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Wu K, Liu Y, Xia J, Liu J, Wang K, Liang H, Xu F, Liu D, Nie D, Tang X, Huang A, Chen C, Tang N. Loss of SLC27A5 Activates Hepatic Stellate Cells and Promotes Liver Fibrosis via Unconjugated Cholic Acid. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2304408. [PMID: 37957540 PMCID: PMC10787101 DOI: 10.1002/advs.202304408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 10/11/2023] [Indexed: 11/15/2023]
Abstract
Although the dysregulation of bile acid (BA) composition has been associated with fibrosis progression, its precise roles in liver fibrosis is poorly understood. This study demonstrates that solute carrier family 27 member 5 (SLC27A5), an enzyme involved in BAs metabolism, is substantially downregulated in the liver tissues of patients with cirrhosis and fibrosis mouse models. The downregulation of SLC27A5 depends on RUNX family transcription factor 2 (RUNX2), which serves as a transcriptional repressor. The findings reveal that experimental SLC27A5 knockout (Slc27a5-/- ) mice display spontaneous liver fibrosis after 24 months. The loss of SLC27A5 aggravates liver fibrosis induced by carbon tetrachloride (CCI4 ) and thioacetamide (TAA). Mechanistically, SLC27A5 deficiency results in the accumulation of unconjugated BA, particularly cholic acid (CA), in the liver. This accumulation leads to the activation of hepatic stellate cells (HSCs) by upregulated expression of early growth response protein 3 (EGR3). The re-expression of hepatic SLC27A5 by an adeno-associated virus or the reduction of CA levels in the liver using A4250, an apical sodium-dependent bile acid transporter (ASBT) inhibitor, ameliorates liver fibrosis in Slc27a5-/- mice. In conclusion, SLC27A5 deficiency in mice drives hepatic fibrosis through CA-induced activation of HSCs, highlighting its significant implications for liver fibrosis treatment.
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Affiliation(s)
- Kang Wu
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Yi Liu
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Jie Xia
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Jiale Liu
- Institute of Life SciencesChongqing Medical UniversityChongqing400016China
| | - Kai Wang
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Huijun Liang
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Fengli Xu
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Dina Liu
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Dan Nie
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Xin Tang
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Ailong Huang
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
| | - Chang Chen
- Institute of Life SciencesChongqing Medical UniversityChongqing400016China
| | - Ni Tang
- Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)Institute for Viral HepatitisDepartment of Infectious DiseasesThe Second Affiliated HospitalChongqing Medical UniversityChongqing400010China
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2
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Xiang T, Deng Z, Yang C, Tan J, Dou C, Luo F, Chen Y. Bile acid metabolism regulatory network orchestrates bone homeostasis. Pharmacol Res 2023; 196:106943. [PMID: 37777075 DOI: 10.1016/j.phrs.2023.106943] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/18/2023] [Accepted: 09/28/2023] [Indexed: 10/02/2023]
Abstract
Bile acids (BAs), synthesized in the liver and modified by the gut microbiota, have been widely appreciated not only as simple lipid emulsifiers, but also as complex metabolic regulators and momentous signaling molecules, which play prominent roles in the complex interaction among several metabolic systems. Recent studies have drawn us eyes on the diverse physiological functions of BAs, to enlarge the knowledge about the "gut-bone" axis due to the participation about the gut microbiota-derived BAs to modulate bone homeostasis at physiological and pathological stations. In this review, we have summarized the metabolic processes of BAs and highlighted the crucial roles of BAs targeting bile acid-activated receptors, promoting the proliferation and differentiation of osteoblasts (OBs), inhibiting the activity of osteoclasts (OCs), as well as reducing articular cartilage degradation, thus facilitating bone repair. In addition, we have also focused on the bidirectional effects of BA signaling networks in coordinating the dynamic balance of bone matrix and demonstrated the promising effects of BAs on the development or treatment for pathological bone diseases. In a word, further clinical applications targeting BA metabolism or modulating gut metabolome and related derivatives may be developed as effective therapeutic strategies for bone destruction diseases.
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Affiliation(s)
- Tingwen Xiang
- Department of Orthopedics, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, China; College of Basic Medical Science, Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Zihan Deng
- Department of Orthopedics, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Chuan Yang
- Department of Biomedical Materials Science, Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Jiulin Tan
- Department of Orthopedics, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Ce Dou
- Department of Orthopedics, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, China.
| | - Fei Luo
- Department of Orthopedics, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, China.
| | - Yueqi Chen
- Department of Orthopedics, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, China.
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3
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Chen CT, Shao Z, Fu Z. Dysfunctional peroxisomal lipid metabolisms and their ocular manifestations. Front Cell Dev Biol 2022; 10:982564. [PMID: 36187472 PMCID: PMC9524157 DOI: 10.3389/fcell.2022.982564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 08/17/2022] [Indexed: 11/13/2022] Open
Abstract
Retina is rich in lipids and dyslipidemia causes retinal dysfunction and eye diseases. In retina, lipids are not only important membrane component in cells and organelles but also fuel substrates for energy production. However, our current knowledge of lipid processing in the retina are very limited. Peroxisomes play a critical role in lipid homeostasis and genetic disorders with peroxisomal dysfunction have different types of ocular complications. In this review, we focus on the role of peroxisomes in lipid metabolism, including degradation and detoxification of very-long-chain fatty acids, branched-chain fatty acids, dicarboxylic acids, reactive oxygen/nitrogen species, glyoxylate, and amino acids, as well as biosynthesis of docosahexaenoic acid, plasmalogen and bile acids. We also discuss the potential contributions of peroxisomal pathways to eye health and summarize the reported cases of ocular symptoms in patients with peroxisomal disorders, corresponding to each disrupted peroxisomal pathway. We also review the cross-talk between peroxisomes and other organelles such as lysosomes, endoplasmic reticulum and mitochondria.
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Affiliation(s)
- Chuck T. Chen
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Zhuo Shao
- Post-Graduate Medical Education, University of Toronto, Toronto, ON, Canada
- Division of Clinical and Metabolic Genetics, the Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- The Genetics Program, North York General Hospital, University of Toronto, Toronto, ON, Canada
| | - Zhongjie Fu
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States
- *Correspondence: Zhongjie Fu,
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Tian Y, Cai J, Allman EL, Smith PB, Patterson AD. Quantitative Analysis of Bile Acid with UHPLC-MS/MS. Methods Mol Biol 2021; 2194:291-300. [PMID: 32926372 DOI: 10.1007/978-1-0716-0849-4_15] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Bile acids are important end products of cholesterol metabolism, having been shown to serve as signaling molecules and intermediates between the host and the gut microbiota. Here we describe a robust and accurate method using ultrahigh-pressure liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) for the quantification of bile acids in stool/cecal and tissue samples.
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Affiliation(s)
- Yuan Tian
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Jingwei Cai
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Erik L Allman
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Philip B Smith
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Andrew D Patterson
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, USA.
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Guideline for the Evaluation of Cholestatic Jaundice in Infants: Joint Recommendations of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition. J Pediatr Gastroenterol Nutr 2017; 64:154-168. [PMID: 27429428 DOI: 10.1097/mpg.0000000000001334] [Citation(s) in RCA: 274] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cholestatic jaundice in infancy affects approximately 1 in every 2500 term infants and is infrequently recognized by primary providers in the setting of physiologic jaundice. Cholestatic jaundice is always pathologic and indicates hepatobiliary dysfunction. Early detection by the primary care physician and timely referrals to the pediatric gastroenterologist/hepatologist are important contributors to optimal treatment and prognosis. The most common causes of cholestatic jaundice in the first months of life are biliary atresia (25%-40%) followed by an expanding list of monogenic disorders (25%), along with many unknown or multifactorial (eg, parenteral nutrition-related) causes, each of which may have time-sensitive and distinct treatment plans. Thus, these guidelines can have an essential role for the evaluation of neonatal cholestasis to optimize care. The recommendations from this clinical practice guideline are based upon review and analysis of published literature and the combined experience of the authors. The committee recommends that any infant noted to be jaundiced after 2 weeks of age be evaluated for cholestasis with measurement of total and direct serum bilirubin, and that an elevated serum direct bilirubin level (direct bilirubin levels >1.0 mg/dL or >17 μmol/L) warrants timely consideration for evaluation and referral to a pediatric gastroenterologist or hepatologist. Of note, current differential diagnostic plans now incorporate consideration of modern broad-based next-generation DNA sequencing technologies in the proper clinical context. These recommendations are a general guideline and are not intended as a substitute for clinical judgment or as a protocol for the care of all infants with cholestasis. Broad implementation of these recommendations is expected to reduce the time to the diagnosis of pediatric liver diseases, including biliary atresia, leading to improved outcomes.
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6
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Styles NA, Shonsey EM, Falany JL, Guidry AL, Barnes S, Falany CN. Carboxy-terminal mutations of bile acid CoA:N-acyltransferase alter activity and substrate specificity. J Lipid Res 2016; 57:1133-43. [PMID: 27230263 DOI: 10.1194/jlr.m064428] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Indexed: 11/20/2022] Open
Abstract
Bile acid CoA:amino acid N-acyltransferase (BAAT) is the terminal enzyme in the synthesis of bile salts from cholesterol and catalyzes the conjugation of taurine or glycine to bile acid CoA thioesters to form bile acid N-acylamidates. BAAT has a dual localization to the cytosol and peroxisomes, possibly due to an inefficient carboxy-terminal peroxisomal targeting signal (PTS), -serine-glutamine-leucine (-SQL). Mutational analysis was used to define the role of the carboxy terminus in peroxisomal localization and kinetic activity. Amidation activity of BAAT and BAAT lacking the final two amino acids (AAs) (BAAT-S) were similar, whereas the activity of BAAT with a canonical PTS sequence (BAAT-SKL) was increased >2.5-fold. Kinetic analysis of BAAT and BAAT-SKL showed that BAAT-SKL had a lower Km for taurine and glycine as well as a greater Vmax There was no difference in the affinity for cholyl-CoA. In contrast to BAAT, BAAT-SKL forms bile acid N-acylamidates with β-alanine. BAAT-S immunoprecipitated when incubated with peroxisomal biogenesis factor 5 (Pex5) and rabbit anti-Pex5 antibodies; however, deleting the final 12 AAs prevented coimmunoprecipitation with Pex5, indicating the Pex5 interaction involves more than the -SQL sequence. These results indicate that even small changes in the carboxy terminus of BAAT can have significant effects on activity and substrate specificity.
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Affiliation(s)
- Nathan A Styles
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Erin M Shonsey
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Josie L Falany
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Amber L Guidry
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Stephen Barnes
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Charles N Falany
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
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7
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Wanders RJA, Waterham HR, Ferdinandusse S. Metabolic Interplay between Peroxisomes and Other Subcellular Organelles Including Mitochondria and the Endoplasmic Reticulum. Front Cell Dev Biol 2016; 3:83. [PMID: 26858947 PMCID: PMC4729952 DOI: 10.3389/fcell.2015.00083] [Citation(s) in RCA: 197] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 12/10/2015] [Indexed: 01/02/2023] Open
Abstract
Peroxisomes are unique subcellular organelles which play an indispensable role in several key metabolic pathways which include: (1.) etherphospholipid biosynthesis; (2.) fatty acid beta-oxidation; (3.) bile acid synthesis; (4.) docosahexaenoic acid (DHA) synthesis; (5.) fatty acid alpha-oxidation; (6.) glyoxylate metabolism; (7.) amino acid degradation, and (8.) ROS/RNS metabolism. The importance of peroxisomes for human health and development is exemplified by the existence of a large number of inborn errors of peroxisome metabolism in which there is an impairment in one or more of the metabolic functions of peroxisomes. Although the clinical signs and symptoms of affected patients differ depending upon the enzyme which is deficient and the extent of the deficiency, the disorders involved are usually (very) severe diseases with neurological dysfunction and early death in many of them. With respect to the role of peroxisomes in metabolism it is clear that peroxisomes are dependent on the functional interplay with other subcellular organelles to sustain their role in metabolism. Indeed, whereas mitochondria can oxidize fatty acids all the way to CO2 and H2O, peroxisomes are only able to chain-shorten fatty acids and the end products of peroxisomal beta-oxidation need to be shuttled to mitochondria for full oxidation to CO2 and H2O. Furthermore, NADH is generated during beta-oxidation in peroxisomes and beta-oxidation can only continue if peroxisomes are equipped with a mechanism to reoxidize NADH back to NAD+, which is now known to be mediated by specific NAD(H)-redox shuttles. In this paper we describe the current state of knowledge about the functional interplay between peroxisomes and other subcellular compartments notably the mitochondria and endoplasmic reticulum for each of the metabolic pathways in which peroxisomes are involved.
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Affiliation(s)
- Ronald J A Wanders
- Laboratory Genetic Metabolic Diseases, Laboratory Division, Departments of Paediatrics and Clinical Chemistry, Academic Medical Center, Emma Children's Hospital, University of Amsterdam Amsterdam, Netherlands
| | - Hans R Waterham
- Laboratory Genetic Metabolic Diseases, Laboratory Division, Departments of Paediatrics and Clinical Chemistry, Academic Medical Center, Emma Children's Hospital, University of Amsterdam Amsterdam, Netherlands
| | - Sacha Ferdinandusse
- Laboratory Genetic Metabolic Diseases, Laboratory Division, Departments of Paediatrics and Clinical Chemistry, Academic Medical Center, Emma Children's Hospital, University of Amsterdam Amsterdam, Netherlands
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8
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Fernández-Pérez L, Santana-Farré R, de Mirecki-Garrido M, García I, Guerra B, Mateo-Díaz C, Iglesias-Gato D, Díaz-Chico JC, Flores-Morales A, Díaz M. Lipid profiling and transcriptomic analysis reveals a functional interplay between estradiol and growth hormone in liver. PLoS One 2014; 9:e96305. [PMID: 24816529 PMCID: PMC4015979 DOI: 10.1371/journal.pone.0096305] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 04/05/2014] [Indexed: 01/21/2023] Open
Abstract
17β-estradiol (E2) may interfere with endocrine, metabolic, and gender-differentiated functions in liver in both females and males. Indirect mechanisms play a crucial role because of the E2 influence on the pituitary GH secretion and the GHR-JAK2-STAT5 signaling pathway in the target tissues. E2, through its interaction with the estrogen receptor, exerts direct effects on liver. Hypothyroidism also affects endocrine and metabolic functions of the liver, rendering a metabolic phenotype with features that mimic deficiencies in E2 or GH. In this work, we combined the lipid and transcriptomic analysis to obtain comprehensive information on the molecular mechanisms of E2 effects, alone and in combination with GH, to regulate liver functions in males. We used the adult hypothyroid-orchidectomized rat model to minimize the influence of internal hormones on E2 treatment and to explore its role in male-differentiated functions. E2 influenced genes involved in metabolism of lipids and endo-xenobiotics, and the GH-regulated endocrine, metabolic, immune, and male-specific responses. E2 induced a female-pattern of gene expression and inhibited GH-regulated STAT5b targeted genes. E2 did not prevent the inhibitory effects of GH on urea and amino acid metabolism-related genes. The combination of E2 and GH decreased transcriptional immune responses. E2 decreased the hepatic content of saturated fatty acids and induced a transcriptional program that seems to be mediated by the activation of PPARα. In contrast, GH inhibited fatty acid oxidation. Both E2 and GH replacements reduced hepatic CHO levels and increased the formation of cholesterol esters and triacylglycerols. Notably, the hepatic lipid profiles were endowed with singular fingerprints that may be used to segregate the effects of different hormonal replacements. In summary, we provide in vivo evidence that E2 has a significant impact on lipid content and transcriptome in male liver and that E2 exerts a marked influence on GH physiology, with implications in human therapy.
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Affiliation(s)
- Leandro Fernández-Pérez
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
- * E-mail:
| | - Ruymán Santana-Farré
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
| | - Mercedes de Mirecki-Garrido
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
| | - Irma García
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
- Department of Animal Biology, University of La Laguna, Laboratory of Membrane Physiology and Biophysics, La Laguna, Spain
| | - Borja Guerra
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Carlos Mateo-Díaz
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Diego Iglesias-Gato
- Molecular Endocrinology group, University of Copenhagen - Novo Nordisk Center for Protein Research, Copenhagen, Denmark
| | - Juan Carlos Díaz-Chico
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Amilcar Flores-Morales
- Molecular Endocrinology group, University of Copenhagen - Novo Nordisk Center for Protein Research, Copenhagen, Denmark
| | - Mario Díaz
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
- Department of Animal Biology, University of La Laguna, Laboratory of Membrane Physiology and Biophysics, La Laguna, Spain
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9
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Anderson CM, Stahl A. SLC27 fatty acid transport proteins. Mol Aspects Med 2013; 34:516-28. [PMID: 23506886 DOI: 10.1016/j.mam.2012.07.010] [Citation(s) in RCA: 202] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 06/18/2012] [Indexed: 12/20/2022]
Abstract
The uptake and metabolism of long chain fatty acids (LCFA) are critical to many physiological and cellular processes. Aberrant accumulation or depletion of LCFA underlie the pathology of numerous metabolic diseases. Protein-mediated transport of LCFA has been proposed as the major mode of LCFA uptake and activation. Several proteins have been identified to be involved in LCFA uptake. This review focuses on the SLC27 family of fatty acid transport proteins, also known as FATPs, with an emphasis on the gain- and loss-of-function animal models that elucidate the functions of FATPs in vivo and how these transport proteins play a role in physiological and pathological situations.
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Affiliation(s)
- Courtney M Anderson
- Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California Berkeley, CA, USA
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Ikegawa S, Ito H, Ohshima M, Maeda M, Hofmann AF, Mitamura K. Chemical synthesis of bile acid acyl-adenylates and formation by a rat liver microsomal fraction. Steroids 2009; 74:751-7. [PMID: 19376146 DOI: 10.1016/j.steroids.2009.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 03/31/2009] [Accepted: 04/06/2009] [Indexed: 11/29/2022]
Abstract
In mammals, unconjugated bile acids formed in the intestine by bacterial deconjugation are reconjugated (N-acylamidated) with taurine or glycine during hepatocyte transport. Activation of the carboxyl group of bile acids to form acyl-adenylates is a likely key intermediate step in bile acid N-acylamidation. To gain more insight into the process of bile acid adenylate formation, we first synthesized the adenylates of five common, natural bile acids (cholic, deoxycholic, chenodeoxycholic, ursodeoxycholic, and lithocholic acid), and confirmed their structure by proton NMR. We then investigated adenylate formation by subcellular fractions of rat liver (microsomes, mitochondria, cytosol) using a newly developed LC method for quantifying adenylate formation. The highest activity was observed in the microsomal fraction. The reaction required Mg(2+) and its optimum pH was about pH 7.0. In term of maximum velocity (V(max)) and the Michaelis constant (K(m)), the catalytic efficiency of the enzyme under the conditions used was highest with cholic acid of the bile acids tested. The formation of cholyl-adenylate was strongly inhibited by lithocholic and deoxycholic acid, as well as by palmitic acid; ibuprofen and valproic acid were weak inhibitors. In cholestatic disease, such adenylate formation might lead to subsequent bile acid conjugation with glutathione or proteins.
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Affiliation(s)
- Shigeo Ikegawa
- Faculty of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-osaka, 577-8502, Japan.
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11
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Thomas C, Pellicciari R, Pruzanski M, Auwerx J, Schoonjans K. Targeting bile-acid signalling for metabolic diseases. Nat Rev Drug Discov 2008; 7:678-93. [PMID: 18670431 DOI: 10.1038/nrd2619] [Citation(s) in RCA: 943] [Impact Index Per Article: 58.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bile acids are increasingly being appreciated as complex metabolic integrators and signalling factors and not just as lipid solubilizers and simple regulators of bile-acid homeostasis. It is therefore not surprising that a number of bile-acid-activated signalling pathways have become attractive therapeutic targets for metabolic disorders. Here, we review how the signalling functions of bile acids can be exploited in the development of drugs for obesity, type 2 diabetes, hypertriglyceridaemia and atherosclerosis, as well as other associated chronic diseases such as non-alcoholic steatohepatitis.
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Affiliation(s)
- Charles Thomas
- Institute of Genetics and Molecular and Cellular Biology, 1 Rue Laurent Fries, 67404 Illkirch, France
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12
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Sundaram SS, Bove KE, Lovell MA, Sokol RJ. Mechanisms of disease: Inborn errors of bile acid synthesis. ACTA ACUST UNITED AC 2008; 5:456-68. [PMID: 18577977 DOI: 10.1038/ncpgasthep1179] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Accepted: 04/23/2008] [Indexed: 02/08/2023]
Abstract
Inborn errors of bile acid synthesis are rare genetic disorders that can present as neonatal cholestasis, neurologic disease or fat-soluble-vitamin deficiencies. There are nine known defects of bile acid synthesis, including oxysterol 7alpha-hydroxylase deficiency, Delta(4)-3-oxosteroid-5beta-reductase deficiency, 3beta-hydroxy-Delta(5)-C(27)-steroid dehydrogenase deficiency, cerebrotendinous xanthomatosis (also known as sterol 27-hydroxylase deficiency), alpha-methylacyl-CoA racemase deficiency, and Zellweger syndrome (also known as cerebrohepatorenal syndrome). These diseases are characterized by a failure to produce normal bile acids and an accumulation of unusual bile acids and bile acid intermediaries. Individuals with inborn errors of bile acid synthesis generally present with the hallmark features of normal or low serum bile acid concentrations, normal gamma-glutamyl transpeptidase concentrations and the absence of pruritus. Failure to diagnose any of these conditions can result in liver failure or progressive chronic liver disease. If recognized early, many patients can have a remarkable clinical response to oral bile acid therapy.
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Affiliation(s)
- Shikha S Sundaram
- Section of Pediatric Gastroenterology, Hepatology and Nutrition, University of Colorado School of Medicine and The Children's Hospital, CO 80045, USA
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13
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Croner RS, Hohenberger W, Jeschke MG. Hepatic gene expression during endotoxemia. J Surg Res 2008; 154:126-34. [PMID: 18952238 DOI: 10.1016/j.jss.2008.04.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2008] [Revised: 04/09/2008] [Accepted: 04/17/2008] [Indexed: 11/24/2022]
Abstract
PURPOSE During the course of sepsis, endotoxins and cytokines activate Kupffer cells, induce the liberation and synthesis of adhesion molecules, and damage hepatocytes, which leads to septic liver failure. The interaction of the different hepatic cell types during these processes is not completely understood and may be clarified by microarray technology. MATERIALS AND METHODS Seven Sprague Dawley rats received either an intraperitoneal injection of lipopolysaccharides (LPS) of 3 mg/kg body weight (n = 4) or sodium chloride (SC) 0.9% (n = 3). Animals were sacrificed 24 h after LPS or SC injection. RNA from liver tissue was isolated and hybridized on GeneChips (RAE 230A; Affymetrix, Santa Clara, CA). Expression of interleukin-1beta, tumor necrosis factor-alpha, and signal transducer and activator of transcription 3 was controlled by reverse transcription-polymerase chain reaction analysis. Immunohistochemical staining for intercellular adhesion molecule-1 of liver tissue was performed. RESULTS We detected 508 differentially expressed genes between LPS and SC. Two hundred forty-eight genes were up-regulated and 260 genes were down-regulated in the LPS versus the SC group. Mainly genes involved in immune response and receptor activity were up-regulated in the LPS group. Genes enrolled in catalytic, transferase activity, and metabolisms were down-regulated in the LPS group. The microarray findings could be verified by reverse transcription-polymerase chain reaction analysis and immunohistochemical staining. CONCLUSIONS The contemporaneous differential regulation of genes involved in metabolism, hepatocellular synthesis, and immune response reflect the liver's central role as immune organ during the course of sepsis. A switch from metabolic to immunological activity is obvious, which aggravates the hepatic damage. The functional interaction of the single genes identified during this process must be further clarified.
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Affiliation(s)
- Roland S Croner
- Department of Surgery, University of Erlangen-Nuremberg, Erlangen, Germany.
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Pellicoro A, Faber KN. Review article: The function and regulation of proteins involved in bile salt biosynthesis and transport. Aliment Pharmacol Ther 2007; 26 Suppl 2:149-60. [PMID: 18081658 DOI: 10.1111/j.1365-2036.2007.03522.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Bile salts are produced and secreted by the liver and are required for intestinal absorption of fatty food components and excretion of endobiotics and xenobiotics. They are reabsorbed in the terminal ileum and transported back to the liver via the portal tract. Dedicated bile salt transporters in hepatocytes and enterocytes are responsible for the unidirectional transport of bile salts in the enterohepatic cycle. AIM To give an overview of the function and regulations of proteins involved in bile salt synthesis and transport. METHODS Data presented are obtained from PubMed-accessible literature combined with our own recent research. RESULT Hepatocytes and enterocytes contain unique bile salt importers (sodium-taurocholate cotransporting polypeptide and apical sodium-dependent bile acid transporter, respectively) and exporters (bile salt export pump and organic solute transporter alpha-beta, respectively). Enzymes involved in bile salt biosynthesis reside in different subcellular locations, including the endoplasmic reticulum, mitochondria, cytosol and peroxisomes. Defective expression or function of the transporters or enzymes may lead to cholastasis. The bile salt-activated transcription factor Farnesoid X receptor controls expression of genes involved in bile salt biosynthesis and transport. CONCLUSIONS Detailed knowledge is available about the enzymes and transporters involved in bile salt homeostasis and how their defective function is associated with cholestasis. In contrast, the process of intracellular bile salt transport is largely unexplored.
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Affiliation(s)
- A Pellicoro
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Styles NA, Falany JL, Barnes S, Falany CN. Quantification and regulation of the subcellular distribution of bile acid coenzyme A:amino acid N-acyltransferase activity in rat liver. J Lipid Res 2007; 48:1305-15. [PMID: 17379925 DOI: 10.1194/jlr.m600472-jlr200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bile acid coenzyme A:amino acid N-acyltransferase (BAT) is responsible for the amidation of bile acids with the amino acids glycine and taurine. To quantify total BAT activity in liver subcellular organelles, livers from young adult male and female Sprague-Dawley rats were fractionated into multiple subcellular compartments. In male and female rats, 65-75% of total liver BAT activity was found in the cytosol, 15-17% was found in the peroxisomes, and 5-10% was found in the heavy mitochondrial fraction. After clofibrate treatment, male rats displayed an increase in peroxisomal BAT specific activity and a decrease in cytosolic BAT specific activity, whereas females showed an opposite response. However, there was no overall change in BAT specific activity in whole liver homogenate. Treatment with rosiglitazone or cholestyramine had no effect on BAT activity in any subcellular compartment. These experiments indicate that the majority of BAT activity in the rat liver resides in the cytosol. Approximately 15% of BAT activity is present in the peroxisomal matrix. These data support the novel finding that clofibrate treatment does not directly regulate BAT activity but does alter the subcellular localization of BAT.
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Affiliation(s)
- Nathan A Styles
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Abstract
PURPOSE OF REVIEW Fatty acid transport proteins are a family of proteins involved in fatty acid uptake and activation. This review summarizes recent progress in elucidating the function of fatty acid transport proteins. RECENT FINDINGS Recent experiments clearly establish FATP1 as a regulated fatty acid transporter in both adipose tissue and muscle with important roles in energy homeostasis, thermogenesis and insulin resistance. Knockout of FATP5 in mice show it to be a bifunctional protein required for both hepatic fatty acid uptake and bile acid reconjugation. The most striking phenotype of FATP4 deletion is a defect in skin homeostasis, which may be due to its very long chain acyl-coenzyme A synthetase activity. Fatty acid transport proteins are increasingly being recognized as multifunctional proteins that can mediate the uptake of fatty acids as well as catalyze the formation of coenzyme A derivatives using long-chain and very-long chain fatty acids, bile acids and bile acid precursors as substrates. SUMMARY Modulation of fatty acid transport protein function can result in altered energy homeostasis and insulin sensitivity, defective skin homeostasis, and altered bile acid metabolism. Both fatty acid uptake and enzymatic activity of fatty acid transport proteins likely contribute to these phenotypes. Future studies are needed to better understand the molecular mechanism of fatty acid transport protein function and the physiological role of FATP2, FATP3, and FATP6.
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Affiliation(s)
- Ruth E Gimeno
- Department of Cardiovascular and Metabolic Diseases, Wyeth Research, Cambridge, Massachusetts 02140, USA.
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Hubbard B, Doege H, Punreddy S, Wu H, Huang X, Kaushik VK, Mozell RL, Byrnes JJ, Stricker-Krongrad A, Chou CJ, Tartaglia LA, Lodish HF, Stahl A, Gimeno RE. Mice deleted for fatty acid transport protein 5 have defective bile acid conjugation and are protected from obesity. Gastroenterology 2006; 130:1259-69. [PMID: 16618417 DOI: 10.1053/j.gastro.2006.02.012] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Accepted: 01/04/2006] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Fatty Acid Transport Protein 5 (FATP5) is a liver-specific member of the FATP/Slc27 family, which has been shown to exhibit both fatty acid transport and bile acid-CoA ligase activity in vitro. Here, we investigate its role in bile acid metabolism and body weight homeostasis in vivo by using a novel FATP5 knockout mouse model. METHODS Bile acid composition was analyzed by mass spectroscopy. Body weight, food intake, energy expenditure, and fat absorption were determined in animals fed either a low- or a high-fat diet. RESULTS Although total bile acid concentrations were unchanged in bile, liver, urine, and feces of FATP5 knockout mice, the majority of gallbladder bile acids was unconjugated, and only a small percentage was conjugated. Primary, but not secondary, bile acids were detected among the remaining conjugated forms in FATP5 deletion mice, suggesting a specific requirement for FATP5 in reconjugation of bile acids during the enterohepatic recirculation. Fat absorption in FATP5 deletion mice was largely normal, and only a small increase in fecal fat was observed on a high-fat diet. Despite normal fat absorption, FATP5 deletion mice failed to gain weight on a high-fat diet because of both decreased food intake and increased energy expenditure. CONCLUSIONS Our findings reveal an important role for FATP5 in bile acid conjugation in vivo and an unexpected function in body weight homeostasis, which will require further analysis. FATP5 deletion mice provide a new model to study the intersection of bile acid metabolism, lipid metabolism, and body weight regulation.
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Affiliation(s)
- Brian Hubbard
- Millennium Pharmaceuticals, Inc, Cambridge, Massachusetts 02140, USA
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Xu CS, Chang CF, Yuan JY, Li WQ, Han HP, Yang KJ, Zhao LF, Li YC, Zhang HY, Rahman S, Zhang JB. Expressed genes in regenerating rat liver after partial hepatectomy. World J Gastroenterol 2005; 11:2932-40. [PMID: 15902731 PMCID: PMC4305662 DOI: 10.3748/wjg.v11.i19.2932] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To reveal the liver regeneration (LR) and its control as well as the occurrence of liver disease and to study the gene expression profiles of 551 genes after partial hepatectomy (PH) in regenerating rat livers.
METHODS: Five hundred and fifty-one expressed sequence tags screened by suppression subtractive hybridization were made into an in-house cDNA microarray, and the expressive genes and their expressive profiles in regenerating rat livers were analyzed by microarray and bioinformatics.
RESULTS: Three hundred of the analyzed 551 genes were up- or downregulated more than twofolds at one or more time points during LR. Most of the genes were up- or downregulated 2-5 folds, but the highest reached 90 folds of the control. One hundred and thirty-nine of them showed upregulation, 135 displayed downregulation, and up or down expression of 26 genes revealed a dependence on regenerating livers. The genes expressed in 24-h regenerating livers were much more than those in the others. Cluster analysis and generalization analysis showed that there were at least six distinct temporal patterns of gene expression in the regenerating livers, that is, genes were expressed in the immediate early phase, early phase, intermediate phase, early-late phase, late phase, terminal phase.
CONCLUSION: In LR, the number of down-regulated genes was almost similar to that of the upregulated genes; the successively altered genes were more than the rapidly transient genes. The temporal patterns of gene expression were similar 2 and 4 h, 12 and 16 h, 48 and 96 h, 72 and 144 h after PH. Microarray combined with suppressive subtractive hybridization can effectively identify the genes related to LR.
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Affiliation(s)
- Cun-Shuan Xu
- College of Life Science, Henan Normal University, Xinxiang 453007, Henan Province, China.
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Shonsey EM, Wheeler J, Johnson M, He D, Falany CN, Falany J, Barnes S. Synthesis of bile acid coenzyme a thioesters in the amino acid conjugation of bile acids. Methods Enzymol 2005; 400:360-73. [PMID: 16399360 DOI: 10.1016/s0076-6879(05)00021-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Bile acids are converted to their glycine and taurine N-acyl amidates by enzymes in the liver in a two-step process. This conjugation reaction increases the aqueous solubility of bile acids, particularly in the acidic environment of the initial portion of the small intestine. In the first step, bile acid coenzyme A (CoA) thioesters are formed by a bile acid CoA ligase (BAL). This chapter describes the methods used to purify BAL from rat liver microsomes and to isolate and clone the cDNAs encoding BAL from a rat liver cDNA library, the expression of BAL, the assays used to measure its activities, and the chemical synthesis of bile acid CoA thioesters.
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Affiliation(s)
- Erin M Shonsey
- Department of Pharmacology and Toxicology, University of Alabama, Birmingham, USA
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Mano N, Kasuga K, Kobayashi N, Goto J. A Nonenzymatic Modification of the Amino-terminal Domain of Histone H3 by Bile Acid Acyl Adenylate. J Biol Chem 2004; 279:55034-41. [PMID: 15465822 DOI: 10.1074/jbc.m409205200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although it has been proposed that the secondary bile acids, deoxycholic acid and lithocholic acid, increase the number of aberrant crypt foci in the colon and may act as colon tumor promoters, there is little evidence detailing their mechanism of action. Histones play an important role in controlling gene expression, and the posttranslational modification of histones plays a role in regulation of intracellular signal transduction. In particular, the amino-terminal tail domain of histone H3 is sensitive to several posttranslational modifications, and acetylation of this domain changes its electrostatic environment and results in the loss of native folding. Therefore, we studied the modification of epsilon-amino groups on human histone H3 by deoxycholyl adenylate, which is an active intermediate in deoxycholyl thioester biosynthesis. After incubation of recombinant human histone H3 with a smaller amount of acyl adenylate, followed by enzymatic digestion, the peptide fragment mixtures were analyzed by matrix-assisted laser desorption ionization mass spectrometry. These data showed the formation of only one adduct fragment, which corresponded to amino acids 3-8 with a deoxycholate adduct, suggesting that the epsilon-amino group of Lys(4) had the highest reactivity. This novel modification, formation of a bile acid adduct on the histone H3 amino-terminal tail domain through an active acyl adenylate, may relate to the carcinogenesis-promoting effects of secondary bile acids.
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Affiliation(s)
- Nariyasu Mano
- Graduate School of Pharmaceutical Sciences, Tohoku University, 101 Seiryo-machi, Aobayama, Aoba-ku, Sendai 980-8578, Japan
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He D, Barnes S, Falany CN. Rat liver bile acid CoA:amino acid N-acyltransferase: expression, characterization, and peroxisomal localization. J Lipid Res 2003; 44:2242-9. [PMID: 12951368 DOI: 10.1194/jlr.m300128-jlr200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bile acid CoA:amino acid N-acyltransferase (BAT) is responsible for the amidation of bile acids with the amino acids taurine and glycine. Rat liver BAT (rBAT) cDNA was isolated from a rat liver lambdaZAP cDNA library and expressed in Sf9 insect cells using a baculoviral vector. rBAT displayed 65% amino acid sequence homology with human BAT (hBAT) and 85% homology with mouse BAT (mBAT). Similar to hBAT, expressed rBAT was capable of forming both taurine and glycine conjugates with cholyl-CoA. mBAT, which is highly homologous to rBAT, forms only taurine conjugated bile acids (Falany, C. N., H. Fortinberry, E. H. Leiter, and S. Barnes. 1997. Cloning and expression of mouse liver bile acid CoA: Amino acid N-acyltransferase. J. Lipid Res. 38: 86-95). Immunoblot analysis of rat tissues detected rBAT only in rat liver cytosol following homogenization and ultracentrifugation. Subcellular localization of rBAT detected activity and immunoreactive protein in both cytosol and isolated peroxisomes. Rat bile acid CoA ligase (rBAL), the enzyme responsible for the formation of bile acid CoA esters, was detected only in rat liver microsomes. Treatment of rats with clofibrate, a known peroxisomal proliferator, significantly induced rBAT activity, message, and immunoreactive protein in rat liver. Peroxisomal membrane protein-70, a marker for peroxisomes, was also induced by clofibrate, whereas rBAL activity and protein amount were not affected. In summary, rBAT is capable of forming both taurine and glycine bile acid conjugates and the enzyme is localized primarily in peroxisomes in rat liver.
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Affiliation(s)
- Dongning He
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Inoue Y, Yu AM, Inoue J, Gonzalez FJ. Hepatocyte nuclear factor 4alpha is a central regulator of bile acid conjugation. J Biol Chem 2003; 279:2480-9. [PMID: 14583614 DOI: 10.1074/jbc.m311015200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Hepatocyte nuclear factor 4alpha (HNF4alpha) has an important role in regulating the expression of liver-specific genes. Because bile acids are produced from cholesterol in liver and many enzymes involved in their biosynthesis are preferentially expressed in liver, the role of HNF4alpha in the regulation of bile acid production was examined. In mice, unconjugated bile acids are conjugated with taurine by the liver-specific enzymes, bile acid-CoA ligase and bile acid-CoA:amino acid N-acyltransferase (BAT). Mice lacking hepatic HNF4alpha expression exhibited markedly decreased expression of the very long chain acyl-CoA synthase-related gene (VLACSR), a mouse candidate for bile acid-CoA ligase, and BAT. This was associated with markedly elevated levels of unconjugated and glycine-conjugated bile acids in gallbladder. HNF4alpha was found to bind directly to the mouse VLACSR and BAT gene promoters, and the promoter activities were dependent on HNF4alpha-binding sites and HNF4alpha expression. In conclusion, HNF4alpha plays a central role in bile acid conjugation by direct regulation of VLACSR and BAT in vivo.
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Affiliation(s)
- Yusuke Inoue
- Laboratory of Metabolism, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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