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Zhang F, Mak SOK, Liu Y, Ke Y, Rao F, Yung WH, Zhang L, Chow BKC. Secretin receptor deletion in the subfornical organ attenuates the activation of excitatory neurons under dehydration. Curr Biol 2022; 32:4832-4841.e5. [PMID: 36220076 DOI: 10.1016/j.cub.2022.09.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 07/22/2022] [Accepted: 09/19/2022] [Indexed: 11/06/2022]
Abstract
In mammals, thirst is strongly influenced by the subfornical organ (SFO), a forebrain structure that integrates circulating signals including osmotic pressure and sodium contents. Secretin (SCT), a classical gastrointestinal hormone, has been implicated as a humoral factor regulating body-fluid homeostasis. However, the neural mechanism of secretin in the central nervous system in managing thirst remains unclear. In this study, we report that the local ablation of SCT receptor (SCTR) in the SFO reduces water but not salt intake in dehydrated mice and this effect could not be rescued by exogenous SCT administration. Electrophysiology with single-cell RT-PCR indicates that SCT elicits inward currents in the SFO neuronal nitric oxide synthase (SFOnNOS) neurons via SCTR in the presence of glutamate receptor antagonists. We further show that the SCTR in the SFO permits the activation of SFOnNOS neurons under distinct thirst types. Projection-specific gene deletion of SCTR in SFO to the median preoptic nucleus (MnPO) pathway also reduces water intake in dehydrated animals. SCT signaling thus plays an indispensable role in driving thirst. These data not only expand the functional boundaries of SCTR but also provide insights into the central mechanisms of homeostatic regulation.
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Affiliation(s)
- Fengwei Zhang
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Sarah O K Mak
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Yuchu Liu
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Ya Ke
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China; Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Hong Kong, China
| | - Feng Rao
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Wing Ho Yung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China; Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Hong Kong, China.
| | - Li Zhang
- Key Laboratory of CNS Regeneration (Ministry of Education), GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China; Neuroscience and Neurorehabilitation Institute, University of Health and Rehabilitation Sciences, Qingdao, China.
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2
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Sussman CR, Wang X, Chebib FT, Torres VE. Modulation of polycystic kidney disease by G-protein coupled receptors and cyclic AMP signaling. Cell Signal 2020; 72:109649. [PMID: 32335259 DOI: 10.1016/j.cellsig.2020.109649] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/11/2022]
Abstract
Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a systemic disorder associated with polycystic liver disease (PLD) and other extrarenal manifestations, the most common monogenic cause of end-stage kidney disease, and a major burden for public health. Many studies have shown that alterations in G-protein and cAMP signaling play a central role in its pathogenesis. As for many other diseases (35% of all approved drugs target G-protein coupled receptors (GPCRs) or proteins functioning upstream or downstream from GPCRs), treatments targeting GPCR have shown effectiveness in slowing the rate of progression of ADPKD. Tolvaptan, a vasopressin V2 receptor antagonist is the first drug approved by regulatory agencies to treat rapidly progressive ADPKD. Long-acting somatostatin analogs have also been effective in slowing the rates of growth of polycystic kidneys and liver. Although no treatment has so far been able to prevent the development or stop the progression of the disease, these encouraging advances point to G-protein and cAMP signaling as a promising avenue of investigation that may lead to more effective and safe treatments. This will require a better understanding of the relevant GPCRs, G-proteins, cAMP effectors, and of the enzymes and A-kinase anchoring proteins controlling the compartmentalization of cAMP signaling. The purpose of this review is to provide an overview of general GPCR signaling; the function of polycystin-1 (PC1) as a putative atypical adhesion GPCR (aGPCR); the roles of PC1, polycystin-2 (PC2) and the PC1-PC2 complex in the regulation of calcium and cAMP signaling; the cross-talk of calcium and cAMP signaling in PKD; and GPCRs, adenylyl cyclases, cyclic nucleotide phosphodiesterases, and protein kinase A as therapeutic targets in ADPKD.
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Affiliation(s)
- Caroline R Sussman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, United States of America
| | - Xiaofang Wang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, United States of America
| | - Fouad T Chebib
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, United States of America
| | - Vicente E Torres
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, United States of America.
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Tanguy E, Wang Q, Vitale N. Role of Phospholipase D-Derived Phosphatidic Acid in Regulated Exocytosis and Neurological Disease. Handb Exp Pharmacol 2020; 259:115-130. [PMID: 30570690 DOI: 10.1007/164_2018_180] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lipids play a vital role in numerous cellular functions starting from a structural role as major constituents of membranes to acting as signaling intracellular or extracellular entities. Accordingly, it has been known for decades that lipids, especially those coming from diet, are important to maintain normal physiological functions and good health. On the other side, the exact molecular nature of these beneficial or deleterious lipids, as well as their precise mode of action, is only starting to be unraveled. This recent improvement in our knowledge is largely resulting from novel pharmacological, molecular, cellular, and genetic tools to study lipids in vitro and in vivo. Among these important lipids, phosphatidic acid plays a unique and central role in a great variety of cellular functions. This review will focus on the proposed functions of phosphatidic acid generated by phospholipase D in the last steps of regulated exocytosis with a specific emphasis on hormonal and neurotransmitter release and its potential impact on different neurological diseases.
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Affiliation(s)
- Emeline Tanguy
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Qili Wang
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France.
- INSERM, Paris, Cedex 13, France.
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Mazzawi T, El-Salhy M. Changes in duodenal enteroendocrine cells in patients with irritable bowel syndrome following dietary guidance. Exp Biol Med (Maywood) 2017; 242:1355-1362. [PMID: 28737477 PMCID: PMC5528200 DOI: 10.1177/1535370217699537] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The densities of enteroendocrine cells are abnormal in patients with irritable bowel syndrome (IBS); however, they tend to change toward normal levels in stomach, ileum, and colon following dietary guidance. The aim was to identify the types of duodenal enteroendocrine cells affected after receiving dietary guidance in the same group of patients with IBS. Fourteen patients with IBS and 14 control subjects were included. The patients received three sessions of dietary guidance. Both groups underwent gastroscopies at baseline, and again for the patients after 3–9 months (median, four months) from receiving dietary guidance. Tissue biopsies were collected from the descending part of the duodenum and were immunostained for all the types of enteroendocrine cells and were then quantified by using computerized image analysis. Using the Kruskal–Wallis non-parametric test with Dunn’s test as a post-test, the results showed a significant difference in the secretin cell densities between control subjects and patients with IBS prior to and following dietary guidance (P = 0.0001 and 0.011, respectively). The corresponding P values for cholecystokinin (CCK) cell densities were 0.03 and 0.42, respectively; gastric inhibitory peptide (GIP) cell densities were 0.06 and 0.43, respectively; serotonin cell densities were <0.0001 and 0.002, respectively; and for somatostatin cell densities were <0.0001 and 0.052, respectively. The Paired t-test showed a significant difference only in the serotonin (P = 0.03) and somatostatin (P < 0.0001) cell densities between IBS patients prior to and following dietary guidance. The changes in the cell densities of secretin, CCK, and GIP were not significant between IBS patients prior to and following dietary guidance. In conclusion, the densities of several duodenal enteroendocrine cells in IBS patients changed toward the values measured in control subjects following dietary guidance. The changes in serotonin and somatostatin cell densities may have contributed to the improvements in IBS symptoms, particularly pain and diarrhea.
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Affiliation(s)
- Tarek Mazzawi
- 1 Division of Gastroenterology, Department of Clinical Medicine, University of Bergen, Bergen 5021, Norway.,2 National Centre for Functional Gastrointestinal Disorders, Division of Gastroenterology, Department of Medicine, Haukeland University Hospital-Helse Bergen, Bergen 5021, Norway
| | - Magdy El-Salhy
- 1 Division of Gastroenterology, Department of Clinical Medicine, University of Bergen, Bergen 5021, Norway.,2 National Centre for Functional Gastrointestinal Disorders, Division of Gastroenterology, Department of Medicine, Haukeland University Hospital-Helse Bergen, Bergen 5021, Norway.,3 Division of Gastroenterology, Department of Medicine, Stord Hospital-Helse Fonna, Stord 5416, Norway
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Sekar R, Wang L, Chow BKC. Central Control of Feeding Behavior by the Secretin, PACAP, and Glucagon Family of Peptides. Front Endocrinol (Lausanne) 2017; 8:18. [PMID: 28223965 PMCID: PMC5293785 DOI: 10.3389/fendo.2017.00018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/18/2017] [Indexed: 12/25/2022] Open
Abstract
Constituting a group of structurally related brain-gut peptides, secretin (SCT), pituitary adenylate cyclase-activating peptide (PACAP), and glucagon (GCG) family of peptide hormones exert their functions via interactions with the class B1 G protein-coupled receptors. In recent years, the roles of these peptides in neuroendocrine control of feeding behavior have been a specific area of research focus for development of potential therapeutic drug targets to combat obesity and metabolic disorders. As a result, some members in the family and their analogs have already been utilized as therapeutic agents in clinical application. This review aims to provide an overview of the current understanding on the important role of SCT, PACAP, and GCG family of peptides in central control of feeding behavior.
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Affiliation(s)
- Revathi Sekar
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Lei Wang
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
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Zhang YA, Ma X, Sathe A, Fujimoto J, Wistuba I, Lam S, Yatabe Y, Wang YW, Stastny V, Gao B, Larsen JE, Girard L, Liu X, Song K, Behrens C, Kalhor N, Xie Y, Zhang MQ, Minna JD, Gazdar AF. Validation of SCT Methylation as a Hallmark Biomarker for Lung Cancers. J Thorac Oncol 2015; 11:346-360. [PMID: 26725182 DOI: 10.1016/j.jtho.2015.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 11/02/2015] [Accepted: 11/04/2015] [Indexed: 12/14/2022]
Abstract
INTRODUCTION The human secretin gene (SCT) encodes secretin, a hormone with limited tissue distribution. Analysis of the 450k methylation array data in The Cancer Genome Atlas (TCGA) indicated that the SCT promoter region is differentially hypermethylated in lung cancer. Our purpose was to validate SCT methylation as a potential biomarker for lung cancer. METHODS We analyzed data from TCGA and developed and applied SCT-specific bisulfite DNA sequencing and quantitative methylation-specific polymerase chain reaction assays. RESULTS The analyses of TCGA 450K data for 801 samples showed that SCT hypermethylation has an area under the curve (AUC) value greater than 0.98 that can be used to distinguish lung adenocarcinomas or squamous cell carcinomas from nonmalignant lung tissue. Bisulfite sequencing of lung cancer cell lines and normal blood cells allowed us to confirm that SCT methylation is highly discriminative. By applying a quantitative methylation-specific polymerase chain reaction assay, we found that SCT hypermethylation is frequently detected in all major subtypes of malignant non-small cell lung cancer (AUC = 0.92, n = 108) and small cell lung cancer (AUC = 0.93, n = 40) but is less frequent in lung carcinoids (AUC = 0.54, n = 20). SCT hypermethylation appeared in samples of lung carcinoma in situ during multistage pathogenesis and increased in invasive samples. Further analyses of TCGA 450k data showed that SCT hypermethylation is highly discriminative in most other types of malignant tumors but less frequent in low-grade malignant tumors. The only normal tissue with a high level of methylation was the placenta. CONCLUSIONS Our findings demonstrated that SCT methylation is a highly discriminative biomarker for lung and other malignant tumors, is less frequent in low-grade malignant tumors (including lung carcinoids), and appears at the carcinoma in situ stage.
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Cardoso JCR, Félix RC, Trindade M, Power DM. Fish genomes provide novel insights into the evolution of vertebrate secretin receptors and their ligand. Gen Comp Endocrinol 2014; 209:82-92. [PMID: 24906176 DOI: 10.1016/j.ygcen.2014.05.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 05/12/2014] [Accepted: 05/15/2014] [Indexed: 01/21/2023]
Abstract
The secretin receptor (SCTR) is a member of Class 2 subfamily B1 GPCRs and part of the PAC1/VPAC receptor subfamily. This receptor has long been known in mammals but has only recently been identified in other vertebrates including teleosts, from which it was previously considered to be absent. The ligand for SCTR in mammals is secretin (SCT), an important gastrointestinal peptide, which in teleosts has not yet been isolated, or the gene identified. This study revises the evolutionary model previously proposed for the secretin-GPCRs in metazoan by analysing in detail the fishes, the most successful of the extant vertebrates. All the Actinopterygii genomes analysed and the Chondrichthyes and Sarcopterygii fish possess a SCTR gene that shares conserved sequence, structure and synteny with the tetrapod homologue. Phylogenetic clustering and gene environment comparisons revealed that fish and tetrapod SCTR shared a common origin and diverged early from the PAC1/VPAC subfamily group. In teleosts SCTR duplicated as a result of the fish specific whole genome duplication but in all the teleost genomes analysed, with the exception of tilapia (Oreochromis niloticus), one of the duplicates was lost. The function of SCTR in teleosts is unknown but quantitative PCR revealed that in both sea bass (Dicentrarchus labrax) and tilapia (Oreochromis mossambicus) transcript abundance is high in the gastrointestinal tract suggesting it may intervene in similar processes to those in mammals. In contrast, no gene encoding the ligand SCT was identified in the ray-finned fishes (Actinopterygii) although it was present in the coelacanth (lobe finned fish, Sarcopterygii) and in the elephant shark (holocephalian). The genes in linkage with SCT in tetrapods and coelacanth were also identified in ray-finned fishes supporting the idea that it was lost from their genome. At present SCTR remains an orphan receptor in ray-finned fishes and it will be of interest in the future to establish why SCT was lost and which ligand substitutes for it so that full characterization of the receptor can occur.
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Affiliation(s)
- João C R Cardoso
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| | - Rute C Félix
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| | - Marlene Trindade
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| | - Deborah M Power
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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Investigation of PACAP Fragments and Related Peptides in Chronic Retinal Hypoperfusion. J Ophthalmol 2014; 2014:563812. [PMID: 24900914 PMCID: PMC4036611 DOI: 10.1155/2014/563812] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 03/24/2014] [Indexed: 12/05/2022] Open
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) has neuroprotective effects in different neuronal and retinal injuries. Retinal ischemia can be effectively modelled by permanent bilateral common carotid artery occlusion (BCCAO), which causes chronic hypoperfusion-induced degeneration in the entire rat retina. The retinoprotective effect of PACAP 1-38 and VIP is well-established in ischemic retinopathy. However, little is known about the effects of related peptides and PACAP fragments in ischemic retinopathy. The aim of the present study was to investigate the potential retinoprotective effects of different PACAP fragments (PACAP 4-13, 4-22, 6-10, 6-15, 11-15, and 20-31) and related peptides (secretin, glucagon) in BCCAO-induced ischemic retinopathy. Wistar rats (3-4 months old) were used in the experiment. After performing BCCAO, the right eyes of the animals were treated with PACAP fragments or related peptides intravitreal (100 pM), while the left eyes were injected with saline serving as control eyes. Sham-operated (without BCCAO) rats received the same treatment. Routine histology was performed 2 weeks after the surgery; cells were counted and the thickness of retinal layers was compared. Our results revealed significant neuroprotection by PACAP 1-38 but did not reveal retinoprotective effect of the PACAP fragments or related peptides. These results suggest that PACAP 1-38 has the greatest efficacy in ischemic retinopathy.
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Sekar R, Chow BKC. Secretin receptor‐knockout mice are resistant to high‐fat diet‐induced obesity and exhibit impaired intestinal lipid absorption. FASEB J 2014; 28:3494-505. [DOI: 10.1096/fj.13-247536] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Revathi Sekar
- School of Biological Sciences, The University of Hong KongHong KongChina
| | - Billy K. C. Chow
- School of Biological Sciences, The University of Hong KongHong KongChina
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Nematode and arthropod genomes provide new insights into the evolution of class 2 B1 GPCRs. PLoS One 2014; 9:e92220. [PMID: 24651821 PMCID: PMC3961327 DOI: 10.1371/journal.pone.0092220] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 02/19/2014] [Indexed: 01/27/2023] Open
Abstract
Nematodes and arthropods are the most speciose animal groups and possess Class 2 B1 G-protein coupled receptors (GPCRs). Existing models of invertebrate Class 2 B1 GPCR evolution are mainly centered on Caenorhabditis elegans and Drosophila melanogaster and a few other nematode and arthropod representatives. The present study reevaluates the evolution of metazoan Class 2 B1 GPCRs and orthologues by exploring the receptors in several nematode and arthropod genomes and comparing them to the human receptors. Three novel receptor phylogenetic clusters were identified and designated cluster A, cluster B and PDF-R-related cluster. Clusters A and B were identified in several nematode and arthropod genomes but were absent from D. melanogaster and Culicidae genomes, whereas the majority of the members of the PDF-R-related cluster were from nematodes. Cluster A receptors were nematode and arthropod-specific but shared a conserved gene environment with human receptor loci. Cluster B members were orthologous to human GCGR, PTHR and Secretin members with which they probably shared a common origin. PDF-R and PDF-R related clusters were present in representatives of both nematodes and arthropods. The results of comparative analysis of GPCR evolution and diversity in protostomes confirm previous notions that C. elegans and D. melanogaster genomes are not good representatives of nematode and arthropod phyla. We hypothesize that at least four ancestral Class 2 B1 genes emerged early in the metazoan radiation, which after the protostome-deuterostome split underwent distinct selective pressures that resulted in duplication and deletion events that originated the current Class 2 B1 GPCRs in nematode and arthropod genomes.
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Abstract
Secretin (Sct), a classical gut hormone, is now known to play pleiotropic functions in the body including osmoregulation, digestion, and feeding control. As Sct has long been implicated to regulate metabolism, in this report, we have investigated a potential lipolytic action of Sct. In our preliminary studies, both Sct levels in circulation and Sct receptor (SctR) transcripts in adipose tissue were upregulated during fasting, suggesting a potential physiological relevance of Sct in regulating lipolysis. Using SctR knockout and Sct knockout mice as controls, we show that Sct is able to stimulate lipolysis in vitro in isolated adipocytes dose- and time-dependently, as well as acute lipolysis in vivo. H-89, a protein kinase A (PKA) inhibitor, was found to attenuate lipolytic effects of 1 μM Sct in vitro, while a significant increase in PKA activity upon Sct injection was observed in the adipose tissue in vivo. Sct was also found to stimulate phosphorylation at 660ser of hormone sensitive lipase (HSL) and to bring about the translocation of HSL from cytosol to the lipid droplet. In summary, our data demonstrate for the first time the in vivo and in vitro lipolytic effects of Sct, and that this function is mediated by PKA and HSL.
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Affiliation(s)
- Revathi Sekar
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong
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Sekar R, Chow BKC. Metabolic effects of secretin. Gen Comp Endocrinol 2013; 181:18-24. [PMID: 23246720 DOI: 10.1016/j.ygcen.2012.11.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Revised: 11/23/2012] [Accepted: 11/27/2012] [Indexed: 12/25/2022]
Abstract
Secretin (Sct), traditionally a gastrointestinal hormone backed by a century long research, is now beginning to be recognized also as a neuroactive peptide. Substantiation by recent evidence on the functional role of Sct in various regions of the brain, especially on its potential neurosecretion from the posterior pituitary, has revealed Sct's physiological actions in regulating water homeostasis. Recent advances in understanding the functional roles of central and peripheral Sct has been made possible by the development of Sct and Sct receptor (SctR) knockout animal models which have led to novel approaches in research on the physiology of this brain-gut peptide. While research on the role of Sct in appetite regulation and fatty acid metabolism has been initiated recently, its role in glucose homeostasis is unclear. This review focuses mainly on the metabolic role of Sct by discussing data from the last century and recent discoveries, with emphasis on the need for revisiting and elucidating the role of Sct in metabolism and energy homeostasis.
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Affiliation(s)
- Revathi Sekar
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong
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Sundaresan S, Shahid R, Riehl TE, Chandra R, Nassir F, Stenson WF, Liddle RA, Abumrad NA. CD36-dependent signaling mediates fatty acid-induced gut release of secretin and cholecystokinin. FASEB J 2012. [PMID: 23233532 DOI: 10.1096/fj.12‐217703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Genetic variants in the fatty acid (FA) translocase FAT/CD36 associate with abnormal postprandial lipids and influence risk for the metabolic syndrome. CD36 is abundant on apical enterocyte membranes in the proximal small intestine, where it facilitates FA uptake and FA-initiated signaling. We explored whether CD36 signaling influences FA-mediated secretion of cholecystokinin (CCK) and secretin, peptides released by enteroendocrine cells (EECs) in the duodenum/jejunum, which regulate events important for fat digestion and homeostasis. CD36 was immunodetected on apical membranes of secretin- and CCK-positive EECs and colocalized with cytosolic granules. Intragastric lipid administration to CD36 mice released less secretin (-60%) and CCK (-50%) compared with wild-type mice. Likewise, diminished secretin and CCK responses to FA were observed with CD36 intestinal segments in vitro, arguing against influence of alterations in fat absorption. Signaling mechanisms underlying peptide release were examined in STC-1 cells stably expressing human CD36 or a signaling-impaired mutant (CD36K/A). FA stimulation of cells expressing CD36 (vs. vector or CD36K/A) released more secretin (3.5- to 4-fold) and CCK (2- to 3-fold), generated more cAMP (2- to 2.5-fold), and enhanced protein kinase A activation. Protein kinase A inhibition (H-89) blunted secretin (80%) but not CCK release, which was reduced (50%) by blocking of calmodulin kinase II (KN-62). Coculture of STC-1 cells with Caco-2 cells stably expressing CD36 did not alter secretin or CCK release, consistent with a minimal effect of adjacent enterocytes. In summary, CD36 is a major mediator of FA-induced release of CCK and secretin. These peptides contribute to the role of CD36 in fat absorption and to its pleiotropic metabolic effects.
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Affiliation(s)
- Sinju Sundaresan
- Department of Medicine, Center for Human Nutrition, 660 S. Euclid Ave., Campus Box 8031, St. Louis, MO 63110, USA
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Sundaresan S, Shahid R, Riehl TE, Chandra R, Nassir F, Stenson WF, Liddle RA, Abumrad NA. CD36-dependent signaling mediates fatty acid-induced gut release of secretin and cholecystokinin. FASEB J 2012; 27:1191-202. [PMID: 23233532 DOI: 10.1096/fj.12-217703] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Genetic variants in the fatty acid (FA) translocase FAT/CD36 associate with abnormal postprandial lipids and influence risk for the metabolic syndrome. CD36 is abundant on apical enterocyte membranes in the proximal small intestine, where it facilitates FA uptake and FA-initiated signaling. We explored whether CD36 signaling influences FA-mediated secretion of cholecystokinin (CCK) and secretin, peptides released by enteroendocrine cells (EECs) in the duodenum/jejunum, which regulate events important for fat digestion and homeostasis. CD36 was immunodetected on apical membranes of secretin- and CCK-positive EECs and colocalized with cytosolic granules. Intragastric lipid administration to CD36 mice released less secretin (-60%) and CCK (-50%) compared with wild-type mice. Likewise, diminished secretin and CCK responses to FA were observed with CD36 intestinal segments in vitro, arguing against influence of alterations in fat absorption. Signaling mechanisms underlying peptide release were examined in STC-1 cells stably expressing human CD36 or a signaling-impaired mutant (CD36K/A). FA stimulation of cells expressing CD36 (vs. vector or CD36K/A) released more secretin (3.5- to 4-fold) and CCK (2- to 3-fold), generated more cAMP (2- to 2.5-fold), and enhanced protein kinase A activation. Protein kinase A inhibition (H-89) blunted secretin (80%) but not CCK release, which was reduced (50%) by blocking of calmodulin kinase II (KN-62). Coculture of STC-1 cells with Caco-2 cells stably expressing CD36 did not alter secretin or CCK release, consistent with a minimal effect of adjacent enterocytes. In summary, CD36 is a major mediator of FA-induced release of CCK and secretin. These peptides contribute to the role of CD36 in fat absorption and to its pleiotropic metabolic effects.
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Affiliation(s)
- Sinju Sundaresan
- Department of Medicine, Center for Human Nutrition, 660 S. Euclid Ave., Campus Box 8031, St. Louis, MO 63110, USA
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Wang X, Ye H, Ward CJ, Chu JYS, Masyuk TV, Larusso NF, Harris PC, Chow BKC, Torres VE. Insignificant effect of secretin in rodent models of polycystic kidney and liver disease. Am J Physiol Renal Physiol 2012; 303:F1089-98. [PMID: 22811488 DOI: 10.1152/ajprenal.00242.2012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Polycystic kidney (PKD) and liver (PLD) diseases cause significant morbidity and mortality. A large body of evidence indicates that cyclic AMP plays an important role in their pathogenesis. Clinical trials of drugs that reduce cyclic AMP levels in target tissues are now in progress. Secretin may contribute to adenylyl cyclase-dependent urinary concentration and is a major agonist of adenylyl cyclase in cholangiocytes. To investigate the role of secretin in PKD and PLD, we have studied the expression of secretin and the secretin receptor in rodent models orthologous to autosomal recessive (PCK rat) and dominant (Pkd2(-/WS25) mouse) PKD; the effects of exogenous secretin administration to PCK rats, PCK rats lacking circulating vasopressin (PCK(di/di)), and Pkd2(-/WS25) mice; and the impact of a nonfunctional secretin receptor on disease development in Pkd2(-/WS25):SCTR(-/-) double mutants. Renal and hepatic secretin and secretin receptor mRNA and plasma secretin were increased in both models, and secretin receptor protein was increased in the kidneys and liver of Pkd2(-/WS25) mice. However, exogenous secretin administered subcutaneously via osmotic pumps had minimal or negligible effects and the absence of a functional secretin receptor had no influence on the severity of PKD or PLD. Therefore, it is unlikely that by itself secretin plays a significant role in the pathogenesis of PKD and/or PLD.
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Affiliation(s)
- Xiaofang Wang
- Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
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16
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Lee VHY, Lam IPY, Choi HS, Chow BKC, Lee LTO. The estrogen-related receptor alpha upregulates secretin expressions in response to hypertonicity and angiotensin II stimulation. PLoS One 2012; 7:e39913. [PMID: 22761926 PMCID: PMC3382582 DOI: 10.1371/journal.pone.0039913] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 06/03/2012] [Indexed: 01/17/2023] Open
Abstract
Osmoregulation via maintenance of water and salt homeostasis is a vital process. In the brain, a functional secretin (SCT) and secretin receptor (SCTR) axis has recently been shown to mediate central actions of angiotensin II (ANGII), including initiation of water intake and stimulation of vasopressin (VP) expression and release. In this report, we provide evidence that estrogen-related receptor α (ERRα, NR3B1), a transcription factor mainly involved in metabolism, acts as an upstream activator of the SCT gene. In vitro studies using mouse hypothalamic cell line N-42 show that ERRα upregulates SCT promoter and gene expression. More importantly, knockdown of endogenous ERRα abolishes SCT promoter activation in response to hypertonic and ANGII stimulations. In mouse brain, ERRα coexpresses with SCT in various osmoregulatory brain regions, including the lamina terminalis and the paraventricular nucleus of the hypothalamus, and its expression is induced by hyperosmotic and ANGII treatments. Based on our data, we propose that both the upregulation of ERRα and/or the increased binding of ERRα to the mouse SCT promoter are two possible mechanisms for the elevated SCT expression upon hyperosmolality and central ANGII stimulation.
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Affiliation(s)
- Vien H. Y. Lee
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Ian P. Y. Lam
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Hueng-Sik Choi
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Billy K. C. Chow
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Leo T. O. Lee
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- * E-mail:
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Paltsev MA, Kvetnoy IM, Polyakova VO, Kvetnaiya TV, Trofimov AV. Neuroimmunoendocrine mechanisms of aging. ADVANCES IN GERONTOLOGY 2011. [DOI: 10.1134/s2079057011010103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Jukkola PI, Rogers JT, Kaspar BK, Weeber EJ, Nishijima I. Secretin deficiency causes impairment in survival of neural progenitor cells in mice. Hum Mol Genet 2010; 20:1000-7. [PMID: 21159798 DOI: 10.1093/hmg/ddq545] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hippocampal neurogenesis is the lifelong production of new neurons in the central nervous system (CNS), and affects many physiological and pathophysiological conditions, including neurobehavioral disorders. The early postnatal stage is the most prominent neurogenesis period; however, the functional role of neurogenesis in this developing stage has not been well characterized. To understand the role of hippocampal neurogenesis in the postnatal developing period, we analyzed secretin, a neuropeptide, which is expressed significantly higher in the development stage. Secretin is a pleiotropic neuropeptide hormone that belongs to the secretin/VIP/glucagon peptide family. Although secretin was originally isolated in the gastrointestinal system, it has been found that secretin itself acts as a neuropeptide in the CNS. Here, we report a new function of secretin as a survival factor for neural progenitor cells in the hippocampus. We found that secretin-deficient mice exhibit decreased numbers of BrdU-labeled new neurons and dramatically increased apoptosis of doublecortin-positive neural progenitor cells in the subgranular zone of the dentate gyrus (DG) during the early postnatal period. Furthermore, we found that reduced survival of neural progenitor cells leads to decreased volume of DG, reduced long-term potentiation and impaired spatial learning ability in adults. Our studies demonstrate that secretin has important implications for neurogenesis in postnatal development, and affects neurobehavioral function in the adult mouse.
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Affiliation(s)
- Peter I Jukkola
- Center for Molecular and Human Genetics, The Research Institute at Nationwide Children's Hospital, Department of Pediatrics, The Ohio State University, Columbus, OH 43205, USA
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Onori P, Wise C, Gaudio E, Franchitto A, Francis H, Carpino G, Lee V, Lam I, Miller T, Dostal DE, Glaser SS. Secretin inhibits cholangiocarcinoma growth via dysregulation of the cAMP-dependent signaling mechanisms of secretin receptor. Int J Cancer 2010; 127:43-54. [DOI: 10.1002/ijc.25028] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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Glaser S, Lam IP, Franchitto A, Gaudio E, Onori P, Chow BK, Wise C, Kopriva S, Venter J, White M, Ueno Y, Dostal D, Carpino G, Mancinelli R, Chiasson V, DeMorrow S, Francis H, Alpini G, Alpini G. Knockout of secretin receptor reduces large cholangiocyte hyperplasia in mice with extrahepatic cholestasis induced by bile duct ligation. Hepatology 2010; 52:204-14. [PMID: 20578263 PMCID: PMC3049759 DOI: 10.1002/hep.23657] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
UNLABELLED During bile duct ligation (BDL), the growth of large cholangiocytes is regulated by the cyclic adenosine monophosphate (cAMP)/extracellular signal-regulated kinase 1/2 (ERK1/2) pathway and is closely associated with increased secretin receptor (SR) expression. Although it has been suggested that SR modulates cholangiocyte growth, direct evidence for secretin-dependent proliferation is lacking. SR wild-type (WT) (SR(+/+)) or SR knockout (SR(-/-)) mice underwent sham surgery or BDL for 3 or 7 days. We evaluated SR expression, cholangiocyte proliferation, and apoptosis in liver sections and proliferating cell nuclear antigen (PCNA) protein expression and ERK1/2 phosphorylation in purified large cholangiocytes from WT and SR(-/-) BDL mice. Normal WT mice were treated with secretin (2.5 nmoles/kg/day by way of osmotic minipumps for 1 week), and biliary mass was evaluated. Small and large cholangiocytes were used to evaluate the in vitro effect of secretin (100 nM) on proliferation, protein kinase A (PKA) activity, and ERK1/2 phosphorylation. SR expression was also stably knocked down by short hairpin RNA, and basal and secretin-stimulated cAMP levels (a functional index of biliary growth) and proliferation were determined. SR was expressed by large cholangiocytes. Knockout of SR significantly decreased large cholangiocyte growth induced by BDL, which was associated with enhanced apoptosis. PCNA expression and ERK1/2 phosphorylation were decreased in large cholangiocytes from SR(-/-) BDL compared with WT BDL mice. In vivo administration of secretin to normal WT mice increased ductal mass. In vitro, secretin increased proliferation, PKA activity, and ERK1/2 phosphorylation of large cholangiocytes that was blocked by PKA and mitogen-activated protein kinase kinase inhibitors. Stable knockdown of SR expression reduced basal cholangiocyte proliferation. SR is an important trophic regulator sustaining biliary growth. CONCLUSION The current study provides strong support for the potential use of secretin as a therapy for ductopenic liver diseases.
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Affiliation(s)
- Shannon Glaser
- Scott & White Digestive Disease Research Center, College of Medicine, Temple, TX, USA.
| | - Ian P Lam
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | | | - Eugenio Gaudio
- Dept. Human Anatomy, University of Rome “La Sapienza”, Rome, Italy
| | - Paolo Onori
- Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Billy K Chow
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Candace Wise
- Scott & White Digestive Disease Research Center, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Division of Research and Education, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
| | - Shelley Kopriva
- Scott & White Digestive Disease Research Center, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
| | - Julie Venter
- Scott & White Digestive Disease Research Center, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
| | - Mellanie White
- Scott & White Digestive Disease Research Center, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
| | - Yoshiyuki Ueno
- Div. Gastroenterol, Tohoku University Graduate School of Medicine, Aobaku, Sendai, Japan
| | - David Dostal
- Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
| | - Guido Carpino
- Dept Health Science, University of Rome “Foro Italico”, Italy
| | - Romina Mancinelli
- Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Dept. Human Anatomy, University of Rome “La Sapienza”, Rome, Italy
| | - Valorie Chiasson
- Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
| | - Sharon DeMorrow
- Scott & White Digestive Disease Research Center, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
| | - Heather Francis
- Scott & White Digestive Disease Research Center, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Division of Research and Education, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
| | - Gianfranco Alpini
- Research, Central Texas Veterans Health Care System, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Scott & White Digestive Disease Research Center, Scott & White, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, Department of Medicine, Division Gastroenterology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504
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Lam IPY, Lee LTO, Choi HS, Alpini G, Chow BKC. Bile acids inhibit duodenal secretin expression via orphan nuclear receptor small heterodimer partner (SHP). Am J Physiol Gastrointest Liver Physiol 2009; 297:G90-7. [PMID: 19372104 PMCID: PMC2711755 DOI: 10.1152/ajpgi.00094.2009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Small heterodimer partner (SHP) is an orphan nuclear receptor in which gene expression can be upregulated by bile acids. It regulates its target genes by repressing the transcriptional activities of other nuclear receptors including NeuroD, which has been shown to regulate secretin gene expression. Here, we evaluated the regulation on duodenal secretin gene expression by SHP and selected bile acids, cholic acid (CA) and chenodeoxycholic acid (CDCA). In vitro treatment of CDCA or fexaramine elevated the SHP transcript level and occupancy on secretin promoter. The increase in the SHP level, induced by bile acid treatment or overexpression, reduced secretin gene expression, whereas this gene inhibitory effect was reversed by silencing of endogenous SHP. In in vivo studies, double-immunofluorescence staining demonstrated the coexpression of secretin and SHP in mouse duodenum. Feeding mice with 1% CA-enriched rodent chow resulted in upregulation of SHP and a concomitant decrease in secretin transcript and protein levels in duodenum compared with the control group fed with normal chow. A diet enriched with 5% cholestyramine led to a decrease in SHP level and a corresponding increase in secretin expression. Overall, this study showed that bile acids via SHP inhibit duodenal secretin gene expression. Because secretin is a key hormone that stimulates bile flow in cholangiocytes, this pathway thus provides a novel means to modulate secretin-stimulated choleresis in response to intraduodenal bile acids.
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Affiliation(s)
- Ian P. Y. Lam
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| | - Leo T. O. Lee
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| | - Hueng-Sik Choi
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| | - Gianfranco Alpini
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| | - Billy K. C. Chow
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
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Lee LTO, Lam IPY, Chow BKC. A functional variable number of tandem repeats is located at the 5' flanking region of the human secretin gene plays a downregulatory role in expression. J Mol Neurosci 2008; 36:125-31. [PMID: 18566919 DOI: 10.1007/s12031-008-9083-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 03/28/2008] [Indexed: 11/26/2022]
Abstract
Secretin is a peptide hormone playing multiple functions in the brain-gut axis. In this report, we investigated, by promoter analysis, the potential function of the variable of tandem repeats (VNTR), located at the 5' upstream region of the human secretin gene, and we demonstrated for the first time that this VNTR could downregulate transcription of the human secretin gene in a promoter-specific manner. The efficiency of VNTR in silencing the promoter was found to be directly related the number of repetitive units residing within. We also showed the deoxyribonucleic acid sequence as well as the length polymorphism of the VNTR of 76 Chinese individuals. These results collectively suggest that VNTR could potentially be a functional regulator to control the expression of the human secretin gene in different individuals.
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Affiliation(s)
- Leo T O Lee
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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