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Xu Z, Tang W, Xie Q, Cao X, Zhang M, Zhang X, Chai J. Dimethyl fumarate attenuates cholestatic liver injury by activating the NRF2 and FXR pathways and suppressing NLRP3/GSDMD signaling in mice. Exp Cell Res 2023; 432:113781. [PMID: 37722551 DOI: 10.1016/j.yexcr.2023.113781] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 08/27/2023] [Accepted: 09/12/2023] [Indexed: 09/20/2023]
Abstract
The progression of cholestasis is characterized by excessive accumulation of bile acids (BAs) in the liver, which leads to oxidative stress (OS), inflammation and liver injury. There are currently limited treatments for cholestasis. Therefore, appropriate drugs for cholestasis treatment need to be developed. Dimethyl fumarate (DMF) has been widely used in the treatment of various diseases and exerts antioxidant and anti-inflammatory effects, but its effect on cholestatic liver disease remains unclarified. We fed mice 3,5-diethoxycarbonyl-1,4-dihydrocollidine or cholic acid to induce cholestatic liver injury and treated these mice with DMF to evaluate its protective ability. Alanine aminotransferase, aspartate aminotransferase, and total liver BAs were assessed as indicators of liver function. The levels of OS, liver inflammation, transporters and metabolic enzymes were also measured. DMF markedly altered the relative ALT and AST levels and enhanced the liver antioxidant capacity. DMF regulated the MST/NRF2 signaling pathway to protect against OS and reduced liver inflammation through the NLRP3/GSDMD signaling pathway. DMF also regulated the levels of BA transporters by promoting FXR protein expression. These findings provide new strategies for the treatment of cholestatic liver disorders.
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Affiliation(s)
- Ziqian Xu
- School of Medicine, Chongqing University, Chongqing 400030, China; Department of Gastroenterology, Institute of Digestive Diseases of PLA, Cholestatic Liver Diseases Center, and Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Wan Tang
- Department of Gastroenterology, Institute of Digestive Diseases of PLA, Cholestatic Liver Diseases Center, and Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Qiaoling Xie
- Department of Gastroenterology, Institute of Digestive Diseases of PLA, Cholestatic Liver Diseases Center, and Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Xinyu Cao
- Department of Gastroenterology, Institute of Digestive Diseases of PLA, Cholestatic Liver Diseases Center, and Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Mengni Zhang
- Department of Gastroenterology, Institute of Digestive Diseases of PLA, Cholestatic Liver Diseases Center, and Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Xiaoxun Zhang
- Department of Gastroenterology, Institute of Digestive Diseases of PLA, Cholestatic Liver Diseases Center, and Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing 400038, China.
| | - Jin Chai
- School of Medicine, Chongqing University, Chongqing 400030, China; Department of Gastroenterology, Institute of Digestive Diseases of PLA, Cholestatic Liver Diseases Center, and Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing 400038, China; The Second Affiliated Hospital, University of South China, Hengyang 421001, China.
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2
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Li X, Xie W, Pan Q, Zhang X, Zhang L, Zhao N, Xie Q, Ding J, Chai J. Semaphorin 7A interacts with nuclear factor NF-kappa-B p105 via integrin β1 and mediates inflammation. Cell Commun Signal 2023; 21:24. [PMID: 36717921 PMCID: PMC9885601 DOI: 10.1186/s12964-022-01024-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 12/22/2022] [Indexed: 02/01/2023] Open
Abstract
Semaphorin7a (SEMA7A), a membrane-anchored member of the semaphorin protein family, could be involved in a diverse range of immune responses via its receptor integrin β1. Recently, we reported that the SEMA7AR148W mutation (a gain-of-function mutation, Sema7aR145W in mice) is a risk factor for progressive familial intrahepatic cholestasis and nonalcoholic fatty liver disease via upregulated membrane localization. In this study, we demonstrated that integrin β1 is a membrane receptor for nuclear factor NF-kappa-B p105 (NF-κB p105) and a critical mediator of inflammation. Integrin β1 could interact with the C-terminal domain of NF-κB p105 to promote p50 generation and stimulate the NF-κB p50/p65 signalling pathway, upregulate TNF-α and IL-1β levels, and subsequently render hepatocytes more susceptible to inflammation. The induction of integrin β1 depends on elevated Sema7a membrane localization. Moreover, we revealed elevated levels of Sema7aWT (SEMA7AWT) in hepatocellular carcinoma (HCC) patients and an HCC mouse model. In line with our findings, the NF-κB p50/p65 pathway could also be activated by high Sema7a expression and repressed by integrin β1 silencing. In conclusion, our findings suggest that the Sema7aR145W (SEMA7AR148W) mutation and high Sema7aWT (SEMA7AWT) expression both activate the NF-κB p50/p65 pathway via integrin β1 and play a crucial role in inflammatory responses. Video Abstract.
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Affiliation(s)
- Xuan Li
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
| | - Wanlu Xie
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
| | - Qiong Pan
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
| | - Xiaoxun Zhang
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
| | - Liangjun Zhang
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
| | - Nan Zhao
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
| | - Qiaoling Xie
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
| | - Jingjing Ding
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
| | - Jin Chai
- grid.410570.70000 0004 1760 6682Department of Gastroenterology, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Institute of Digestive Diseases of PLA, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Cholestatic Liver Diseases Center, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China ,grid.410570.70000 0004 1760 6682Center for Metabolic Associated Fatty Liver Disease, The First Affiliated Hospital (Southwest Hospital) to Third Military Medical University (Army Medical University), Chongqing, 400038 China
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3
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Pan Q, Luo G, Qu J, Chen S, Zhang X, Zhao N, Ding J, Yang H, Li M, Li L, Cheng Y, Li X, Xie Q, Li Q, Zhou X, Zou H, Fan S, Zou L, Liu W, Deng G, Cai S, Boyer JL, Chai J. A homozygous R148W mutation in Semaphorin 7A causes progressive familial intrahepatic cholestasis. EMBO Mol Med 2021; 13:e14563. [PMID: 34585848 PMCID: PMC8573601 DOI: 10.15252/emmm.202114563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 12/15/2022] Open
Abstract
Semaphorin 7A (SEMA7A) is a membrane-bound protein that involves axon growth and other biological processes. SEMA7A mutations are associated with vertebral fracture and Kallmann syndrome. Here, we report a case with a mutation in SEMA7A that displays familial cholestasis. WGS reveals a SEMA7AR148W homozygous mutation in a female child with elevated levels of serum ALT, AST, and total bile acid (TBA) of unknown etiology. This patient also carried a SLC10A1S267F allele, but Slc10a1S267F homozygous mice exhibited normal liver function. Similar to the child, Sema7aR145W homozygous mice displayed elevated levels of serum ALT, AST, and TBA. Remarkably, liver histology and LC-MS/MS analyses exhibited hepatocyte hydropic degeneration and increased liver bile acid (BA) levels in Sema7aR145W homozygous mice. Further mechanistic studies demonstrated that Sema7aR145W mutation reduced the expression of canalicular membrane BA transporters, bile salt export pump (Bsep), and multidrug resistance-associated protein-2 (Mrp2), causing intrahepatic cholestasis in mice. Administration with ursodeoxycholic acid and a dietary supplement glutathione improved liver function in the child. Therefore, Sema7aR145W homozygous mutation causes intrahepatic cholestasis by reducing hepatic Bsep and Mrp2 expression.
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Affiliation(s)
- Qiong Pan
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Gang Luo
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Jiaquan Qu
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Sheng Chen
- Department of PediatricsSouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Xiaoxun Zhang
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Nan Zhao
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Jingjing Ding
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Hong Yang
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Mingqiao Li
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Ling Li
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Ying Cheng
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Xuan Li
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Qiaoling Xie
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Qiao Li
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Xueqian Zhou
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Huiling Zou
- Department of PediatricsChangsha Hospital for Maternal & Child Health CareChangshaChina
| | - Shijun Fan
- Medical Research CenterSouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Lingyun Zou
- Bao'an Maternal and Child Health HospitalJinan UniversityShenzhenChina
| | - Wei Liu
- Institute of ImmunologyThird Military Medical University (Army Medical University)ChongqingChina
| | - Guohong Deng
- Department of Infectious DiseasesSouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
| | - Shi‐Ying Cai
- Department of Internal Medicine and Liver CenterYale University School of MedicineNew HavenCTUSA
| | - James L Boyer
- Department of Internal Medicine and Liver CenterYale University School of MedicineNew HavenCTUSA
| | - Jin Chai
- Cholestatic Liver Diseases CenterDepartment of GastroenterologySouthwest HospitalThird Military Medical University (Army Medical University)ChongqingChina
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4
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Yang Y, Sangwung P, Kondo R, Jung Y, McConnell MJ, Jeong J, Utsumi T, Sessa WC, Iwakiri Y. Alcohol-induced Hsp90 acetylation is a novel driver of liver sinusoidal endothelial dysfunction and alcohol-related liver disease. J Hepatol 2021; 75:377-386. [PMID: 33675874 PMCID: PMC8292196 DOI: 10.1016/j.jhep.2021.02.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 02/20/2021] [Accepted: 02/24/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Liver sinusoidal endothelial cell (LSEC) dysfunction has been reported in alcohol-related liver disease, yet it is not known whether LSECs metabolize alcohol. Thus, we investigated this, as well as the mechanisms of alcohol-induced LSEC dysfunction and a potential therapeutic approach for alcohol-induced liver injury. METHODS Primary human, rat and mouse LSECs were used. Histone deacetylase 6 (HDAC6) was overexpressed specifically in liver ECs via adeno-associated virus (AAV)-mediated gene delivery to decrease heat shock protein 90 (Hsp90) acetylation in ethanol-fed mice. RESULTS LSECs expressed CYP2E1 and alcohol dehydrogenase 1 (ADH1) and metabolized alcohol. Ethanol induced CYP2E1 in LSECs, but not ADH1. Alcohol metabolism by CYP2E1 increased Hsp90 acetylation and decreased its interaction with endothelial nitric oxide synthase (eNOS) leading to a decrease in nitric oxide (NO) production. A non-acetylation mutant of Hsp90 increased its interaction with eNOS and NO production, whereas a hyperacetylation mutant decreased NO production. These results indicate that Hsp90 acetylation is responsible for decreases in its interaction with eNOS and eNOS-derived NO production. AAV8-driven HDAC6 overexpression specifically in liver ECs deacetylated Hsp90, restored Hsp90's interaction with eNOS and ameliorated alcohol-induced liver injury in mice. CONCLUSION Restoring LSEC function is important for ameliorating alcohol-induced liver injury. To this end, blocking acetylation of Hsp90 specifically in LSECs via AAV-mediated gene delivery has the potential to be a new therapeutic strategy. LAY SUMMARY Alcohol metabolism in liver sinusoidal endothelial cells (LSECs) and the mechanism of alcohol-induced LSEC dysfunction are largely unknown. Herein, we demonstrate that LSECs can metabolize alcohol. We also uncover a mechanism by which alcohol induces LSEC dysfunction and liver injury, and we identify a potential therapeutic strategy to prevent this.
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Affiliation(s)
- Yilin Yang
- Department of Internal Medicine, Section of Digestive Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Panjamaporn Sangwung
- Department of Internal Medicine, Section of Digestive Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Reiichiro Kondo
- Department of Internal Medicine, Section of Digestive Diseases, Yale School of Medicine, New Haven, CT, USA,Department of Pathology, Kurume University School of Medicine, Kurume, Japan
| | - Yirang Jung
- Department of Internal Medicine, Section of Digestive Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Matthew J. McConnell
- Department of Internal Medicine, Section of Digestive Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Jain Jeong
- Department of Internal Medicine, Section of Digestive Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Teruo Utsumi
- Department of Internal Medicine, Section of Digestive Diseases, Yale School of Medicine, New Haven, CT, USA
| | - William C. Sessa
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
| | - Yasuko Iwakiri
- Department of Internal Medicine, Section of Digestive Diseases, Yale School of Medicine, New Haven, CT, USA.
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5
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de Miranda MC, Rodrigues MA, de Angelis Campos AC, Faria JAQA, Kunrath-Lima M, Mignery GA, Schechtman D, Goes AM, Nathanson MH, Gomes DA. Epidermal growth factor (EGF) triggers nuclear calcium signaling through the intranuclear phospholipase Cδ-4 (PLCδ4). J Biol Chem 2019; 294:16650-16662. [PMID: 31537645 DOI: 10.1074/jbc.ra118.006961] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 09/10/2019] [Indexed: 02/06/2023] Open
Abstract
Calcium (Ca2+) signaling within the cell nucleus regulates specific cellular events such as gene transcription and cell proliferation. Nuclear and cytosolic Ca2+ levels can be independently regulated, and nuclear translocation of receptor tyrosine kinases (RTKs) is one way to locally activate signaling cascades within the nucleus. Nuclear RTKs, including the epidermal growth factor receptor (EGFR), are important for processes such as transcriptional regulation, DNA-damage repair, and cancer therapy resistance. RTKs can hydrolyze phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) within the nucleus, leading to Ca2+ release from the nucleoplasmic reticulum by inositol 1,4,5-trisphosphate receptors. PI(4,5)P2 hydrolysis is mediated by phospholipase C (PLC). However, it is unknown which nuclear PLC isoform is triggered by EGFR. Here, using subcellular fractionation, immunoblotting and fluorescence, siRNA-based gene knockdowns, and FRET-based biosensor reporter assays, we investigated the role of PLCδ4 in epidermal growth factor (EGF)-induced nuclear Ca2+ signaling and downstream events. We found that EGF-induced Ca2+ signals are inhibited when translocation of EGFR is impaired. Nuclear Ca2+ signals also were reduced by selectively buffering inositol 1,4,5-trisphosphate (InsP3) within the nucleus. EGF induced hydrolysis of nuclear PI(4,5)P2 by the intranuclear PLCδ4, rather than by PLCγ1. Moreover, protein kinase C, a downstream target of EGF, was active in the nucleus of stimulated cells. Furthermore, PLCδ4 and InsP3 modulated cell cycle progression by regulating the expression of cyclins A and B1. These results provide evidence that EGF-induced nuclear signaling is mediated by nuclear PLCδ4 and suggest new therapeutic targets to modulate the proliferative effects of this growth factor.
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Affiliation(s)
- Marcelo Coutinho de Miranda
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais (UFMG), Av. Antonio Carlos, 6627 Belo Horizonte-MG, 31270-901, Brazil.,Section of Digestive Diseases, Internal Medicine, Yale University, New Haven, Connecticut 06520-8056
| | - Michele Angela Rodrigues
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais (UFMG), Av. Antonio Carlos, 6627 Belo Horizonte-MG, 31270-901, Brazil.,Section of Digestive Diseases, Internal Medicine, Yale University, New Haven, Connecticut 06520-8056
| | - Ana Carolina de Angelis Campos
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais (UFMG), Av. Antonio Carlos, 6627 Belo Horizonte-MG, 31270-901, Brazil.,Section of Digestive Diseases, Internal Medicine, Yale University, New Haven, Connecticut 06520-8056
| | | | - Marianna Kunrath-Lima
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais (UFMG), Av. Antonio Carlos, 6627 Belo Horizonte-MG, 31270-901, Brazil
| | - Gregory A Mignery
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois 60153
| | - Deborah Schechtman
- Department of Biochemistry, University of São Paulo, Av. Professor Lineu Prestes, 748, São Paulo-SP 05508-900, Brazil
| | - Alfredo Miranda Goes
- Department of Pathology, Universidade Federal de Minas Gerais (UFMG), Av. Antonio Carlos, 6627 Belo Horizonte-MG, 31270-901, Brazil
| | - Michael H Nathanson
- Section of Digestive Diseases, Internal Medicine, Yale University, New Haven, Connecticut 06520-8056
| | - Dawidson A Gomes
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais (UFMG), Av. Antonio Carlos, 6627 Belo Horizonte-MG, 31270-901, Brazil .,Section of Digestive Diseases, Internal Medicine, Yale University, New Haven, Connecticut 06520-8056
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6
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Zhao G, Xu D, Yuan Z, Jiang Z, Zhou W, Li Z, Yin M, Zhou Z, Zhang L, Wang T. 8-Methoxypsoralen disrupts MDR3-mediated phospholipids efflux and bile acid homeostasis and its relevance to hepatotoxicity. Toxicology 2017; 386:40-48. [PMID: 28552422 DOI: 10.1016/j.tox.2017.05.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/03/2017] [Accepted: 05/16/2017] [Indexed: 02/07/2023]
Abstract
Since its discovery in 1987, multidrug resistance 3 P-glycoprotein (MDR3) had recognized to play a crucial role in the translocation of phospholipids from the inner to outer leaflets of bile canalicular membranes. An increasing number of reports suggest that drug-mediated functional disruption of MDR3 is responsible for drug-induced cholestasis. 8-Methoxypsoralen (8-MOP) is used clinically to treat psoriasis, vitiligo and other skin disorders. However, psoralens safety for long-term use is a concern. In the current study, we evaluate 8-MOP's potential hepatotoxicity and effects on bile formation. Sprague Dawley (SD) rats were treated daily 200mg/kg or 400mg/kg of 8-MOP orally for 28 days. The result showed a prominent decrease in biliary phospholipids output, which associated with the down-regulation of MDR3. Elevated bile acid serum level and increased biliary bile acid outputs were observed in 8-MOP-treated groups. The disturbance of bile acid homeostasis was associated with changes in enzymes and proteins involved in bile acid synthesis, regulation and transport. Human liver cell line L02 was used to determine on the mRNA and protein levels of MDR3. Cells treated with 8-MOP reveled a decrease in fluorescent PC (phosphatidylcholine) secretion into the pseudocanaliculi (formed between adjacent cells) compared with untreated cells. Our investigation represent the first evidence that 8-MOP can induce cholestatic liver injury by disturbing MDR3-mediated phospholipids efflux and bile acid homeostasis.
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Affiliation(s)
- Guolin Zhao
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Dengqiu Xu
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Ziqiao Yuan
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Zhenzhou Jiang
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China; Key Laboratory of Drug Quality Control and Pharmacovigilance, China Pharmaceutical University, Nanjing 210009, China
| | - Wang Zhou
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Zhijian Li
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China; Department of Pharmacology and Toxicology Laboratory, Xinjiang Institute of Traditional Uighur Medicine, Urumqi, Xinjiang 830049, China
| | - Mengyue Yin
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Zhixing Zhou
- Tianjin Key Laboratory of Molecular Design and Drug Discovery, Tianjin Institute of Pharmaceutical Research, Tianjin 300193, China
| | - Luyong Zhang
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China; Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing 210009, China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China.
| | - Tao Wang
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, China; Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing 210009, China.
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7
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Li M, Soroka CJ, Harry K, Boyer JL. CFTR-associated ligand is a negative regulator of Mrp2 expression. Am J Physiol Cell Physiol 2016; 312:C40-C46. [PMID: 27834195 DOI: 10.1152/ajpcell.00100.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 11/03/2016] [Indexed: 01/15/2023]
Abstract
The multidrug resistance-associated protein 2 (Mrp2) is an ATP-binding cassette transporter that transports a wide variety of organic anions across the apical membrane of epithelial cells. The expression of Mrp2 on the plasma membrane is regulated by protein-protein interactions. Cystic fibrosis transmembrane conductance regulator (CFTR)-associated ligand (CAL) interacts with transmembrane proteins via its PDZ domain and reduces their cell surface expression by increasing lysosomal degradation and intracellular retention. Our results showed that CAL is localized at the trans-Golgi network of rat hepatocytes. The expression of CAL is increased, and Mrp2 expression is decreased, in the liver of mice deficient in sodium/hydrogen exchanger regulatory factor-1. To determine whether CAL interacts with Mrp2 and is involved in the posttranscriptional regulation of Mrp2, we used glutathione S-transferase (GST) fusion proteins with or without the COOH-terminal PDZ binding motif of Mrp2 as the bait in GST pull-down assays. We demonstrated that Mrp2 binds to CAL via its COOH-terminal PDZ-binding motif in GST pull-down assays, an interaction verified by coimmunoprecipitation of these two proteins in cotransfected COS-7 cells. In COS-7 and LLC-PK1 cells transfected with Mrp2 alone, only a mature, high-molecular-mass band of Mrp2 was detected. However, when cells were cotransfected with Mrp2 and CAL, Mrp2 was expressed as both mature and immature forms. Biotinylation and streptavidin pull-down assays confirmed that CAL dramatically reduces the expression level of total and cell surface Mrp2 in Huh-7 cells. Our findings suggest that CAL interacts with Mrp2 and is a negative regulator of Mrp2 expression.
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Affiliation(s)
- Man Li
- The Yale Liver Center, Yale University School of Medicine, New Haven, Connecticut
| | - Carol J Soroka
- The Yale Liver Center, Yale University School of Medicine, New Haven, Connecticut
| | - Kathy Harry
- The Yale Liver Center, Yale University School of Medicine, New Haven, Connecticut
| | - James L Boyer
- The Yale Liver Center, Yale University School of Medicine, New Haven, Connecticut
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8
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Li M, Mennone A, Soroka CJ, Hagey LR, Ouyang X, Weinman EJ, Boyer JL. Na(+) /H(+) exchanger regulatory factor 1 knockout mice have an attenuated hepatic inflammatory response and are protected from cholestatic liver injury. Hepatology 2015; 62:1227-36. [PMID: 26108984 PMCID: PMC4589453 DOI: 10.1002/hep.27956] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 06/17/2015] [Indexed: 12/31/2022]
Abstract
UNLABELLED The intercellular adhesion molecule 1 (ICAM-1) is induced in mouse liver after bile duct ligation (BDL) and plays a key role in neutrophil-mediated liver injury in BDL mice. ICAM-1 has been shown to interact with cytoskeletal ezrin-radixin-moesin (ERM) proteins that also interact with the PDZ protein, Na(+) /H(+) exchanger regulatory factor 1 (NHERF-1/EBP50). In NHERF-1(-/-) mice, ERM proteins are significantly reduced in brush-border membranes from kidney and small intestine. ERM knockdown reduces ICAM-1 expression in response to tumor necrosis factor alpha. Here we show that NHERF-1 assembles ERM proteins, ICAM-1 and F-actin into a macromolecule complex that is increased in mouse liver after BDL. Compared to wild-type (WT) mice, both sham-operated and BDL NHERF-1(-/-) mice have lower levels of activated ERM and ICAM-1 protein in the liver accompanied by significantly reduced hepatic neutrophil accumulation, serum alanine aminotransferase, and attenuated liver injury after BDL. However, total bile acid concentrations in serum and liver of sham and BDL NHERF-1(-/-) mice were not significantly different from WT controls, although hepatic tetrahydroxylated bile acids and Cyp3a11 messenger RNA levels were higher in NHERF-1(-/-) BDL mice. CONCLUSION NHERF-1 participates in the inflammatory response that is associated with BDL-induced liver injury. Deletion of NHERF-1 in mice leads to disruption of the formation of ICAM-1/ERM/NHERF-1 complex and reduction of hepatic ERM proteins and ICAM-1, molecules that are up-regulated and are essential for neutrophil-mediated liver injury in cholestasis. Further study of the role of NHERF-1 in the inflammatory response in cholestasis and other forms of liver injury should lead to discovery of new therapeutic targets in hepatic inflammatory diseases.
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Affiliation(s)
- Man Li
- Yale Liver Center, Yale University School of Medicine, New Haven, CT
| | - Albert Mennone
- Yale Liver Center, Yale University School of Medicine, New Haven, CT
| | - Carol J. Soroka
- Yale Liver Center, Yale University School of Medicine, New Haven, CT
| | - Lee R. Hagey
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Xinshou Ouyang
- Yale Liver Center, Yale University School of Medicine, New Haven, CT
| | - Edward J. Weinman
- Department of Medicine, Baltimore, MD,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - James L. Boyer
- Yale Liver Center, Yale University School of Medicine, New Haven, CT
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9
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Feriod CN, Nguyen L, Jurczak MJ, Kruglov EA, Nathanson MH, Shulman GI, Bennett AM, Ehrlich BE. Inositol 1,4,5-trisphosphate receptor type II (InsP3R-II) is reduced in obese mice, but metabolic homeostasis is preserved in mice lacking InsP3R-II. Am J Physiol Endocrinol Metab 2014; 307:E1057-64. [PMID: 25315698 PMCID: PMC4254986 DOI: 10.1152/ajpendo.00236.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Inositol 1,4,5-trisphosphate receptor type II (InsP3R-II) is the most prevalent isoform of the InsP3R in hepatocytes and is concentrated under the canalicular membrane, where it plays an important role in bile secretion. We hypothesized that altered calcium (Ca(2+)) signaling may be involved in metabolic dysfunction, as InsP3R-mediated Ca(2+) signals have been implicated in the regulation of hepatic glucose homeostasis. Here, we find that InsP3R-II, but not InsP3R-I, is reduced in the livers of obese mice. In our investigation of the functional consequences of InsP3R-II deficiency, we found that organic anion secretion at the canalicular membrane and Ca(2+) signals were impaired. However, mice lacking InsP3R-II showed no deficits in energy balance, glucose production, glucose tolerance, or susceptibility to hepatic steatosis. Thus, our results suggest that reduced InsP3R-II expression is not sufficient to account for any disruptions in metabolic homeostasis that are observed in mouse models of obesity. We conclude that metabolic homeostasis is maintained independently of InsP3R-II. Loss of InsP3R-II does impair secretion of bile components; therefore, we suggest that conditions of obesity would lead to a decrease in this Ca(2+)-sensitive process.
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Affiliation(s)
- Colleen N Feriod
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, Connecticut
| | - Lily Nguyen
- Department of Pharmacology, Yale University School of Medicine New Haven, Connecticut
| | - Michael J Jurczak
- Department of Internal Medicine, Yale University School of Medicine New Haven, Connecticut
| | - Emma A Kruglov
- Section of Digestive Diseases, Yale University School of Medicine New Haven, Connecticut
| | - Michael H Nathanson
- Section of Digestive Diseases, Yale University School of Medicine New Haven, Connecticut
| | - Gerald I Shulman
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, Connecticut; Department of Internal Medicine, Yale University School of Medicine New Haven, Connecticut; Howard Hughes Medical Institute, Chevy Chase, Maryland
| | - Anton M Bennett
- Department of Pharmacology, Yale University School of Medicine New Haven, Connecticut; Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine New Haven, Connecticut; and
| | - Barbara E Ehrlich
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, Connecticut; Department of Pharmacology, Yale University School of Medicine New Haven, Connecticut;
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10
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Miyahara S, Saito M, Kanemaru T, Villanueva SYAM, Gloriani NG, Yoshida SI. Destruction of the hepatocyte junction by intercellular invasion of Leptospira causes jaundice in a hamster model of Weil's disease. Int J Exp Pathol 2014; 95:271-81. [PMID: 24945433 PMCID: PMC4170969 DOI: 10.1111/iep.12085] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 04/19/2014] [Indexed: 11/27/2022] Open
Abstract
Weil's disease, the most severe form of leptospirosis, is characterized by jaundice, haemorrhage and renal failure. The mechanisms of jaundice caused by pathogenic Leptospira remain unclear. We therefore aimed to elucidate the mechanisms by integrating histopathological changes with serum biochemical abnormalities during the development of jaundice in a hamster model of Weil's disease. In this work, we obtained three-dimensional images of infected hamster livers using scanning electron microscope together with freeze-cracking and cross-cutting methods for sample preparation. The images displayed the corkscrew-shaped bacteria, which infiltrated the Disse's space, migrated between hepatocytes, detached the intercellular junctions and disrupted the bile canaliculi. Destruction of bile canaliculi coincided with the elevation of conjugated bilirubin, aspartate transaminase and alkaline phosphatase levels in serum, whereas serum alanine transaminase and γ-glutamyl transpeptidase levels increased slightly, but not significantly. We also found in ex vivo experiments that pathogenic, but not non-pathogenic leptospires, tend to adhere to the perijunctional region of hepatocyte couplets isolated from hamsters and initiate invasion of the intercellular junction within 1 h after co-incubation. Our results suggest that pathogenic leptospires invade the intercellular junctions of host hepatocytes, and this invasion contributes in the disruption of the junction. Subsequently, bile leaks from bile canaliculi and jaundice occurs immediately. Our findings revealed not only a novel pathogenicity of leptospires, but also a novel mechanism of jaundice induced by bacterial infection.
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Affiliation(s)
- Satoshi Miyahara
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu UniversityFukuoka, Japan
| | - Mitsumasa Saito
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu UniversityFukuoka, Japan
| | | | - Sharon Y A M Villanueva
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu UniversityFukuoka, Japan
| | - Nina G Gloriani
- Department of Medical Microbiology, College of Public Health, University of the Philippines-ManilaManila, Philippines
| | - Shin-ichi Yoshida
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu UniversityFukuoka, Japan
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11
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Ghonem NS, Ananthanarayanan M, Soroka CJ, Boyer JL. Peroxisome proliferator-activated receptor α activates human multidrug resistance transporter 3/ATP-binding cassette protein subfamily B4 transcription and increases rat biliary phosphatidylcholine secretion. Hepatology 2014; 59:1030-42. [PMID: 24122873 PMCID: PMC4049334 DOI: 10.1002/hep.26894] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 09/19/2013] [Accepted: 09/20/2013] [Indexed: 12/11/2022]
Abstract
UNLABELLED Multidrug resistance transporter 3/ATP-binding cassette protein subfamily B4 (MDR3/ABCB4) is a critical determinant of biliary phosphatidylcholine (PC) secretion. Clinically, mutations and partial deficiencies in MDR3 result in cholestatic liver injury. Thus, MDR3 is a potential therapeutic target for cholestatic liver disease. Fenofibrate is a peroxisome proliferator-activated receptor (PPAR) α ligand that has antiinflammatory actions and regulates bile acid detoxification. Here we examined the mechanism by which fenofibrate regulates MDR3 gene expression. Fenofibrate significantly up-regulated MDR3 messenger RNA (mRNA) and protein expression in primary cultured human hepatocytes, and stimulated MDR3 promoter activity in HepG2 cells. In silico analysis of 5'-upstream region of human MDR3 gene revealed a number of PPARα response elements (PPRE). Electrophoretic mobility shift (EMSA) and chromatin immunoprecipitation (ChIP) assays demonstrated specific binding of PPARα to the human MDR3 promoter. Targeted mutagenesis of three novel PPREs reduced inducibility of the MDR3 promoter by fenofibrate. In collagen sandwich cultured rat hepatocytes, treatment with fenofibrate increased secretion of fluorescent PC into bile canaliculi. CONCLUSION Fenofibrate transactivates MDR3 gene transcription by way of the binding of PPARα to three novel and functionally critical PPREs in the MDR3 promoter. Fenofibrate treatment further stimulates biliary phosphatidylcholine secretion in rat hepatocytes, thereby providing a functional correlate. We have established a molecular mechanism that may contribute to the beneficial use of fenofibrate therapy in human cholestatic liver disease.
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Affiliation(s)
- Nisanne S. Ghonem
- Department of Internal Medicine, Liver Center; Yale University School of Medicine; New Haven CT
| | | | - Carol J. Soroka
- Department of Internal Medicine, Liver Center; Yale University School of Medicine; New Haven CT
| | - James L. Boyer
- Department of Internal Medicine, Liver Center; Yale University School of Medicine; New Haven CT
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12
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Svejda B, Kidd M, Timberlake A, Harry K, Kazberouk A, Schimmack S, Lawrence B, Pfragner R, Modlin IM. Serotonin and the 5-HT7 receptor: the link between hepatocytes, IGF-1 and small intestinal neuroendocrine tumors. Cancer Sci 2013; 104:844-55. [PMID: 23578138 DOI: 10.1111/cas.12174] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 03/26/2013] [Accepted: 03/30/2013] [Indexed: 12/14/2022] Open
Abstract
Platelet-derived serotonin (5-HT) is involved in liver regeneration. The liver is also the metastatic site for malignant enterochromaffin (EC) cell "carcinoid" (neuroendocrine) neoplasms, the principal cellular source of 5-HT. We hypothesized that 5-HT produced by metastatic EC cells played a role in the hepatic tumor-microenvironment principally via 5-HT₇ receptor-mediated activation of hepatocyte IGF-1 synthesis and secretion. Using isolated rat hepatocytes, we evaluated 5-HT₇ receptor expression (using PCR, sequencing and western blot). ELISA, cell transfection and western blots delineated 5-HT-mediated signaling pathways (pCREB, AKT and ERK). IGF-1 synthesis/secretion was evaluated using QPCR and ELISA. IGF-1 was tested on small intestinal neuroendocrine neoplasm proliferation, while IGF-1 production and 5-HT₇ expression were examined in an in vivo SCID metastasis model. Our results demonstrated evidence for a functional 5-HT₇ receptor. 5-HT activated cAMP/PKA activity, pCREB (130-205%, P < 0.05) and pERK/pAKT (1.2-1.75, P < 0.05). Signaling was reversed by the 5-HT₇ receptor antagonist SB269970. IGF-1 significantly stimulated proliferation of two small intestinal neuroendocrine neoplasm cell lines (EC₅₀: 7-70 pg/mL) and could be reversed by the small molecule inhibitor BMS-754807. IGF-1 and 5-HT were elevated (40-300×) in peri-tumoral hepatic tissue in nude mice, while 5-HT₇ was increased fourfold compared to sham-operated animals. We conclude that hepatocytes express a cAMP-coupled 5-HT₇ receptor, which, at elevated 5-HT concentrations that occur in liver metastases, signals via CREB/AKT and is linked to IGF-1 synthesis and secretion. Because IGF-1 regulates NEN proliferation, identification of a role for 5-HT₇ in the hepatic metastatic tumor microenvironment suggests the potential for novel therapeutic strategies for amine-producing mid-gut tumors.
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Affiliation(s)
- Bernhard Svejda
- Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, CT, USA
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13
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De Angelis Campos AC, Rodrigues MA, de Andrade C, de Goes AM, Nathanson MH, Gomes DA. Epidermal growth factor receptors destined for the nucleus are internalized via a clathrin-dependent pathway. Biochem Biophys Res Commun 2011; 412:341-6. [PMID: 21821003 DOI: 10.1016/j.bbrc.2011.07.100] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 07/22/2011] [Indexed: 10/17/2022]
Abstract
The epidermal growth factor (EGF) transduces its actions via the EGF receptor (EGFR), which can traffic from the plasma membrane to either the cytoplasm or the nucleus. However, the mechanism by which EGFR reaches the nucleus is unclear. To investigate these questions, liver cells were analyzed by immunoblot of cell fractions, confocal immunofluorescence and real time confocal imaging. Cell fractionation studies showed that EGFR was detectable in the nucleus after EGF stimulation with a peak in nuclear receptor after 10 min. Movement of EGFR to the nucleus was confirmed by confocal immunofluorescence and labeled EGF moved with the receptor to the nucleus. Small interference RNA (siRNA) was used to knockdown clathrin in order to assess the first endocytic steps of EGFR nuclear translocation in liver cells. A mutant dynamin (dynamin K44A) was also used to determine the pathways for this traffic. Movement of labeled EGF or EGFR to the nucleus depended upon dynamin and clathrin. This identifies the pathway that mediates the first steps for EGFR nuclear translocation in liver cells.
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14
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Flach RJR, Qin H, Zhang L, Bennett AM. Loss of mitogen-activated protein kinase phosphatase-1 protects from hepatic steatosis by repression of cell death-inducing DNA fragmentation factor A (DFFA)-like effector C (CIDEC)/fat-specific protein 27. J Biol Chem 2011; 286:22195-202. [PMID: 21521693 DOI: 10.1074/jbc.m110.210237] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The integration of metabolic signals required for the regulation of hepatic lipid homeostasis is complex. Previously, we showed that mice lacking expression of the mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) have increased fatty acid oxidation and are protected from the development of hepatic steatosis. Here, we show that leptin receptor-deficient (db/db) mice lacking MKP-1 are also resistant to the development of hepatic steatosis. Microarray analyses of livers from db/db mice lacking MKP-1 showed suppression of peroxisome proliferator-activated receptor γ (PPARγ) target genes. We identified the fat-specific protein 27 (Fsp27), which promotes PPARγ-mediated hepatic steatosis, as repressed in livers of both db/db and high fat diet-fed mice lacking MKP-1. Hepatocytes from MKP-1-deficient mice exhibited reduced PPARγ-induced lipid droplet formation. Mechanistically, loss of MKP-1 inhibited PPARγ function by increasing MAPK-dependent phosphorylation on PPARγ at its inhibitory residue of serine 112. These results demonstrate that in addition to inhibiting hepatic fatty acid oxidation, MKP-1 promotes hepatic lipogenic gene expression through PPARγ. Hence, MKP-1 plays an important role in MAPK-mediated control of hepatic lipid homeostasis.
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Affiliation(s)
- Rachel J Roth Flach
- Department of Pharmacology and Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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15
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Jessner W, Zsembery A, Graf J. Transcellular water transport in hepatobiliary secretion and role of aquaporins in liver. Wien Med Wochenschr 2009; 158:565-9. [PMID: 18998074 DOI: 10.1007/s10354-008-0597-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Accepted: 03/28/2008] [Indexed: 01/11/2023]
Abstract
In the context of the osmotic model of bile formation, we used isolated rat hepatocyte couplets and performed volume measurements by video image analysis to analyze the transport of water between the bile canalicular lumen, liver cells and the surrounding bathing medium. Increasing bath osmolarity by the addition of sucrose led to shrinkage of cells that preceded shrinkage of the canalicular lumen by approx. 1 sec. Thermodynamic modeling of water transport across the basolateral and apical cell membranes and across a paracellular pathway (tight junctions) revealed high hydraulic water permeabilities of both cell membranes of approx. 3*10(-4) cm*sec(-1)*(osmol/kg)(-1) indicating transcellular water flux between bathing medium and bile. Tight junctions exhibited low water permeability but allowed for electrolyte permeation that enables canalicular spaces to shrink below van't Hoff equilibrium during the osmotic maneuver. The results are discussed with respect to the role of different types of membrane aquaporins being expressed in hepatocytes.
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Affiliation(s)
- Wolfgang Jessner
- Department of Pathophysiology, Medical University of Vienna, Vienna, Austria.
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16
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Rodrigues MA, Gomes DA, Andrade VA, Leite MF, Nathanson MH. Insulin induces calcium signals in the nucleus of rat hepatocytes. Hepatology 2008; 48:1621-31. [PMID: 18798337 PMCID: PMC2825885 DOI: 10.1002/hep.22424] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Insulin is an hepatic mitogen that promotes liver regeneration. Actions of insulin are mediated by the insulin receptor, which is a receptor tyrosine kinase. It is currently thought that signaling via the insulin receptor occurs at the plasma membrane, where it binds to insulin. Here we report that insulin induces calcium oscillations in isolated rat hepatocytes, and that these calcium signals depend upon activation of phospholipase C and the inositol 1,4,5-trisphosphate receptor, but not upon extracellular calcium. Furthermore, insulin-induced calcium signals occur in the nucleus, and are temporally associated with selective depletion of nuclear phosphatidylinositol bisphosphate and translocation of the insulin receptor to the nucleus. These findings suggest that the insulin receptor translocates to the nucleus to initiate nuclear, inositol 1,4,5-trisphosphate-mediated calcium signals in rat hepatocytes. This novel signaling mechanism may be responsible for insulin's effects on liver growth and regeneration.
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Affiliation(s)
- Michele A Rodrigues
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8019, USA
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17
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Wittmer CR, Phelps JA, Lepus CM, Saltzman WM, Harding MJ, Van Tassel PR. Multilayer nanofilms as substrates for hepatocellular applications. Biomaterials 2008; 29:4082-90. [PMID: 18653230 DOI: 10.1016/j.biomaterials.2008.06.027] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Accepted: 06/28/2008] [Indexed: 11/18/2022]
Abstract
Multilayer nanofilms, formed by the layer-by-layer (LbL) adsorption of positively and negatively charged polyelectrolytes, are promising substrates for tissue engineering. We investigate here the attachment and function of hepatic cells on multilayer films in terms of film composition, terminal layer, rigidity, charge, and presence of biofunctional species. Human hepatocellular carcinoma (HepG2) cells, adult rat hepatocytes (ARH), and human fetal hepatoblasts (HFHb) are studied on films composed of the polysaccharides chitosan (CHI) and alginate (ALG), the polypeptides poly(l-lysine) (PLL) and poly(l-glutamic acid) (PGA), and the synthetic polymers poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS). The influence of chemical cross-linking following LbL assembly is also investigated. We find HepG2 to reach confluence after 7 days of culture on only 2 of 18 candidate multilayer systems: (PAH-PSS)(n) (i.e. nPAH-PSS bilayers) and cross-linked (PLL-ALG)(n)-PLL. Cross-linked PLL-ALG and PLL-PGA films support attachment and function of ARH, independently of the terminal layer, provided collagen is adsorbed to the top of the film. (PAH-PSS)(n), cross-linked (PLL-ALG)(n), and cross-linked (PLL-PGA)(n)-PLL films all support attachment, layer confluence, and function of HFHb, with the latter film promoting the greatest level of function at 8 days. Overall, film composition, terminal layer, and rigidity are key variables in promoting attachment and function of hepatic cells, while film charge and biofunctionality are somewhat less important. These studies reveal optimal candidate multilayer biomaterials for human liver tissue engineering applications.
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Affiliation(s)
- Corinne R Wittmer
- Department of Chemical Engineering, Yale University, New Haven, CT 06520-8286, USA
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18
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Denk GU, Hohenester S, Wimmer R, Böhland C, Rust C, Beuers U. Role of mitogen-activated protein kinases in tauroursodeoxycholic acid-induced bile formation in cholestatic rat liver. Hepatol Res 2008; 38:717-26. [PMID: 18328068 DOI: 10.1111/j.1872-034x.2008.00321.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Ursodeoxycholic acid exerts anticholestatic effects in various cholestatic disorders and experimental models of cholestasis. Its taurine conjugate (TUDCA) stimulates bile salt secretion in isolated perfused rat livers (IPRL) under physiological, non-cholestatic conditions, in part by mitogen-activated protein kinase (MAPK)-dependent mechanisms. The role of MAPK in the anticholestatic effect of TUDCA, however, is unclear. Therefore, we studied the role of MAPK in the anticholestatic effect of TUDCA in IPRL and isolated rat hepatocytes (IRH) in taurolithocholic acid (TLCA)-induced cholestasis. METHODS Bile flow, biliary levels of 2,4-dinitrophenyl-S-glutathione (GS-DNP) as a marker of hepatobiliary organic anion secretion and activity of lactate dehydrogenase (LDH) in hepatovenous effluate as a marker of hepatocellular damage in IPRL perfused with TUDCA and/or TLCA were determined in the presence or absence of MAPK inhibitors. In addition, phosphorylation of Erk 1/2 and p38(MAPK) induced by TUDCA and/or TLCA was studied by Western immunoblot in IPRL and IRH. RESULTS TUDCA-induced bile flow was impaired by the Erk 1/2 inhibitor PD98059 in normal livers (-28%), but not in livers made cholestatic by TLCA. GS-DNP secretion was unaffected by PD98059 under both conditions. TUDCA-induced bile formation and organic anion secretion both in the presence and absence of TLCA were unaffected by the p38(MAPK) inhibitor SB202190. Erk 1/2 phosphorylation in liver tissue was unchanged after bile salt exposure for 70 min, but was transiently enhanced by TUDCA in IRH. CONCLUSION MAPK do not mediate the anticholestatic effects of TUDCA in TLCA-induced cholestasis.
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Affiliation(s)
- Gerald Ulrich Denk
- Department of Medicine II-Grosshadern, Klinikum of the University of Munich, Munich, Germany
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19
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Bow DAJ, Perry JL, Miller DS, Pritchard JB, Brouwer KLR. Localization of P-gp (Abcb1) and Mrp2 (Abcc2) in freshly isolated rat hepatocytes. Drug Metab Dispos 2007; 36:198-202. [PMID: 17954525 DOI: 10.1124/dmd.107.018200] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Freshly isolated hepatocytes are widely accepted as the "gold standard" for providing reliable data on drug uptake across the sinusoidal (basolateral) membrane. However, the suitability of freshly isolated hepatocytes in suspension to assess efflux by canalicular (apical) proteins or predict biliary excretion in the intact organ is unclear. After collagenase digestion, hepatocytes rapidly lose polarity, but localization of canalicular transport proteins in the first few hours after isolation has not been well characterized. In this study, immunostaining and confocal microscopy have provided, for the first time, a detailed examination of canalicular transport protein localization in freshly isolated rat hepatocytes fixed within 1 h of isolation and in cells cultured for 1 h. Organic anion transporting polypeptide 1a1 (Oatp1a1) was expressed in all hepatocytes and distributed evenly across the basolateral membrane; there was no evidence for colocalization of Oatp1a1 with P-glycoprotein (P-gp) or multidrug resistance-associated protein 2 (Mrp2). In contrast, P-gp and Mrp2 expression was lower than Oatp1a1 and confined to junctions between adjacent cells, intracellular compartments, and "legacy" network structures at or near the cell surface. P-gp and Mrp2 staining was more predominant in regions adjacent to former canalicular spaces, identified by zonula occludens-1 staining. Functional analysis of rat hepatocytes cultured for 1 h demonstrated that the fluorescent anion and Mrp2 substrate, 5-(and-6)-carboxy-2',7'-dichlorofluorescein (CDF), accumulated in cellular compartments; compartmental accumulation of CDF was sensitive to (E)-3-[[[3-[2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-[[3-dimethylamino)-3-oxopropyl]thio]methyl]thio]-propanoic acid (MK571, Mrp inhibitor) and was not observed in hepatocytes isolated from Mrp2-deficient rats. Drug efflux from freshly isolated hepatocytes as an estimate of apical efflux/biliary excretion would give an inaccurate assessment of true apical elimination and, as such, should not be used to make in vivo extrapolations.
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Affiliation(s)
- Daniel A J Bow
- Division of Pharmacotherapy and Experimental Therapeutics, School of Pharmacy, University of North Carolina, CB #7360 Kerr Hall, Chapel Hill, NC 27599-7360, USA
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Wilson JH, Paturzo FX, Johnson LK, Carreiro MP, Hixson DC, Mennone A, Boyer JL, Pober JS, Harding MJ. Rat hepatocyte engraftment in severe combined immunodeficient x beige mice using mouse-specific anti-fas antibody. Xenotransplantation 2006; 13:53-62. [PMID: 16497212 DOI: 10.1111/j.1399-3089.2005.00259.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Hepatocyte transplantation holds promise as a treatment for acute and chronic liver failure; however, robust model systems needed to study xenogeneic hepatocyte transfer are lacking. Severe combined immunodeficient x beige (SCID/bg) hybrid mice readily accept foreign tissue. Repopulation of C.B-17 SCID/bg mouse liver with rat hepatocytes was studied following induction of mouse hepatocyte apoptosis using an anti-mouse agonistic fas monoclonal antibody (Jo2 mAb) that does not engage xenogeneic fas. METHODS SCID/bg mice were transplanted with 1 x 10(6) fresh adult rat hepatocytes intrasplenically and treated with various doses, routes and frequencies of Jo2 mAb. Rat cell repopulation was characterized by quantitative immunofluorescent antibody (q-IFA) staining specific for rat dipeptidyl peptidase type IV (DPP-IV) and leucine amino peptidase, amplification of rat genomic DNA using polymerase chain reaction and histopathological and serum biochemistry analyses. RESULTS Analysis of liver sections from mice treated twice weekly for 12 weeks with 0.4 mg/kg Jo2 mAb intraperitoneally consistently demonstrated >50% rat hepatocytes in the parenchymal mass by q-IFA. Rat hepatocyte engraftment protected mice from Jo2 mAb-mediated liver hemorrhage and hepatocyte apoptosis. Serum liver enzyme levels did not increase in Jo2 mAb-treated mice that were highly engrafted with rat hepatocytes, in contrast to matched non-engrafted mice. At 12 weeks post-engraftment, minimal fibrosis and inflammation were apparent and liver architecture had returned to near normal. Jo2 mAb did not induce histopathological abnormalities in other tissues known to express fas antigen (i.e. heart, lung). CONCLUSIONS This novel model represents a simple and robust system of xenogeneic hepatocyte transplantation that could be applied to studies of liver biology, regeneration and hepatocyte transplantation.
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Affiliation(s)
- Jean H Wilson
- Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520-8016, USA
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21
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Wang W, Soroka CJ, Mennone A, Rahner C, Harry K, Pypaert M, Boyer JL. Radixin is required to maintain apical canalicular membrane structure and function in rat hepatocytes. Gastroenterology 2006; 131:878-84. [PMID: 16952556 PMCID: PMC1820831 DOI: 10.1053/j.gastro.2006.06.013] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Accepted: 06/02/2006] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Ezrin-radixin-moesin proteins are cross-linkers between the plasma membrane and actin filaments. Radixin, the dominant ezrin-radixin-moesin protein in hepatocytes, has been reported to selectively tether multidrug-resistance-associated protein 2 to the apical canalicular membrane. However, it remains to be determined if this is its primary function. METHODS An adenovirus-mediated short interfering RNA (siRNA) was used to down-regulate radixin expression in collagen sandwich-cultured rat hepatocytes and morphologic and functional changes were characterized quantitatively. RESULTS In control cultures, an extensive bile canalicular network developed with properly localized apical and basolateral transporters that provided for functional excretion of fluorescent cholephiles into the bile canalicular lumina. siRNA-induced suppression of radixin was associated with a marked reduction in the canalicular membrane structure as observed by differential interference contrast microscopy and F-actin staining, in contrast to control cells exposed to adenovirus encoding scrambled siRNA. Indirect immunofluorescence showed that apical transporters (multidrug-resistance-associated protein 2, bile salt export pump, and multidrug-resistance protein 1) dissociated from their normal location at the apical membrane and were found largely associated with Rab11-containing endosomes. Localization of the basolateral membrane transporter, organic anion transporting polypeptide 2 (Oatp2), was not affected. Consistent with this dislocation of apical transporters, the biliary excretion of glutathione-methylfluorescein and cholylglycylamido-fluorescein was decreased significantly in the radixin-deficient cells, but not in the control siRNA cells. CONCLUSIONS Radixin is essential for maintaining the polarized targeting and/or retaining of canalicular membrane transporters and is a critical determinant of the overall structure and function of the apical membrane of hepatocytes.
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Affiliation(s)
- Wei Wang
- Liver Center, Yale University School of Medicine, New Haven, Connecticut 06520-8019, USA
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22
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Wu JJ, Roth RJ, Anderson EJ, Hong EG, Lee MK, Choi CS, Neufer PD, Shulman GI, Kim JK, Bennett AM. Mice lacking MAP kinase phosphatase-1 have enhanced MAP kinase activity and resistance to diet-induced obesity. Cell Metab 2006; 4:61-73. [PMID: 16814733 DOI: 10.1016/j.cmet.2006.05.010] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 04/07/2006] [Accepted: 05/18/2006] [Indexed: 12/31/2022]
Abstract
The mitogen-activated protein kinases (MAPK) play critical roles in the pathogenesis of diabetes and obesity. The MAPKs are inactivated by MAPK phosphatases (MKPs) either in the cytosol or nucleus. Here we show that mice lacking the nuclear-localized MKP, MKP-1 (mkp-1(-/-)), have enhanced Erk, p38 MAPK and c-Jun NH(2)-terminal kinase (JNK) activities in insulin-responsive tissues as compared with wild-type mice. Although JNK promotes insulin resistance, mkp-1(-/-) mice exhibited unimpaired insulin-mediated signaling and glucose homeostasis. We reconciled these results by demonstrating that in mkp-1(-/-) mice, JNK activity was increased in the nucleus, but not the cytosol. Significantly, mkp-1(-/-) mice are resistant to diet-induced obesity due to enhanced energy expenditure, but succumb to glucose intolerance on a high fat diet. These results suggest that nuclear regulation of the MAPKs by MKP-1 is essential for the management of metabolic homeostasis in a manner that is spatially uncoupled from the cytosolic actions of the MAPKs.
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Affiliation(s)
- J Julie Wu
- Department of Pharmacology, Section of Endocrinology and Metabolism, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Masereeuw R, Russel F. Screening for the role of transporters in hepatic and renal drug handling. DRUG DISCOVERY TODAY. TECHNOLOGIES 2004; 1:357-364. [PMID: 24981615 DOI: 10.1016/j.ddtec.2004.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Transport proteins expressed in liver and kidney have been studied in great detail on the molecular and cellular level, using membrane vesicles and (transport protein transfected) cell lines. Regulation of transport is studied best in cell systems, whereas an accurate determination of overall hepatic or renal drug clearance can be studied in organs. Hence, translation of this information into a physiological and pharmacological context of individual transporters in hepatic and renal drug handling still needs to be addressed adequately.:
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Affiliation(s)
- Rosalinde Masereeuw
- Department of Pharmacology and Toxicology 233, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
| | - Frans Russel
- Department of Pharmacology and Toxicology 233, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Abstract
Transcytosis, the vesicular transport of macromolecules from one side of a cell to the other, is a strategy used by multicellular organisms to selectively move material between two environments without altering the unique compositions of those environments. In this review, we summarize our knowledge of the different cell types using transcytosis in vivo, the variety of cargo moved, and the diverse pathways for delivering that cargo. We evaluate in vitro models that are currently being used to study transcytosis. Caveolae-mediated transcytosis by endothelial cells that line the microvasculature and carry circulating plasma proteins to the interstitium is explained in more detail, as is clathrin-mediated transcytosis of IgA by epithelial cells of the digestive tract. The molecular basis of vesicle traffic is discussed, with emphasis on the gaps and uncertainties in our understanding of the molecules and mechanisms that regulate transcytosis. In our view there is still much to be learned about this fundamental process.
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Affiliation(s)
- Pamela L Tuma
- Hunterian 119, Department of Cell Biology, 725 N Wolfe St, Baltimore, MD 21205, USA
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25
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Wurzinger R, Englisch R, Roka S, Langer R, Roden M, Graf J. Intracellular calcium in the isolated rat liver: correlation to glucose release, K(+) balance and bile flow. Cell Calcium 2001; 30:403-12. [PMID: 11728135 DOI: 10.1054/ceca.2001.0248] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study correlates whole organ measurements of intracellular calcium concentration ([Ca(2+)](i)) with hormone-induced (epinephrine, vasopressin) changes of liver functions (glucose release, K(+) balance and bile flow). [Ca(2+)](i) was measured in the isolated perfused rat liver using the sensor Fura-2 and applying liver surface fluorescence spectroscopy. The technique was improved by (i) minimizing biliary elimination of the sensor by employing a rat strain deficient in canalicular organic anion transport (TR(-) mutation) and (ii) by correcting for changes of interfering intrinsic organ fluorescence that was shown to depend on the oxidation-reduction state (NAD(P)H content) of the organ. Epinephrine (50 nM) elicits an instantaneous peak rise of [Ca(2+)](i) to approx. 400 nM, followed by a sustained elevation that depends on the presence of extracellular Ca(2+). The rise of [Ca(2+)](i) coincides with initiation of glucose release, transient K(+) uptake, and transient stimulation of bile flow. Vasopressin (2 nM) exerts qualitatively similar effects. The transient rise of bile flow is attributed to Ca(2+)-mediated contraction of the pericanalicular actin-myosin web of hepatocytes.
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Affiliation(s)
- R Wurzinger
- Department of Pathophysiology, University of Vienna, Austria
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Mitnick MA, Grey A, Masiukiewicz U, Bartkiewicz M, Rios-Velez L, Friedman S, Xu L, Horowitz MC, Insogna K. Parathyroid hormone induces hepatic production of bioactive interleukin-6 and its soluble receptor. Am J Physiol Endocrinol Metab 2001; 280:E405-12. [PMID: 11171594 DOI: 10.1152/ajpendo.2001.280.3.e405] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Interleukin-6 (IL-6) is an important mediator of parathyroid hormone (PTH)-induced bone resorption. Serum levels of IL-6 and its soluble receptor (IL-6sR) are regulated in part by PTH. The PTH/PTH-related protein type 1 receptor is highly expressed in the liver, and in the current study we investigated whether the liver produces IL-6 or IL-6sR in response to PTH. Perfusion of the isolated rat liver with PTH-(1-84) stimulated rapid, dose-dependent production of bioactive IL-6 and the IL-6sR. These effects were observed at near physiological concentrations of the hormone such that 1 pM PTH induced hepatic IL-6 production at a rate of approximately 0.6 ng/min. In vitro, hepatocytes, hepatic endothelial cells, and Kupffer cells, but not hepatic stellate cells, were each found to produce both IL-6 and IL-6sR in response to higher (10 nM) concentrations of PTH. Our data suggest that hepatic-derived IL-6 and IL-6sR contribute to the increase in circulating levels of these cytokines induced by PTH in vivo and raise the possibility that PTH-induced, liver-derived IL-6 may exert endocrine effects on tissues such as bone.
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Affiliation(s)
- M A Mitnick
- Yale University School of Medicine, New Haven, CT 06520-8020, USA
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27
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Soroka CJ, Pate MK, Boyer JL. Canalicular export pumps traffic with polymeric immunoglobulin A receptor on the same microtubule-associated vesicle in rat liver. J Biol Chem 1999; 274:26416-24. [PMID: 10473600 DOI: 10.1074/jbc.274.37.26416] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Basolateral to apical vesicular transcytosis in the hepatocyte is an essential pathway for the delivery of compounds from the sinusoidal blood to the bile and to traffic newly synthesized resident apical membrane proteins to their site of function at the canalicular membrane front. To characterize this pathway better, microtubules in a hepatocyte homogenate were polymerized by addition of taxol, and associated membrane-bound vesicles were isolated. This fraction was enriched in polymeric immunoglobulin A receptor and contained apical membrane proteins. Immunoelectron microscopy demonstrated that polymeric immunoglobulin A receptor was localized predominantly on vesicles ranging from 100 to 160 nm and that the multidrug resistance protein 2 and the bile salt export pump co-localized on these vesicles. The minus-ended microtubule motor, dynein, was highly enriched in the fraction, and its intermediate chain could be released effectively by incubation with 1 mM ATP or GTP. However, the association of the transcytotic vesicles with the microtubules was not sensitive to hydrolyzable or non-hydrolyzable nucleotides. This study characterizes a fraction of microtubule-associated vesicles from rat hepatocytes and demonstrates that several resident apical membrane transport proteins and the polymeric immunoglobulin A receptor traffic on the same vesicle.
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Affiliation(s)
- C J Soroka
- Department of Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut 06520-8019, USA.
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28
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Cho WK, Boyer JL. Vasoactive intestinal polypeptide is a potent regulator of bile secretion from rat cholangiocytes. Gastroenterology 1999; 117:420-8. [PMID: 10419925 DOI: 10.1053/gast.1999.0029900420] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND & AIMS Vasoactive intestinal polypeptide (VIP) is a neuropeptide with diverse biological functions including stimulatory effects on bile secretion. The effects of VIP on bile secretion and its site of action were examined. METHODS Choleretic effects of VIP were examined using isolated perfused livers, hepatocyte couplets, isolated bile duct units, and cholangiocytes from rat liver. RESULTS VIP (100 nmol/L) produced a small increase in bile flow and bile salt output in taurocholate-supplemented isolated perfused livers but had no significant effect on bile flow in the absence of bile salt supplements or on fluid secretion in isolated hepatocyte couplets. In addition, VIP significantly increased bile pH, bicarbonate concentration, and output in the isolated perfused livers from both normal and 2 week bile duct-ligated rats, although bile flow increased only in the bile duct-ligated model. VIP also produced a dose-dependent increase in fluid secretion in isolated bile duct units, which was inhibited significantly by VIP antagonist, a specific VIP receptor inhibitor. This VIP-stimulated secretory response in isolated bile duct units was more potent than those produced by bombesin or secretin. Neither somatostatin nor substance P inhibited the VIP response in isolated bile duct units. In contrast to secretin, VIP had no significant effect on adenosine 3', 5'-cyclic monophosphate (cAMP) levels in isolated cholangiocytes. CONCLUSIONS VIP is a potent stimulant of fluid and bicarbonate secretion from cholangiocytes via cAMP-independent pathways, suggesting that this neuropeptide plays a major regulatory role in biliary transport and secretion.
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Affiliation(s)
- W K Cho
- Department of Medicine, Division of Gastroenterology/Hepatology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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29
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Puviani AC, Ottolenghi C, Tassinari B, Pazzi P, Morsiani E. An update on high-yield hepatocyte isolation methods and on the potential clinical use of isolated liver cells. Comp Biochem Physiol A Mol Integr Physiol 1998; 121:99-109. [PMID: 9883573 DOI: 10.1016/s1095-6433(98)10109-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Isolated hepatocytes are a suitable system for the study of hepatic physiology and metabolism. They are also used for pharmacological and toxicological studies related to hepatic uptake, metabolism, excretion and toxicity of xenobiotics, as well as morphological and metabolic effects induced in the liver as a result of drug or toxic substance exposure. In this paper, the enzymatic methods for hepatocyte isolation in some mammalian species are reviewed, and methods for evaluating cell purification and assessment of cellular morphology and function are also examined. More recently, interest in hepatocyte transplantation has increased, and the clinical experimentation of hepatocyte-based liver support systems has attracted the attention of scientists and hepatologists. From a clinical perspective, using isolated hepatocytes could be useful both for supporting an acutely devastated liver, a chronically diseased liver, and for correcting genetic disorders resulting in metabolically deficient states. Reports of clinical usage of isolated allogenic hepatocytes in hepatocellular transplantation and of xenogenic liver cells in constructing bio-artificial liver support systems are promising, and are renewing interest in the development of methods for isolation and purification of hepatocytes.
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Affiliation(s)
- A C Puviani
- Department of Biology, University of Ferrara, Italy
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30
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Trauner M, Arrese M, Lee H, Boyer JL, Karpen SJ. Endotoxin downregulates rat hepatic ntcp gene expression via decreased activity of critical transcription factors. J Clin Invest 1998; 101:2092-100. [PMID: 9593765 PMCID: PMC508797 DOI: 10.1172/jci1680] [Citation(s) in RCA: 206] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Sodium-dependent uptake of bile acids across the hepatic basolateral membrane is rapidly and profoundly diminished during sepsis, thus contributing to the pathogenesis of sepsis-associated cholestasis. This effect is mediated by endotoxin or effector cytokines, which reduce expression of several hepatobiliary transporters, including the sodium-dependent bile acid transporter gene, ntcp. We test here the hypothesis that endotoxin treatment leads to impaired binding activity of ntcp promoter trans-acting factors, resulting in reduction of ntcp mRNA expression. After endotoxin administration, ntcp mRNA levels reached their nadir by 16 h, and nuclear run-on assays demonstrated a marked reduction in ntcp gene transcription. At 16 h after treatment, nuclear binding activities of two key factors that transactivate the ntcp promoter, hepatocyte nuclear factor (HNF) 1 and Footprint B binding protein (FpB BP), decreased to 44 and 47% of pretreatment levels, respectively, while levels of the other known ntcp promoter transactivator, signal transducer and activator of transcription 5, were unaffected. In contrast, the universal inflammatory response factors nuclear factor kappaB and activating protein 1 were both upregulated significantly. Examination of nuclear extracts obtained at sequential time points revealed that the maximal decrease in nuclear activities of both HNF1 and FpB BP preceded the nadir of ntcp mRNA expression by 6-10 h. Furthermore, these two nuclear factors returned towards normal levels before the recovery of ntcp mRNA levels observed by 48 h. Since HNF1alpha mRNA levels were unchanged at all time points, HNF1 is likely to be regulated posttranscriptionally by endotoxin. We conclude that the downregulation of ntcp gene expression by endotoxin is mediated at the level of transcription through tandem reductions in the nuclear binding activity of two critical transcription factors. These findings provide new insight into the coordinated downregulation of hepatobiliary transporters during sepsis.
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Affiliation(s)
- M Trauner
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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31
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Moriarty PM, Reddy CC, Maquat LE. Selenium deficiency reduces the abundance of mRNA for Se-dependent glutathione peroxidase 1 by a UGA-dependent mechanism likely to be nonsense codon-mediated decay of cytoplasmic mRNA. Mol Cell Biol 1998; 18:2932-9. [PMID: 9566912 PMCID: PMC110672 DOI: 10.1128/mcb.18.5.2932] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/1997] [Accepted: 02/17/1998] [Indexed: 02/07/2023] Open
Abstract
The mammalian mRNA for selenium-dependent glutathione peroxidase 1 (Se-GPx1) contains a UGA codon that is recognized as a codon for the nonstandard amino acid selenocysteine (Sec). Inadequate concentrations of selenium (Se) result in a decrease in Se-GPx1 mRNA abundance by an uncharacterized mechanism that may be dependent on translation, independent of translation, or both. In this study, we have begun to elucidate this mechanism. We demonstrate using hepatocytes from rats fed either a Se-supplemented or Se-deficient diet for 9 to 13 weeks that Se deprivation results in an approximately 50-fold reduction in Se-GPx1 activity and an approximately 20-fold reduction in Se-GPx1 mRNA abundance. Reverse transcription-PCR analyses of nuclear and cytoplasmic fractions revealed that Se deprivation has no effect on the levels of either nuclear pre-mRNA or nuclear mRNA but reduces the level of cytoplasmic mRNA. The regulation of Se-GPx1 gene expression by Se was recapitulated in transient transfections of NIH 3T3 cells, and experiments were extended to examine the consequences of converting the Sec codon (TGA) to either a termination codon (TAA) or a cysteine codon (TGC). Regardless of the type of codon, an alteration in the Se concentration was of no consequence to the ratio of nuclear Se-GPx1 mRNA to nuclear Se-GPx1 pre-mRNA. The ratio of cytoplasmic Se-GPx1 mRNA to nuclear Se-GPx1 mRNA from the wild-type (TGA-containing) allele was reduced twofold when cells were deprived of Se for 48 h after transfection, which has been shown to be the extent of the reduction for the endogenous Se-GPx1 mRNA of cultured cells incubated as long as 20 days in Se-deficient medium. In contrast to the TGA allele, Se had no effect on expression of either the TAA allele or the TGC allele. Under Se-deficient conditions, the TAA and TGC alleles generated, respectively, 1.7-fold-less and 3-fold-more cytoplasmic Se-GPx1 mRNA relative to the amount of nuclear Se-GPx1 mRNA than the TGA allele. These results indicate that (i) under conditions of Se deprivation, the Sec codon reduces the abundance of cytoplasmic Se-GPx1 mRNA by a translation-dependent mechanism and (ii) there is no additional mechanism by which Se regulates Se-GPx1 mRNA production. These data suggest that the inefficient incorporation of Sec at the UGA codon during mRNA translation augments the nonsense-codon-mediated decay of cytoplasmic Se-GPx1 mRNA.
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Affiliation(s)
- P M Moriarty
- Department of Human Genetics, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
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Iyer KR, Spitz L, Clayton P. BAPS prize lecture: New insight into mechanisms of parenteral nutrition-associated cholestasis: role of plant sterols. British Association of Paediatric Surgeons. J Pediatr Surg 1998; 33:1-6. [PMID: 9473088 DOI: 10.1016/s0022-3468(98)90349-9] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND PURPOSE Infants on long-term parenteral nutrition frequently will have progressive cholestatic liver disease, the cause of which remains largely unknown. The aim of this study is to establish a possible role for plant sterols (phytosterols) in the pathogenesis of parenteral nutrition-associated cholestasis (PNAC). METHODS Two experimental studies were used: (1) A study on neonatal piglets involved the daily injection of plant sterols; measurement of their concentrations in serum, liver, and bile during a 14-day period; and determination of serum bile acid concentrations, bile acid secretion, and bile flow at the end of the 14-day period. (2) Isolated rat hepatocyte couplets were used to study the effects of sterols on canalicular secretion. RESULTS The daily injection of phytosterols (in amounts similar to those given to infants who receive parenteral nutrition) led to their progressive accumulation in the piglets' serum, liver, and bile. Serum bile acid levels were significantly higher in the sterol-treated piglets. Maximal bile acid excretion was significantly lower in the sterol group. Phytosterols caused a significant inhibition of secretory function in isolated rat hepatocyte couplets. CONCLUSION Important contaminants of commercial lipid emulsions (phytosterols) have been identified as a possible cause of PNAC.
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Boyer JL, Soroka CJ. Vesicle targeting to the apical domain regulates bile excretory function in isolated rat hepatocyte couplets. Gastroenterology 1995; 109:1600-11. [PMID: 7557144 DOI: 10.1016/0016-5085(95)90649-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND & AIMS Plasma membrane solute transport may be regulated in many epithelial cells by vesicle traffic to and from the site of residence of the transporter. The aim of this study was to determine if this phenomenon may also play a role in the regulation of canalicular transport of bile acids. METHODS Confocal microscopy and image analysis were performed to quantitatively assess changes in secretory capacity and vesicle targeting in isolated rat hepatocyte couplets that had been exposed to fluorescent bile acid after pretreatment with dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP) and/or nocodazole. RESULTS DBcAMP stimulated bile acid secretion by 240% while significantly increasing canalicular circumference. Nocodazole decreased secretion by 410% and significantly decreased canalicular circumference. When DBcAMP was added to nocodazole-treated couplets, a slight but significant increase was found in both fluorescent bile acid secretion and canalicular circumference as compared with nocodazole alone. Finally, DBcAMP stimulated translocation of vesicles to the canalicular membrane as determined by immunocytochemical localization of a putative bile acid transporter, Ca2+, Mg2+-ecto-adenosine triphosphatase. CONCLUSIONS The findings support the view that apical membrane transport activity in the rat hepatocyte is highly regulated by the insertion of vesicles into this domain and that this process involves both microtubule-dependent and -independent mechanisms.
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Affiliation(s)
- J L Boyer
- Department of Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut, USA
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Oude Elferink RP, Meijer DK, Kuipers F, Jansen PL, Groen AK, Groothuis GM. Hepatobiliary secretion of organic compounds; molecular mechanisms of membrane transport. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1241:215-68. [PMID: 7640297 DOI: 10.1016/0304-4157(95)00006-d] [Citation(s) in RCA: 249] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- R P Oude Elferink
- Department of Gastrointestinal and Liver Diseases, Academic Medical Center, AZ Amsterdam, The Netherlands
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Anwer MS, Berk PD, Suchy FJ, Wolkoff AW. Characterization of membrane transport mechanisms: a summary of the 1991 AASLD single topic conference. Hepatology 1992; 15:1179-93. [PMID: 1350564 DOI: 10.1002/hep.1840150633] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- M S Anwer
- Tufts University, North Grafton, Massachusetts 01536
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Berry MN, Halls HJ, Grivell MB. Techniques for pharmacological and toxicological studies with isolated hepatocyte suspensions. Life Sci 1992; 51:1-16. [PMID: 1614269 DOI: 10.1016/0024-3205(92)90212-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Since its introduction in 1969, the high-yield preparation of isolated hepatocytes has become a frequently used tool for the study of hepatic uptake, excretion, metabolism and toxicity of drugs and other xenobiotics. Basic preparative methods are now firmly established involving perfusion of the liver with a balanced-saline solution containing collagenase. Satisfactory procedures are available for determining cell yields, for expressing cellular activities and for establishing optimal incubation conditions. Gross cellular damage can be detected by means of trypan blue or by measuring enzyme leakage, and damaged cells can be removed from the preparation. Specialized techniques are available for preparing hepatocyte couplets and suspensions enriched with periportal or perivenous hepatocytes. The isolated hepatocyte preparation is particularly convenient for the study of the kinetics of hepatic drug uptake and excretion because the cells can be rapidly separated from the incubation medium. Isolated liver cells have also proved valuable for investigating drug metabolism since they show many of the features of the intact liver. However, they also show important differences such as losses of membrane specialization, some degree of cell polarity and the capacity to form bile. The many consequences of the hepatic toxicity of xenobiotics including lipid peroxidation, free radical formation, glutathione depletion, and covalent binding to macromolecules are also readily studied with the isolated liver cell preparation. A particular advantage is the ease with which morphological changes as a result of drug exposure can be observed in isolated hepatocytes. However, it must be remembered that the isolation procedure inevitably introduces changes that may make the cells more susceptible than the normal liver to damage by xenobiotic agents. Despite its limitations, the isolated hepatocyte preparation is now firmly established in the armamentarium of the investigator examining the interaction of the liver with xenobiotics.
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Affiliation(s)
- M N Berry
- Department of Medical Biochemistry, School of Medicine, Flinders University of South Australia, Adelaide
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