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Cassidy BM, Zino S, Fjeld K, Molven A, Lowe ME, Xiao X. Single nucleotide polymorphisms in CEL-HYB1 increase risk for chronic pancreatitis through proteotoxic misfolding. Hum Mutat 2020; 41:1967-1978. [PMID: 32906201 DOI: 10.1002/humu.24105] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/19/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022]
Abstract
Genetic variants contribute to the risk of chronic pancreatitis (CP) in adults and children. The risk variant CEL-HYB1, a recombinant hybrid allele of CEL and its neighboring pseudogene (CELP), encodes a pathogenic variant of the pancreatic digestive enzyme carboxyl ester lipase (CEL). We previously identified combinations of two non-synonymous SNPs, c.1463T>C (p. Ile488Thr) and c.1643C>T (p. Thr548Ile), in the break point region of CEL-HYB1. Herein, we tested whether these missense variants alter CP risk and their impact on functional properties of the CEL-HYB1 protein. Examination of CEL-HYB1 haplotypes in European patients and controls revealed that the combinationThr488-Ile548 was present only in cases (p ≤ .001). The lipase activity of purified recombinant CEL-HYB1 variants showed normal or near normal activity. CEL-HYB variants expressed in HEK293T cells all had decreased secretion compared with CEL, formed intracellular protein aggregates, and triggered endoplasmic reticulum stress. Thus, we propose that the presence of missense variants in CEL-HYB increases the pathogenicity of CEL-HYB1 through misfolding and gain-of-function proteotoxicity. Interestingly, Thr488-Ile548 and Thr488-Thr548 were equally pathogenic in the functional assays even though only the Thr488-Ile548 haplotype was significantly enriched in cases. The explanation for the mismatch between genetic and functional data requires further investigation.
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Affiliation(s)
- Brett M Cassidy
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sammy Zino
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Karianne Fjeld
- The Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway.,Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - Anders Molven
- The Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway.,Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Mark E Lowe
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Xunjun Xiao
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
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2
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Fjeld K, Masson E, Lin JH, Michl P, Stokowy T, Gravdal A, El Jellas K, Steine SJ, Hoem D, Johansson BB, Dalva M, Ruffert C, Zou WB, Li ZS, Njølstad PR, Chen JM, Liao Z, Johansson S, Rosendahl J, Férec C, Molven A. Characterization of CEL-DUP2: Complete duplication of the carboxyl ester lipase gene is unlikely to influence risk of chronic pancreatitis. Pancreatology 2020; 20:377-384. [PMID: 32007358 DOI: 10.1016/j.pan.2020.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 01/17/2020] [Accepted: 01/18/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND/OBJECTIVES Carboxyl ester lipase is a pancreatic enzyme encoded by CEL, an extremely polymorphic human gene. Pathogenic variants of CEL either increases the risk for chronic pancreatitis (CP) or cause MODY8, a syndrome of pancreatic exocrine and endocrine dysfunction. Here, we aimed to characterize a novel duplication allele of CEL (CEL-DUP2) and to investigate whether it associates with CP or pancreatic cancer. METHODS The structure of CEL-DUP2 was determined by a combination of Sanger sequencing, DNA fragment analysis, multiplex ligation-dependent probe amplification and whole-genome sequencing. We developed assays for screening of CEL-DUP2 and analyzed cohorts of idiopathic CP, alcoholic CP and pancreatic cancer. CEL protein expression was analyzed by immunohistochemistry. RESULTS CEL-DUP2 consists of an extra copy of the complete CEL gene. The allele has probably arisen from non-allelic, homologous recombination involving the adjacent pseudogene of CEL. We found no association between CEL-DUP2 carrier frequency and CP in cohorts from France (cases/controls: 2.5%/2.4%; P = 1.0), China (10.3%/8.1%; P = 0.08) or Germany (1.6%/2.3%; P = 0.62). Similarly, no association with disease was observed in alcohol-induced pancreatitis (Germany: 3.2%/2.3%; P = 0.51) or pancreatic cancer (Norway; 2.5%/3.2%; P = 0.77). Notably, the carrier frequency of CEL-DUP2 was more than three-fold higher in Chinese compared with Europeans. CEL protein expression was similar in tissues from CEL-DUP2 carriers and controls. CONCLUSIONS Our results support the contention that the number of CEL alleles does not influence the risk of pancreatic exocrine disease. Rather, the pathogenic CEL variants identified so far involve exon 11 sequence changes that substantially alter the protein's tail region.
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Affiliation(s)
- Karianne Fjeld
- The Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway; Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.
| | - Emmanuelle Masson
- Univ Brest, Inserm, EFS, UMR 1078, GGB, F-29200, Brest, France; CHRU Brest, Service de Génétique, Brest, France
| | - Jin-Huan Lin
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Patrick Michl
- Department of Internal Medicine I, Martin Luther University, Halle, Germany
| | - Tomasz Stokowy
- Genomics Core Facility, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Anny Gravdal
- The Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway; Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Khadija El Jellas
- The Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Solrun J Steine
- The Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Dag Hoem
- Department of Gastrointestinal Surgery, Haukeland University Hospital, Bergen, Norway
| | - Bente B Johansson
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Monica Dalva
- The Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - Claudia Ruffert
- Department of Internal Medicine I, Martin Luther University, Halle, Germany
| | - Wen-Bin Zou
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Zhao-Shen Li
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Pål R Njølstad
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, Norway
| | - Jian-Min Chen
- Univ Brest, Inserm, EFS, UMR 1078, GGB, F-29200, Brest, France
| | - Zhuan Liao
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Stefan Johansson
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway; Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Jonas Rosendahl
- Department of Internal Medicine I, Martin Luther University, Halle, Germany
| | - Claude Férec
- Univ Brest, Inserm, EFS, UMR 1078, GGB, F-29200, Brest, France; CHRU Brest, Service de Génétique, Brest, France
| | - Anders Molven
- The Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Pathology, Haukeland University Hospital, Bergen, Norway
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3
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de Santana LS, Caetano LA, Costa‐Riquetto AD, Franco PC, Dotto RP, Reis AF, Weinert LS, Silveiro SP, Vendramini MF, do Prado FA, Abrahão GCP, de Almeida AGFP, Tavares MDGR, Gonçalves WRB, Santomauro Junior AC, Halpern B, Jorge AAL, Nery M, Teles MG. Targeted sequencing identifies novel variants in common and rare MODY genes. Mol Genet Genomic Med 2019; 7:e962. [PMID: 31595705 PMCID: PMC6900361 DOI: 10.1002/mgg3.962] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 08/09/2019] [Accepted: 08/13/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Maturity-onset diabetes of the young (MODY) is a form of monogenic diabetes with autosomal dominant inheritance. To date, mutations in 11 genes have been frequently associated with this phenotype. In Brazil, few cohorts have been screened for MODY, all using a candidate gene approach, with a high prevalence of undiagnosed cases (MODY-X). METHODS We conducted a next-generation sequencing target panel (tNGS) study to investigate, for the first time, a Brazilian cohort of MODY patients with a negative prior genetic analysis. One hundred and two patients were selected, of which 26 had an initial clinical suspicion of MODY-GCK and 76 were non-GCK MODY. RESULTS After excluding all benign and likely benign variants and variants of uncertain significance, we were able to assign a genetic cause for 12.7% (13/102) of the probands. Three rare MODY subtypes were identified (PDX1/NEUROD1/ABCC8), and eight variants had not been previously described/mapped in genomic databases. Important clinical findings were evidenced in some cases after genetic diagnosis, such as MODY-PDX1/HNF1B. CONCLUSION A multiloci genetic approach allowed the identification of rare MODY subtypes, reducing the large percentage of MODY-X in Brazilian cases and contributing to a better clinical, therapeutic, and prognostic characterization of these rare phenotypes.
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Affiliation(s)
- Lucas S. de Santana
- Monogenic Diabetes GroupGenetic Endocrinology Unit and Laboratory of Molecular & Cellular Endocrinology/LIM25School of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
| | - Lilian A. Caetano
- Monogenic Diabetes GroupGenetic Endocrinology Unit and Laboratory of Molecular & Cellular Endocrinology/LIM25School of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
- Diabetes UnitClinics HospitalSchool of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
| | - Aline D. Costa‐Riquetto
- Monogenic Diabetes GroupGenetic Endocrinology Unit and Laboratory of Molecular & Cellular Endocrinology/LIM25School of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
- Diabetes UnitClinics HospitalSchool of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
| | - Pedro C. Franco
- Monogenic Diabetes GroupGenetic Endocrinology Unit and Laboratory of Molecular & Cellular Endocrinology/LIM25School of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
- Diabetes UnitClinics HospitalSchool of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
| | - Renata P. Dotto
- Departamento de MedicinaDisciplina de EndocrinologiaUniversidade Federal de São Paulo (UNIFESP)Sao PauloSPBrazil
| | - André F. Reis
- Departamento de MedicinaDisciplina de EndocrinologiaUniversidade Federal de São Paulo (UNIFESP)Sao PauloSPBrazil
| | | | | | - Marcio F. Vendramini
- Serviço de EndocrinologiaHospital do Servidor Público Estadual de São Paulo (HSPE‐SP)Sao PauloSPBrazil
| | - Flaviene A. do Prado
- Hospital Regional de Taguatinga da Secretaria de Saúde do Distrito FederalTaguatingaDFBrazil
| | | | | | | | | | - Augusto C. Santomauro Junior
- Serviço de Endocrinologia Prof. Dr. Fadlo Fraige FilhoHospital Beneficência Portuguesa de São Paulo (BP‐SP)Sao PauloSPBrazil
| | - Bruno Halpern
- Departamento de Endocrinologia e MetabologiaHospital das ClínicasFaculdade de MedicinaUniversidade de São Paulo (USP)Sao PauloSPBrazil
| | - Alexander A. L. Jorge
- Monogenic Diabetes GroupGenetic Endocrinology Unit and Laboratory of Molecular & Cellular Endocrinology/LIM25School of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
| | - Marcia Nery
- Diabetes UnitClinics HospitalSchool of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
| | - Milena G. Teles
- Monogenic Diabetes GroupGenetic Endocrinology Unit and Laboratory of Molecular & Cellular Endocrinology/LIM25School of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
- Diabetes UnitClinics HospitalSchool of MedicineUniversity of Sao Paulo (USP)Sao PauloSPBrazil
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4
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Lombardo D, Silvy F, Crenon I, Martinez E, Collignon A, Beraud E, Mas E. Pancreatic adenocarcinoma, chronic pancreatitis, and MODY-8 diabetes: is bile salt-dependent lipase (or carboxyl ester lipase) at the crossroads of pancreatic pathologies? Oncotarget 2018; 9:12513-12533. [PMID: 29552330 PMCID: PMC5844766 DOI: 10.18632/oncotarget.23619] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 11/06/2017] [Indexed: 12/22/2022] Open
Abstract
Pancreatic adenocarcinomas and diabetes mellitus are responsible for the deaths of around two million people each year worldwide. Patients with chronic pancreatitis do not die directly of this disease, except where the pathology is hereditary. Much current literature supports the involvement of bile salt-dependent lipase (BSDL), also known as carboxyl ester lipase (CEL), in the pathophysiology of these pancreatic diseases. The purpose of this review is to shed light on connections between chronic pancreatitis, diabetes, and pancreatic adenocarcinomas by gaining an insight into BSDL and its variants. This enzyme is normally secreted by the exocrine pancreas, and is diverted within the intestinal lumen to participate in the hydrolysis of dietary lipids. However, BSDL is also expressed by other cells and tissues, where it participates in lipid homeostasis. Variants of BSDL resulting from germline and/or somatic mutations (nucleotide insertion/deletion or nonallelic homologous recombination) are expressed in the pancreas of patients with pancreatic pathologies such as chronic pancreatitis, MODY-8, and pancreatic adenocarcinomas. We discuss the possible link between the expression of BSDL variants and these dramatic pancreatic pathologies, putting forward the suggestion that BSDL and its variants are implicated in the cell lipid metabolism/reprogramming that leads to the dyslipidemia observed in chronic pancreatitis, MODY-8, and pancreatic adenocarcinomas. We also propose potential strategies for translation to therapeutic applications.
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Affiliation(s)
- Dominique Lombardo
- Aix Marseille Univ, INSERM, CRO2, Centre de Recherche en Oncologie Biologique et Oncopharmacologie, Marseille, France
| | - Françoise Silvy
- Aix Marseille Univ, INSERM, CRO2, Centre de Recherche en Oncologie Biologique et Oncopharmacologie, Marseille, France
| | - Isabelle Crenon
- Aix Marseille Univ, INSERM, CRO2, Centre de Recherche en Oncologie Biologique et Oncopharmacologie, Marseille, France
| | - Emmanuelle Martinez
- Aix Marseille Univ, INSERM, CRO2, Centre de Recherche en Oncologie Biologique et Oncopharmacologie, Marseille, France
| | - Aurélie Collignon
- Aix Marseille Univ, INSERM, CRO2, Centre de Recherche en Oncologie Biologique et Oncopharmacologie, Marseille, France
| | - Evelyne Beraud
- Aix Marseille Univ, INSERM, CRO2, Centre de Recherche en Oncologie Biologique et Oncopharmacologie, Marseille, France
| | - Eric Mas
- Aix Marseille Univ, INSERM, CRO2, Centre de Recherche en Oncologie Biologique et Oncopharmacologie, Marseille, France
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5
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Johansson BB, Fjeld K, El Jellas K, Gravdal A, Dalva M, Tjora E, Ræder H, Kulkarni RN, Johansson S, Njølstad PR, Molven A. The role of the carboxyl ester lipase (CEL) gene in pancreatic disease. Pancreatology 2018; 18:12-19. [PMID: 29233499 DOI: 10.1016/j.pan.2017.12.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 11/28/2017] [Accepted: 12/01/2017] [Indexed: 12/11/2022]
Abstract
The enzyme carboxyl ester lipase (CEL), also known as bile salt-dependent or -stimulated lipase (BSDL, BSSL), hydrolyzes dietary fat, cholesteryl esters and fat-soluble vitamins in the duodenum. CEL is mainly expressed in pancreatic acinar cells and lactating mammary glands. The human CEL gene resides on chromosome 9q34.3 and contains a variable number of tandem repeats (VNTR) region that encodes a mucin-like protein tail. Although the number of normal repeats does not appear to significantly influence the risk for pancreatic disease, single-base pair deletions in the first VNTR repeat cause a syndrome of endocrine and exocrine dysfunction denoted MODY8. Hallmarks are low fecal elastase levels and pancreatic lipomatosis manifesting before the age of twenty, followed by development of diabetes and pancreatic cysts later in life. The mutant protein forms intracellular and extracellular aggregates, suggesting that MODY8 is a protein misfolding disease. Recently, a recombined allele between CEL and its pseudogene CELP was discovered. This allele (CEL-HYB) encodes a chimeric protein with impaired secretion increasing five-fold the risk for chronic pancreatitis. The CEL gene has proven to be exceptionally polymorphic due to copy number variants of the CEL-CELP locus and alterations involving the VNTR. Genome-wide association studies or deep sequencing cannot easily pick up this wealth of genetic variation. CEL is therefore an attractive candidate gene for further exploration of links to pancreatic disease.
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Affiliation(s)
- Bente B Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, Norway
| | - Karianne Fjeld
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Khadija El Jellas
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Anny Gravdal
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Monica Dalva
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Erling Tjora
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, Norway
| | - Helge Ræder
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, Norway
| | - Rohit N Kulkarni
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA, USA; Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Stefan Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Pål R Njølstad
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, Norway
| | - Anders Molven
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Pathology, Haukeland University Hospital, Bergen, Norway.
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6
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Dalva M, El Jellas K, Steine SJ, Johansson BB, Ringdal M, Torsvik J, Immervoll H, Hoem D, Laemmerhirt F, Simon P, Lerch MM, Johansson S, Njølstad PR, Weiss FU, Fjeld K, Molven A. Copy number variants and VNTR length polymorphisms of the carboxyl-ester lipase (CEL) gene as risk factors in pancreatic cancer. Pancreatology 2016; 17:83-88. [PMID: 27773618 DOI: 10.1016/j.pan.2016.10.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 10/05/2016] [Accepted: 10/09/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND/OBJECTIVES We have recently described copy number variants (CNVs) of the human carboxyl-ester lipase (CEL) gene, including a recombined deletion allele (CEL-HYB) that is a genetic risk factor for chronic pancreatitis. Associations with pancreatic disease have also been reported for the variable number of tandem repeat (VNTR) region located in CEL exon 11. Here, we examined if CEL CNVs and VNTR length polymorphisms affect the risk for developing pancreatic cancer. METHODS CEL CNVs and VNTR were genotyped in a German family with non-alcoholic chronic pancreatitis and pancreatic cancer, in 265 German and 197 Norwegian patients diagnosed with pancreatic adenocarcinoma, and in 882 controls. CNV screening was performed using PCR assays followed by agarose gel electrophoresis whereas VNTR lengths were determined by DNA fragment analysis. RESULTS The investigated family was CEL-HYB-positive. However, an association of CEL-HYB or a duplication CEL allele with pancreatic cancer was not seen in our two patient cohorts. The frequency of the 23-repeat VNTR allele was borderline significant in Norwegian cases compared to controls (1.2% vs. 0.3%; P = 0.05). For all other VNTR lengths, no statistically significant difference in frequency was observed. Moreover, no association with pancreatic cancer was detected when CEL VNTR lengths were pooled into groups of short, normal or long alleles. CONCLUSIONS We could not demonstrate an association between CEL CNVs and pancreatic cancer. An association is also unlikely for CEL VNTR lengths, although analyses in larger materials are necessary to completely exclude an effect of rare VNTR alleles.
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Affiliation(s)
- Monica Dalva
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Khadija El Jellas
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Solrun J Steine
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Bente B Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Monika Ringdal
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Janniche Torsvik
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Heike Immervoll
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Dag Hoem
- Department of Gastrointestinal Surgery, Haukeland University Hospital, Bergen, Norway
| | - Felix Laemmerhirt
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Peter Simon
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Markus M Lerch
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Stefan Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Pål R Njølstad
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Frank U Weiss
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Karianne Fjeld
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway.
| | - Anders Molven
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Pathology, Haukeland University Hospital, Bergen, Norway
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7
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Martinez E, Silvy F, Fina F, Bartoli M, Krahn M, Barlesi F, Figarella-Branger D, Iovanna J, Laugier R, Ouaissi M, Lombardo D, Mas E. Rs488087 single nucleotide polymorphism as predictive risk factor for pancreatic cancers. Oncotarget 2016; 6:39855-64. [PMID: 26498142 PMCID: PMC4741865 DOI: 10.18632/oncotarget.5627] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 10/05/2015] [Indexed: 12/20/2022] Open
Abstract
Pancreatic cancer (PC) is a devastating disease progressing asymptomatically until death within months after diagnosis. Defining at-risk populations should promote its earlier diagnosis and hence also avoid its development. Considering the known involvement in pancreatic disease of exon 11 of the bile salt-dependent lipase (BSDL) gene that encodes variable number of tandem repeat (VNTR) sequences, we hypothesized upon the existence of a genetic link between predisposition to PC and mutations in VNTR loci. To test this, BSDL VNTR were amplified by touchdown-PCR performed on genomic DNA extracted from cancer tissue or blood samples from a French patient cohort and amplicons were Sanger sequenced. A robust method using probes for droplet digital (dd)-PCR was designed to discriminate the C/C major from C/T or T/T minor genotypes. We report that the c.1719C > T transition (SNP rs488087) present in BSDL VNTR may be a useful marker for defining a population at risk of developing PC (occurrence: 63.90% in the PC versus 27.30% in the control group). The odds ratio of 4.7 for the T allele was larger than those already determined for other SNPs suspected to be predictive of PC. Further studies on tumor pancreatic tissue suggested that a germline T allele may favor Kras G12R/G12D somatic mutations which represent negative prognostic factors associated with reduced survival. We propose that the detection of the T allele in rs488087 SNP should lead to an in-depth follow-up of patients in whom an association with other potential risk factors of pancreatic cancer may be present.
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Affiliation(s)
- Emmanuelle Martinez
- Aix-Marseille Université, CRO2, Centre de Recherche en Oncologie biologique et Oncopharmacologie, F-13005, Marseille, France.,INSERM, UMR_S 911, F-13005, Marseille, France
| | - Françoise Silvy
- Aix-Marseille Université, CRO2, Centre de Recherche en Oncologie biologique et Oncopharmacologie, F-13005, Marseille, France.,INSERM, UMR_S 911, F-13005, Marseille, France
| | - Fréderic Fina
- Aix-Marseille Université, CRO2, Centre de Recherche en Oncologie biologique et Oncopharmacologie, F-13005, Marseille, France.,INSERM, UMR_S 911, F-13005, Marseille, France.,LBM- Assistance Publique Hôpitaux de Marseille, Hôpital Nord, Service de Transfert d'Oncologie Biologique, F-13015, Marseille, France
| | - Marc Bartoli
- Aix-Marseille Université, INSERM, UMR 910, F-13005, Marseille, France
| | - Martin Krahn
- Aix-Marseille Université, INSERM, UMR 910, F-13005, Marseille, France.,Assistance Publique Hôpitaux de Marseille, Hôpital de la Timone-Enfants, Département de Génétique Médicale, F-13005, Marseille, France
| | - Fabrice Barlesi
- Aix-Marseille Université, CRO2, Centre de Recherche en Oncologie biologique et Oncopharmacologie, F-13005, Marseille, France.,INSERM, UMR_S 911, F-13005, Marseille, France.,Assistance Publique Hôpitaux de Marseille, Hôpital Nord, Service d'Oncologie Multidisciplinaire & Innovation Thérapeutique, F-13915, Marseille, France
| | - Dominique Figarella-Branger
- Aix-Marseille Université, CRO2, Centre de Recherche en Oncologie biologique et Oncopharmacologie, F-13005, Marseille, France.,INSERM, UMR_S 911, F-13005, Marseille, France.,Assistance Publique Hôpitaux de Marseille, Hôpital de la Timone, Service d'Anatomopathologie, F-13005, Marseille, France
| | - Juan Iovanna
- Aix-Marseille Université, CRCM, Centre de Recherche en Cancérologie de Marseille, F-13009, Marseille, France.,INSERM, UMR_S 1068, F-13009, Marseille, France.,CNRS, UMR 7258, F-13009, Marseille, France
| | - René Laugier
- Assistance Publique Hôpitaux de Marseille, Hôpital de la Timone, Service de Gastroentérologie, F-13005, Marseille, France
| | - Mehdi Ouaissi
- Aix-Marseille Université, CRO2, Centre de Recherche en Oncologie biologique et Oncopharmacologie, F-13005, Marseille, France.,INSERM, UMR_S 911, F-13005, Marseille, France.,Assistance Publique Hôpitaux de Marseille, Hôpital de la Timone, Service de Chirurgie Digestive et Viscérale, F-13005, Marseille, France
| | - Dominique Lombardo
- Aix-Marseille Université, CRO2, Centre de Recherche en Oncologie biologique et Oncopharmacologie, F-13005, Marseille, France.,INSERM, UMR_S 911, F-13005, Marseille, France
| | - Eric Mas
- Aix-Marseille Université, CRO2, Centre de Recherche en Oncologie biologique et Oncopharmacologie, F-13005, Marseille, France.,INSERM, UMR_S 911, F-13005, Marseille, France
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8
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Fjeld K, Weiss FU, Lasher D, Rosendahl J, Chen JM, Johansson BB, Kirsten H, Ruffert C, Masson E, Steine SJ, Bugert P, Cnop M, Grützmann R, Mayerle J, Mössner J, Ringdal M, Schulz HU, Sendler M, Simon P, Sztromwasser P, Torsvik J, Scholz M, Tjora E, Férec C, Witt H, Lerch MM, Njølstad PR, Johansson S, Molven A. A recombined allele of the lipase gene CEL and its pseudogene CELP confers susceptibility to chronic pancreatitis. Nat Genet 2015; 47:518-522. [PMID: 25774637 PMCID: PMC5321495 DOI: 10.1038/ng.3249] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 02/19/2015] [Indexed: 12/13/2022]
Abstract
Carboxyl-ester lipase is a digestive pancreatic enzyme encoded by the highly polymorphic CEL gene1. Mutations in CEL cause maturity-onset diabetes of the young (MODY) with pancreatic exocrine dysfunction2. Here we identified a hybrid allele (CEL-HYB), originating from a crossover between CEL and its neighboring pseudogene CELP. In a discovery cohort of familial chronic pancreatitis cases, the carrier frequency of CEL-HYB was 14.1% (10/71) compared with 1.0% (5/478) in controls (odds ratio [OR] = 15.5, 95% confidence interval [CI] = 5.1-46.9, P = 1.3 × 10−6). Three replication studies in non-alcoholic chronic pancreatitis cohorts identified CEL-HYB in a total of 3.7% (42/1,122) cases and 0.7% (30/4,152) controls (OR = 5.2, 95% CI = 3.2-8.5, P = 1.2 × 10−11; formal meta-analysis). The allele was also enriched in alcoholic chronic pancreatitis. Expression of CEL-HYB in cellular models revealed reduced lipolytic activity, impaired secretion, prominent intracellular accumulation and induced autophagy. The hybrid variant of CEL is the first chronic pancreatitis gene identified outside the protease/antiprotease system of pancreatic acinar cells.
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Affiliation(s)
- Karianne Fjeld
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Frank Ulrich Weiss
- Department of Internal Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany
| | - Denise Lasher
- Pediatric Nutritional Medicine, Technische Universität München (TUM), Freising, Germany.,Else Kröner-Fresenius-Zentrum für Ernährungsmedizin (EKFZ), Technische Universität München (TUM), Freising, Germany
| | - Jonas Rosendahl
- Department for Internal Medicine, Neurology and Dermatology, Division of Gastroenterology, University of Leipzig, Leipzig, Germany
| | - Jian-Min Chen
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1078, Brest, France.,Etablissement Français du Sang (EFS)-Bretagne, Brest, France.,Faculté de Médecine et des Sciences de la Santé, Université de Bretagne Occidentale, Brest, France
| | - Bente B Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Holger Kirsten
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Leipzig, Germany.,LIFE-Leipzig Research Center for Civilization Diseases, Universität Leipzig, Leipzig, Germany.,Institute for Medical Informatics, Statistics and Epidemiology (IMISE), Universität Leipzig, Leipzig, Germany
| | - Claudia Ruffert
- Department for Internal Medicine, Neurology and Dermatology, Division of Gastroenterology, University of Leipzig, Leipzig, Germany.,Department of Internal Medicine, Neurology and Dermatology, Division of Endocrinology, University of Leipzig, Leipzig, Germany.,Integrated Research and Treatment Centre (IFB) Adiposity Diseases, University of Leipzig, Leipzig, Germany
| | - Emmanuelle Masson
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1078, Brest, France.,Laboratoire de Génétique Moléculaire et d'Histocompatibilité, Centre Hospitalier Universitaire (CHU) Brest, Hôpital Morvan, Brest, France
| | - Solrun J Steine
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Peter Bugert
- Institute of Transfusion Medicine and Immunology, Medical Faculty Mannheim, Heidelberg University, German Red Cross Blood Service of Baden-Württemberg-Hessen, Mannheim, Germany
| | - Miriam Cnop
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium.,Division of Endocrinology, Erasmus Hospital, Brussels, Belgium
| | - Robert Grützmann
- Department of Surgery, Universitätsklinikum Dresden, Dresden, Germany
| | - Julia Mayerle
- Department of Internal Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany
| | - Joachim Mössner
- Department for Internal Medicine, Neurology and Dermatology, Division of Gastroenterology, University of Leipzig, Leipzig, Germany
| | - Monika Ringdal
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Hans-Ulrich Schulz
- Department of Surgery, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Matthias Sendler
- Department of Internal Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany
| | - Peter Simon
- Department of Internal Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany
| | - Paweł Sztromwasser
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway.,Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Janniche Torsvik
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Markus Scholz
- LIFE-Leipzig Research Center for Civilization Diseases, Universität Leipzig, Leipzig, Germany.,Institute for Medical Informatics, Statistics and Epidemiology (IMISE), Universität Leipzig, Leipzig, Germany
| | - Erling Tjora
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Claude Férec
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1078, Brest, France.,Etablissement Français du Sang (EFS)-Bretagne, Brest, France.,Faculté de Médecine et des Sciences de la Santé, Université de Bretagne Occidentale, Brest, France.,Laboratoire de Génétique Moléculaire et d'Histocompatibilité, Centre Hospitalier Universitaire (CHU) Brest, Hôpital Morvan, Brest, France
| | - Heiko Witt
- Pediatric Nutritional Medicine, Technische Universität München (TUM), Freising, Germany.,Else Kröner-Fresenius-Zentrum für Ernährungsmedizin (EKFZ), Technische Universität München (TUM), Freising, Germany
| | - Markus M Lerch
- Department of Internal Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany
| | - Pål R Njølstad
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Stefan Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Anders Molven
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway.,Department of Pathology, Haukeland University Hospital, Bergen, Norway
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9
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Comparative Structures and Evolution of Vertebrate Carboxyl Ester Lipase (CEL) Genes and Proteins with a Major Role in Reverse Cholesterol Transport. CHOLESTEROL 2011; 2011:781643. [PMID: 22162806 PMCID: PMC3227413 DOI: 10.1155/2011/781643] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Accepted: 08/30/2011] [Indexed: 12/20/2022]
Abstract
Bile-salt activated carboxylic ester lipase (CEL) is a major triglyceride, cholesterol ester and vitamin ester hydrolytic enzyme contained within pancreatic and lactating mammary gland secretions. Bioinformatic methods were used to predict the amino acid sequences, secondary and tertiary structures and gene locations for CEL genes, and encoded proteins using data from several vertebrate genome projects. A proline-rich and O-glycosylated 11-amino acid C-terminal repeat sequence (VNTR) previously reported for human and other higher primate CEL proteins was also observed for other eutherian mammalian CEL sequences examined. In contrast, opossum CEL contained a single C-terminal copy of this sequence whereas CEL proteins from platypus, chicken, lizard, frog and several fish species lacked the VNTR sequence. Vertebrate CEL genes contained 11 coding exons. Evidence is presented for tandem duplicated CEL genes for the zebrafish genome. Vertebrate CEL protein subunits shared 53-97% sequence identities; demonstrated sequence alignments and identities for key CEL amino acid residues; and conservation of predicted secondary and tertiary structures with those previously reported for human CEL. Phylogenetic analyses demonstrated the relationships and potential evolutionary origins of the vertebrate CEL family of genes which were related to a nematode carboxylesterase (CES) gene and five mammalian CES gene families.
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10
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Mutations in the VNTR of the carboxyl-ester lipase gene (CEL) are a rare cause of monogenic diabetes. Hum Genet 2009; 127:55-64. [DOI: 10.1007/s00439-009-0740-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 08/30/2009] [Indexed: 10/20/2022]
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11
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Lombardo D. Bile salt-dependent lipase: its pathophysiological implications. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1533:1-28. [PMID: 11514232 DOI: 10.1016/s1388-1981(01)00130-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- D Lombardo
- INSERM Unité 559, Faculté de Médecine-Timone, 27 Blv Jean Moulin, 13385 Cedex 05, Marseille, France.
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12
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Madeyski K, Lidberg U, Bjursell G, Nilsson J. Characterization of the gorilla carboxyl ester lipase locus, and the appearance of the carboxyl ester lipase pseudogene during primate evolution. Gene 1999; 239:273-82. [PMID: 10548728 DOI: 10.1016/s0378-1119(99)00410-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this study we report on the isolation and characterization of the gorilla carboxyl ester lipase gene, CEL, and the corresponding CEL pseudogene. We also report on the age of the CEL pseudogene. The gorilla CEL gene is 10.5kb long and comprises 11exons intervened by introns similar to the situation in man, mouse and rat. The encoded protein is 998amino acids long and includes a 23amino acid-long leader peptide. Comparison of the coding sequence, excluding exon 11, of CEL from gorilla and man reveals a 97% similarity. Exon 11, which encodes the characteristic proline rich repeats, contains 39 repeated units in gorilla compared to 16 in man. A truncated CEL pseudogene, with the same organization as that found in man, is also shown to be present in the gorilla genome. The gorilla CEL pseudogene is 4.9kb in length and consists of 5exons interrupted by introns. Southern analysis of the gorilla CEL locus shows that the locus is arranged in a similar way as in man with the functional CEL gene being the most 5' one. To bring further insight to the events involved in the rearrangement of the CEL locus, genomic Southern analyses were performed across several primates; Homo sapiens, Pan troglodytes, Gorilla gorilla, Pongo pygmaeus and Macaca arctoides. Results presented show that the CEL gene duplication occurred prior to the separation of Hominidae (man, chimpanzee, gorilla and orangutan) from Old World monkeys (macaque). The deletion of the original CEL gene giving rise to the truncated version of the CEL gene seems, however, to be restricted to man and the great apes only.
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Affiliation(s)
- K Madeyski
- Department of Cell and Molecular Biology, Göteborg Universitet, Box 462, S-413 30, Göteborg, Sweden
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13
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Lidberg U, Kannius-Janson M, Nilsson J, Bjursell G. Transcriptional regulation of the human carboxyl ester lipase gene in exocrine pancreas. Evidence for a unique tissue-specific enhancer. J Biol Chem 1998; 273:31417-26. [PMID: 9813053 DOI: 10.1074/jbc.273.47.31417] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human carboxyl ester lipase (CEL) is an important enzyme for the intestinal absorption of dietary lipids. The gene is highly expressed in exocrine pancreas and in the mammary gland during pregnancy and lactation. In this paper, we have focused on its transcriptional regulation in exocrine pancreas. Reporter gene analysis in cell cultures reveals that a high level of tissue-specific expression is established by the proximal 839 base pairs of the 5'-flanking region. This is due to a strong enhancer, located at -672 to -637. Transfections in mammary gland-derived cells reveal that the enhancer is pancreas-specific and does not contribute to the mammary gland expression. This indicates that the expression of the CEL gene in the mammary gland and pancreas, respectively, is due to two different regulatory systems. Further characterizations of the enhancer reveal that it is composed of two closely located cis-elements. The proximal element mediates a positive effect, whereas the distal element exerts a silencing effect on the positive proximal element. The functional enhancer complex is composed of ubiquitously expressed factors, since similar interactions are achieved with nuclear extracts from cells derived from other tissues. However, no enhancer activity is achieved in such cells. Hence, the net enhancer activity is the result of a tissue-specific balance between factors interacting with the two elements. Since none of the described cis-elements show any clear homology to known cis-elements, we propose that the interacting complex is composed of yet unidentified transcription factors.
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Affiliation(s)
- U Lidberg
- Department of Molecular Biology, Göteborg 40 530, Sweden.
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