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Zhang W, Ding D, Lu Y, Chen H, Jiang P, Zuo P, Wang G, Luo J, Yin Y, Luo J, Yin Y. Structural and functional insights into the lipid regulation of human anion exchanger 2. Nat Commun 2024; 15:759. [PMID: 38272905 PMCID: PMC10810954 DOI: 10.1038/s41467-024-44966-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 01/11/2024] [Indexed: 01/27/2024] Open
Abstract
Anion exchanger 2 (AE2) is an electroneutral Na+-independent Cl-/HCO3- exchanger belongs to the SLC4 transporter family. The widely expressed AE2 participates in a variety of physiological processes, including transepithelial acid-base secretion and osteoclastogenesis. Both the transmembrane domains (TMDs) and the N-terminal cytoplasmic domain (NTD) are involved in regulation of AE2 activity. However, the regulatory mechanism remains unclear. Here, we report a 3.2 Å cryo-EM structure of the AE2 TMDs in complex with PIP2 and a 3.3 Å full-length mutant AE2 structure in the resting state without PIP2. We demonstrate that PIP2 at the TMD dimer interface is involved in the substrate exchange process. Mutation in the PIP2 binding site leads to the displacement of TM7 and further stabilizes the interaction between the TMD and the NTD. Reduced substrate transport activity and conformation similar to AE2 in acidic pH indicating the central contribution of PIP2 to the function of AE2.
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Affiliation(s)
- Weiqi Zhang
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center for Life Sciences, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Dian Ding
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center for Life Sciences, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yishuo Lu
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center for Life Sciences, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Hongyi Chen
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center for Life Sciences, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Peijun Jiang
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center for Life Sciences, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Peng Zuo
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center for Life Sciences, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Guangxi Wang
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center for Life Sciences, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Juan Luo
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
| | - Yue Yin
- Department of Pharmacology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Jianyuan Luo
- Department of Medical Genetics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Yuxin Yin
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center for Life Sciences, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China.
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China.
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Reshetnyak VI, Maev IV. New insights into the pathogenesis of primary biliary cholangitis asymptomatic stage. World J Gastroenterol 2023; 29:5292-5304. [PMID: 37899787 PMCID: PMC10600802 DOI: 10.3748/wjg.v29.i37.5292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/10/2023] [Accepted: 09/14/2023] [Indexed: 09/25/2023] Open
Abstract
Primary biliary cholangitis (PBC) is a chronic cholestatic progressive liver disease and one of the most important progressive cholangiopathies in adults. Damage to cholangiocytes triggers the development of intrahepatic cholestasis, which progresses to cirrhosis in the terminal stage of the disease. Accumulating data indicate that damage to biliary epithelial cells [(BECs), cholangiocytes] is most likely associated with the intracellular accumulation of bile acids, which have potent detergent properties and damaging effects on cell membranes. The mechanisms underlying uncontrolled bile acid intake into BECs in PBC are associated with pH change in the bile duct lumen, which is controlled by the bicarbonate (HCO3-) buffer system "biliary HCO3- umbrella". The impaired production and entry of HCO3- from BECs into the bile duct lumen is due to epigenetic changes in expression of the X-linked microRNA 506. Based on the growing body of knowledge on the molecular mechanisms of cholangiocyte damage in patients with PBC, we propose a hypothesis explaining the pathogenesis of the first morphologic (ductulopenia), immunologic (antimitochondrial autoantibodies) and clinical (weakness, malaise, rapid fatigue) signs of the disease in the asymptomatic stage. This review focuses on the consideration of these mechanisms.
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Affiliation(s)
- Vasiliy Ivanovich Reshetnyak
- Department of Propaedeutics of Internal Diseases and Gastroenterology, A.I. Yevdokimov Moscow State University of Medicine and Dentistry, Moscow 127473, Russia
| | - Igor Veniaminovich Maev
- Department of Propaedeutics of Internal Diseases and Gastroenterology, A.I. Yevdokimov Moscow State University of Medicine and Dentistry, Moscow 127473, Russia
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Abubakar AA, Ali AK, Ibrahim SM, Handool KO, Khan MS, Mustapha NM, Ibrahim TAT, Kaka U, Yusof LM. Roles of Sodium Hydrogen Exchanger (NHE1) and Anion Exchanger (AE2) across Chondrocytes Plasma Membrane during Longitudinal Bone Growth. Membranes (Basel) 2022; 12:membranes12070707. [PMID: 35877910 PMCID: PMC9321928 DOI: 10.3390/membranes12070707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 06/27/2022] [Accepted: 06/30/2022] [Indexed: 12/10/2022]
Abstract
Mammalian long bone growth occurs through endochondral ossification, majorly regulated by the controlled enlargement of chondrocytes at the growth plate (GP). This study aimed to investigate the roles of Na+/H+ (sodium hydrogen exchanger (NHE1)) and HCO3− (anion exchanger [AE2]) during longitudinal bone growth in mammals. Bones from P10 SpragueDawley rat pups were cultured exvivo in the presence or absence of NHE1 and AE2 inhibitors to determine their effect on long bone growth. Gross morphometry, histomorphometry, and immunohistochemistry were used to assess the bone growth. The results revealed that the culture of the bones in the presence of NHE1 and AE2 inhibitors reduces bone growth significantly (p < 0.05) by approximately 11%. The inhibitor significantly (p < 0.05) reduces bone growth velocity and the length of the hypertrophic chondrocyte zone without any effect on the total GP length. The total GP chondrocyte density was significantly (p < 0.05) reduced, but hypertrophic chondrocyte densities remained constant. NHE1 fluorescence signaling across the GP length was higher than AE2, and their localization was significantly (p < 0.05) inhibited at the hypertrophic chondrocytes zone. The GP lengthening was majorly driven by an increase in the overall GP chondrocyte and hypertrophic chondrocyte densities apart from the regulatory volume phenomenon. This may suggest that NHE1 and AE2 could have a regulatory role in long bone growth.
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Affiliation(s)
- Adamu Abdul Abubakar
- Department of Companion Animal Medicine and Surgery, Universiti Putra Malaysia, Serdang 43400, Malaysia; (A.A.A.); (A.K.A.); (S.M.I.); (K.O.H.); (M.S.K.); (U.K.)
- Department of Veterinary Surgery and Radiology, Usmanu Danfodiyo University, Sokoto PMB 2346, Nigeria
| | - Ahmed Khalaf Ali
- Department of Companion Animal Medicine and Surgery, Universiti Putra Malaysia, Serdang 43400, Malaysia; (A.A.A.); (A.K.A.); (S.M.I.); (K.O.H.); (M.S.K.); (U.K.)
- Department of Surgery and Theriogenology, College of Veterinary Medicine, University of Mosul, Mosul 00964, Iraq
| | - Sahar Mohammed Ibrahim
- Department of Companion Animal Medicine and Surgery, Universiti Putra Malaysia, Serdang 43400, Malaysia; (A.A.A.); (A.K.A.); (S.M.I.); (K.O.H.); (M.S.K.); (U.K.)
- Department of Surgery and Theriogenology, College of Veterinary Medicine, University of Mosul, Mosul 00964, Iraq
| | - Kareem Obayes Handool
- Department of Companion Animal Medicine and Surgery, Universiti Putra Malaysia, Serdang 43400, Malaysia; (A.A.A.); (A.K.A.); (S.M.I.); (K.O.H.); (M.S.K.); (U.K.)
| | - Mohammad Shuaib Khan
- Department of Companion Animal Medicine and Surgery, Universiti Putra Malaysia, Serdang 43400, Malaysia; (A.A.A.); (A.K.A.); (S.M.I.); (K.O.H.); (M.S.K.); (U.K.)
- Faculty of Veterinary and Animal Science, Gomal University, Dera Ismail Khan 29050, Pakistan
| | - Noordin Mohamed Mustapha
- Department of Veterinary Pathology and Microbiology, Universiti Putra Malaysia, Serdang 43400, Malaysia;
| | | | - Ubedullah Kaka
- Department of Companion Animal Medicine and Surgery, Universiti Putra Malaysia, Serdang 43400, Malaysia; (A.A.A.); (A.K.A.); (S.M.I.); (K.O.H.); (M.S.K.); (U.K.)
| | - Loqman Mohamad Yusof
- Department of Companion Animal Medicine and Surgery, Universiti Putra Malaysia, Serdang 43400, Malaysia; (A.A.A.); (A.K.A.); (S.M.I.); (K.O.H.); (M.S.K.); (U.K.)
- Correspondence: ; Tel.: +60-192-590-571; Fax: +60-386-093-959
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Verstraeten L, Jochmans I. Sense and Sensibilities of Organ Perfusion as a Kidney and Liver Viability Assessment Platform. Transpl Int 2022; 35:10312. [PMID: 35356401 PMCID: PMC8958413 DOI: 10.3389/ti.2022.10312] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/26/2022] [Indexed: 12/13/2022]
Abstract
Predicting organ viability before transplantation remains one of the most challenging and ambitious objectives in transplant surgery. Waitlist mortality is high while transplantable organs are discarded. Currently, around 20% of deceased donor kidneys and livers are discarded because of “poor organ quality”, Decisions to discard are still mainly a subjective judgement since there are only limited reliable tools predictive of outcome available. Organ perfusion technology has been posed as a platform for pre-transplant organ viability assessment. Markers of graft injury and function as well as perfusion parameters have been investigated as possible viability markers during ex-situ hypothermic and normothermic perfusion. We provide an overview of the available evidence for the use of kidney and liver perfusion as a tool to predict posttransplant outcomes. Although evidence shows post-transplant outcomes can be predicted by both injury markers and perfusion parameters during hypothermic kidney perfusion, the predictive accuracy is too low to warrant clinical decision making based upon these parameters alone. In liver, further evidence on the usefulness of hypothermic perfusion as a predictive tool is needed. Normothermic perfusion, during which the organ remains fully metabolically active, seems a more promising platform for true viability assessment. Although we do not yet fully understand “on-pump” organ behaviour at normothermia, initial data in kidney and liver are promising. Besides the need for well-designed (registry) studies to advance the field, the catch-22 of selection bias in clinical studies needs addressing.
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Affiliation(s)
- Laurence Verstraeten
- Lab of Abdominal Transplantation, Transplantation Research Group, Department of Microbiology, Immunology and Transplantation, KU Leuven, Leuven, Belgium
| | - Ina Jochmans
- Lab of Abdominal Transplantation, Transplantation Research Group, Department of Microbiology, Immunology and Transplantation, KU Leuven, Leuven, Belgium
- Department of Abdominal Transplantation, University Hospitals Leuven, Leuven, Belgium
- *Correspondence: Ina Jochmans,
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Abstract
PURPOSE OF REVIEW Primary biliary cholangitis (PBC) is characterized by autoimmune damage of intrahepatic bile ducts associated with a loss of tolerance to mitochondrial antigens. PBC etiopathogenesis is intriguing because of different perplexing features, namely: a) although mitochondria are present in all cell types and tissues, the damage is mainly restricted to biliary epithelial cells (BECs); b) despite being an autoimmune disorder, it does not respond to immunosuppressive drugs but rather to ursodeoxycholic acid, a bile salt that induces HCO3- rich choleresis; c) the overwhelming female preponderance of the disease remains unexplained. Here we present an etiopathogenic view of PBC which sheds light on these puzzling facts of the disease. RECENT FINDINGS PBC develops in patients with genetic predisposition to autoimmunity in whom epigenetic mechanisms silence the Cl-/HCO3- exchanger AE2 in both cholangiocytes and lymphoid cells. Defective AE2 function can produce BECs damage as a result of decreased biliary HCO3- secretion with disruption of the protective alkaline umbrella that normally prevents the penetration of toxic apolar bile salts into cholangiocytes. AE2 dysfunction also causes increased intracellular pH (pHi) in cholangiocytes, leading to the activation of soluble adenylyl cyclase, which sensitizes BECs to bile salt-induced apoptosis. Recently, mitophagy was found to be inhibited by cytosolic alkalization and stimulated by acidification. Accordingly, we propose that AE2 deficiency may disturb mitophagy in BECs, thus, promoting the accumulation of defective mitochondria, oxidative stress and presentation of mitochondrial antigens to the immune cells. As women possess a more acidic endolysosomal milieu than men, mitophagy might be more affected in women in an AE2-defective background. Apart from affecting BECs function, AE2 downregulation in lymphocytes may also contribute to alter immunoregulation facilitating autoreactive T-cell responses. SUMMARY PBC can be considered as a disorder of Cl-/HCO3- exchange in individuals with genetic predisposition to autoimmunity.
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Affiliation(s)
- Jesús Prieto
- Center for Applied Medical Research (Centro de Investigación Médica Aplicada, CIMA), University of Navarra, Pamplona
| | - Jesus M. Banales
- Department of Liver and Gastrointestinal Diseases, Biodonostia Health Research Institute – Donostia University Hospital – University of the Basque Country (UPV/EHU), San Sebastian
- National Institute for the Study of Liver and Gastrointestinal Diseases (CIBERehd, ‘Instituto de Salud Carlos III’)
- IKERBASQUE, Basque Foundation for Science, Bilbao
| | - Juan F. Medina
- Unit of Medical Training, School of Medicine, University of Navarra, Pamplona, Spain
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Ribet ABP, Ng PY, Pavlos NJ. Membrane Transport Proteins in Osteoclasts: The Ins and Outs. Front Cell Dev Biol 2021; 9:644986. [PMID: 33718388 PMCID: PMC7952445 DOI: 10.3389/fcell.2021.644986] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/09/2021] [Indexed: 12/12/2022] Open
Abstract
During bone resorption, the osteoclast must sustain an extraordinarily low pH environment, withstand immense ionic pressures, and coordinate nutrient and waste exchange across its membrane to sustain its unique structural and functional polarity. To achieve this, osteoclasts are equipped with an elaborate set of membrane transport proteins (pumps, transporters and channels) that serve as molecular ‘gatekeepers’ to regulate the bilateral exchange of ions, amino acids, metabolites and macromolecules across the ruffled border and basolateral domains. Whereas the importance of the vacuolar-ATPase proton pump and chloride voltage-gated channel 7 in osteoclasts has long been established, comparatively little is known about the contributions of other membrane transport proteins, including those categorized as secondary active transporters. In this Special Issue review, we provide a contemporary update on the ‘ins and outs’ of membrane transport proteins implicated in osteoclast differentiation, function and bone homeostasis and discuss their therapeutic potential for the treatment of metabolic bone diseases.
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Affiliation(s)
- Amy B P Ribet
- Bone Biology and Disease Laboratory, School of Biomedical Sciences, The University of Western Australia, Nedlands, WA, Australia
| | - Pei Ying Ng
- Bone Biology and Disease Laboratory, School of Biomedical Sciences, The University of Western Australia, Nedlands, WA, Australia
| | - Nathan J Pavlos
- Bone Biology and Disease Laboratory, School of Biomedical Sciences, The University of Western Australia, Nedlands, WA, Australia
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Trampert DC, van de Graaf SFJ, Jongejan A, Oude Elferink RPJ, Beuers U. Hepatobiliary acid-base homeostasis: Insights from analogous secretory epithelia. J Hepatol 2021; 74:428-441. [PMID: 33342564 DOI: 10.1016/j.jhep.2020.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/03/2020] [Accepted: 10/19/2020] [Indexed: 12/14/2022]
Abstract
Many epithelia secrete bicarbonate-rich fluid to generate flow, alter viscosity, control pH and potentially protect luminal and intracellular structures from chemical stress. Bicarbonate is a key component of human bile and impaired biliary bicarbonate secretion is associated with liver damage. Major efforts have been undertaken to gain insight into acid-base homeostasis in cholangiocytes and more can be learned from analogous secretory epithelia. Extrahepatic examples include salivary and pancreatic duct cells, duodenocytes, airway and renal epithelial cells. The cellular machinery involved in acid-base homeostasis includes carbonic anhydrase enzymes, transporters of the solute carrier family, and intra- and extracellular pH sensors. This pH-regulatory system is orchestrated by protein-protein interactions, the establishment of an electrochemical gradient across the plasma membrane and bicarbonate sensing of the intra- and extracellular compartment. In this review, we discuss conserved principles identified in analogous secretory epithelia in the light of current knowledge on cholangiocyte physiology. We present a framework for cholangiocellular acid-base homeostasis supported by expression analysis of publicly available single-cell RNA sequencing datasets from human cholangiocytes, which provide insights into the molecular basis of pH homeostasis and dysregulation in the biliary system.
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Affiliation(s)
- David C Trampert
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Stan F J van de Graaf
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Aldo Jongejan
- Amsterdam UMC, University of Amsterdam, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Meibergdreef 9, Amsterdam, the Netherlands
| | - Ronald P J Oude Elferink
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Ulrich Beuers
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands.
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Huynh MT, Nguyen TT, Grison S, Lascols O, Fernandez E, Barbu V. Clinical characteristics and genetic profiles of young and adult patients with cholestatic liver disease. Rev Esp Enferm Dig 2020; 111:775-788. [PMID: 31538484 DOI: 10.17235/reed.2019.6168/2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND AND AIMS heterozygous ABCB4, ABCB11 and ATP8B1 sequence variants were previously reported to be associated with low phospholipid-associated cholelithiasis, intrahepatic cholestasis of pregnancy, benign recurrent intrahepatic cholestasis and biliary lithiasis. The present study aimed to identify the presence of sequence variations in genes responsible for Mendelian liver disorders in patients with cholestatic liver disease. METHODS targeted massive parallel sequencing of a panel of genes involved in bile acid homeostasis was performed in 105 young and adult patients with cholestatic liver disease in our laboratory for molecular diagnosis. The effects of novel variants were evaluated using bioinformatics prediction tools and the Protter and Phyre2 software programs were used to create 2D, 3D topology protein modeling. Genotype-phenotype correlation was established according to molecular analysis and clinical records. RESULTS twenty novel heterozygous ABCB4 sequence variations, one heterozygous ABCB4 large intragenic deletion and only one novel missense variant in ABCB11 and ATP8B1 were identified. Interestingly, heterozygous and homozygous SLC4A2 missense variants were detected in patients with low phospholipid-associated cholelithiasis. Two patients harbored heterozygous GPBAR1 variants. Common variants such as homozygous ABCB11 p.Val444Ala and heterozygous ABCG8 p.Asp19His were also identified in 12 cases. CONCLUSIONS forty-eight variants were identified in five genes including ABCB4, ABCB11, ATP8B1, SLC4A2 and GPBAR1, twenty-five of which were novel. This study expands the phenotypic and mutational spectrum in genes involved in bile acid homeostasis and highlights the genetic and phenotypic heterogeneity in patients with inherited liver disorders.
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Affiliation(s)
| | - Truong-Tam Nguyen
- Service de Médecine Interne, Université de Médecine Pham Ngoc Thach, Viet Nam
| | - Sophie Grison
- Hôpitaux universitaires Est Parisien, hôpital Sain, Laboratoire commun de Biologie et Génétique Moléculaires, France
| | - Olivier Lascols
- Hôpitaux universitaires Est Parisien, hôpital Sain, Laboratoire commun de Biologie et Génétique Moléculaires, France
| | - Eric Fernandez
- Hôpitaux universitaires Est Parisien, hôpital Sain, Laboratoire commun de Biologie et Génétique Moléculaires, France
| | - Véronique Barbu
- Genetics Service, Laboratoire commun de Biologie et Génétique Moléculaires, Hôpitaux universitaires Est Parisien, hôpi, France
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Bertolini A, Bodewes FAJA, Slae M, Wilschanski M. Hepatobiliary Involvement in Cystic Fibrosis. Respir Med 2020. [DOI: 10.1007/978-3-030-42382-7_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Arenas F, Hervías I, Sáez E, Melero S, Prieto J, Parés A, Medina JF. Promoter hypermethylation of the AE2/SLC4A2 gene in PBC. JHEP Rep 2019; 1:145-153. [PMID: 32039364 PMCID: PMC7001545 DOI: 10.1016/j.jhepr.2019.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 05/13/2019] [Accepted: 05/16/2019] [Indexed: 12/12/2022] Open
Abstract
Background & Aims Patients with primary biliary cholangitis (PBC) exhibit reduced AE2/SLC4A2 gene expression in the liver and peripheral blood mononuclear cells (PBMCs). AE2 encodes a Cl–/HCO3– exchanger involved in biliary bicarbonate secretion and intracellular pH regulation. Reduced AE2 expression in PBC may be pathogenic, as Ae2-knockout mice reproduce characteristic PBC features. Herein, we aimed to identify CpG-methylation abnormalities in AE2 promoter regions that might contribute to the reduced gene transcription in PBC livers and PBMCs. Methods CpG-cytosine methylation rates were interrogated at 1-base pair resolution in upstream and alternate AE2 promoter regions through pyrosequencing of bisulphite-modified genomic DNA from liver specimens and PBMCs. AE2a and alternative AE2b1 and AE2b2 mRNA levels were measured by real-time PCR. Human lymphoblastoid-T2 cells were treated with 5-aza-2´-deoxycytidine for demethylation assays. Results AE2 promoters were found to be hypermethylated in PBC livers compared to normal and diseased liver specimens. Receiver operating characteristic (ROC) curve analysis showed that minimal CpG-hypermethylation clusters of 3 AE2a-CpG sites and 4 alternate-AE2b2-CpG sites specifically differentiated PBC from normal and diseased controls, with mean methylation rates inversely correlating with respective transcript levels. Additionally, in PBMCs a minimal cluster of 3 hypermethylated AE2a-CpG sites distinguished PBC from controls, and mean methylation rates correlated negatively with AE2a mRNA levels in these immune cells. Alternate AE2b2/AE2b1 promoters in PBMCs were constitutively hypermethylated, in line with absent alternative mRNA expression in diseased and healthy PBMCs. Demethylation assays treating lymphoblastoid-T2 cells with 5-aza-2´-deoxycytidine triggered AE2b2/AE2b1 expression and upregulated AE2a-promoter expression. Conclusions Disease-specific hypermethylation of AE2 promoter regions and subsequent downregulation of AE2-gene expression in the liver and PBMCs of patients with PBC might be critically involved in the pathogenesis of this complex disease. Lay summary Primary biliary cholangitis (PBC) is a chronic immune-associated cholestatic liver disease with unclear complex/multifactorial etiopathogenesis affecting mostly middle-aged women. Patients with PBC exhibit reduced expression of the AE2/SLC4A2 gene. Herein, we found that AE2 promoter regions are hypermethylated in the liver and peripheral blood mononuclear cells of patients with PBC. This increased methylation is associated with downregulated AE2-gene expression, which might contribute to the pathogenesis of PBC. Therefore, novel epigenetic targets may improve treatment in patients with PBC who respond poorly to current pharmacological therapies. Patients with PBC have higher AE2 CpG methylation in upstream AE2a and/or AE2b2/AE2b1 promoter regions in liver and PBMCs. Combined methylation rates of 2 minimal CpG-clusters in the liver and 1 minimal CpG-cluster in PBMCs specifically distinguished PBC from normal and diseased controls. Methylation rates of AE2 promoter regions inversely correlated with levels of respective AE2 mRNAs in liver and PBMCs. Alternate AE2b2/AE2b1 promoter regions were found to be densely methylated in both normal and diseased PBMC samples.
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Affiliation(s)
- Fabián Arenas
- Division of Gene Therapy and Hepatology, CIMA, School of Medicine and Clinic University of Navarra, and Ciberehd, Pamplona
| | - Isabel Hervías
- Division of Gene Therapy and Hepatology, CIMA, School of Medicine and Clinic University of Navarra, and Ciberehd, Pamplona
| | - Elena Sáez
- Division of Gene Therapy and Hepatology, CIMA, School of Medicine and Clinic University of Navarra, and Ciberehd, Pamplona
| | - Saida Melero
- Division of Gene Therapy and Hepatology, CIMA, School of Medicine and Clinic University of Navarra, and Ciberehd, Pamplona
| | - Jesús Prieto
- Division of Gene Therapy and Hepatology, CIMA, School of Medicine and Clinic University of Navarra, and Ciberehd, Pamplona
| | - Albert Parés
- Liver Unit, Hospital Clinic, IDIBAPS, University of Barcelona, and Ciberehd, Barcelona, Spain
| | - Juan F. Medina
- Division of Gene Therapy and Hepatology, CIMA, School of Medicine and Clinic University of Navarra, and Ciberehd, Pamplona
- Corresponding author. Address: Division of Gene Therapy and Hepatology, Center for Applied Medical Research (CIMA) University of Navarra School of Medicine, Pamplona, Spain.
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Abstract
Cholangiocytes, the epithelial cells lining the intrahepatic and extrahepatic bile ducts, are highly specialized cells residing in a complex anatomic niche where they participate in bile production and homeostasis. Cholangiocytes are damaged in a variety of human diseases termed cholangiopathies, often causing advanced liver failure. The regulation of cholangiocyte transport properties is increasingly understood, as is their anatomical and functional heterogeneity along the biliary tract. Furthermore, cholangiocytes are pivotal in liver regeneration, especially when hepatocyte regeneration is compromised. The role of cholangiocytes in innate and adaptive immune responses, a critical subject relevant to immune-mediated cholangiopathies, is also emerging. Finally, reactive ductular cells are present in many cholestatic and other liver diseases. In chronic disease states, this repair response contributes to liver inflammation, fibrosis and carcinogenesis and is a subject of intense investigation. This Review highlights advances in cholangiocyte research, especially their role in development and liver regeneration, their functional and biochemical heterogeneity, their activation and involvement in inflammation and fibrosis and their engagement with the immune system. We aim to focus further attention on cholangiocyte pathobiology and the search for new disease-modifying therapies targeting the cholangiopathies.
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Wang Y, Wang X, Chen S, Tian X, Zhang L, Huang Y, Tang C, Du J, Jin H. Sulfur Dioxide Activates Cl -/HCO 3 - Exchanger via Sulphenylating AE2 to Reduce Intracellular pH in Vascular Smooth Muscle Cells. Front Pharmacol 2019; 10:313. [PMID: 30971931 PMCID: PMC6446831 DOI: 10.3389/fphar.2019.00313] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 03/14/2019] [Indexed: 12/28/2022] Open
Abstract
Sulfur dioxide (SO2) is a colorless and irritating gas. Recent studies indicate that SO2 acts as the gas signal molecule and inhibits vascular smooth muscle cell (VSMC) proliferation. Cell proliferation depends on intracellular pH (pHi). Transmembrane cystein mutation of Na+- independent Cl-/HCO3 - exchanger (anion exchanger, AE) affects pHi. However, whether SO2 inhibits VSMC proliferation by reducing pHi is still unknown. Here, we investigated whether SO2 reduced pHi to inhibit the proliferation of VSMCs and explore its molecular mechanisms. Within a range of 50-200 μM, SO2 was found to lower the pHi in VSMCs. Concurrently, NH4Cl pre-perfusion showed that SO2 significantly activated AE, whereas the AE inhibitor 4,4'-diisothiocyanatostilbene- 2,20-disulfonic acid (DIDS) significantly attenuated the effect of SO2 on pHi in VSMCs. While 200 μM SO2 sulphenylated AE2, while dithiothreitol (DTT) blocked the sulphenylation of AE2 and subsequent AE activation by SO2, thereby restoring the pHi in VSMCs. Furthermore, DIDS pretreatment eliminated SO2-induced inhibition of PDGF-BB-stimulated VSMC proliferation. We report for the first time that SO2 inhibits VSMC proliferation in part by direct activation of the AE via posttranslational sulphenylation and induction of intracellular acidification.
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Affiliation(s)
- Yi Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xiuli Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Selena Chen
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, United States
| | - Xiaoyu Tian
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Lulu Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yaqian Huang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Chaoshu Tang
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China.,Key Laboratory of Molecular Cardiology, Ministry of Education, Beijing, China
| | - Junbao Du
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Hongfang Jin
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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13
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Chen Y, Devalliere J, Bulutoglu B, Yarmush ML, Uygun BE. Repopulation of intrahepatic bile ducts in engineered rat liver grafts. Technology (Singap World Sci) 2019; 7:46-55. [PMID: 31388515 PMCID: PMC6684151 DOI: 10.1142/s2339547819500043] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Engineered liver grafts for transplantation with sufficient hepatic function have been developed both in small and large animal models using the whole liver engineering approach. However, repopulation of the bile ducts in the whole liver scaffolds has not been addressed yet. In this study, we show the feasibility of repopulating the bile ducts in decellularized rat livers. Biliary epithelial cells were introduced into the bile ducts of the decellularized liver scaffolds with or without hepatocytes in the parenchymal space. The recellularized grafts were cultured under perfusion for up to 2 days and histological analysis revealed that the biliary epithelial cells formed duct-like structures, with the viable hepatocyte mass residing in the parenchymal space, in an arrangement highly comparable to the native tissue. The grafts were viable and functional as confirmed by both albumin and urea assay results and the gene expression analysis of biliary epithelial cells in recellularized liver grafts. This study provides the proof-of-concept results for rat liver grafts co-populated with parenchymal and biliary epithelial cells.
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Affiliation(s)
- Yibin Chen
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Julie Devalliere
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Beyza Bulutoglu
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Martin L Yarmush
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, Shriners Hospitals for Children, Boston, MA 02114, USA
- Department of Biomedical Engineering, Rutgers University, Piscataway, NJ 08854, USA
| | - Basak E Uygun
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, Shriners Hospitals for Children, Boston, MA 02114, USA
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14
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Abstract
Bile acids are synthesized in the liver and are the major component in bile. Impaired bile flow leads to cholestasis that is characterized by elevated levels of bile acid in the liver and serum, followed by hepatocyte and biliary injury. Although the causes of cholestasis have been extensively studied, the molecular mechanisms as to how bile acids initiate liver injury remain controversial. In this chapter, we summarize recent advances in the pathogenesis of bile acid induced liver injury. These include bile acid signaling pathways in hepatocytes as well as the response of cholangiocytes and innate immune cells in the liver in both patients with cholestasis and cholestatic animal models. We focus on how bile acids trigger the production of molecular mediators of neutrophil recruitment and the role of the inflammatory response in this pathological process. These advances point to a number of novel targets where drugs might be judged to be effective therapies for cholestatic liver injury.
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Affiliation(s)
- Man Li
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Shi-Ying Cai
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - James L Boyer
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA.
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15
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Li M, Cai SY, Boyer JL. Mechanisms of bile acid mediated inflammation in the liver. Mol Aspects Med 2017; 56:45-53. [PMID: 28606651 DOI: 10.1016/j.mam.2017.06.001] [Citation(s) in RCA: 147] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 05/26/2017] [Accepted: 06/07/2017] [Indexed: 02/07/2023]
Abstract
Bile acids are synthesized in the liver and are the major component in bile. Impaired bile flow leads to cholestasis that is characterized by elevated levels of bile acid in the liver and serum, followed by hepatocyte and biliary injury. Although the causes of cholestasis have been extensively studied, the molecular mechanisms as to how bile acids initiate liver injury remain controversial. In this chapter, we summarize recent advances in the pathogenesis of bile acid induced liver injury. These include bile acid signaling pathways in hepatocytes as well as the response of cholangiocytes and innate immune cells in the liver in both patients with cholestasis and cholestatic animal models. We focus on how bile acids trigger the production of molecular mediators of neutrophil recruitment and the role of the inflammatory response in this pathological process. These advances point to a number of novel targets where drugs might be judged to be effective therapies for cholestatic liver injury.
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Affiliation(s)
- Man Li
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Shi-Ying Cai
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - James L Boyer
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA.
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16
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Abstract
Store-operated Ca2+ entry (SOCE) is a conserved mechanism of Ca2+ influx that regulates Ca2+ signaling in many cell types. SOCE is activated by depletion of endoplasmic reticulum (ER) Ca2+ stores in response to physiological agonist stimulation. After it was first postulated by J.W. Putney Jr. in 1986, SOCE has been described in a large number of non-excitable cell types including secretory cells of different exocrine glands. Here we discuss the mechanisms by which SOCE controls salt and fluid secretion in exocrine glands, with a special focus on eccrine sweat glands. In sweat glands, SOCE plays an important, non-redundant role in regulating the function of Ca2+-activated Cl- channels (CaCC), Cl- secretion and sweat production. In the absence of key regulators of SOCE such as the CRAC channel pore subunit ORAI1 and its activator STIM1, the Ca2+-activated chloride channel TMEM16A is inactive and fails to secrete Cl-, resulting in anhidrosis in mice and human patients.
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Affiliation(s)
- Axel R Concepcion
- Department of Pathology, New York University School of Medicine, New York, NY, 10016, USA
| | - Stefan Feske
- Department of Pathology, New York University School of Medicine, New York, NY, 10016, USA.
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17
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Concepcion AR, Salas JT, Sáez E, Sarvide S, Ferrer A, Portu A, Uriarte I, Hervás-Stubbs S, Oude Elferink RPJ, Prieto J, Medina JF. CD8+ T cells undergo activation and programmed death-1 repression in the liver of aged Ae2a,b-/- mice favoring autoimmune cholangitis. Oncotarget 2016; 6:28588-606. [PMID: 26396175 PMCID: PMC4745679 DOI: 10.18632/oncotarget.5665] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 08/31/2015] [Indexed: 12/15/2022] Open
Abstract
UNLABELLED Primary biliary cirrhosis (PBC) is a chronic cholestatic disease of unknown etiopathogenesis showing progressive autoimmune-mediated cholangitis. In PBC patients, the liver and lymphocytes exhibit diminished expression of AE2/SLC4A2, a Cl-/HCO3- anion exchanger involved in biliary bicarbonate secretion and intracellular pH regulation. Decreased AE2 expression may be pathogenic as Ae2a,b(-/-) mice reproduce hepatobiliary and immunological features resembling PBC. To understand the role of AE2 deficiency for autoimmunity predisposition we focused on the phenotypic changes of T cells that occur over the life-span of Ae2a,b(-/-) mice. At early ages (1-9 months), knockout mice had reduced numbers of intrahepatic T cells, which exhibited increased activation, programmed-cell-death (PD)-1 expression, and apoptosis. Moreover, young knockouts had upregulated PD-1 ligand (PD-L1) on bile-duct cells, and administration of neutralizing anti-PD-L1 antibodies prevented their intrahepatic T-cell deletion. Older (≥ 10 months) knockouts, however, showed intrahepatic accumulation of cytotoxic CD8(+) T cells with downregulated PD-1 and diminished apoptosis. In-vitro DNA demethylation with 5-aza-2'-deoxycytidine partially reverted PD-1 downregulation of intrahepatic CD8(+) T cells from aged knockouts. CONCLUSION Early in life, AE2 deficiency results in intrahepatic T-cell activation and PD-1/PD-L1 mediated deletion. With aging, intrahepatic CD8+ T cells epigenetically suppress PD-1, and their consequential expansion and further activation favor autoimmune cholangitis.
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Affiliation(s)
- Axel R Concepcion
- Center for Applied Medical Research (CIMA), School of Medicine and Clinic University of Navarra, and CIBERehd, Pamplona, Spain
| | - January T Salas
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Elena Sáez
- Center for Applied Medical Research (CIMA), School of Medicine and Clinic University of Navarra, and CIBERehd, Pamplona, Spain
| | - Sarai Sarvide
- Center for Applied Medical Research (CIMA), School of Medicine and Clinic University of Navarra, and CIBERehd, Pamplona, Spain
| | - Alex Ferrer
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Ainhoa Portu
- Center for Applied Medical Research (CIMA), School of Medicine and Clinic University of Navarra, and CIBERehd, Pamplona, Spain
| | - Iker Uriarte
- Center for Applied Medical Research (CIMA), School of Medicine and Clinic University of Navarra, and CIBERehd, Pamplona, Spain
| | - Sandra Hervás-Stubbs
- Center for Applied Medical Research (CIMA), School of Medicine and Clinic University of Navarra, and CIBERehd, Pamplona, Spain
| | - Ronald P J Oude Elferink
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | - Jesús Prieto
- Center for Applied Medical Research (CIMA), School of Medicine and Clinic University of Navarra, and CIBERehd, Pamplona, Spain
| | - Juan F Medina
- Center for Applied Medical Research (CIMA), School of Medicine and Clinic University of Navarra, and CIBERehd, Pamplona, Spain
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18
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Wang W, Ren X, Cai Y, Chen L, Zhang W, Xu J. Rifampicin Induces Bicarbonate-Rich Choleresis in Rats: Involvement of Anion Exchanger 2. Dig Dis Sci 2016; 61:126-36. [PMID: 26319954 DOI: 10.1007/s10620-015-3850-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 08/10/2015] [Indexed: 01/22/2023]
Abstract
BACKGROUND AND AIM Previous studies have shown that rifampicin induced choleresis, the mechanisms of which have not been described. The aim of this study was to investigate the mechanisms underlying in vivo rifampicin-induced choleresis. METHODS In one experimental set, rats were treated chronically with rifampicin on days 1, 3 and 7. Serum and biliary parameters were assayed, and mRNA and protein levels, as well as the locations of the hepatic export transporters were analyzed by real-time PCR, western blot and immunofluorescence. Ductular mass was evaluated immunohistochemically. In another experimental set, rats received an acute infusion of rifampicin. The amount of rifampicin in bile was detected using HPLC. Biliary parameters were monitored following intrabiliary retrograde fluxes of the Cl(-)/HCO3 (-) exchange inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) or 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) in the infused rats. RESULTS Biliary bicarbonate output increased in parallel to the augmented bile flow in response to rifampicin, and this effect was abolished with intrabiliary administration of DIDS, but not NPPB. The biliary secretion of rifampicin with increases in bile flow and biliary rifampicin in response to different infused doses of the antibiotic show no significant correlations. After rifampicin treatment, the expression level of anion exchanger 2 (AE2) increased, while the location of hepatic transporters did not change. However, RIF treatment did not increase ductular mass significantly. CONCLUSIONS These results indicate that the increase in bile flow induced by rifampicin is mainly due to increased HCO3 (-) excretion mediated by increased AE2 protein expression and activity.
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Affiliation(s)
- Wei Wang
- Department of Gastroenterology, The First Affiliated Hospital, Anhui Medical University, Hefei, 230022, Anhui Province, China.
| | - Xiaofei Ren
- Department of Gastroenterology, The First Affiliated Hospital, Anhui Medical University, Hefei, 230022, Anhui Province, China.
| | - Yi Cai
- Department of Gastroenterology, The First Affiliated Hospital, Anhui Medical University, Hefei, 230022, Anhui Province, China.
| | - Lihong Chen
- Department of Gastroenterology, The First Affiliated Hospital, Anhui Medical University, Hefei, 230022, Anhui Province, China.
| | - Weiping Zhang
- Department of Gastroenterology, The First Affiliated Hospital, Anhui Medical University, Hefei, 230022, Anhui Province, China.
| | - Jianming Xu
- Department of Gastroenterology, The First Affiliated Hospital, Anhui Medical University, Hefei, 230022, Anhui Province, China.
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19
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Xie Y, Ma H, Lian Z. Epigenetics and Primary Biliary Cirrhosis: a Comprehensive Review and Implications for Autoimmunity. Clin Rev Allergy Immunol 2016; 50:390-403. [DOI: 10.1007/s12016-015-8502-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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20
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De Assuncao TM, Sun Y, Jalan-Sakrikar N, Drinane M, Huang BQ, Li Y, Davila JI, Wang R, O’Hara SP, Lomberk GA, Urrutia RA, Ikeda Y, Huebert RC. Development and characterization of human-induced pluripotent stem cell-derived cholangiocytes. J Transl Med 2015; 95:684-96. [PMID: 25867762 PMCID: PMC4447567 DOI: 10.1038/labinvest.2015.51] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/26/2015] [Accepted: 02/04/2015] [Indexed: 12/25/2022] Open
Abstract
Cholangiocytes are the target of a heterogeneous group of liver diseases known as the cholangiopathies. An evolving understanding of the mechanisms driving biliary development provides the theoretical underpinnings for rational development of induced pluripotent stem cell (iPSC)-derived cholangiocytes (iDCs). Therefore, the aims of this study were to develop an approach to generate iDCs and to fully characterize the cells in vitro and in vivo. Human iPSC lines were generated by forced expression of the Yamanaka pluripotency factors. We then pursued a stepwise differentiation strategy toward iDCs, using precise temporal exposure to key biliary morphogens, and we characterized the cells, using a variety of morphologic, molecular, cell biologic, functional, and in vivo approaches. Morphology shows a stepwise phenotypic change toward an epithelial monolayer. Molecular analysis during differentiation shows appropriate enrichment in markers of iPSC, definitive endoderm, hepatic specification, hepatic progenitors, and ultimately cholangiocytes. Immunostaining, western blotting, and flow cytometry demonstrate enrichment of multiple functionally relevant biliary proteins. RNA sequencing reveals that the transcriptome moves progressively toward that of human cholangiocytes. iDCs generate intracellular calcium signaling in response to ATP, form intact primary cilia, and self-assemble into duct-like structures in three-dimensional culture. In vivo, the cells engraft within mouse liver, following retrograde intrabiliary infusion. In summary, we have developed a novel approach to generate mature cholangiocytes from iPSCs. In addition to providing a model of biliary differentiation, iDCs represent a platform for in vitro disease modeling, pharmacologic testing, and individualized, cell-based, regenerative therapies for the cholangiopathies.
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Affiliation(s)
- Thiago M. De Assuncao
- Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, MN,Gastroenterology Research Unit, Mayo Clinic and Foundation, Rochester, MN
| | - Yan Sun
- Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, MN,Gastroenterology Research Unit, Mayo Clinic and Foundation, Rochester, MN
| | - Nidhi Jalan-Sakrikar
- Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, MN,Gastroenterology Research Unit, Mayo Clinic and Foundation, Rochester, MN
| | - Mary Drinane
- Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, MN,Gastroenterology Research Unit, Mayo Clinic and Foundation, Rochester, MN
| | - Bing Q. Huang
- Center for Basic Research in Digestive Diseases, Mayo Clinic and Foundation, Rochester, MN
| | - Ying Li
- Division of Biomedical Statistics and Informatics, Mayo Clinic and Foundation, Rochester, MN
| | - Jaime I. Davila
- Division of Biomedical Statistics and Informatics, Mayo Clinic and Foundation, Rochester, MN
| | - Ruisi Wang
- Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, MN,Gastroenterology Research Unit, Mayo Clinic and Foundation, Rochester, MN
| | - Steven P. O’Hara
- Center for Basic Research in Digestive Diseases, Mayo Clinic and Foundation, Rochester, MN
| | - Gwen A. Lomberk
- Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, MN,Gastroenterology Research Unit, Mayo Clinic and Foundation, Rochester, MN,Center for Cell Signaling in Gastroenterology, Mayo Clinic and Foundation, Rochester, MN
| | - Raul A. Urrutia
- Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, MN,Gastroenterology Research Unit, Mayo Clinic and Foundation, Rochester, MN,Center for Cell Signaling in Gastroenterology, Mayo Clinic and Foundation, Rochester, MN
| | - Yasuhiro Ikeda
- Department of Molecular Medicine; Mayo Clinic and Foundation, Rochester, MN
| | - Robert C. Huebert
- Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, MN,Gastroenterology Research Unit, Mayo Clinic and Foundation, Rochester, MN,Center for Cell Signaling in Gastroenterology, Mayo Clinic and Foundation, Rochester, MN
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Abstract
Amelogenins are the most abundant protein species in forming dental enamel, taken to regulate crystal shape and crystal growth. Unprotonated amelogenins can bind protons, suggesting that amelogenins could regulate the pH in enamel in situ. We hypothesized that without amelogenins the enamel would acidify unless ameloblasts were buffered by alternative ways. To investigate this, we measured the mineral and chloride content in incisor enamel of amelogenin-knockout (AmelX(-/-)) mice and determined the pH of enamel by staining with methyl-red. Ameloblasts were immunostained for anion exchanger-2 (Ae2), a transmembrane pH regulator sensitive for acid that secretes bicarbonate in exchange for chloride. The enamel of AmelX(-/-) mice was 10-fold thinner, mineralized in the secretory stage 1.8-fold more than wild-type enamel and containing less chloride (suggesting more bicarbonate secretion). Enamel of AmelX(-/-) mice stained with methyl-red contained no acidic bands in the maturation stage as seen in wild-type enamel. Secretory ameloblasts of AmelX(-/-) mice, but not wild-type mice, were immunopositive for Ae2, and stained more intensely in the maturation stage compared with wild-type mice. Exposure of AmelX(-/-) mice to fluoride enhanced the mineral content in the secretory stage, lowered chloride, and intensified Ae2 immunostaining in the enamel organ in comparison with non-fluorotic mutant teeth. The results suggest that unprotonated amelogenins may regulate the pH of forming enamel in situ. Without amelogenins, Ae2 could compensate for the pH drop associated with crystal formation.
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Affiliation(s)
- J Guo
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, the Netherlands
| | - D M Lyaruu
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, the Netherlands
| | - Y Takano
- Section of Biostructural Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - C W Gibson
- Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - P K DenBesten
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California in San Francisco, CA, USA
| | - A L J J Bronckers
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, the Netherlands
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