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Azoury ME, Tarayrah M, Afonso G, Pais A, Colli ML, Maillard C, Lavaud C, Alexandre-Heymann L, Gonzalez-Duque S, Verdier Y, Vinh J, Pinto S, Buus S, Dubois-Laforgue D, Larger E, Beressi JP, Bruno G, Eizirik DL, You S, Mallone R. Peptides Derived From Insulin Granule Proteins Are Targeted by CD8 + T Cells Across MHC Class I Restrictions in Humans and NOD Mice. Diabetes 2020; 69:2678-2690. [PMID: 32928873 DOI: 10.2337/db20-0013] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 08/31/2020] [Indexed: 11/13/2022]
Abstract
The antigenic peptides processed by β-cells and presented through surface HLA class I molecules are poorly characterized. Each HLA variant (e.g., the most common being HLA-A2 and HLA-A3) carries some peptide-binding specificity. Hence, features that, despite these specificities, remain shared across variants may reveal factors favoring β-cell immunogenicity. Building on our previous description of the HLA-A2/A3 peptidome of β-cells, we analyzed the HLA-A3-restricted peptides targeted by circulating CD8+ T cells. Several peptides were recognized by CD8+ T cells within a narrow frequency (1-50/106), which was similar in donors with and without type 1 diabetes and harbored variable effector/memory fractions. These epitopes could be classified as conventional peptides or neoepitopes, generated either via peptide cis-splicing or mRNA splicing (e.g., secretogranin-5 [SCG5]-009). As reported for HLA-A2-restricted peptides, several epitopes originated from β-cell granule proteins (e.g., SCG3, SCG5, and urocortin-3). Similarly, H-2Kd-restricted CD8+ T cells recognizing the murine orthologs of SCG5, urocortin-3, and proconvertase-2 infiltrated the islets of NOD mice and transferred diabetes into NOD/scid recipients. The finding of granule proteins targeted in both humans and NOD mice supports their disease relevance and identifies the insulin granule as a rich source of epitopes, possibly reflecting its impaired processing in type 1 diabetes.
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Affiliation(s)
| | - Mahmoud Tarayrah
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
| | - Georgia Afonso
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
| | - Aurore Pais
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
| | - Maikel L Colli
- Université Libre de Bruxelles Center for Diabetes Research and Welbio, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium
| | - Claire Maillard
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
| | - Cassandra Lavaud
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
| | - Laure Alexandre-Heymann
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
- Assistance Publique Hôpitaux de Paris, Hôpitaux Universitaires de Paris Centre-Université de Paris, Cochin Hospital, Service de Diabétologie et Immunologie Clinique, Paris, France
| | - Sergio Gonzalez-Duque
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
- École Supérieure de Physique et de Chimie Industrielles Paris, Université Paris Sciences et Lettres, Spectrométrie de Masse Biologique et Protéomique, CNRS USR3149, Paris, France
| | - Yann Verdier
- École Supérieure de Physique et de Chimie Industrielles Paris, Université Paris Sciences et Lettres, Spectrométrie de Masse Biologique et Protéomique, CNRS USR3149, Paris, France
| | - Joelle Vinh
- École Supérieure de Physique et de Chimie Industrielles Paris, Université Paris Sciences et Lettres, Spectrométrie de Masse Biologique et Protéomique, CNRS USR3149, Paris, France
| | - Sheena Pinto
- Division of Developmental Immunology, Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Soren Buus
- Laboratory of Experimental Immunology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Danièle Dubois-Laforgue
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
- Assistance Publique Hôpitaux de Paris, Hôpitaux Universitaires de Paris Centre-Université de Paris, Cochin Hospital, Service de Diabétologie et Immunologie Clinique, Paris, France
| | - Etienne Larger
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
- Assistance Publique Hôpitaux de Paris, Hôpitaux Universitaires de Paris Centre-Université de Paris, Cochin Hospital, Service de Diabétologie et Immunologie Clinique, Paris, France
| | - Jean-Paul Beressi
- Service de Diabétologie, Centre Hospitalier de Versailles André Mignot, Le Chesnay, France
| | - Graziella Bruno
- Department of Medical Sciences, University of Turin, Turin, Italy
| | - Decio L Eizirik
- Université Libre de Bruxelles Center for Diabetes Research and Welbio, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium
| | - Sylvaine You
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
| | - Roberto Mallone
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
- Assistance Publique Hôpitaux de Paris, Hôpitaux Universitaires de Paris Centre-Université de Paris, Cochin Hospital, Service de Diabétologie et Immunologie Clinique, Paris, France
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Jarvela TS, Womack T, Georgiou P, Gould TD, Eriksen JL, Lindberg I. 7B2 chaperone knockout in APP model mice results in reduced plaque burden. Sci Rep 2018; 8:9813. [PMID: 29955078 PMCID: PMC6023903 DOI: 10.1038/s41598-018-28031-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/08/2018] [Indexed: 01/18/2023] Open
Abstract
Impairment of neuronal proteostasis is a hallmark of Alzheimer's and other neurodegenerative diseases. However, the underlying molecular mechanisms leading to pathogenic protein aggregation, and the role of secretory chaperone proteins in this process, are poorly understood. We have previously shown that the neural-and endocrine-specific secretory chaperone 7B2 potently blocks in vitro fibrillation of Aβ42. To determine whether 7B2 can function as a chaperone in vivo, we measured plaque formation and performed behavioral assays in 7B2-deficient mice in an hAPPswe/PS1dE9 Alzheimer's model mouse background. Surprisingly, immunocytochemical analysis of cortical levels of thioflavin S- and Aβ-reactive plaques showed that APP mice with a partial or complete lack of 7B2 expression exhibited a significantly lower number and burden of thioflavin S-reactive, as well as Aβ-immunoreactive, plaques. However, 7B2 knockout did not affect total brain levels of either soluble or insoluble Aβ. While hAPP model mice performed poorly in the Morris water maze, their brain 7B2 levels did not impact performance. Since 7B2 loss reduced amyloid plaque burden, we conclude that brain 7B2 can impact Aβ disposition in a manner that facilitates plaque formation. These results are reminiscent of prior findings in hAPP model mice lacking the ubiquitous secretory chaperone clusterin.
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Affiliation(s)
- Timothy S Jarvela
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Tasha Womack
- Department of Pharmacology, College of Pharmacy, University of Houston, Houston, TX, USA
| | - Polymnia Georgiou
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Todd D Gould
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jason L Eriksen
- Department of Pharmacology, College of Pharmacy, University of Houston, Houston, TX, USA
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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Yamamoto H, Ramos-Molina B, Lick AN, Prideaux M, Albornoz V, Bonewald L, Lindberg I. Posttranslational processing of FGF23 in osteocytes during the osteoblast to osteocyte transition. Bone 2016; 84:120-130. [PMID: 26746780 PMCID: PMC4755901 DOI: 10.1016/j.bone.2015.12.055] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/04/2015] [Accepted: 12/09/2015] [Indexed: 11/29/2022]
Abstract
FGF23 is an O-glycosylated circulating peptide hormone with a critical role in phosphate homeostasis; it is inactivated by cellular proprotein convertases in a pre-release degradative pathway. We have here examined the metabolism of FGF23 in a model bone cell line, IDG-SW3, prior to and following differentiation, as well as in regulated secretory cells. Labeling experiments showed that the majority of (35)S-labeled FGF23 was cleaved to smaller fragments which were constitutively secreted by all cell types. Intact FGF23 was much more efficiently stored in differentiated than in undifferentiated IDG-SW3 cells. The prohormone convertase PC2 has recently been implicated in FGF23 degradation; however, FGF23 was not targeted to forskolin-stimulatable secretory vesicles in a regulated cell line, suggesting that it lacks a targeting signal to PC2-containing compartments. In vitro, PC1/3 and PC2, but not furin, efficiently cleaved glycosylated FGF23; surprisingly, PC5/6 accomplished a small amount of conversion. FGF23 has recently been shown to be phosphorylated by the kinase FAM20C, a process which was shown to reduce FGF23 glycosylation and promote its cleavage; our in vitro data, however, show that phosphorylation does not directly impact cleavage, as both PC5/6 and furin were able to efficiently cleave unglycosylated, phosphorylated FGF23. Using qPCR, we found that the expression of FGF23 and PC5/6, but not PC2 or furin, increased substantially following osteoblast to osteocyte differentiation. Western blotting confirmed the large increase in PC5/6 expression upon differentiation. FGF23 has been linked to a variety of bone disorders ranging from autosomal dominant hypophosphatemic rickets to chronic kidney disease. A better understanding of the biosynthetic pathway of this hormone may lead to new treatments for these diseases.
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Affiliation(s)
- Hiroyuki Yamamoto
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Bruno Ramos-Molina
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Adam N Lick
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Matthew Prideaux
- School of Dentistry, Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Valeria Albornoz
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Lynda Bonewald
- School of Dentistry, Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Abstract
Prohormone convertase 2 (PC2) requires interaction with the neuroendocrine protein 7B2 for the production of an activatable zymogen; the mechanism for this effect is unknown. 7B2 could act proactively to generate an activation-competent form of pro-PC2 during synthesis, or block spontaneous generation of activation-incompetent forms. We here demonstrate that addition of exogenous recombinant 7B2 to CHO cells expressing pro-PC2 prevented the unfolding and aggregation of secreted PC2 forms in a dose-dependent manner, as assessed by aggregation assays, activity assays, cross-linking experiments, and sucrose density gradients. Intracellular pro-PC2 was also found to exist in part as higher-order oligomers that were reduced in the presence of coexpressed 7B2. 7B2 addition did not result in the acquisition of enzymatic competence unless added before or very rapidly after pro-PC2 secretion, indicating that an activation-competent structure cannot be maintained in the absence of 7B2. Velocity sedimentation experiments showed that addition of extracellular 7B2 solubilized three different PC2 species from a precipitable aggregate: two activatable pro-PC2 species, the intact zymogen and a zymogen with a partially cleaved propeptide, and an inactive 66-kDa form. Our results suggest that 7B2 possesses chaperone activity that blocks partially unfolded pro-PC2 forms from losing catalytic competence and then aggregating. The loss of the catalytically competent conformer appears to represent the earliest indicator of pro-PC2 unfolding and is followed on a slower time scale by the appearance of aggregates. Because 7B2 expression is not confined to areas expressing pro-PC2, 7B2 may represent a general intracellular and extracellular secretory chaperone.
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Affiliation(s)
- Sang-Nam Lee
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center/Research Institute for Children, New Orleans, Louisiana 70118, USA
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Schmidt G, Sirois F, Anini Y, Kauri LM, Gyamera-Acheampong C, Fleck E, Scott FW, Chrétien M, Mbikay M. Differences of pancreatic expression of 7B2 between C57BL/6J and C3H/HeJ mice and genetic polymorphisms at its locus (Sgne1). Diabetes 2006; 55:452-9. [PMID: 16443780 DOI: 10.2337/diabetes.55.02.06.db05-0733] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
C57BL/6 (B6) mice develop glucose intolerance with age, whereas C3H/He (C3H) mice do not. In this study, we examined whether this differential glucose homeostasis was associated with differences of proteolytic activation of pancreatic prohormones. Radioimmunoassays showed comparable levels of fasting plasma insulin between the two strains but a significantly lower glucagon level in B6 mice. Pulse-chase analysis of glucagon biosynthesis in isolated pancreatic islets revealed that proglucagon was less efficiently processed in B6 mice. Because proprotein convertase (PC)2 and its 7B2 helper protein are required for this processing, we quantified islet mRNA levels by RT-PCR and protein levels by immunoblotting. The levels of proPC2 mRNA were similar between the two strains, but B6 protein extracts contained less of the mature PC2. In contrast, 7B2 mRNA and protein levels were both significantly lower in B6 pancreas. Sequencing of the 7B2 gene promoter and cDNA in the two strains revealed seven single nucleotide polymorphisms and one dinucleotide insertion/deletion in the cDNA as well as a single nucleotide polymorphism and two insertions/deletions in the promoter. Differential expression of 7B2 may contribute to the difference between B6 and C3H mice not only in glucagon production and secretion but also in glucose tolerance.
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Affiliation(s)
- Gunther Schmidt
- Diseases of Aging Program, Ottawa Health Research Institute, Ottawa Hospital, University of Ottawa, Ontario, Canada
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Abstract
The prohormone convertases play important roles in the maturation of neuropeptides and peptide hormone precursors. Prohormone convertase-2 (PC2) is the only convertase that requires the expression of another neuroendocrine protein, 7B2, for expression of enzyme activity. In this study, we determined that 7B2 can be phosphorylated in Rin cells (a rat insulinoma cell line) and cultured chromaffin cells, but not in AtT-20 cells (derived from mouse anterior pituitary). Phosphoamino acid analysis of Rin cell 7B2 indicated the presence of phosphorylated serine and threonine. Phosphorylation of Ser115 (located within the minimally active 36-residue peptide) was confirmed by mutagenesis, although Ser115 did not represent the sole residue phosphorylated. Two independent assays were used to investigate the effect of phosphorylated 7B2 on PC2 activation: the ability of 7B2 to bind to pro-PC2 was assessed by co-immunoprecipitation, and activation of pro-PC2 was assessed in a cell-free assay. Phosphorylated 7B2 was unable to bind pro-PC2, and the phosphorylated 7B2 peptide (residues 86-121, known to be the minimally active peptide for pro-PC2 activation) was impaired in its ability to facilitate the generation of PC2 activity in membrane fractions containing pro-PC2. In vitro phosphorylation experiments using Golgi membrane fractions showed that 7B2 could be phosphorylated by endogenous Golgi kinases. Golgi kinase activity was strongly inhibited by the broad-range kinase inhibitor staurosporine and partially inhibited by the protein kinase C inhibitor bisindolylmaleimide I, but not by the other protein kinase A, Ca2+/calmodulin-dependent kinase II, myosin light chain kinase, and protein kinase G inhibitors tested. We conclude that phosphorylation of 7B2 functionally inactivates this protein and suggest that this may be analogous to the phosphorylating inactivation of BiP, which impairs its ability to bind substrate.
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Affiliation(s)
- Sang-Nam Lee
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Böhm M, Eickelmann M, Li Z, Schneider SW, Oji V, Diederichs S, Barsh GS, Vogt A, Stieler K, Blume-Peytavi U, Luger TA. Detection of functionally active melanocortin receptors and evidence for an immunoregulatory activity of alpha-melanocyte-stimulating hormone in human dermal papilla cells. Endocrinology 2005; 146:4635-46. [PMID: 16081629 DOI: 10.1210/en.2005-0665] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Proopiomelanocortin (POMC)-derived peptides and their receptors have been identified in many peripheral organs including the skin in which they exert a diversity of biological actions. We investigated the expression and potential role of the POMC system in human dermal papilla cells (DPCs), a specialized cutaneous mesenchymal cell type regulating hair follicle activity. In culture, these cells expressed POMC and displayed immunoreactivity for ACTH, alphaMSH, and beta-endorphin. Among the prohormone convertases (PCs) tested, only PC2, its chaperone 7B2, and furin convertase but not PC1 and paired basic amino acid cleaving enzyme 4 gene were detected. Human DPCs in vitro expressed both the melanocortin-1 receptor (MC-1R) and MC-4R, and immunoreactivity for these receptors was also present in cells of the human dermal papilla in situ. In contrast to the dermal papilla of agouti mice, agouti signaling protein, a natural and highly selective MC-1R and MC-4R antagonist, was undetectable in human DPCs. The MC-Rs detected in human DPCs were functionally active because alphaMSH increased intracellular cAMP and calcium. Preincubation of the cells with a synthetic peptide corresponding to the C-terminal domain of agouti signaling protein abrogated cAMP induction by alphaMSH. Furthermore, alphaMSH was capable of antagonizing the expression of intercellular adhesion molecule-1 induced by the proinflammatory cytokine interferon-gamma. Our data suggest a regulatory function of alphaMSH within the dermal papilla whose disruption may lead to deregulation of immune and inflammatory responses of the hair follicle, thereby possibly contributing to the development of inflammatory forms of alopecia.
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Affiliation(s)
- Markus Böhm
- Department of Dermatology, University of Münster, Von Esmarch-Str. 58, D-48149 Münster, Germany.
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