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Zhu G, Wilhelm SJ, George LG, Cassidy BM, Zino S, Luke CJ, Hanna M, Stone S, Phan N, Matiwala N, Ballentine SJ, Lowe ME, Xiao X. Preclinical mouse model of a misfolded PNLIP variant develops chronic pancreatitis. Gut 2023:gutjnl-2022-327960. [PMID: 36631248 DOI: 10.1136/gutjnl-2022-327960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 12/28/2022] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Increasing evidence implicates mutation-induced protein misfolding and endoplasm reticulum (ER) stress in the pathophysiology of chronic pancreatitis (CP). The paucity of animal models harbouring genetic risk variants has hampered our understanding of how misfolded proteins trigger CP. We previously showed that pancreatic triglyceride lipase (PNLIP) p.T221M, a variant associated with steatorrhoea and possibly CP in humans, misfolds and elicits ER stress in vitro suggesting proteotoxicity as a potential disease mechanism. Our objective was to create a mouse model to determine if PNLIP p.T221M causes CP and to define the mechanism. DESIGN We created a mouse model of Pnlip p.T221M and characterised the structural and biochemical changes in the pancreas aged 1-12 months. We used multiple methods including histochemistry, immunostaining, transmission electron microscopy, biochemical assays, immunoblotting and qPCR. RESULTS We demonstrated the hallmarks of human CP in Pnlip p.T221M homozygous mice including progressive pancreatic atrophy, acinar cell loss, fibrosis, fatty change, immune cell infiltration and reduced exocrine function. Heterozygotes also developed CP although at a slower rate. Immunoblot showed that pancreatic PNLIP T221M misfolded as insoluble aggregates. The level of aggregates in homozygotes declined with age and was much lower in heterozygotes at all ages. The Pnlip p.T221M pancreas had increased ER stress evidenced by dilated ER, increased Hspa5 (BiP) mRNA abundance and a maladaptive unfolded protein response leading to upregulation of Ddit3 (CHOP), nuclear factor-κB and cell death. CONCLUSION Expression of PNLIP p.T221M in a preclinical mouse model results in CP caused by ER stress and proteotoxicity of misfolded mutant PNLIP.
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Affiliation(s)
- Guoying Zhu
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA.,Department of Clinical Nutrition, Putuo People's Hospital, School of Medicine,Tongji University, Shanghai, China
| | - Steven J Wilhelm
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA
| | - Leah G George
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA
| | - 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
| | - Cliff J Luke
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA.,Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri, USA
| | - Mina Hanna
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA
| | - Stephen Stone
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA
| | - Nhung Phan
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA
| | - Neel Matiwala
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA
| | - Samuel J Ballentine
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, USA
| | - 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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Zhu G, Fang Q, Zhu F, Huang D, Yang C. Structure and Function of Pancreatic Lipase-Related Protein 2 and Its Relationship With Pathological States. Front Genet 2021; 12:693538. [PMID: 34290745 PMCID: PMC8287333 DOI: 10.3389/fgene.2021.693538] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 05/26/2021] [Indexed: 11/28/2022] Open
Abstract
Pancreatic lipase is critical for the digestion and absorption of dietary fats. The most abundant lipolytic enzymes secreted by the pancreas are pancreatic triglyceride lipase (PTL or PNLIP) and its family members, pancreatic lipase-related protein 1 (PNLIPRP1or PLRP1) and pancreatic lipase-related protein 2 (PNLIPRP2 or PLRP2). Unlike the family’s other members, PNLIPRP2 plays an elemental role in lipid digestion, especially for newborns. Therefore, if genetic factors cause gene mutation, or other factors lead to non-expression, it may have an effect on fat digestion and absorption, on the susceptibility to pancreas and intestinal pathogens. In this review, we will summarize what is known about the structure and function of PNLIPRP2 and the levels of PNLIPRP2 and associated various pathological states.
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Affiliation(s)
- Guoying Zhu
- Department of Clinical Nutrition, Putuo People's Hospital, School of Medicine, Tongji University, Shanghai, China.,Department of Pediatrics Gastroenterology, School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
| | - Qing Fang
- Department of Clinical Nutrition, Putuo People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Fengshang Zhu
- Department of Gastroenterology, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Dongping Huang
- Department of Clinical Nutrition, Putuo People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Changqing Yang
- Department of Gastroenterology, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
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3
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Khatua B, Trivedi RN, Noel P, Patel K, Singh R, de Oliveira C, Trivedi S, Mishra V, Lowe M, Singh VP. Carboxyl Ester Lipase May Not Mediate Lipotoxic Injury during Severe Acute Pancreatitis. THE AMERICAN JOURNAL OF PATHOLOGY 2019; 189:1226-1240. [PMID: 30954473 DOI: 10.1016/j.ajpath.2019.02.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/19/2019] [Accepted: 02/21/2019] [Indexed: 12/12/2022]
Abstract
Acute lipolysis of visceral fat or circulating triglycerides may worsen acute pancreatitis (AP)-associated local and systemic injury. The pancreas expresses pancreatic triacylglycerol lipase (PNLIP), pancreatic lipase-related protein 2 (PNLIPRP2), and carboxyl ester lipase (CEL), which may leak into the visceral fat or systemic circulation during pancreatitis. We, thus, aimed to determine the pancreatic lipase(s) regulating lipotoxicity during AP. For this AP, associated fat necrosis was analyzed using Western blot analysis. Bile acid (using liquid chromatography-tandem mass spectrometry) and fatty acid (using gas chromatography) concentrations were measured in human fat necrosis. The fat necrosis milieu was simulated in vitro using glyceryl trilinoleate because linoleic acid is increased in fat necrosis. Bile acid requirements to effectively hydrolyze glyceryl trilinoleate were studied using exogenous or overexpressed lipases. The renal cell line (HEK 293) was used to study lipotoxic injury. Because dual pancreatic lipase knockouts are lethal, exocrine parotid acini lacking lipases were used to verify the results. PNLIP, PNLIPRP2, and CEL were increased in fat necrosis. Although PNLIP and PNLIPRP2 were equipotent in inducing lipolysis and lipotoxic injury, CEL required bile acid concentrations higher than in human fat necrosis. The high bile acid requirements for effective lipolysis make CEL an unlikely mediator of lipotoxic injury in AP. It remains to be explored whether PNLIP or PNLIPRP2 worsens AP severity in vivo.
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Affiliation(s)
| | - Ram N Trivedi
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Pawan Noel
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Krutika Patel
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Ravinder Singh
- Department of Lab Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | | | | | - Vivek Mishra
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Mark Lowe
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Vijay P Singh
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona.
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4
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Lavrador MSF, Afonso MS, Cintra DE, Koike M, Nunes VS, Demasi M, Lin CJ, Beda LMM, Gioielli LA, Bombo RDPA, Machado RM, Catanozi S, Nakandakare ER, Lottenberg AM. Interesterified Fats Induce Deleterious Effects on Adipose Tissue and Liver in LDLr-KO Mice. Nutrients 2019; 11:nu11020466. [PMID: 30813339 PMCID: PMC6412707 DOI: 10.3390/nu11020466] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 02/03/2019] [Accepted: 02/13/2019] [Indexed: 12/13/2022] Open
Abstract
Interesterified fats are being widely used by the food industry in an attempt to replace trans fatty acids. The effect of interesterified fats containing palmitic or stearic acids on lipid metabolism and inflammatory signaling pathways in adipose and hepatic tissues was evaluated. Male LDLr-KO mice were fed a high-fat diet containing polyunsaturated (PUFA), palmitic (PALM), palmitic interesterified (PALM INTER), stearic (STEAR), or stearic interesterified (STEAR INTER) fats for 16 weeks. The expression of genes and protein levels involved in lipid metabolism and inflammatory processes in liver and white adipose tissue was determined by quantitative RT-PCR and by Western blot, respectively. The infiltration of inflammatory cells in hepatic and adipose tissues was determined by eosin and hematoxylin, while liver collagen content was determined by Sirius Red staining. Both interesterified fats increased liver collagen content and JNK phosphorylation. Additionally, the STEAR INTER group developed nonalcoholic steatohepatitis (NASH) associated with higher neutrophil infiltration. PALM INTER induced adipose tissue expansion and enlargement of adipocytes. Furthermore, PALM INTER triggered increased IKK phosphorylation and TNFα protein content, conditions associated with the upstream activation of the NFkB signaling pathway. STEAR INTER induced NASH, while PALM INTER triggered hepatic fibrosis and adipocyte hypertrophy with inflammatory response in LDLr-KO mice.
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Affiliation(s)
- Maria Silvia Ferrari Lavrador
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Milessa Silva Afonso
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Dennys Esper Cintra
- Laboratory of Nutritional Genomics-School of Applied Science, University of Campinas (UNICAMP), Limeira, São Paulo 13484-350, Brazil.
| | - Marcia Koike
- Emergency Care Research Unit Laboratory (LIM51), Faculty of Medical Sciences of the University of São Paulo, São Paulo 01246-903, Brazil.
| | - Valeria Sutti Nunes
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Marina Demasi
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Chin Jia Lin
- Laboratory of Molecular Biology (LIM22), Department of Pathology, Faculty of Medical Sciences of the University of São Paulo, São Paulo 01246-903, Brazil.
| | - Lis Mie Masuzawa Beda
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Luiz Antonio Gioielli
- Department of Biochemical and Pharmaceutical Technology, Faculty of Pharmaceutical Sciences of the University of São Paulo, São Paulo 05508-000, Brazil.
| | - Renata de Paula Assis Bombo
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Roberta Marcondes Machado
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Sergio Catanozi
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Edna Regina Nakandakare
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
| | - Ana Maria Lottenberg
- Laboratorio de Lipides (LIM10), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR 01246-903, Brazil.
- Faculdade Israelita de Ciências da Saúde Albert Einstein, São Paulo, SP, BR 05521-200, Brazil.
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5
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Blocking β₁/β₂-Adrenergic Signaling Reduces Dietary Fat Absorption by Suppressing Expression of Pancreatic Lipase in High Fat-Fed Mice. Int J Mol Sci 2018. [PMID: 29538343 PMCID: PMC5877718 DOI: 10.3390/ijms19030857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We investigated whether β-adrenergic antagonists attenuates dietary fat absorption through the regulation of pancreatic lipase (PNLIP) expression in pancreatic acinar cells in the context of high fat diet feeding. Male six-week-old C57BL/6 mice were assigned into an ad libitum fed control diet (CON) and a high fat diet (HIGH). Within each diet group, subgroups of mice were treated with vehicle (VEH) or propranolol, a β-adrenergic antagonist (BB). Over 12 weeks, body weight gain observed in HIGHVEH was mitigated in HIGHBB (+103% vs. +72%). Increase in fecal fat amount observed in HIGHVEH was further increased in HIGHBB. Increase in PNLIP expressions observed in HIGHVEH pancreatic tissues was abolished in HIGHBB. PNLIP expression in mouse primary pancreatic acinar cells and 266-6 cell lines increased with isoproterenol treatment, which was blocked by propranolol. Isoproterenol increased PNLIP expression in a cAMP/protein kinase A/ cyclic AMP response element binding protein (CREB)-dependent manner. CREB directly bound to the CRE on the mouse PNLIP promoter and transactivated PNLIP expression. These results suggest that sympathetic activation increases dietary fat absorption through the upregulation of PNLIP expression and that a β-adrenergic antagonist attenuates obesity development partly through the downregulation of PNLIP expression and inhibition of dietary fat absorption in the context of high fat diet feeding.
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6
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Smichi N, Fendri A, Triki S, Arondel V, Rebai A, Gargouri Y, Miled N. Biochemical characterization, cloning and molecular modeling of a digestive lipase from red seabream ( Pagrus major): Structural explanation of the interaction deficiency with colipase and lipidic interface. Eng Life Sci 2017; 17:664-677. [PMID: 32624812 DOI: 10.1002/elsc.201600246] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 11/30/2016] [Accepted: 01/05/2017] [Indexed: 11/12/2022] Open
Abstract
Red seabream digestive lipase (RsDL) was purified from fresh pyloric caeca. Pure RsDL has an apparent molecular mass of 50 kDa. The RsDL is more active on short-chain triacylglycerols (TC4), and enzymatic activity decreases when medium (TC8) or long-chain (olive oil) triacylglycerols were used as substrates. The specific activities of RsDL are very weak as compared to those obtained with classical pancreatic lipases. No colipase was detected in the red seabream pyloric caeca. Furthermore, the RsDL was not activated by a mammal colipase. Similar results were reported for annular seabream lipase. In order to explain structurally the discrepancies between sparidae and mammal lipases, genes encoding mature RsDL and five other lipases from sparidae fish species were cloned and sequenced. Phylogenetic studies indicated the closest homology of sparidae lipases to bird pancreatic ones. Structural models were built for annular seabream and RsDL under their closed and open forms using mammal pancreatic lipases as templates. Several differences were noticed when analyzing the amino acids corresponding to those involved in HPL binding to colipase. This is likely to prevent interaction between the fish lipase and the mammalian colipase and may explain the fact that mammalian colipase is not effective in activating sparidae lipases. In addition, several hydrophobic residues, playing a key role in anchoring pancreatic lipase onto the lipid interface, are replaced by polar residues in fish lipases. This might explain the reason why the latter enzymes display weak activity levels when compared to mammalian pancreatic lipases.
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Affiliation(s)
- Nabil Smichi
- Laboratory of Biochemistry and Enzymatic Engineering of Lipases ENIS Sfax Tunisia
| | - Ahmed Fendri
- Laboratory of Biochemistry and Enzymatic Engineering of Lipases ENIS Sfax Tunisia
| | - Soumaya Triki
- Department of Bioinformatics and Human Genetics Center of Biotechnology of Sfax Sfax Tunisia
| | - Vincent Arondel
- Laboratory of Membrane Biogenesis, CNRS, UMR5200 Bordeaux University BP81, 71 Edouard Bourlaux Villenave d'Ornon France
| | - Ahmed Rebai
- Department of Bioinformatics and Human Genetics Center of Biotechnology of Sfax Sfax Tunisia
| | - Youssef Gargouri
- Laboratory of Biochemistry and Enzymatic Engineering of Lipases ENIS Sfax Tunisia
| | - Nabil Miled
- Laboratory of Biochemistry and Enzymatic Engineering of Lipases ENIS Sfax Tunisia
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7
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Xiao X, Ross LE, Sevilla WA, Wang Y, Lowe ME. Porcine pancreatic lipase related protein 2 has high triglyceride lipase activity in the absence of colipase. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1435-41. [PMID: 23770034 DOI: 10.1016/j.bbalip.2013.06.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 05/03/2013] [Accepted: 06/05/2013] [Indexed: 11/17/2022]
Abstract
Efficient dietary fat digestion is essential for newborns who consume more dietary fat per body weight than at any other time of life. In many mammalian newborns, pancreatic lipase related protein 2 (PLRP2) is the predominant duodenal lipase. Pigs may be an exception since PLRP2 expression has been documented in the intestine but not in the pancreas. Because of the differences in tissue-specific expression, we hypothesized that the kinetic properties of porcine PLRP2 would differ from those of other mammals. To characterize its properties, recombinant porcine PLRP2 was expressed in HEK293T cells and purified to homogeneity. Porcine PLRP2 had activity against tributyrin, trioctanoin and triolein. The activity was not inhibited by bile salts and colipase, which is required for the activity of pancreatic triglyceride lipase (PTL), minimally stimulated PLRP2 activity. Similar to PLRP2 from other species, PLRP2 from pigs had activity against galactolipids and phospholipids. Importantly, porcine PLRP2 hydrolyzed a variety of dietary substrates including pasteurized human mother's milk and infant formula and its activity was comparable to that of PTL. In conclusion, porcine PLRP2 has broad substrate specificity and has high triglyceride lipase activity even in the absence of colipase. The data suggest that porcine PLRP2 would be a suitable lipase for inclusion in recombinant preparations for pancreatic enzyme replacement therapy.
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Affiliation(s)
- Xunjun Xiao
- Department of Pediatrics, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA
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8
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Xiao X, Mukherjee A, Ross LE, Lowe ME. Pancreatic lipase-related protein-2 (PLRP2) can contribute to dietary fat digestion in human newborns. J Biol Chem 2011; 286:26353-63. [PMID: 21652702 DOI: 10.1074/jbc.m111.249813] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In newborn mice, PLRP2 is essential for fat digestion. In human infants, the role of PLRP2 in fat digestion is unclear, as it has poor activity against long-chain triglycerides in vitro. Also, many infants carry a genetic polymorphism resulting in a truncated protein, PLRP2 W340X, which may impact function significantly. We re-examined the properties of recombinant human PLRP2 and studied the impact of W340X mutation on its function. In the presence of bile salt micelles and colipase, human PLRP2 hydrolyzed long-chain tri-, di-, and monoglycerides. It hydrolyzed triolein at a level much lower than that of pancreatic triglyceride lipase, but close to that of carboxyl ester lipase, after a long lag phase, which could be eliminated by the addition of oleic acids. Human PLRP2 W340X was poorly secreted and largely retained inside the cell. The retention of the mutant protein triggered endoplasmic reticulum stress and unfolded protein responses. Our results show that earlier studies underestimated human PLRP2 activity against triolein by employing suboptimal assay conditions. In vivo, dietary fat emulsions contain fatty acids as a result of the action of gastric lipase. Consequently, PLRP2 can contribute to fat digestion during early infancy. Furthermore, infants with homozygous W340X alleles will not secrete functional PLRP2 and may have inefficient dietary fat digestion, particularly when breastfeeding is unavailable. Additionally, the aberrant folding of W340X mutant may cause chronic cellular stress and increase susceptibility of pancreatic exocrine cells to other metabolic stressors.
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Affiliation(s)
- Xunjun Xiao
- Department of Pediatrics, Children's Hospital of Pittsburgh at University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15224, USA
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9
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Xiao X, Ross LE, Miller RA, Lowe ME. Kinetic properties of mouse pancreatic lipase-related protein-2 suggest the mouse may not model human fat digestion. J Lipid Res 2011; 52:982-90. [PMID: 21382969 DOI: 10.1194/jlr.m014290] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genetically engineered mice have been employed to understand the role of lipases in dietary fat digestion with the expectation that the results can be extrapolated to humans. However, little is known about the properties of mouse pancreatic triglyceride lipase (mPTL) and pancreatic lipase-related protein-2 (mPLRP2). In this study, both lipases were expressed in Pichia Pastoris GS115, purified to near homogeneity, and their properties were characterized. Mouse PTL displayed the kinetics typical of PTL from other species. Like mPTL, mPLRP2 exhibited strong activity against various triglycerides. In contrast to mPTL, mPLRP2 was not inhibited by increasing bile salt concentration. Colipase stimulated mPLRP2 activity 2- to 4-fold. Additionally, mPTL absolutely required colipase for absorption to a lipid interface, whereas mPLRP2 absorbed fully without colipase. mPLRP2 had full activity in the presence of BSA, whereas BSA completely inhibited mPTL unless colipase was present. All of these properties of mPLRP2 differ from the properties of human PLRP2 (hPLRP2). Furthermore, mPLRP2 appears capable of compensating for mPTL deficiency. These findings suggest that the molecular mechanisms of dietary fat digestion may be different in humans and mice. Thus, extrapolation of dietary fat digestion in mice to humans should be done with care.
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Affiliation(s)
- Xunjun Xiao
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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10
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Miller R, Lowe ME. Carboxyl ester lipase from either mother's milk or the pancreas is required for efficient dietary triglyceride digestion in suckling mice. J Nutr 2008; 138:927-30. [PMID: 18424603 PMCID: PMC3687517 DOI: 10.1093/jn/138.5.927] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Because dietary fats provide an important source of energy in the newborn, the efficient digestion of dietary fats is critical to their well-being. Despite the importance of dietary fat digestion, newborns have a deficiency of pancreatic triglyceride lipase, the predominant digestive lipase in adults. The efficient dietary fat digestion in newborns suggests that other lipases must compensate for the lack of pancreatic triglyceride lipase. In this study, we test the hypothesis that breast milk, pancreatic carboxyl ester lipase (CEL), or both contribute to dietary fat digestion in the newborn. To test this hypothesis, we determined the amount and composition of fecal fat in wild-type and CEL-deficient newborns nursed by either wild-type or CEL-deficient dams. We tested all genetic permutations of the nursing pairs. An interaction between the genotype of the dam and of the pup determined the amount of fecal fat (P < 0.001). Fecal fat was highest in CEL-deficient pups nursed by CEL-deficient dams. Furthermore, only the feces from the CEL-deficient pups nursed by CEL-deficient dams contained undigested lipids. Even with increased fecal fats, the CEL-deficient pups had normal weight gain. Our results demonstrate that CEL contributes significantly to dietary triglyceride digestion whether it originates from mother's milk or pancreatic secretions. However, only the absence of both mother's milk and pancreatic CEL produces fat maldigestion. The absence of a single CEL source makes no difference in the efficiency of dietary fat absorption.
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11
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Li X, Lindquist S, Lowe M, Noppa L, Hernell O. Bile salt-stimulated lipase and pancreatic lipase-related protein 2 are the dominating lipases in neonatal fat digestion in mice and rats. Pediatr Res 2007; 62:537-41. [PMID: 17805199 PMCID: PMC3488855 DOI: 10.1203/pdr.0b013e3181559e75] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
During infancy, the basic conditions for digestion of dietary fat differ from later in life. The bile salt-stimulated lipase (BSSL) is an enzyme expressed in the exocrine pancreas and in some species (including human) also in the lactating mammary gland and secreted with the milk. The aim of this study was to compare the ontogeny of four pancreatic lipases [BSSL, pancreatic triglyceride lipase (PL), pancreatic lipase-related protein 2 (PLRP2), and phospholipase A2 (PLA2)] in one species that supplies BSSL with milk (the mouse) and one that does not (the rat). We followed expression of the four pancreatic lipases from postnatal d 1 until after weaning in both species. We found that BSSL and PLRP2, two lipases with broad substrate specificity, dominated. It was not until weaning that significant expression of PL and PLA2 were induced. Thus, BSSL and PLRP2 seem to be responsible for fat digestion as long as milk is the main food. Moreover, the early temporal pattern of BSSL expression differed between species. We speculate that the milk-borne BSSL is able to compensate for a slower ontogeny of pancreatic BSSL expression in the mouse.
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Affiliation(s)
- Xiaonan Li
- Department of Clinical Sciences, Umeå University, SE-901 87 Umeå, Sweden
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12
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Gilham D, Labonté ED, Rojas JC, Jandacek RJ, Howles PN, Hui DY. Carboxyl ester lipase deficiency exacerbates dietary lipid absorption abnormalities and resistance to diet-induced obesity in pancreatic triglyceride lipase knockout mice. J Biol Chem 2007; 282:24642-9. [PMID: 17604277 PMCID: PMC2045644 DOI: 10.1074/jbc.m702530200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study evaluated the contributions of carboxyl ester lipase (CEL) and pancreatic triglyceride lipase (PTL) in lipid nutrient absorption. Results showed PTL deficiency has minimal effect on triacylglycerol (TAG) absorption under low fat dietary conditions. Interestingly, PTL(-)(/)(-) mice displayed significantly reduced TAG absorption compared with wild type mice under high fat/high cholesterol dietary conditions (80.1 +/- 3.7 versus 91.5 +/- 0.7%, p < 0.05). Net TAG absorption was reduced further to 61.1 +/- 3.8% in mice lacking both PTL and CEL. Cholesterol absorption was 41% lower in PTL(-/-) mice compared with control mice (p < 0.05), but this difference was not exaggerated in PTL(-/-), CEL(-/-) mice. Retinyl palmitate absorption was reduced by 45 and 60% in PTL(-/-) mice (p < 0.05) and PTL(-/-), CEL(-/-) mice (p < 0.01), respectively. After 15 weeks of feeding, the high fat/high cholesterol diet, wild type, and CEL(-/-) mice gained approximately 24 g of body weight. However, body weight gain was 6.2 and 8.6 g less (p < 0.01) in PTL(-/-) and PTL(-/-), CEL(-/-) mice, respectively, despite their consumption of comparable amounts of the high fat/high cholesterol diet. The decrease body weight gain in PTL(-/-) and PTL(-/-), CEL(-/-) mice was attributed to their absorption of fewer calories from the high fat/high cholesterol diet, thereby resulting in less fat mass accumulation than that observed in wild type and CEL(-/-) mice. Thus, this study documents that PTL and CEL serve complementary functions, working together to mediate the absorption of a major portion of dietary fat and fat-soluble vitamin esters. The reduced lipid absorption efficiency due to PTL and CEL inactivation also resulted in protection against diet-induced obesity.
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Affiliation(s)
- Dean Gilham
- Department of Pathology and Laboratory Medicine, Genome Research Institute, University of Cincinnati College of Medicine, Cincinnati, Ohio 45237, USA
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Abstract
A primary function of the pancreas is to produce digestive enzymes that are delivered to the small intestine for the hydrolysis of complex nutrients. Much of our understanding of digestive enzymes comes from studies in animals. New technologies and the availability of the sequence of the human genome allow for a critical review of older reports and assumptions based on animal studies. This report updates our understanding of human pancreatic digestive enzymes with a focus on new insights into the biology of human proteases, lipases and amylases.
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Affiliation(s)
- David C Whitcomb
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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D’Agostino D, Lowe ME. Pancreatic lipase-related protein 2 is the major colipase-dependent pancreatic lipase in suckling mice. J Nutr 2004; 134:132-4. [PMID: 14704305 PMCID: PMC2528064 DOI: 10.1093/jn/134.1.132] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Suckling mice express colipase before the expression of pancreatic triglyceride lipase. Yet, efficient fat digestion in newborns requires colipase, suggesting that colipase may act as a cofactor for another lipase such as pancreatic lipase-related protein 2 (PLRP2). We determined whether PLRP2 or another lipase depends on colipase for maximal activity in newborn mice by analyzing extracts from the pancreas of 4-d-old colipase-deficient and PLRP2-deficient mice. Pancreatic extracts from colipase-deficient pups had lipase activity that was stimulated onefold by the addition of exogenous colipase (P<0.001). The activity was completely inhibited by an antibody against pancreatic triglyceride lipase that also recognizes PLRP2. In contrast, pancreatic extracts from PLRP2-deficient pups had significantly lower baseline activity and no colipase-dependent activity. The baseline activity was not inhibited by the anti-pancreatic triglyceride lipase antibody or an antibody against carboxyl ester lipase. We next separated the extracts into two fractions, one containing PLRP2 and the other devoid of PLRP2. All of the colipase-dependent activity segregated with the PLRP2-containing fraction, consistent with the conclusion that PLRP2 is the major colipase-dependent lipase in the pancreas of newborns.
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Affiliation(s)
- Dymphna D’Agostino
- Departments of Pediatrics and of Molecular Biology and Pharmacology, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO 63110
| | - Mark E. Lowe
- Departments of Pediatrics and of Molecular Biology and Pharmacology, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO 63110
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Rippe C, Berger K, Mei J, Lowe ME, Erlanson-Albertsson C. Effect of long-term high-fat feeding on the expression of pancreatic lipases and adipose tissue uncoupling proteins in mice. Pancreas 2003; 26:e36-42. [PMID: 12604926 PMCID: PMC3488857 DOI: 10.1097/00006676-200303000-00024] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
INTRODUCTION A diet containing a high amount of fat has been shown, in short-term studies, to increase the expression of pancreatic lipase and colipase. AIM To investigate the effects of long-term high-fat-feeding (113 days) on the mRNA expression of pancreatic lipase, colipase, pancreatic lipase-related proteins (1 and 2), and uncoupling proteins during the development of obesity and glucose intolerance. METHODOLOGY Mice were fed either a high-fat or standard diet and killed after 3, 13, 57, and 113 days. Brown and white adipose tissue and pancreas were collected for mRNA extraction [corrected]. RESULTS The high-fat-fed mice became obese and glucose-intolerant by 113 days. The high-fat diet increased lipase (p < 0.05) expression initially. At the end of the experiment, the lipase levels had decreased to the level of the control. Colipase levels did not change during the first 57 days of high-fat feeding but decreased below control levels by 113 days (p < 0.05). The high-fat diet increased brown adipose tissue uncoupling protein 1 (UCP1)(p < 0.005) expression but not the expression of uncoupling protein 2. CONCLUSION Long-term high-fat feeding, leading to glucose intolerance, occurs with a simultaneous decrease in the mRNA expression of pancreatic lipase and colipase and an increase in UCP1 expression.
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Affiliation(s)
- Catarina Rippe
- Department of Cell and Molecular Biology, Section for Molecular Signaling, University of Lund, Lund, Sweden.
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Mahan JT, Heda GD, Rao RH, Mansbach CM. The intestine expresses pancreatic triacylglycerol lipase: regulation by dietary lipid. Am J Physiol Gastrointest Liver Physiol 2001; 280:G1187-96. [PMID: 11352812 DOI: 10.1152/ajpgi.2001.280.6.g1187] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We identified the enzyme responsible for alkaline lipolysis in mucosa of rat small intestine. RT-PCR was used to amplify a transcript that, by cloning and sequencing, is identical to pancreatic triacylglycerol lipase. In rats fed normal laboratory chow, pancreatic triacylglycerol lipase mRNA was detected in all four quarters of the small intestine, with the first quarter expressing about three times as much of this transcript as was found in the more distal three-quarters combined. Both acutely and chronically administered dietary fat were shown to regulate pancreatic triacylglycerol lipase mRNA expression and lipase activity. The synthesis of pancreatic triacylglycerol lipase protein by the small intestine was demonstrated by in vivo radiolabeling experiments using [(35)S]methionine/cysteine followed by immunoprecipitation with an anti-pancreatic triacylglycerol lipase antibody. Immunohistochemical studies suggest that pancreatic triacylglycerol lipase protein expression is restricted to enterocytes throughout the small intestine. To our knowledge, this is the first report identifying rat small intestinal mucosa as a site of pancreatic triacylglycerol lipase synthesis and the first demonstration of its modulation in the mucosa by dietary fat. We propose that pancreatic triacylglycerol lipase is used by the intestine to hydrolyze the mucosal triacylglycerol that is not transported in chylomicrons.
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Affiliation(s)
- J T Mahan
- Department of Medicine, Division of Gastroenterology, The University of Tennessee-Memphis, Memphis, TN 38163, USA
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Lowe ME, Kaplan MH, Jackson-Grusby L, D'Agostino D, Grusby MJ. Decreased neonatal dietary fat absorption and T cell cytotoxicity in pancreatic lipase-related protein 2-deficient mice. J Biol Chem 1998; 273:31215-21. [PMID: 9813028 PMCID: PMC3690502 DOI: 10.1074/jbc.273.47.31215] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The pancreas secretes several different lipases. The most abundant is pancreatic triglyceride lipase (PTL). The pancreas also synthesizes two homologues of PTL, the pancreatic lipase-related proteins 1 and 2 (PLRP1 and PLRP2). Cytotoxic T-lymphocytes also express PLRP2 under certain conditions. We sought to determine the role of PLRP2 in fat absorption and in T-cell cytotoxicity by creating a PLRP2-deficient mouse. Adult PLRP2-deficient mice had normal fat absorption. In contrast, suckling PLRP2-deficient mice had fat malabsorption evidenced by increased fecal weight, increased fecal fats, and the presence of undigested and partially digested dietary triglycerides in the feces. As a result, the PLRP2-deficient pups had a decreased rate of weight gain. To assess T cell cytotoxicity, we immunized PLRP2-deficient mice with a mastocytoma cell line, P815, and determined the ability of splenocytes from the immunized mice to kill P815 cells in a 51Cr release assay. PLRP2-deficient cells had deficient killing activity in this assay, and PLRP2-deficient splenocytes released fewer fatty acid from the target cells than did control cells. Our results provide the first evidence of a physiological function for PLRP2. PLRP2 participates in T cell cytotoxicity, and PLRP2 performs a crucial role in the digestion of dietary fats in suckling animals.
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Affiliation(s)
- M E Lowe
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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