnfΔARE/+ and IL10−/−) and disease-free (Tnf+/+ and IL10−/+) offspring were raised in inflamed and non-inflamed dams. Ileal, caecal and colonic pathology was evaluated in the offspring at 8 or 12 weeks of age. Ly6G-positive cells in inflamed sections from the distal ileum and distal colon were analysed by immunofluorescence microscopy. Gene expression of pro-inflammatory cytokines was measured in whole tissue specimens by quantitative PCR. Microarray analyses were performed on laser microdissected intestinal epithelium. Caecal bacterial communities were assessed by Illumina sequencing of 16S rRNA amplicons. Results: Disease severity, the number of infiltrated neutrophils as well as Tnf and Il12p40 mRNA expression were independent of maternal inflammation in the offspring of mouse models for ileitis (TnfΔARE/+) and colitis (IL10−/−). Although TNF-driven maternal inflammation regulated 2,174 (wild type) and 3,345 (TnfΔARE/+) genes in the fetal epithelium, prenatal gene expression patterns were completely overwritten after birth. In addition, co-housing experiments revealed no change in phylogenetic diversity of the offspring's caecal microbiota in response to maternal inflammation. This is independent of the offspring's genotype before and after the onset of tissue pathology. Conclusions: Disease risk and activity in mouse models of chronic ileitis and colitis was independent of the fetal exposure to maternal inflammation. Likewise, maternal inflammation did not alter the diversity and composition of offspring's caecal microbiota, clearly demonstrating that changes of the gene expression program in the fetal gut epithelium were not relevant for the development of chronic inflammatory disorders in the gut.
Collapse
Affiliation(s)
- Jana Hemmerling
- Chair of Nutrition and Immunology, Technische Universität München, Freising- Weihenstephan, Bavaria, Germany
- ZIEL - Research Center for Nutrition and Food Sciences, Freising-Weihenstephan, Bavaria, Germany
| | - Katharina Heller
- Chair of Nutrition and Immunology, Technische Universität München, Freising- Weihenstephan, Bavaria, Germany
- ZIEL - Research Center for Nutrition and Food Sciences, Freising-Weihenstephan, Bavaria, Germany
| | - Gabriele Hörmannsperger
- Chair of Nutrition and Immunology, Technische Universität München, Freising- Weihenstephan, Bavaria, Germany
- ZIEL - Research Center for Nutrition and Food Sciences, Freising-Weihenstephan, Bavaria, Germany
| | - Monika Bazanella
- Chair of Nutrition and Immunology, Technische Universität München, Freising- Weihenstephan, Bavaria, Germany
- ZIEL - Research Center for Nutrition and Food Sciences, Freising-Weihenstephan, Bavaria, Germany
| | - Thomas Clavel
- Chair of Nutrition and Immunology, Technische Universität München, Freising- Weihenstephan, Bavaria, Germany
- ZIEL - Research Center for Nutrition and Food Sciences, Freising-Weihenstephan, Bavaria, Germany
| | - George Kollias
- Biomedical Sciences Research Centre, Institute for Immunology, Alexander Fleming, Vari, Athens, Greece
| | - Dirk Haller
- Chair of Nutrition and Immunology, Technische Universität München, Freising- Weihenstephan, Bavaria, Germany
- ZIEL - Research Center for Nutrition and Food Sciences, Freising-Weihenstephan, Bavaria, Germany
- * E-mail: .
| |
Collapse
|
8
|
Gajda AM, Zhou YX, Agellon LB, Fried SK, Kodukula S, Fortson W, Patel K, Storch J. Direct comparison of mice null for liver or intestinal fatty acid-binding proteins reveals highly divergent phenotypic responses to high fat feeding. J Biol Chem 2013; 288:30330-30344. [PMID: 23990461 DOI: 10.1074/jbc.m113.501676] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The enterocyte expresses two fatty acid-binding proteins (FABP), intestinal FABP (IFABP; FABP2) and liver FABP (LFABP; FABP1). LFABP is also expressed in liver. Despite ligand transport and binding differences, it has remained uncertain whether these intestinally coexpressed proteins, which both bind long chain fatty acids (FA), are functionally distinct. Here, we directly compared IFABP(-/-) and LFABP(-/-) mice fed high fat diets containing long chain saturated or unsaturated fatty acids, reasoning that providing an abundance of dietary lipid would reveal unique functional properties. The results showed that mucosal lipid metabolism was indeed differentially modified, with significant decreases in FA incorporation into triacylglycerol (TG) relative to phospholipid (PL) in IFABP(-/-) mice, whereas LFABP(-/-) mice had reduced monoacylglycerol incorporation in TG relative to PL, as well as reduced FA oxidation. Interestingly, striking differences were found in whole body energy homeostasis; LFABP(-/-) mice fed high fat diets became obese relative to WT, whereas IFABP(-/-) mice displayed an opposite, lean phenotype. Fuel utilization followed adiposity, with LFABP(-/-) mice preferentially utilizing lipids, and IFABP(-/-) mice preferentially metabolizing carbohydrate for energy production. Changes in body weight and fat may arise, in part, from altered food intake; mucosal levels of the endocannabinoids 2-arachidonoylglycerol and arachidonoylethanolamine were elevated in LFABP(-/-), perhaps contributing to increased energy intake. This direct comparison provides evidence that LFABP and IFABP have distinct roles in intestinal lipid metabolism; differential intracellular functions in intestine and in liver, for LFABP(-/-) mice, result in divergent downstream effects at the systemic level.
Collapse
Affiliation(s)
- Angela M Gajda
- From the Department of Nutritional Sciences and; the Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901
| | | | - Luis B Agellon
- the School of Dietetics and Human Nutrition, McGill University, Montréal, Québec H9X 3V9, Canada, and
| | - Susan K Fried
- the Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118
| | | | | | | | - Judith Storch
- From the Department of Nutritional Sciences and; the Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901,.
| |
Collapse
|
9
|
Transport and biological activities of bile acids. Int J Biochem Cell Biol 2013; 45:1389-98. [PMID: 23603607 DOI: 10.1016/j.biocel.2013.04.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 03/30/2013] [Accepted: 04/09/2013] [Indexed: 12/29/2022]
Abstract
Bile acids have emerged as important biological molecules that support the solubilization of various lipids and lipid-soluble compounds in the gut, and the regulation of gene expression and cellular function. Bile acids are synthesized from cholesterol in the liver and eventually released into the small intestine. The majority of bile acids are recovered in the distal end of the small intestine and then returned to the liver for reuse. The components of the mechanism responsible for the recycling of bile acids within the enterohepatic circulation have been identified whereas the mechanism for intracellular transport is less understood. Recently, the ileal lipid binding protein (ILBP; human gene symbol FABP6) was shown to be needed for the efficient transport of bile acids from the apical side to the basolateral side of enterocytes in the distal intestine. This review presents an overview of the transport of bile acids between the liver and the gut as well as within hepatocytes and enterocytes. A variety of pathologies is associated with the malfunction of the bile acid transport system.
Collapse
|
10
|
Praslickova D, Torchia EC, Sugiyama MG, Magrane EJ, Zwicker BL, Kolodzieyski L, Agellon LB. The ileal lipid binding protein is required for efficient absorption and transport of bile acids in the distal portion of the murine small intestine. PLoS One 2012; 7:e50810. [PMID: 23251388 PMCID: PMC3519535 DOI: 10.1371/journal.pone.0050810] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 10/25/2012] [Indexed: 12/11/2022] Open
Abstract
The ileal lipid binding protein (ilbp) is a cytoplasmic protein that binds bile acids with high affinity. However evidence demonstrating the role of this protein in bile acid transport and homeostasis is missing. We created a mouse strain lacking ilbp (Fabp6−/− mice) and assessed the impact of ilbp deficiency on bile acid homeostasis and transport in vivo. Elimination of ilbp increased fecal bile acid excretion (54.2%, P<0.05) in female but not male Fabp6−/− mice. The activity of cholesterol 7α-hydroxylase (cyp7a1), the rate-controlling enzyme of the classical bile acid biosynthetic pathway, was significantly increased in female (63.5%, P<0.05) but not in male Fabp6−/− mice. The amount of [3H]taurocholic acid (TCA) excreted by 24 h after oral administration was 102% (P<0.025) higher for female Fabp6−/− mice whereas it was 57.3% (P<0.01) lower for male Fabp6−/− mice, compared to wild-type mice. The retained fraction of the [3H]TCA localized in the small and large intestines was increased by 22% (P<0.02) and decreased by 62.7% (P<0.01), respectively, in male Fabp6−/− mice relative wild-type mice, whereas no changes were seen in female Fabp6−/− mice. Mucosal to serosal bile acid transport using everted distal gut sacs was decreased by 74% (P<0.03) in both sexes of Fabp6−/− mice as compared to wild-type mice. The results demonstrate that ilbp is involved in the apical to basolateral transport of bile acids in ileal enterocytes, and is vital for the maintenance of bile acid homeostasis in the enterohepatic circulation (EHC) in mice.
Collapse
Affiliation(s)
- Dana Praslickova
- School of Dietetics and Human Nutrition, McGill University, Ste. Anne de Bellevue, Québec, Canada
| | - Enrique C. Torchia
- Canadian Institutes of Health Research Group in Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada
| | - Michael G. Sugiyama
- School of Dietetics and Human Nutrition, McGill University, Ste. Anne de Bellevue, Québec, Canada
| | - Elijah J. Magrane
- School of Dietetics and Human Nutrition, McGill University, Ste. Anne de Bellevue, Québec, Canada
| | - Brittnee L. Zwicker
- School of Dietetics and Human Nutrition, McGill University, Ste. Anne de Bellevue, Québec, Canada
| | - Lev Kolodzieyski
- School of Dietetics and Human Nutrition, McGill University, Ste. Anne de Bellevue, Québec, Canada
- ITR Laboratories Canada, Baie D'Urfe, Québec, Canada
| | - Luis B. Agellon
- School of Dietetics and Human Nutrition, McGill University, Ste. Anne de Bellevue, Québec, Canada
- Canadian Institutes of Health Research Group in Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
| |
Collapse
|
11
|
Velkov T, Lim MLR, Capuano B, Prankerd R. A protocol for the combined sub-fractionation and delipidation of lipid binding proteins using hydrophobic interaction chromatography. J Chromatogr B Analyt Technol Biomed Life Sci 2008; 867:238-46. [PMID: 18456580 DOI: 10.1016/j.jchromb.2008.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Revised: 04/04/2008] [Accepted: 04/09/2008] [Indexed: 10/22/2022]
Abstract
Cellular lipids frequently co-purify with lipid binding proteins isolated from tissue extracts or heterologous host systems and as such hinder in vitro ligand binding approaches for which the apo-protein is a prerequisite. Here we present a technique for the complete removal of unesterified fatty acids, phospholipids, steroids and other lipophilic ligands bound to soluble proteins, without protein denaturation. Peroxisome proliferator activated receptor gamma ligand binding domain and intracellular fatty acid binding proteins were expressed in an Escherichia coli host and completely delipidated by hydrophobic interaction chromatography using phenyl sepharose. The delipidation procedure operates at room temperature with complete removal of bound lipids in a single step, as ascertained by mass spectrometry analysis of organic solvent extracts from purified protein samples. The speed and capacity of this method makes it amenable to scale-up and high-throughput applications. The method can also easily be adapted for other lipid binding proteins that require delipidation under native conditions.
Collapse
Affiliation(s)
- Tony Velkov
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville 3052 Victoria, Australia.
| | | | | | | |
Collapse
|
12
|
Agellon LB, Drozdowski L, Li L, Iordache C, Luong L, Clandinin MT, Uwiera RRE, Toth MJ, Thomson ABR. Loss of intestinal fatty acid binding protein increases the susceptibility of male mice to high fat diet-induced fatty liver. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:1283-8. [PMID: 17905650 DOI: 10.1016/j.bbalip.2007.08.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 08/07/2007] [Accepted: 08/08/2007] [Indexed: 01/20/2023]
Abstract
Mice lacking I-FABP (encoded by the Fabp2 gene) exhibit a gender dimorphic response to a high fat/cholesterol diet challenge characterized by hepatomegaly in male I-FABP-deficient mice. In this study, we determined if this gender-specific modification of liver mass in mice lacking I-FABP is attributable to the high fat content of the diet alone and whether hepatic Fabp1 gene (encodes L-FABP) expression contributes to this difference. Wild-type and Fabp2-/- mice of both genders were fed a diet enriched with either polyunsaturated or saturated fatty acids (PUFA or SFA, respectively) in the absence of cholesterol. Male Fabp2-/- mice, but not female Fabp2-/- mice, exhibited increased liver mass and hepatic triacylglycerol (TG) deposition as compared to corresponding wild-type mice. In wild-type mice that were fed the standard chow diet, there was no difference in the concentration of hepatic L-FABP protein between males and females although the loss of I-FABP did cause a slight reduction of hepatic L-FABP abundance in both genders. The hepatic L-FABP mRNA abundance in both male and female wild-type and Fabp2-/- mice was higher in the PUFA-fed group than in the SFA-fed group, and was correlated with L-FABP protein abundance. No correlation between hepatic L-FABP protein abundance and hepatic TG concentration was found. The results obtained demonstrate that loss of I-FABP renders male mice sensitive to high fat diet-induced fatty liver, and this effect is independent of hepatic L-FABP.
Collapse
Affiliation(s)
- Luis B Agellon
- Canadian Institutes of Health Research Molecular and Cell Biology of Lipids Research Group and Department of Biochemistry, University of Alberta, Edmonton, AB, Canada T6G 2S2.
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Groen A, Kunne C, Paulusma CC, Kramer W, Agellon LB, Bull LN, Oude Elferink RPJ. Intestinal bile salt absorption in Atp8b1 deficient mice. J Hepatol 2007; 47:114-22. [PMID: 17448567 DOI: 10.1016/j.jhep.2007.02.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 02/04/2007] [Accepted: 02/12/2007] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Mutations in the ATP8B1 gene can cause Progressive Familial Intrahepatic Cholestasis type 1. We have previously reported that Atp8b1(G308V/G308V) mice, a model for PFIC1, have slightly, but significantly, higher baseline serum bile salt (BS) concentrations compared to wt mice. Upon BS feeding, serum BS concentrations strongly increased in Atp8b1-deficient mice. Despite these findings, we observed only mildly impaired canalicular BS transport. In the present report we tested the hypothesis that Atp8b1(G308V/G308V) mice hyperabsorb BS in the intestine during BS feeding. METHODS Intestinal BS absorption was measured in intestinal perfusion and in intestinal explants. In addition, we measured BS concentrations in portal blood. Ileal expression of the Fxr-targets Asbt, Ilbp and Shp was assessed. RESULTS In wt and Atp8b1(G308V/G308V) mice, intestinal taurocholate absorption is primarily mediated by the ileal bile salt transporter Asbt. Neither of the experimental systems revealed enhanced absorption of BS in Atp8b1(G308V/G308V) mice compared to wt mice. In line with these observations, we found no difference in the ileal protein expression of Asbt. Induction of Shp expression during BS feeding also demonstrated that Fxr signalling is intact in Atp8b1(G308V/G308V) mice. CONCLUSIONS The accumulation of BS in plasma of Atp8b1(G308V/G308V) mice during BS feeding is not caused by increased intestinal BS absorption.
Collapse
Affiliation(s)
- Annemiek Groen
- AMC Liver Center, Academic Medical Center, Room S1-166, Meibergdreef 69-71, 1105 BK Amsterdam, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
14
|
Agellon LB, Li L, Luong L, Uwiera RRE. Adaptations to the loss of intestinal fatty acid binding protein in mice. Mol Cell Biochem 2006; 284:159-66. [PMID: 16532262 DOI: 10.1007/s11010-005-9042-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
It was shown previously that the intestinal fatty acid binding protein (I-FABP) is not essential for the absorption of dietary fat. One notable feature of I-FABP deficiency was the enhancement of body weight gain in male mice but not in female mice. To explore a possible cause for this gender dimorphic effect, we examined the changes in expression of genes that encode liver fatty acid binding protein (L-FABP) and ileal lipid binding protein in the small intestine resulting from I-FABP deficiency. The results indicate that both L-FABP and ilbp levels are modestly increased in the small intestine of chow-fed mice lacking I-FABP. There was no discernible alteration of overall morphology or histology in the small intestine but changes in liver histology were evident in I-FABP deficient male mice. Glucose tolerance was also investigated in aged mice. I-FABP deficiency had no effect on glucose tolerance in male mice but it appeared to be improved in female mice. Thus, male and female mice clearly respond differently to the loss of I-FABP from the small intestine but the observed changes in the abundance of L-FABP and ilbp protein do not readily account for this phenomenon.
Collapse
Affiliation(s)
- Luis B Agellon
- Department of Biochemistry, Canadian Institutes of Health Research Group in Molecular and Cell Biology of Lipids, Edmonton, Canada.
| | | | | | | |
Collapse
|
15
|
Hulzebos CV, Voshol PJ, Wolters H, Kruit JK, Ottenhof R, Groen AK, Stellaard F, Verkade HJ, Kuipers F. Bile duct proliferation associated with bile salt-induced hypercholeresis in Mdr2 P-glycoprotein-deficient mice. Liver Int 2005; 25:604-12. [PMID: 15910498 DOI: 10.1111/j.1478-3231.2005.01036.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND/AIMS Bile flow consists of bile salt-dependent bile flow (BSDF), generated by canalicular secretion of bile salts, and bile salt-independent flow (BSIF), probably of combined canalicular and ductular origin. Bile salt transport proteins have been identified in cholangiocytes, suggesting a role in control of BSDF and/or in control of bile salt synthesis through cholehepatic shunting. METHODS We studied effects of bile duct proliferation under non-cholestatic conditions in multidrug resistance-2 P-glycoprotein (Abcb4)-deficient multidrug resistance gene-2 (Mdr2(-/-)) mice. BSDF and BSIF were determined in wild-type and Mdr2(-/-) mice during infusion of step-wise increasing dosages of tauroursodeoxycholate (TUDC). Cholate synthesis rate was determined by 2H4-cholate dilution. Results were related to expression of transport proteins in liver and intestine. RESULTS During TUDC infusion, BSDF was increased by approximately 50% and BSIF by approximately 100% in Mdr2(-/-) mice compared with controls. Cholate synthesis rate was unaffected in Mdr2(-/-) mice. Hepatic expression of the apical sodium-dependent bile salt transporter (Asbt), its truncated form (tAsbt) and the multidrug resistance-related protein 3 were upregulated in Mdr2(-/-) mice. CONCLUSIONS Bile duct proliferation in Mdr2(-/-) mice enhances cholehepatic shunting of bile salts, which is associated with a disproportionally high bile flow but does not affect bile salt synthesis.
Collapse
Affiliation(s)
- Christian V Hulzebos
- Center for Liver, Digestive and Metabolic Diseases, Department of Pediatrics, University Hospital Groningen, Groningen, The Netherlands
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Kok T, Hulzebos CV, Wolters H, Havinga R, Agellon LB, Stellaard F, Shan B, Schwarz M, Kuipers F. Enterohepatic circulation of bile salts in farnesoid X receptor-deficient mice: efficient intestinal bile salt absorption in the absence of ileal bile acid-binding protein. J Biol Chem 2003; 278:41930-7. [PMID: 12917447 DOI: 10.1074/jbc.m306309200] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bile salt-activated farnesoid X receptor (FXR; NR1H4) controls expression of several genes considered crucial in maintenance of bile salt homeostasis. We evaluated the physiological consequences of FXR deficiency on bile formation and on the kinetics of the enterohepatic circulation of cholate, the major bile salt species in mice. The pool size, fractional turnover rate, synthesis rate, and intestinal absorption of cholate were determined by stable isotope dilution and were related to expression of relevant transporters in the livers and intestines of FXR-deficient (Fxr-/-) mice. Fxr-/- mice showed only mildly elevated plasma bile salt concentrations associated with a 2.4-fold higher biliary bile salt output, whereas hepatic mRNA levels of the bile salt export pump were decreased. Cholate pool size and total bile salt pool size were increased by 67 and 39%, respectively, in Fxr-/- mice compared with wild-type mice. The cholate synthesis rate was increased by 85% in Fxr-/- mice, coinciding with a 2.5-fold increase in cholesterol 7alpha-hydroxylase (Cyp7a1) and unchanged sterol 12alpha-hydroxylase (Cyp8b1) expression in the liver. Despite a complete absence of ileal bile acid-binding protein mRNA and protein, the fractional turnover rate and cycling time of the cholate pool were not affected. The calculated amount of cholate reabsorbed from the intestine per day was approximately 2-fold higher in Fxr-/- mice than in wild-type mice. Thus, the absence of FXR in mice is associated with defective feedback inhibition of hepatic cholate synthesis, which leads to enlargement of the circulating cholate pool with an unaltered fractional turnover rate. The absence of ileal bile acid-binding protein does not negatively interfere with the enterohepatic circulation of cholate in mice.
Collapse
Affiliation(s)
- Tineke Kok
- Groningen University Institute for Drug Exploration, Center for Liver, Digestive, and Metabolic Diseases, University Hospital Groningen, CMC IV, Rm. Y2.163, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
| | | | | | | | | | | | | | | | | |
Collapse
|