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Tarvo Rajasalu - One of the best experts on this subject based on the ideXlab platform.
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deficiency in b7 h1 pd l1 pd 1 coinhibition triggers pancreatic β cell destruction by insulin specific murine cd8 t cells
Diabetes, 2010Co-Authors: Tarvo Rajasalu, Helen Brosi, Cornelia Schuster, Andreas Spyrantis, Bernhard O Boehm, Lieping Chen, Jorg Reimann, Reinhold SchirmbeckAbstract:OBJECTIVE RIP-B7.1 mice expressing the costimulator molecule B7.1 (CD80) on pancreatic β-cells are a well established model to characterize Preproinsulin-specific CD8 T-cell responses and experimental autoimmune diabetes (EAD). Different immunization strategies could prime Preproinsulin-specific CD8 T-cells in wild-type C57BL/6 (B6) mice, but did not induce diabetes. We tested whether altering the B7-H1 (PD-L1) coinhibition on pancreatic β-cells can reveal a diabetogenic potential of Preproinsulin-specific CD8 T-cells. RESEARCH DESIGN AND METHODS DNA-based immunization and adoptive T-cell transfers were used to characterize the induction of Preproinsulin-specific CD8 T-cell responses and EAD in RIP-B7.1, B6, B7-H1 −/− , PD-1 −/− or bone marrow chimeric mice. RESULTS Preproinsulin-specific CD8 T-cells primed in B6 mice revealed their diabetogenic potential after adoptive transfer into congenic RIP-B7.1 hosts. Furthermore, Preproinsulin-specific CD8 T-cells primed in anti-B7-H1 antibody-treated B6 mice, or primed in B7-H1 −/− or PD-1 −/− mice induced EAD. Immunization of bone marrow chimeric mice showed that deficiency of either B7-H.1 in pancreatic β-cells or of PD-1 in autoreactive CD8 T-cells induced EAD. CONCLUSIONS An imbalance between costimulator (B7.1) and coinhibitor (B7-H1) signals on pancreatic β-cells can trigger pancreatic β-cell-destruction by Preproinsulin-specific CD8 T-cells. Hence, regulation of the susceptibility of the β-cells for a Preproinsulin-specific CD8 T-cell attack can allow or suppress EAD.
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Preproinsulin specific cd8 t cells secrete ifnγ in human type 1 diabetes
Annals of the New York Academy of Sciences, 2004Co-Authors: Silvia Rathmann, Tarvo Rajasalu, Bernhard O Boehm, M Schlosser, Silke Rosinger, Thomas Eiermann, Ivana DurinovicbelloAbstract:In animal models autoreactive CD8(+) T cells are crucial in the development of type 1 diabetes (T1D); however, their role in human T1D is still not known. To address the role of CD81 T cells we performed a pilot study by investigating CD8(+) T cell-mediated cytokine secretion after in vitro stimulation with 94 Preproinsulin (PPI) peptides. We were able to show that CD8(+) T cells contribute to a strong IFNgamma reactivity against PPI in human T1D. Further investigations defining epitope specificity, cytokine secretion, and cytotoxic capacity are important to clarify their role in T1D development.
Reinhold Schirmbeck - One of the best experts on this subject based on the ideXlab platform.
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Preproinsulin Designer Antigens Excluded from Endoplasmic Reticulum Suppressed Diabetes Development in NOD Mice by DNA Vaccination
Elsevier, 2019Co-Authors: Katja Stifter, Cornelia Schuster, Andreas Spyrantis, Jana Krieger, Bernhard Otto Boehm, Reinhold SchirmbeckAbstract:DNA vaccines against autoimmune type 1 diabetes (T1D) contain a nonpredictable risk to induce autoreactive T cell responses rather than a protective immunity. Little is known if (and how) antigen expression and processing requirements favor the induction of autoreactive or protective immune responses by DNA immunization. Here, we analyzed whether structural properties of Preproinsulin (ppins) variants and/or subcellular targeting of ppins designer antigens influence the priming of effector CD8+ T cell responses by DNA immunization. Primarily, we used H-2b RIP-B7.1 tg mice, expressing the co-stimulator molecule B7.1 in beta cells, to identify antigens that induce or fail to induce autoreactive ppins-specific (Kb/A12-21 and/or Kb/B22-29) CD8+ T cell responses. Female NOD mice, expressing the diabetes-susceptible H-2g7 haplotype, were used to test ppins variants for their potential to suppress spontaneous diabetes development. We showed that ppins antigens excluded from expression in the endoplasmic reticulum (ER) did not induce CD8+ T cells or autoimmune diabetes in RIP-B7.1 tg mice, but efficiently suppressed spontaneous diabetes development in NOD mice as well as ppins-induced CD8+ T cell-mediated autoimmune diabetes in PD-L1−/− mice. The induction of a ppins-specific therapeutic immunity in mice has practical implications for the design of immune therapies against T1D in individuals expressing different major histocompatibility complex (MHC) I and II molecules. Keywords: type 1 diabetes, mouse models, DNA vaccines, endoplasmic reticulum, Preproinsulin/proinsulin antigen
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deficiency in b7 h1 pd l1 pd 1 coinhibition triggers pancreatic β cell destruction by insulin specific murine cd8 t cells
Diabetes, 2010Co-Authors: Tarvo Rajasalu, Helen Brosi, Cornelia Schuster, Andreas Spyrantis, Bernhard O Boehm, Lieping Chen, Jorg Reimann, Reinhold SchirmbeckAbstract:OBJECTIVE RIP-B7.1 mice expressing the costimulator molecule B7.1 (CD80) on pancreatic β-cells are a well established model to characterize Preproinsulin-specific CD8 T-cell responses and experimental autoimmune diabetes (EAD). Different immunization strategies could prime Preproinsulin-specific CD8 T-cells in wild-type C57BL/6 (B6) mice, but did not induce diabetes. We tested whether altering the B7-H1 (PD-L1) coinhibition on pancreatic β-cells can reveal a diabetogenic potential of Preproinsulin-specific CD8 T-cells. RESEARCH DESIGN AND METHODS DNA-based immunization and adoptive T-cell transfers were used to characterize the induction of Preproinsulin-specific CD8 T-cell responses and EAD in RIP-B7.1, B6, B7-H1 −/− , PD-1 −/− or bone marrow chimeric mice. RESULTS Preproinsulin-specific CD8 T-cells primed in B6 mice revealed their diabetogenic potential after adoptive transfer into congenic RIP-B7.1 hosts. Furthermore, Preproinsulin-specific CD8 T-cells primed in anti-B7-H1 antibody-treated B6 mice, or primed in B7-H1 −/− or PD-1 −/− mice induced EAD. Immunization of bone marrow chimeric mice showed that deficiency of either B7-H.1 in pancreatic β-cells or of PD-1 in autoreactive CD8 T-cells induced EAD. CONCLUSIONS An imbalance between costimulator (B7.1) and coinhibitor (B7-H1) signals on pancreatic β-cells can trigger pancreatic β-cell-destruction by Preproinsulin-specific CD8 T-cells. Hence, regulation of the susceptibility of the β-cells for a Preproinsulin-specific CD8 T-cell attack can allow or suppress EAD.
Bernhard O Boehm - One of the best experts on this subject based on the ideXlab platform.
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deficiency in b7 h1 pd l1 pd 1 coinhibition triggers pancreatic β cell destruction by insulin specific murine cd8 t cells
Diabetes, 2010Co-Authors: Tarvo Rajasalu, Helen Brosi, Cornelia Schuster, Andreas Spyrantis, Bernhard O Boehm, Lieping Chen, Jorg Reimann, Reinhold SchirmbeckAbstract:OBJECTIVE RIP-B7.1 mice expressing the costimulator molecule B7.1 (CD80) on pancreatic β-cells are a well established model to characterize Preproinsulin-specific CD8 T-cell responses and experimental autoimmune diabetes (EAD). Different immunization strategies could prime Preproinsulin-specific CD8 T-cells in wild-type C57BL/6 (B6) mice, but did not induce diabetes. We tested whether altering the B7-H1 (PD-L1) coinhibition on pancreatic β-cells can reveal a diabetogenic potential of Preproinsulin-specific CD8 T-cells. RESEARCH DESIGN AND METHODS DNA-based immunization and adoptive T-cell transfers were used to characterize the induction of Preproinsulin-specific CD8 T-cell responses and EAD in RIP-B7.1, B6, B7-H1 −/− , PD-1 −/− or bone marrow chimeric mice. RESULTS Preproinsulin-specific CD8 T-cells primed in B6 mice revealed their diabetogenic potential after adoptive transfer into congenic RIP-B7.1 hosts. Furthermore, Preproinsulin-specific CD8 T-cells primed in anti-B7-H1 antibody-treated B6 mice, or primed in B7-H1 −/− or PD-1 −/− mice induced EAD. Immunization of bone marrow chimeric mice showed that deficiency of either B7-H.1 in pancreatic β-cells or of PD-1 in autoreactive CD8 T-cells induced EAD. CONCLUSIONS An imbalance between costimulator (B7.1) and coinhibitor (B7-H1) signals on pancreatic β-cells can trigger pancreatic β-cell-destruction by Preproinsulin-specific CD8 T-cells. Hence, regulation of the susceptibility of the β-cells for a Preproinsulin-specific CD8 T-cell attack can allow or suppress EAD.
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Preproinsulin specific cd8 t cells secrete ifnγ in human type 1 diabetes
Annals of the New York Academy of Sciences, 2004Co-Authors: Silvia Rathmann, Tarvo Rajasalu, Bernhard O Boehm, M Schlosser, Silke Rosinger, Thomas Eiermann, Ivana DurinovicbelloAbstract:In animal models autoreactive CD8(+) T cells are crucial in the development of type 1 diabetes (T1D); however, their role in human T1D is still not known. To address the role of CD81 T cells we performed a pilot study by investigating CD8(+) T cell-mediated cytokine secretion after in vitro stimulation with 94 Preproinsulin (PPI) peptides. We were able to show that CD8(+) T cells contribute to a strong IFNgamma reactivity against PPI in human T1D. Further investigations defining epitope specificity, cytokine secretion, and cytotoxic capacity are important to clarify their role in T1D development.
Shinichi Oikawa - One of the best experts on this subject based on the ideXlab platform.
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oxidized but not acetylated low density lipoprotein reduces Preproinsulin mrna expression and secretion of insulin from hit t15 cells
Biochimica et Biophysica Acta, 2005Co-Authors: Fumitaka Okajima, Mikiko Kurihara, Yasushi Nakajima, K Tanimura, Hitoshi Sugihara, Atsushi Tatsuguchi, Kiyotaka Nakagawa, Teruo Miyazawa, Shinichi OikawaAbstract:Abstract We examined the effect of oxidized low-density lipoprotein (oxLDL) on the insulin secretion in the culture of HIT-T15 cell line, an islet β-cell line derived from a hamster pancreatic tumor. In order to check the uptake of modified LDL by HIT-T15 cells, we prepared DiI-labeled native LDL (nLDL), acetylated LDL (AcLDL), and oxLDL. After the addition of each LDL into the cultures of HIT-T15 cells, fluorescence microscopic study was done. It was suggested that AcLDL and oxLDL were taken up by HIT-T15 cells, as well as nLDL. mRNA expression of the LDL receptor, CD36, and SR-B1 was detected in HIT-T15 by RT-PCR. The medium insulin level was measured in the culture of HIT-T15 cells with each LDL. oxLDL significantly reduced the insulin secretion stimulated by various concentrations of glucose, the intracellular content of insulin, and the expression of Preproinsulin mRNA compared to the control cultures without LDL addition. In contrast, nLDL and AcLDL had no effect on the insulin secretion, the intracellular insulin level, or the expression of Preproinsulin mRNA. MTT assay findings (reflecting cell numbers) were not different between cultures with and without LDLs. These results indicated that oxLDL disturbed the insulin metabolism of HIT-T15 cells.
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oxidized but not acetylated low density lipoprotein reduces Preproinsulin mrna expression and secretion of insulin from hit t15 cells
Biochimica et Biophysica Acta, 2005Co-Authors: Fumitaka Okajima, Mikiko Kurihara, Yasushi Nakajima, K Tanimura, Hitoshi Sugihara, Atsushi Tatsuguchi, Kiyotaka Nakagawa, Teruo Miyazawa, Chihaya Ono, Shinichi OikawaAbstract:We examined the effect of oxidized low-density lipoprotein (oxLDL) on the insulin secretion in the culture of HIT-T15 cell line, an islet beta-cell line derived from a hamster pancreatic tumor. In order to check the uptake of modified LDL by HIT-T15 cells, we prepared DiI-labeled native LDL (nLDL), acetylated LDL (AcLDL), and oxLDL. After the addition of each LDL into the cultures of HIT-T15 cells, fluorescence microscopic study was done. It was suggested that AcLDL and oxLDL were taken up by HIT-T15 cells, as well as nLDL. mRNA expression of the LDL receptor, CD36, and SR-B1 was detected in HIT-T15 by RT-PCR. The medium insulin level was measured in the culture of HIT-T15 cells with each LDL. oxLDL significantly reduced the insulin secretion stimulated by various concentrations of glucose, the intracellular content of insulin, and the expression of Preproinsulin mRNA compared to the control cultures without LDL addition. In contrast, nLDL and AcLDL had no effect on the insulin secretion, the intracellular insulin level, or the expression of Preproinsulin mRNA. MTT assay findings (reflecting cell numbers) were not different between cultures with and without LDLs. These results indicated that oxLDL disturbed the insulin metabolism of HIT-T15 cells.
Peter Arvan - One of the best experts on this subject based on the ideXlab platform.
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requirement for translocon associated protein trap α in insulin biogenesis
Science Advances, 2019Co-Authors: Omar A Itani, Leena Haataja, Peter Arvan, Kathleen J Dumas, Jing Yang, Jeeyeon Cha, Stephane Flibotte, Hungjen Shih, Colin Delaney, Ming LiuAbstract:The mechanistic basis for the biogenesis of peptide hormones and growth factors is poorly understood. Here, we show that the conserved endoplasmic reticulum membrane translocon-associated protein α (TRAPα), also known as signal sequence receptor 1, plays a critical role in the biosynthesis of insulin. Genetic analysis in the nematode Caenorhabditis elegans and biochemical studies in pancreatic β cells reveal that TRAPα deletion impairs Preproinsulin translocation while unexpectedly disrupting distal steps in insulin biogenesis including proinsulin processing and secretion. The association of common intronic single-nucleotide variants in the human TRAPα gene with susceptibility to type 2 diabetes and pancreatic β cell dysfunction suggests that impairment of Preproinsulin translocation and proinsulin trafficking may contribute to the pathogenesis of type 2 diabetes.
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requirement for translocon associated protein trap α in insulin biogenesis
bioRxiv, 2019Co-Authors: Omar A Itani, Ming Liu, Leena Haataja, Peter Arvan, Kathleen J Dumas, Jing Yang, Jeeyeon Cha, Stephane Flibotte, Hungjen ShihAbstract:The mechanistic basis for the biogenesis of peptide hormones and growth factors is poorly understood. Here we show that the conserved endoplasmic reticulum (ER) membrane translocon-associated protein (TRAP) α, also known as signal sequence receptor 1 (SSR1)1, plays a critical role in the biosynthesis of insulin. A genetic screen in the nematode Caenorhabditis elegans revealed trap-1, which encodes the C. elegans TRAPα ortholog, as a modifier of DAF-2 insulin receptor (InsR) signaling. Genetic analysis indicates that TRAP-1 acts upstream of DAF-2/InsR to control C. elegans development. Endogenous C. elegans TRAP-1 and mammalian TRAPα both localized to the ER. In pancreatic beta cells, TRAPα deletion impaired Preproinsulin translocation but did not affect the synthesis of α1-antitrypsin, indicating that TRAPα selectively influences the translocation of a subset of secreted proteins. Surprisingly, loss of TRAPα function also resulted in disruption of distal steps in insulin biogenesis including proinsulin processing and secretion. These results show that TRAPα assists in the ER translocation of Preproinsulin and unveil unanticipated additional consequences of TRAPα loss-of-function on the intracellular trafficking and maturation of proinsulin. The association of common intronic single nucleotide variants in the human TRAPα gene with susceptibility to Type 2 diabetes and pancreatic beta cell dysfunction2 suggests that impairment of Preproinsulin translocation and proinsulin trafficking may contribute to the pathogenesis of Type 2 diabetes.
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ins gene mutations from genetics and beta cell biology to clinical disease
Molecular Aspects of Medicine, 2015Co-Authors: Ming Liu, Fabrizio Barbetti, Huan Guo, Jinhong Sun, Jinqiu Cui, Wei Chen, Peter ArvanAbstract:A growing list of insulin gene mutations causing a new form of monogenic diabetes has drawn increasing attention over the past seven years. The mutations have been identified in the untranslated regions of the insulin gene as well as the coding sequence of Preproinsulin including within the signal peptide, insulin B-chain, C-peptide, insulin A-chain, and the proteolytic cleavage sites both for signal peptidase and the prohormone convertases. These mutations affect a variety of different steps of insulin biosynthesis in pancreatic beta cells. Importantly, although many of these mutations cause proinsulin misfolding with early onset autosomal dominant diabetes, some of the mutant alleles appear to engage different cellular and molecular mechanisms that underlie beta cell failure and diabetes. In this article, we review the most recent advances in the field and discuss challenges as well as potential strategies to prevent/delay the development and progression of autosomal dominant diabetes caused by INS-gene mutations. It is worth noting that although diabetes caused by INS gene mutations is rare, increasing evidence suggests that defects in the pathway of insulin biosynthesis may also be involved in the progression of more common types of diabetes. Collectively, the (pre)proinsulin mutants provide insightful molecular models to better understand the pathogenesis of all forms of diabetes in which Preproinsulin processing defects, proinsulin misfolding, and ER stress are involved.
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proinsulin entry and transit through the endoplasmic reticulum in pancreatic beta cells
Vitamins and Hormones Series, 2014Co-Authors: Ming Liu, Jordan J Wright, Huan Guo, Yi Xiong, Peter ArvanAbstract:Insulin is an essential hormone for maintaining metabolic homeostasis in the body. To make fully bioactive insulin, pancreatic beta cells initiate synthesis of the insulin precursor, Preproinsulin, at the cytosolic side of the endoplasmic reticulum (ER), whereupon it undergoes co- and post-translational translocation across the ER membrane. Preproinsulin is cleaved by signal peptidase to form proinsulin that folds on the luminal side of the ER, forming three evolutionarily conserved disulfide bonds. Properly folded proinsulin forms dimers and exits from the ER, trafficking through Golgi complex into immature secretory granules wherein C-peptide is endoproteolytically excised, allowing fully bioactive two-chain insulin to ultimately be stored in mature granules for insulin secretion. Although insulin biosynthesis has been intensely studied in recent decades, the earliest events, including proinsulin entry and exit from the ER, have been relatively understudied. However, over the past 5 years, more than 20 new insulin gene mutations have been reported to cause a new syndrome termed Mutant INS-gene-induced Diabetes of Youth (MIDY). Although these mutants have not been completely characterized, most of them affect proinsulin entry and exit from the ER. Here, we summarize our current knowledge about the early events of insulin biosynthesis and review recent advances in understanding how defects in these events may lead to pancreatic beta cell failure.
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impaired cleavage of Preproinsulin signal peptide linked to autosomal dominant diabetes
Diabetes, 2012Co-Authors: Ming Liu, Leena Haataja, Roberto Laralemus, Shuou Shan, Jordan J Wright, Fabrizio Barbetti, Huan Guo, Dennis Larkin, Peter ArvanAbstract:Recently, missense mutations upstream of Preproinsulin’s signal peptide (SP) cleavage site were reported to cause mutant INS gene-induced diabetes of youth (MIDY). Our objective was to understand the molecular pathogenesis using metabolic labeling and assays of proinsulin export and insulin and C-peptide production to examine the earliest events of insulin biosynthesis, highlighting molecular mechanisms underlying β-cell failure plus a novel strategy that might ameliorate the MIDY syndrome. We find that whereas Preproinsulin-A(SP23)S is efficiently cleaved, producing authentic proinsulin and insulin, Preproinsulin-A(SP24)D is inefficiently cleaved at an improper site, producing two subpopulations of molecules. Both show impaired oxidative folding and are retained in the endoplasmic reticulum (ER). Preproinsulin-A(SP24)D also blocks ER exit of coexpressed wild-type proinsulin, accounting for its dominant-negative behavior. Upon increased expression of ER–oxidoreductin-1, Preproinsulin-A(SP24)D remains blocked but oxidative folding of wild-type proinsulin improves, accelerating its ER export and increasing wild-type insulin production. We conclude that the efficiency of SP cleavage is linked to the oxidation of (pre)proinsulin. In turn, impaired (pre)proinsulin oxidation affects ER export of the mutant as well as that of coexpressed wild-type proinsulin. Improving oxidative folding of wild-type proinsulin may provide a feasible way to rescue insulin production in patients with MIDY.