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Jiao TY, Ma YD, Guo XZ, Ye YF, Xie C. Bile acid and receptors: biology and drug discovery for nonalcoholic fatty liver disease. Acta Pharmacol Sin 2022; 43:1103-1119. [PMID: 35217817 PMCID: PMC9061718 DOI: 10.1038/s41401-022-00880-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 01/25/2022] [Indexed: 02/07/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD), a series of liver metabolic disorders manifested by lipid accumulation within hepatocytes, has become the primary cause of chronic liver diseases worldwide. About 20%-30% of NAFLD patients advance to nonalcoholic steatohepatitis (NASH), along with cell death, inflammation response and fibrogenesis. The pathogenesis of NASH is complex and its development is strongly related to multiple metabolic disorders (e.g. obesity, type 2 diabetes and cardiovascular diseases). The clinical outcomes include liver failure and hepatocellular cancer. There is no FDA-approved NASH drug so far, and thus effective therapeutics are urgently needed. Bile acids are synthesized in hepatocytes, transported into the intestine, metabolized by gut bacteria and recirculated back to the liver by the enterohepatic system. They exert pleiotropic roles in the absorption of fats and regulation of metabolism. Studies on the relevance of bile acid disturbance with NASH render it as an etiological factor in NASH pathogenesis. Recent findings on the functional identification of bile acid receptors have led to a further understanding of the pathophysiology of NASH such as metabolic dysregulation and inflammation, and bile acid receptors are recognized as attractive targets for NASH treatment. In this review, we summarize the current knowledge on the role of bile acids and the receptors in the development of NAFLD and NASH, especially the functions of farnesoid X receptor (FXR) in different tissues including liver and intestine. The progress in the development of bile acid and its receptors-based drugs for the treatment of NASH including bile acid analogs and non-bile acid modulators on bile acid metabolism is also discussed.
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Affiliation(s)
- Ting-Ying Jiao
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yuan-di Ma
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiao-Zhen Guo
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yun-Fei Ye
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Cen Xie
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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Thibaut MM, Gillard J, Dolly A, Roumain M, Leclercq IA, Delzenne NM, Muccioli GG, Bindels LB. Bile Acid Dysregulation Is Intrinsically Related to Cachexia in Tumor-Bearing Mice. Cancers (Basel) 2021; 13:6389. [PMID: 34945009 DOI: 10.3390/cancers13246389] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/03/2021] [Accepted: 12/14/2021] [Indexed: 12/12/2022] Open
Abstract
Simple Summary Cancer cachexia is considered a multi-organ syndrome. An improved understanding of how circulating molecules can affect tissues and mediate their crosstalk in the pathogenesis of cancer cachexia is emerging. Considering the various actions of bile acids on host metabolism and immunity, they could represent innovative targets in cancer cachexia. In this study, we investigated how bile acids could contribute to this syndrome by assessing the bile flow, by comparing the impact on bile acid pathways of cachexia-inducing and non-cachexia-inducing cell sublines, and by investigating the effects of ursodeoxycholic acid, a choleretic compound, in cachectic mice. Altogether, our analyses strengthen the importance of bile acids and their receptors as key players in the metabolic disorders associated with cancer, thereby laying the foundation for new therapeutic opportunities. Abstract Bile acids exert diverse actions on host metabolism and immunity through bile acid-activated receptors, including Takeda G protein-coupled receptor 5 (TGR5). We have recently evidenced an alteration in bile acids in cancer cachexia, an inflammatory and metabolic syndrome contributing to cancer death. This current study aims to further explore the links emerging between bile acids and cancer cachexia. First, we showed that bile flow is reduced in cachectic mice. Next, comparing mice inoculated with cachexia-inducing and with non-cachexia-inducing C26 colon carcinoma cells, we demonstrated that alterations in the bile acid pathways and profile are directly associated with cachexia. Finally, we performed an interventional study using ursodeoxycholic acid (UDCA), a compound commonly used in hepatobiliary disorders, to induce bile acid secretion and decrease inflammation. We found that UDCA does not improve hepatic inflammation and worsens muscle atrophy in cachectic mice. This exacerbation of the cachectic phenotype upon UDCA was accompanied by a decreased TGR5 activity, suggesting that TGR5 agonists, known to reduce inflammation in several pathological conditions, could potentially counteract cachectic features. This work brings to light major evidence sustaining the emerging links between bile acids and cancer cachexia and reinforces the interest in studying bile acid-activated receptors in this context.
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Xie G, Jiang R, Wang X, Liu P, Zhao A, Wu Y, Huang F, Liu Z, Rajani C, Zheng X, Qiu J, Zhang X, Zhao S, Bian H, Gao X, Sun B, Jia W. Conjugated secondary 12α-hydroxylated bile acids promote liver fibrogenesis. EBioMedicine 2021; 66:103290. [PMID: 33752128 PMCID: PMC8010625 DOI: 10.1016/j.ebiom.2021.103290] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 02/24/2021] [Accepted: 03/04/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Significantly elevated serum and hepatic bile acid (BA) concentrations have been known to occur in patients with liver fibrosis. However, the roles of different BA species in liver fibrogenesis are not fully understood. METHODS We quantitatively measured blood BA concentrations in nonalcoholic steatohepatitis (NASH) patients with liver fibrosis and healthy controls. We characterized BA composition in three mouse models induced by carbon tetrachloride (CCl4), streptozotocin-high fat diet (STZ-HFD), and long term HFD, respectively. The molecular mechanisms underlying the fibrosis-promoting effects of BAs were investigated in cell line models, a 3D co-culture system, and a Tgr5 (HSC-specific) KO mouse model. FINDINGS We found that a group of conjugated 12α-hydroxylated (12α-OH) BAs, such as taurodeoxycholate (TDCA) and glycodeoxycholate (GDCA), significantly increased in NASH patients and liver fibrosis mouse models. 12α-OH BAs significantly increased HSC proliferation and protein expression of fibrosis-related markers. Administration of TDCA and GDCA directly activated HSCs and promoted liver fibrogenesis in mouse models. Blockade of BA binding to TGR5 or inhibition of ERK1/2 and p38 MAPK signaling both significantly attenuated the BA-induced fibrogenesis. Liver fibrosis was attenuated in mice with Tgr5 depletion. INTERPRETATION Increased hepatic concentrations of conjugated 12α-OH BAs significantly contributed to liver fibrosis via TGR5 mediated p38MAPK and ERK1/2 signaling. Strategies to antagonize TGR5 or inhibit ERK1/2 and p38 MAPK signaling may effectively prevent or reverse liver fibrosis. FUNDINGS This study was supported by the National Institutes of Health/National Cancer Institute Grant 1U01CA188387-01A1, the National Key Research and Development Program of China (2017YFC0906800); the State Key Program of National Natural Science Foundation (81430062); the National Natural Science Foundation of China (81974073, 81774196), China Postdoctoral Science Foundation funded project, China (2016T90381), and E-institutes of Shanghai Municipal Education Commission, China (E03008).
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Affiliation(s)
- Guoxiang Xie
- Center for Translational Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China; Human Metabolomics Institute, Inc., Shenzhen, Guangdong 518109, China
| | - Runqiu Jiang
- Department of Hepatobiliary Surgery, The Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210009, China
| | - Xiaoning Wang
- E-institute of Shanghai Municipal Education Committee, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Ping Liu
- E-institute of Shanghai Municipal Education Committee, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Aihua Zhao
- Center for Translational Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Yiran Wu
- The iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Fengjie Huang
- Human Metabolomics Institute, Inc., Shenzhen, Guangdong 518109, China
| | - Zhipeng Liu
- Medical School of Southeast University, Nanjing, Jiangsu 210096, China
| | - Cynthia Rajani
- University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Xiaojiao Zheng
- Center for Translational Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Jiannan Qiu
- E-institute of Shanghai Municipal Education Committee, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Xiaoling Zhang
- Department of Hygienic Analysis and Detection, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Suwen Zhao
- The iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Hua Bian
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Xin Gao
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Beicheng Sun
- Department of Hepatobiliary Surgery, The Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210009, China
| | - Wei Jia
- Center for Translational Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China; University of Hawaii Cancer Center, Honolulu, HI 96813, USA; Hong Kong Traditional Chinese Medicine Phenome Research Centre, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong 999077, China; Lead contact.
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Tough IR, Schwartz TW, Cox HM. Synthetic G protein-coupled bile acid receptor agonists and bile acids act via basolateral receptors in ileal and colonic mucosa. Neurogastroenterol Motil 2020; 32:e13943. [PMID: 32656959 DOI: 10.1111/nmo.13943] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/29/2020] [Accepted: 06/22/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND The G protein-coupled bile acid (BA) receptor, GPBA (previously named TGR5), mediates BA gastrointestinal (GI) activities. Our aim was to elucidate the mucosal and motility responses to selective GPBA agonists compared with conjugated BA (eg, taurodeoxycholate, TDCA) in mouse and human colon. METHODS Ion transport responses to GPBA agonists or BAs were measured in mucosal preparations with intact submucous innervation, from C57Bl/6, PYY-/-, or GPBA-/- mice and compared with GPBA signaling in human colon. We also investigated the mechanisms underlying GPBA agonism in mucosae and on natural fecal pellet propulsion. KEY RESULTS GPBA agonist Merck V stimulated basolateral responses involving peptide YY (PYY), cholinergic, and 5-HT mechanisms in colonic mucosa. The PYY-mediated GPBA signal was glucose-sensitive. Luminal TDCA crossed the epithelial lining via the apical sodium-dependent BA transporter (ASBT) and its inhibitor, GSK2330672 significantly reduced luminal, but not basolateral TDCA activity. Merck V also slowed natural fecal pellet progression in wild-type and PYY-/- colons but not in GPBA-/- colon, while TDCA increased motility in wild-type colon. The antimotile GPBA effect was reversed by blockade of glucagon-like peptide 1 (GLP-1) receptors or nitric oxide synthase, indicating involvement of GLP-1 and nitric oxide. CONCLUSIONS & INFERENCES We conclude that several different targets within the lamina propria express GPBA, including L cells (that release PYY and GLP-1), enterochromaffin cells and neurons (that release 5-HT), and other enteric neurons. Furthermore, luminal-conjugated BAs require transport across the epithelium via ASBT in order to activate basolateral GPBA.
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Affiliation(s)
- Iain R Tough
- King's College London, Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, London, UK
| | - Thue W Schwartz
- Novo Nordisk Foundation Centre for Basic Metabolic Research, Section for Metabolic Receptology and Enteroendocrinology, University of Copenhagen, Copenhagen, Denmark
| | - Helen M Cox
- King's College London, Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, London, UK
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Kim H, Fang S. Crosstalk between FXR and TGR5 controls glucagon-like peptide 1 secretion to maintain glycemic homeostasis. Lab Anim Res. 2018;34:140-146. [PMID: 30671099 PMCID: PMC6333617 DOI: 10.5625/lar.2018.34.4.140] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Accepted: 12/05/2018] [Indexed: 12/28/2022] Open
Abstract
Though bile acids have been well known as digestive juice, recent studies have demonstrated that bile acids bind to their endogenous receptors, including Farnesoid X receptor (FXR) and G protein-coupled bile acid receptor 1 (GPBAR1; TGR5) and serve as hormone to control various biological processes, including cholesterol/bile acid metabolism, glucose/lipid metabolism, immune responses, and energy metabolism. Deficiency of those bile acid receptors has been reported to induce diverse metabolic syndromes such as obesity, hyperlipidemia, hyperglycemia, and insulin resistance. As consistent, numerous studies have reported alteration of bile acid signaling pathways in type II diabetes patients. Interestingly, bile acids have shown to activate TGR5 in intestinal L cells and enhance secretion of glucagon-like peptide 1 (GLP-1) to potentiate insulin secretion in response to glucose. Moreover, FXR has been shown to crosstalk with TGR5 to control GLP-1 secretion. Altogether, bile acid receptors, FXR and TGR5 are potent therapeutic targets for the treatment of metabolic diseases, including type II diabetes.
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Abstract
Many receptors can be activated by bile acids (BAs) and their derivatives. These include nuclear receptors farnesoid X receptor (FXR), pregnane X receptor (PXR), and vitamin D receptor (VDR), as well as membrane receptors Takeda G protein receptor 5 (TGR5), sphingosine-1-phosphate receptor 2 (S1PR2), and cholinergic receptor muscarinic 2 (CHRM2). All of them are implicated in the development of metabolic and immunological diseases in response to endobiotic and xenobiotic exposure. Because epigenetic regulation is critical for organisms to adapt to constant environmental changes, this review article summarizes epigenetic regulation as well as post-transcriptional modification of bile acid receptors. In addition, the focus of this review is on the liver and digestive tract although these receptors may have effects on other organs. Those regulatory mechanisms are implicated in the disease process and critically important in uncovering innovative strategy for prevention and treatment of metabolic and immunological diseases.
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Abstract
BACKGROUND The G protein-coupled bile acid receptor (TGR5) is a cell surface receptor which induces the production of intracellular cAMP and promotes epithelial-mesenchymal transition in gastric cancer cell lines. TGR5 is found in a wide variety of tissues including the kidney. However, the patterns of TGR5 expression have not been well characterized in physiologic kidney or renal neoplasms. We explore the expression of TGR5 in benign renal tissue and renal neoplasms and assess its utility as a diagnostic marker. METHODS Sixty-one renal cortical neoplasms from 2000 to 2014 were retrieved. TGR5 protein expression was examined by immunohistochemistry. TGR5 mRNA was also measured by real-time PCR. RESULTS In normal renal tissue, TGR5 was strongly positive in collecting ducts, distal convoluted tubules and thin loop of Henle. Proximal convoluted tubules showed absent or focal weak staining. In clear cell renal cell carcinomas (RCCs), 25 of 27 cases (92%) were negative for TGR5 (p < 0.001). TGR5 mRNA was also significantly decreased in clear cell RCCs, suggesting that decreased TGR5 protein expression may be attributable to the downregulation of TGR5 mRNA in these tumors. All 11 papillary RCCs expressed TGR5 with 45% (5/11) exhibiting moderate to strong staining. All chromophobe RCCs and oncocytomas were positive for TGR5 with weak to moderate staining. TGR5 mRNA expression in these tumors was similar to normal kidney. All urothelial carcinomas of the renal pelvis strongly expressed TGR5 including a poorly differentiated urothelial carcinoma with sarcomatoid features. CONCLUSION TGR5 is strongly expressed in collecting ducts, distal convoluted tubules and thin loop of Henle. TGR5 protein and mRNA expression were notably decreased in clear cell RCCs and may be helpful in differentiating these tumors from other RCCs.
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Affiliation(s)
- Chaohui Lisa Zhao
- Department of Pathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, 593 Eddy Street, APC 12, Providence, RI, 02903, USA
| | - Ali Amin
- Department of Pathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, 593 Eddy Street, APC 12, Providence, RI, 02903, USA
| | - Yiang Hui
- Department of Pathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, 593 Eddy Street, APC 12, Providence, RI, 02903, USA
| | - Dongfang Yang
- Department of Pathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, 593 Eddy Street, APC 12, Providence, RI, 02903, USA
| | - Weibiao Cao
- Department of Pathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, 593 Eddy Street, APC 12, Providence, RI, 02903, USA. .,Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA.
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Sepe V, Renga B, Festa C, Finamore C, Masullo D, Carino A, Cipriani S, Distrutti E, Fiorucci S, Zampella A. Investigation on bile acid receptor regulators. Discovery of cholanoic acid derivatives with dual G-protein coupled bile acid receptor 1 (GPBAR1) antagonistic and farnesoid X receptor (FXR) modulatory activity. Steroids 2016; 105:59-67. [PMID: 26607331 DOI: 10.1016/j.steroids.2015.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 11/12/2015] [Accepted: 11/17/2015] [Indexed: 12/21/2022]
Abstract
Bile acids, the end products of cholesterol metabolism, activate multiple mechanisms through the interaction with membrane G-protein coupled receptors including the bile acid receptor GPBAR1 and nuclear receptors such as the bile acid sensor, farnesoid X receptor (FXR). Even if dual FXR/GPBAR1 agonists are largely considered a novel opportunity in the treatment of several liver and metabolic diseases, selective targeting of one of these receptors represents an attractive therapeutic approach for a wide range of disorders in which dual modulation is associated to severe side effects. In the present study we have investigated around the structure of LCA generating a small library of cholane derivatives, endowed with dual FXR agonism/GPBAR1 antagonism. To the best of our knowledge, this is the first report of bile acid derivatives able to antagonize GPBAR1.
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Affiliation(s)
- Valentina Sepe
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano, 49, I-80131 Naples, Italy
| | - Barbara Renga
- Department of Surgery and Biomedical Sciences, Nuova Facoltà di Medicina, P.zza L. Severi, 1-06132 Perugia, Italy
| | - Carmen Festa
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano, 49, I-80131 Naples, Italy
| | - Claudia Finamore
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano, 49, I-80131 Naples, Italy
| | - Dario Masullo
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano, 49, I-80131 Naples, Italy
| | - Adriana Carino
- Department of Surgery and Biomedical Sciences, Nuova Facoltà di Medicina, P.zza L. Severi, 1-06132 Perugia, Italy
| | - Sabrina Cipriani
- Department of Surgery and Biomedical Sciences, Nuova Facoltà di Medicina, P.zza L. Severi, 1-06132 Perugia, Italy
| | - Eleonora Distrutti
- Hospital S. Maria della Misericordia, S. Andrea delle Fratte, 06126 Perugia, Italy
| | - Stefano Fiorucci
- Department of Surgery and Biomedical Sciences, Nuova Facoltà di Medicina, P.zza L. Severi, 1-06132 Perugia, Italy
| | - Angela Zampella
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano, 49, I-80131 Naples, Italy.
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Masyuk AI, Huang BQ, Radtke BN, Gajdos GB, Splinter PL, Masyuk TV, Gradilone SA, LaRusso NF. Ciliary subcellular localization of TGR5 determines the cholangiocyte functional response to bile acid signaling. Am J Physiol Gastrointest Liver Physiol 2013; 304:G1013-24. [PMID: 23578785 PMCID: PMC3680685 DOI: 10.1152/ajpgi.00383.2012] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
TGR5, the G protein-coupled bile acid receptor that transmits bile acid signaling into a cell functional response via the intracellular cAMP signaling pathway, is expressed in human and rodent cholangiocytes. However, detailed information on the localization and function of cholangiocyte TGR5 is limited. We demonstrated that in human (H69 cells) and rat cholangiocytes, TGR5 is localized to multiple, diverse subcellular compartments, with its strongest expression on the apical plasma, ciliary, and nuclear membranes. To evaluate the relationship between ciliary TGR5 and the cholangiocyte functional response to bile acid signaling, we used a model of ciliated and nonciliated H69 cells and demonstrated that TGR5 agonists induce opposite changes in cAMP and ERK levels in cells with and without primary cilia. The cAMP level was increased in nonciliated cholangiocytes but decreased in ciliated cells. In contrast, ERK signaling was induced in ciliated cholangiocytes but suppressed in cells without cilia. TGR5 agonists inhibited proliferation of ciliated cholangiocytes but activated proliferation of nonciliated cells. The observed differential effects of TGR5 agonists were associated with the coupling of TGR5 to Gαi protein in ciliated cells and Gαs protein in nonciliated cholangiocytes. The functional responses of nonciliated and ciliated cholangiocytes to TGR5-mediated bile acid signaling may have important pathophysiological significance in cilia-related liver disorders (i.e., cholangiociliopathies), such as polycystic liver disease. In summary, TGR5 is expressed on diverse cholangiocyte compartments, including a primary cilium, and its ciliary localization determines the cholangiocyte functional response to bile acid signaling.
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Affiliation(s)
- Anatoliy I. Masyuk
- Mayo Clinic College of Medicine, Department of Internal Medicine, Rochester, Minnesota
| | - Bing Q. Huang
- Mayo Clinic College of Medicine, Department of Internal Medicine, Rochester, Minnesota
| | - Brynn N. Radtke
- Mayo Clinic College of Medicine, Department of Internal Medicine, Rochester, Minnesota
| | - Gabriella B. Gajdos
- Mayo Clinic College of Medicine, Department of Internal Medicine, Rochester, Minnesota
| | - Patrick L. Splinter
- Mayo Clinic College of Medicine, Department of Internal Medicine, Rochester, Minnesota
| | - Tatyana V. Masyuk
- Mayo Clinic College of Medicine, Department of Internal Medicine, Rochester, Minnesota
| | - Sergio A. Gradilone
- Mayo Clinic College of Medicine, Department of Internal Medicine, Rochester, Minnesota
| | - Nicholas F. LaRusso
- Mayo Clinic College of Medicine, Department of Internal Medicine, Rochester, Minnesota
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