1
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Gravdal A, Xiao X, Cnop M, El Jellas K, Johansson S, Njølstad PR, Lowe ME, Johansson BB, Molven A, Fjeld K. The position of single-base deletions in the VNTR sequence of the carboxyl ester lipase (CEL) gene determines proteotoxicity. J Biol Chem 2021; 296:100661. [PMID: 33862081 PMCID: PMC8692231 DOI: 10.1016/j.jbc.2021.100661] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 04/05/2021] [Accepted: 04/12/2021] [Indexed: 02/06/2023] Open
Abstract
Variable number of tandem repeat (VNTR) sequences in the genome can have functional consequences that contribute to human disease. This is the case for the CEL gene, which is specifically expressed in pancreatic acinar cells and encodes the digestive enzyme carboxyl ester lipase. Rare single-base deletions (DELs) within the first (DEL1) or fourth (DEL4) VNTR segment of CEL cause maturity-onset diabetes of the young, type 8 (MODY8), an inherited disorder characterized by exocrine pancreatic dysfunction and diabetes. Studies on the DEL1 variant have suggested that MODY8 is initiated by CEL protein misfolding and aggregation. However, it is unclear how the position of single-base deletions within the CEL VNTR affects pathogenic properties of the protein. Here, we investigated four naturally occurring CEL variants, arising from single-base deletions in different VNTR segments (DEL1, DEL4, DEL9, and DEL13). When the four variants were expressed in human embryonic kidney 293 cells, only DEL1 and DEL4 led to significantly reduced secretion, increased intracellular aggregation, and increased endoplasmic reticulum stress compared with normal CEL protein. The level of O-glycosylation was affected in all DEL variants. Moreover, all variants had enzymatic activity comparable with that of normal CEL. We conclude that the longest aberrant protein tails, resulting from single-base deletions in the proximal VNTR segments, have highest pathogenic potential, explaining why DEL1 and DEL4 but not DEL9 and DEL13 have been observed in patients with MODY8. These findings further support the view that CEL mutations cause pancreatic disease through protein misfolding and proteotoxicity, leading to endoplasmic reticulum stress and activation of the unfolded protein response.
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Affiliation(s)
- Anny Gravdal
- 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 Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - Xunjun Xiao
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Washington University School of Medicine, St Louis, Missouri, USA
| | - Miriam Cnop
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium; Division of Endocrinology, ULB Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - 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
| | - Stefan Johansson
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - 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
| | - Mark E Lowe
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Washington University School of Medicine, St Louis, Missouri, USA
| | - Bente B Johansson
- 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
- 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.
| | - Karianne Fjeld
- 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 Medical Genetics, Haukeland University Hospital, Bergen, Norway
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2
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Deglaire A, Oliveira SD, Jardin J, Briard-Bion V, Kroell F, Emily M, Ménard O, Bourlieu C, Dupont D. Impact of human milk pasteurization on the kinetics of peptide release during in vitro dynamic digestion at the preterm newborn stage. Food Chem 2018; 281:294-303. [PMID: 30658760 DOI: 10.1016/j.foodchem.2018.12.086] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 01/25/2023]
Abstract
Holder pasteurization (62.5 °C, 30 min) of human milk denatures beneficial proteins. The present paper aimed to assess whether this can affect the kinetics of peptide release during digestion at the preterm stage. Raw (RHM) or pasteurized (PHM) human milk were digested in triplicates using an in vitro dynamic system. Mass spectrometry and multivariate statistics were conducted. Pre-proteolysis occurred mostly on β-casein, for which cumulative peptide abundance was significantly greater in PHM over 28% of the hydrolysed sequence. Eight clusters resumed the kinetics of peptide release during digestion, which differed on seven clusters (69% of the 1134 peptides). Clusters associated to the heat-denaturated proteins, lactoferrin and bile salt-stimulated lipase, presented different kinetics of release during digestion, unlike that for β-casein. Some bioactive peptides from β-casein presented significant different abundances between PHM and RHM before digestion (1-18, 185-211) or in during intestinal digestion (154-160, 161-166). Further physiological consequences should be investigated.
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Affiliation(s)
| | | | | | | | - Florian Kroell
- STLO, Agrocampus Ouest, INRA, 35042 Rennes, France; IRMAR, Agrocampus Ouest, CNRS, 35042 Rennes, France
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3
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El Jellas K, Johansson BB, Fjeld K, Antonopoulos A, Immervoll H, Choi MH, Hoem D, Lowe ME, Lombardo D, Njølstad PR, Dell A, Mas E, Haslam SM, Molven A. The mucinous domain of pancreatic carboxyl-ester lipase (CEL) contains core 1/core 2 O-glycans that can be modified by ABO blood group determinants. J Biol Chem 2018; 293:19476-19491. [PMID: 30315106 DOI: 10.1074/jbc.ra118.001934] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 09/11/2018] [Indexed: 12/20/2022] Open
Abstract
Carboxyl-ester lipase (CEL) is a pancreatic fat-digesting enzyme associated with human disease. Rare mutations in the CEL gene cause a syndrome of pancreatic exocrine and endocrine dysfunction denoted MODY8, whereas a recombined CEL allele increases the risk for chronic pancreatitis. Moreover, CEL has been linked to pancreatic ductal adenocarcinoma (PDAC) through a postulated oncofetal CEL variant termed feto-acinar pancreatic protein (FAPP). The monoclonal antibody mAb16D10 was previously reported to detect a glycotope in the highly O-glycosylated, mucin-like C terminus of CEL/FAPP. We here assessed the expression of human CEL in malignant pancreatic lesions and cell lines. CEL was not detectably expressed in neoplastic cells, implying that FAPP is unlikely to be a glycoisoform of CEL in pancreatic cancer. Testing of the mAb16D10 antibody in glycan microarrays then demonstrated that it recognized structures containing terminal GalNAc-α1,3(Fuc-α1,2)Gal (blood group A antigen) and also repeated protein sequences containing GalNAc residues linked to Ser/Thr (Tn antigen), findings that were supported by immunostainings of human pancreatic tissue. To examine whether the CEL glycoprotein might be modified by blood group antigens, we used high-sensitivity MALDI-TOF MS to characterize the released O-glycan pool of CEL immunoprecipitated from human pancreatic juice. We found that the O-glycome of CEL consisted mainly of core 1/core 2 structures with a composition depending on the subject's FUT2 and ABO gene polymorphisms. Thus, among digestive enzymes secreted by the pancreas, CEL is a glycoprotein with some unique characteristics, supporting the view that it could serve additional biological functions to its cholesteryl esterase activity in the duodenum.
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Affiliation(s)
- Khadija El Jellas
- From the Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, N-5020 Bergen, Norway.,Department of Pathology, Haukeland University Hospital, N-5021 Bergen, Norway.,KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020 Bergen, Norway
| | - Bente B Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020 Bergen, Norway.,Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Karianne Fjeld
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020 Bergen, Norway.,Center for Medical Genetics, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Aristotelis Antonopoulos
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Heike Immervoll
- From the Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, N-5020 Bergen, Norway.,Department of Pathology, Ålesund Hospital, N-6017 Ålesund, Norway
| | - Man H Choi
- From the Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, N-5020 Bergen, Norway.,Department of Pathology, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Dag Hoem
- Department of Gastrointestinal Surgery, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Mark E Lowe
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, and
| | - Dominique Lombardo
- INSERM, CRO2, Center for Research in Biological Oncology and Oncopharmacology, Aix-Marseille University, 13284 Marseille Cedex 07, France
| | - Pål R Njølstad
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020 Bergen, Norway.,Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Anne Dell
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Eric Mas
- INSERM, CRO2, Center for Research in Biological Oncology and Oncopharmacology, Aix-Marseille University, 13284 Marseille Cedex 07, France
| | - Stuart M Haslam
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Anders Molven
- From the Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, N-5020 Bergen, Norway, .,Department of Pathology, Haukeland University Hospital, N-5021 Bergen, Norway.,KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020 Bergen, Norway
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4
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Wolters-Eisfeld G, Mercanoglu B, Hofmann BT, Wolpers T, Schnabel C, Harder S, Steffen P, Bachmann K, Steglich B, Schrader J, Gagliani N, Schlüter H, Güngör C, Izbicki JR, Wagener C, Bockhorn M. Loss of complex O-glycosylation impairs exocrine pancreatic function and induces MODY8-like diabetes in mice. Exp Mol Med 2018; 50:1-13. [PMID: 30305605 PMCID: PMC6180059 DOI: 10.1038/s12276-018-0157-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 06/18/2018] [Accepted: 06/22/2018] [Indexed: 02/06/2023] Open
Abstract
Cosmc is ubiquitously expressed and acts as a specific molecular chaperone assisting the folding and stability of core 1 synthase. Thus, it plays a crucial role in the biosynthesis of O-linked glycosylation of proteins. Here, we show that ablation of Cosmc in the exocrine pancreas of mice causes expression of truncated O-glycans (Tn antigen), resulting in exocrine pancreatic insufficiency with decreased activities of digestive enzymes and diabetes. To understand the molecular causes of the pleiotropic phenotype, we used Vicia villosa agglutinin to enrich Tn antigen-modified proteins from Cosmc-KO pancreatic lysates and performed a proteomic analysis. Interestingly, a variety of proteins were identified, of which bile salt-activated lipase (also denoted carboxyl-ester lipase, Cel) was the most abundant. In humans, frameshift mutations in CEL cause maturity-onset diabetes of the young type 8 (MODY8), a monogenic syndrome of diabetes and pancreatic exocrine dysfunction. Here, we provide data suggesting that differentially O-glycosylated Cel could negatively affect beta cell function. Taken together, our findings demonstrate the importance of correct O-glycan formation for normal exocrine and endocrine pancreatic function, implying that aberrant O-glycans might be relevant for pathogenic mechanisms of the pancreas.
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Affiliation(s)
- Gerrit Wolters-Eisfeld
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany.
| | - Baris Mercanoglu
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Bianca T Hofmann
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Thomas Wolpers
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Claudia Schnabel
- Metabolic Laboratory and Newborn Screening, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Sönke Harder
- Mass Spectrometric Proteomics-Institute for Clinical Chemistry & Laboratory Medicine, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Pascal Steffen
- Mass Spectrometric Proteomics-Institute for Clinical Chemistry & Laboratory Medicine, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Kai Bachmann
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Babett Steglich
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Jörg Schrader
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Nicola Gagliani
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Hartmut Schlüter
- Mass Spectrometric Proteomics-Institute for Clinical Chemistry & Laboratory Medicine, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Cenap Güngör
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Jakob R Izbicki
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
| | - Christoph Wagener
- Center for Diagnostics, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Maximilian Bockhorn
- Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg- Eppendorf (UKE), Hamburg, Germany
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5
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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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6
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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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7
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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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8
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Torsvik J, Johansson BB, Dalva M, Marie M, Fjeld K, Johansson S, Bjørkøy G, Saraste J, Njølstad PR, Molven A. Endocytosis of secreted carboxyl ester lipase in a syndrome of diabetes and pancreatic exocrine dysfunction. J Biol Chem 2014; 289:29097-111. [PMID: 25160620 PMCID: PMC4200264 DOI: 10.1074/jbc.m114.574244] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 08/21/2014] [Indexed: 12/17/2022] Open
Abstract
Maturity-onset diabetes of the young, type 8 (MODY8) is characterized by a syndrome of autosomal dominantly inherited diabetes and exocrine pancreatic dysfunction. It is caused by deletion mutations in the last exon of the carboxyl ester lipase (CEL) gene, resulting in a CEL protein with increased tendency to aggregate. In this study we investigated the intracellular distribution of the wild type (WT) and mutant (MUT) CEL proteins in cellular models. We found that both CEL-WT and CEL-MUT were secreted via the endoplasmic reticulum and Golgi compartments. However, their subcellular distributions differed, as only CEL-MUT was observed as an aggregate at the cell surface and inside large cytoplasmic vacuoles. Many of the vacuoles were identified as components of the endosomal system, and after its secretion, the mutant CEL protein was re-internalized, transported to the lysosomes, and degraded. Internalization of CEL-MUT also led to reduced viability of pancreatic acinar and beta cells. These findings may have implications for the understanding of how the acinar-specific CEL-MUT protein causes both exocrine and endocrine pancreatic disease.
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Affiliation(s)
- Janniche Torsvik
- From the 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
| | - Bente B Johansson
- From the 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
| | - Monica Dalva
- From the 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, N-5021 Bergen, Norway
| | - Michaël Marie
- Department of Biomedicine and Molecular Imaging Center, University of Bergen, Bergen, Norway
| | - Karianne Fjeld
- From the 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
| | - Stefan Johansson
- From the 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
| | - Geir Bjørkøy
- Centre of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway, Department of Technology, University College of Sør-Trøndelag, Trondheim, Norway
| | - Jaakko Saraste
- Department of Biomedicine and Molecular Imaging Center, University of Bergen, Bergen, Norway
| | - Pål R Njølstad
- From the KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway, Department of Pediatrics, Haukeland University Hospital, Bergen, Norway, and
| | - Anders Molven
- From the 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, N-5021 Bergen, Norway, Department of Pathology, Haukeland University Hospital, Bergen, Norway
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9
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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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10
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Raeder H, Johansson S, Holm PI, Haldorsen IS, Mas E, Sbarra V, Nermoen I, Eide SA, Grevle L, Bjørkhaug L, Sagen JV, Aksnes L, Søvik O, Lombardo D, Molven A, Njølstad PR. Mutations in the CEL VNTR cause a syndrome of diabetes and pancreatic exocrine dysfunction. Nat Genet 2005; 38:54-62. [PMID: 16369531 DOI: 10.1038/ng1708] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Accepted: 10/27/2005] [Indexed: 01/19/2023]
Abstract
Dysfunction of the exocrine pancreas is observed in diabetes, but links between concurrent exocrine and endocrine pancreatic disease and contributing genetic factors are poorly characterized. We studied two families with diabetes and exocrine pancreatic dysfunction by genetic, physiological and in vitro functional studies. A genome-wide screen in Family 1 linked diabetes to chromosome 9q34 (maximal lod score 5.07). Using fecal elastase deficiency as a marker of exocrine pancreatic dysfunction refined the critical chromosomal region to 1.16 Mb (maximal lod score 11.6). Here, we identified a single-base deletion in the variable number of tandem repeats (VNTR)-containing exon 11 of the carboxyl ester lipase (CEL) gene, a major component of pancreatic juice and responsible for the duodenal hydrolysis of cholesterol esters. Screening subjects with maturity-onset diabetes of the young identified Family 2, with another single-base deletion in CEL and a similar phenotype with beta-cell failure and pancreatic exocrine disease. The in vitro catalytic activities of wild-type and mutant CEL protein were comparable. The mutant enzyme was, however, less stable and secreted at a lower rate. Furthermore, we found some evidence for an association between common insertions in the CEL VNTR and exocrine dysfunction in a group of 182 unrelated subjects with diabetes (odds ratio 4.2 (1.6, 11.5)). Our findings link diabetes to the disrupted function of a lipase in the pancreatic acinar cells.
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Affiliation(s)
- Helge Raeder
- Section for Pediatrics, Department of Clinical Medicine, University of Bergen, Bergen, Norway
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11
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Lindquist S, Bläckberg L, Hernell O. Human bile salt-stimulated lipase has a high frequency of size variation due to a hypervariable region in exon 11. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:759-67. [PMID: 11846777 DOI: 10.1046/j.0014-2956.2001.02666.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The apparent molecular mass of human milk bile salt-stimulated lipase (BSSL) varies between mothers. The molecular basis for this is unknown, but indirect evidence has suggested the differences to reside in a region of repeats located in the C-terminal part of the protein. We here report that a polymorphism within exon 11 of the BSSL gene is the explanation for the molecular variants of BSSL found in milk. By Southern blot hybridization we analyzed the BSSL gene from mothers known to have BSSL of different molecular masses in their milk. A polymorphism was found within exon 11, previously shown to consist of 16 near identical repeats of 33 bp each. We detected deletions or, in one case, an insertion corresponding to the variation in molecular mass of the BSSL protein found in milk from the respective woman. Furthermore, we found that 56%, out of 295 individuals studied, carry deletions or insertions within exon 11 in one or both alleles of the BSSL gene. Hence, this is a hypervariable region and the current understanding that exon 11 in the human BSSL gene encodes 16 repeats is an oversimplification and needs to be revisited. Natural variation in the molecular mass of BSSL may have clinical implications.
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Affiliation(s)
- Susanne Lindquist
- Department of Clinical Sciences, Pediatrics, Umeå University, Sweden.
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12
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Moore SA, Kingston RL, Loomes KM, Hernell O, Bläckberg L, Baker HM, Baker EN. The structure of truncated recombinant human bile salt-stimulated lipase reveals bile salt-independent conformational flexibility at the active-site loop and provides insights into heparin binding. J Mol Biol 2001; 312:511-23. [PMID: 11563913 DOI: 10.1006/jmbi.2001.4979] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human bile salt-stimulated lipase (BSSL), which is secreted from the pancreas into the digestive tract and from the lactating mammary gland into human milk, is important for the effective absorption of dietary lipids. The dependence of BSSL on bile acids for activity with water-insoluble substrates differentiates it from other lipases. We have determined the crystal structure of a truncated variant of human BSSL (residues 1-5.8) and refined it at 2.60 A resolution, to an R-factor of 0.238 and R(free) of 0.275. This variant lacks the C-terminal alpha-helix and tandem C-terminal repeat region of native BSSL, but retains full catalytic activity. A short loop (residues 115-126) capable of occluding the active-site (the active site loop) is highly mobile and exists in two conformations, the most predominant of which leaves the active-site open for interactions with substrate. The bile salt analogue 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonic acid (CHAPS) was present in the crystallisation medium, but was not observed bound to the enzyme. However, the structure reveals a sulfonate group from the buffer piperizine ethane sulfonic acid (PIPES), making interactions with Arg63 and His115. His115 is part of the active-site loop, indicating that the loop could participate in the binding of a sulphate group from either the glycosaminoglycan heparin (known to bind BSSL) or a bile acid such as deoxycholate. Opening of the 115-126 active-site loop may be cooperatively linked to a sulphate anion binding at this site. The helix bundle domain of BSSL (residues 319-398) exhibits weak electron density and high temperature factors, indicating considerable structural mobility. This domain contains an unusual Asp:Glu pair buried in a hydrophobic pocket between helices alpha(H) and alpha(K) that may be functionally important. We have also solved the structure of full-length glycosylated human BSSL at 4.1 A resolution, using the refined coordinates of the truncated molecule as a search model. This structure reveals the position of the C-terminal helix, missing in the truncated variant, and also shows the active-site loop to be in a closed conformation.
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Affiliation(s)
- S A Moore
- Institute of Molecular Biosciences, Massey University, Palmerston North, New Zealand
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13
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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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14
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Terzyan S, Wang CS, Downs D, Hunter B, Zhang XC. Crystal structure of the catalytic domain of human bile salt activated lipase. Protein Sci 2000; 9:1783-90. [PMID: 11045623 PMCID: PMC2144702 DOI: 10.1110/ps.9.9.1783] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Bile-salt activated lipase (BAL) is a pancreatic enzyme that digests a variety of lipids in the small intestine. A distinct property of BAL is its dependency on bile salts in hydrolyzing substrates of long acyl chains or bulky alcoholic motifs. A crystal structure of the catalytic domain of human BAL (residues 1-538) with two surface mutations (N186D and A298D), which were introduced in attempting to facilitate crystallization, has been determined at 2.3 A resolution. The crystal form belongs to space group P2(1)2(1)2(1) with one monomer per asymmetric unit, and the protein shows an alpha/beta hydrolase fold. In the absence of bound bile salt molecules, the protein possesses a preformed catalytic triad and a functional oxyanion hole. Several surface loops around the active site are mobile, including two loops potentially involved in substrate binding (residues 115-125 and 270-285).
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Affiliation(s)
- S Terzyan
- Crystallography Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA
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15
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Loomes KM, Senior HE, West PM, Roberton AM. Functional protective role for mucin glycosylated repetitive domains. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 266:105-11. [PMID: 10542055 DOI: 10.1046/j.1432-1327.1999.00824.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mucins carry out a number of protective roles, some of which are more easily studied than others. One mucin function is believed to be the protection of the mucosal epithelium against acidic and proteolytic damage in the stomach and intestines. In the present work, a portion of stomach mucin tandem repeat sequence (Muc6) was joined to the catalytic domain of a reporter enzyme [human milk cholesterol esterase (CE)] to determine whether the former can protect the latter protein from damage. This Muc6 domain replaced a unique series of glycosylated C-terminal repeats normally present in CE. The chimeric protein (CE/Muc6) was expressed in two different cell lines and its properties compared to recombinant full-length CE and a truncated version of CE which contained only the catalytic domain (CE/trunc). Results showed that both CE and CE/Muc6 were resistant to denaturation by acid and to proteolysis by pepsin at low pH values or by pancreatic proteases compared to CE/trunc. Thus, a stomach Muc6 domain is sufficient to confer stability on the CE catalytic domain, demonstrating a protective effect by a glycosylated mucin sequence.
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Affiliation(s)
- K M Loomes
- School of Biological Sciences, The University of Auckland, New Zealand.
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16
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Wang CS, Jackson KW, Dashti A, Downs D, Zhang X, Tang JJ. Mass spectrometric characterization and glycosylation profile of bovine pancreatic bile salt-activated lipase. Protein Expr Purif 1998; 12:259-68. [PMID: 9518468 DOI: 10.1006/prep.1997.0848] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We developed a procedure for the large scale isolation of bovine bile salt-activated lipase (BAL) for its crystallization [Wang, X., et al. (1997) Structure 5, 1209-1218] and also carried out a study on the molecule's glycosylation profile for a better deduction of the structure of the enzyme. Mass spectrometric analysis of the CNBr-generated peptides indicated that only one (Asn-361) of the two potential N-glycosylation sites (Asn-187 and Asn-361) with NXT motif is glycosylated. The analysis of the isolated CNBr peptide containing Asn-361 showed that it existed in three glycoforms in a ratio of 1.0:2.8:1.0, with oligosaccharide moieties weighing 1900.1, 2045.2, and 2336.4 Da, respectively. The major oligosaccharide chain contained mannose: galactose:N-acetylglucosamine:fucose:sialic acid in a molar ratio of 2:2:4:2:1. It was also determined that the potential O-glycosylated peptide (CB13) is not O-glycosylated and, in addition, it was found that there was microheterogeneity in the C-terminus of the isolated bovine BAL. The results obtained from this mass spectrometric study combined with the X-ray crystallographic studies provide more precise structural information on BAL. The procedure described here for the mass spectrometric analysis of CNBr-generated peptides also has general applicability for analysis of the glycosylation profile of glycoproteins and the C-terminal peptide structure of proteins.
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Affiliation(s)
- C S Wang
- Protein Studies Program, Oklahoma Medical Research Foundation, Oklahoma City 73014, USA
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17
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McKillop AM, O'Hare MM, Craig JS, Dodge JA, Halliday HL. Incidence of molecular forms of bile salt-stimulated lipase in preterm and term human milk. Pediatr Res 1998; 43:101-4. [PMID: 9432119 DOI: 10.1203/00006450-199801000-00015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Preterm and term human milk samples obtained at various times after delivery were analyzed for the presence of molecular forms of the human milk enzyme, bile salt-stimulated lipase (BSSL). Thirty-five percent of both the preterm and term milk samples contained two molecular forms of BSSL, of variable molecular mass. The remainder contained only one molecular species of either 115 kD (50%) or 120 kD (15%). The number of molecular forms present was not related to length of lactation, maternal age, gestation, or maternal blood group. The specific activity of BSSL purified from term milk was similar to that purified from preterm milk, and there was no difference in specific activity whether one or two molecular forms were present. This study demonstrates heterogeneity of both molecular mass and molecular forms. We conclude that preterm babies fed their own mother's milk are unlikely to be disadvantaged with respect to fat digestion as BSSL secreted in preterm milk appears to be very similar to that produced in term milk, although we cannot exclude other functional differences.
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Affiliation(s)
- A M McKillop
- Department of Child Health, The Queen's University of Belfast, Institute of Clinical Science, Northern Ireland
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18
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Mas E, Sadoulet MO, el Battari A, Lombardo D. Glycosylation of bile salt-dependent lipase (cholesterol esterase). Methods Enzymol 1997; 284:340-53. [PMID: 9379944 DOI: 10.1016/s0076-6879(97)84022-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- E Mas
- Inserm U 260, Marseille, France
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19
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Lee YP, Adimoolam S, Liu M, Subbaiah PV, Glenn K, Jonas A. Analysis of human lecithin-cholesterol acyltransferase activity by carboxyl-terminal truncation. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1344:250-61. [PMID: 9059515 DOI: 10.1016/s0005-2760(96)00149-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Lecithin-cholesterol acyltransferase (LCAT) is a key enzyme in reverse cholesterol transport and catalyzes the esterification of cholesterol in human plasma. Human LCAT is a glycosylated protein, containing 416 amino acids and a proline-rich region at the C-terminus. To address the function of the C-terminal region of LCAT as well as that of the proline-rich region, we constructed and expressed LCAT mutants with C-terminal truncations at different positions. The expression of wild-type LCAT in COS-1 cells resulted in an enzymatically active protein that was secreted by the cells. The mutants lacking the proline-rich region at the C-terminus were expressed and secreted at levels comparable to those of wild-type (approximately 50% of wild-type concentrations in cell media). The proline-deletion mutants were similar to wild-type LCAT in terms of phospholipase or transferase activities with various interfacial substrates, including reconstituted HDL, proteoliposomes, LDL, and micelles of platelet activating factor. Thus, the binding of LCAT to the diverse interfaces is not affected by the removal of its C-terminal region. Also, the activation by apolipoproteins and access of water-insoluble substrates to the active site are not significantly affected by the deletion of the proline-rich region. However, deletions of the proline-rich region, including the five amino acids nearest to the C-terminus, resulted in approximately an 8-fold increase in the specific activity of LCAT towards the water-soluble substrate, p-nitrophenylbutyrate. This suggests that the C-terminal proline-rich region may interfere with the access of this water-soluble substrate to the active site of LCAT, and may form part of a protective covering of the active site of LCAT while in solution. Further deletions at the C-terminus, beyond the proline-rich region, impaired the secretion of the enzyme, implying that this region may play a critical role in either the secretion or folding of LCAT in COS-1 cells.
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Affiliation(s)
- Y P Lee
- Department of Biochemistry, College of Medicine, University of Illinois at Urbana-Champaign 61801, USA
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20
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Mas E, Franc JL, Lecestre D, Crotte C, Lombardo D, Sadoulet MO. Investigation of two glycosylated forms of bile-salt-dependent lipase in human pancreatic juice. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 243:299-305. [PMID: 9030752 DOI: 10.1111/j.1432-1033.1997.0299a.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pure human pancreatic bile-salt-dependent lipase, devoid of its oncofetal glycoform [Mas, E., Abouakil, N., Roudani, S., Miralles, F., Guy-Crotte., O., Figarella, C., Escribano, M. J. & Lombardo, D. (1993) Biochem. J. 289, 609-615], was analyzed on immobilized concanavalin A (ConA). Two variants were separated: an unabsorbed ConA-unreactive fraction; and an absorbed ConA-reactive fraction. Carbohydrate compositions of ConA-reactive and ConA-unreactive fractions were not significantly different, and analysis of 3H-labelled oligosaccharides liberated from these fractions on the ConA-Sepharose column indicated that the fractionation of the bile-salt-dependent lipase on this column depends upon oligosaccharide structures. The activity of the ConA-reactive fraction was however much lower, independent of the substrate (4-nitrophenyl hexanoate or cholesteryl esters), than that of the ConA-unreactive fraction. Therefore, catalytic constants for the hydrolysis of 4-nitrophenyl hexanoate were determined; both fractions had quite similar Km, while the kcat for the ConA-unreactive fraction was 3-4-fold higher than that of the ConA-reactive fraction. ConA-reactive and ConA-unreactive fractions were shown to have slightly different molecular masses and different amino acid compositions. Cleavage patterns after cyanogen bromide treatment of the ConA-reactive and ConA-unreactive fractions suggested that the ConA-reactive (high Mr form) and ConA-unreactive (low Mr form) forms could be different isoforms of the bile-salt-dependent lipase secreted by the human pancreas.
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Affiliation(s)
- E Mas
- INSERM U 260, Faculté de Médecine Marseille, France
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21
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Wang CS, Dashti A, Jackson KW, Yeh JC, Cummings RD, Tang J. Isolation and characterization of human milk bile salt-activated lipase C-tail fragment. Biochemistry 1995; 34:10639-44. [PMID: 7654718 DOI: 10.1021/bi00033a039] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Glycosylation positions and oligosaccharide characteristics in the proline-rich, mucin-like, C-terminal region (C-tail) of human milk bile salt-activated lipase (BAL) were studied in order to assess the possible physiological functions of this region. A large-scale purification method has been devised to purify the C-tail fragment from human milk BAL. Chymotryptic, tryptic, and cyanogen bromide cleavages of partially purified BAL and subsequent molecular sieve chromatography yielded 20-30 mg of C-tail fragment from 1 L of human milk. The N-terminal sequence and amino acid composition of the purified C-tail fragment establish that it is derived from residues 528-712 of the enzyme. The O-glycosylated carbohydrates of the C-tail fragment contain fucose, galactose, glucosamine, galactosamine, and neuraminic acid in a molar ratio of 1:3:2:1:0.3, respectively. beta-Elimination reaction revealed that nine threonine residues and less than one serine residue were glycosylated. Edman degradation of C-tail fragment and its pronase subfragment suggest a number of glycosylation sites which are flanked by a consensus motif of PVPP. We suggest that this motif may serve as a signal for O-glycosylation in the C-tail region of BAL. Immunochemical studies indicated that the oligosaccharide chains in the C-tail region of BAL contain Lewis x and Lewis a antigens and, less prominently, sialyl Lewis x and sialyl Lewis a antigens. C-tail fragment was also found to bind jacalin lectin. These observations suggest the possibility that the C-tail region may contribute to adhesive activity in the physiological function of BAL.
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Affiliation(s)
- C S Wang
- Protein Studies Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA
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22
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Loomes KM. Structural organisation of human bile-salt-activated lipase probed by limited proteolysis and expression of a recombinant truncated variant. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 230:607-13. [PMID: 7607235 DOI: 10.1111/j.1432-1033.1995.tb20602.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Bile-salt-activated lipase belongs to the cholinesterase alpha/beta-hydrolase-fold family of proteins. Here, we have investigated the structural organisation of the human isoform by mapping tryptic cleavage sites using limited proteolysis and by expression studies using a recombinant truncated variant. Two accessible regions in the tertiary structure were identified. The first is defined by a tryptic cleavage at Lys429 and lies within the alpha/beta-hydrolase fold in bile-salt-activated lipase between a central beta-sheet and an active-site histidine residue, as deduced from sequence similarity across the cholinesterases and known structural properties. This region exhibits a proteolytic and topological similarity to the lid region in pancreatic lipase. The other accessible region in the tertiary structure is defined by a tryptic cleavage at Arg520 and occurs within a catalytically non-essential segment Leu519-Gln535, as identified by expression of a truncated variant which lacks the C-terminus starting from Leu519. This region is consistent with an interdomain region between the cholinesterase-related part of the protein structure and the unique proline-rich C-terminal repeats. Both protease-sensitive regions appear to occur at domain borders, and, therefore, are consistent with a multi-domain structure. The truncated variant was fully functional as a lipase and as a bile-salt-stimulated esterase. However, compared to the full-length enzyme, the truncated variant showed an increased susceptibility to limited proteolysis, suggesting that the C-terminal repeats may regulate proteolytic degradation of the protein.
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Affiliation(s)
- K M Loomes
- Biochemistry and Molecular Biology Group, School of Biological Sciences, University of Auckland, New Zealand
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