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Kim MK, Shin HM, Jung H, Lee E, Kim TK, Kim TN, Kwon MJ, Lee SH, Rhee BD, Park JH. Comparison of pancreatic beta cells and alpha cells under hyperglycemia: Inverse coupling in pAkt-FoxO1. Diabetes Res Clin Pract 2017; 131:1-11. [PMID: 28666105 DOI: 10.1016/j.diabres.2017.05.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 05/04/2017] [Accepted: 05/16/2017] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes manifests beta cell deficiencies and alpha cell expansion which is consistent with relative insulin deficiency and glucagon oversecretion. The effects of hyperglycemia on alpha cells are not as understood in comparison to beta cells. Hyperglycemia increases oxidative stress, which induces Akt activation or FoxO activation, depending on cell type. Several studies independently reported that FoxO1 translocations in alpha cells and beta cells were opposite. We compared the responses of pancreatic alpha cells and beta cells against hyperglycemia. Alpha TC-1 cells and Beta TC-6 cells were incubated with control (5mM Glucose) or high glucose (33mM Glucose) with or without PI3K inhibitor or FoxO1 inhibitor. We assessed PI3K, pAkt and phosphorylated FoxO1 (pFoxO1) in both cell lines. Immunostaining of BrdU and FoxO1 was detected by green fluorescence microscopy and confocal microscopy. Hyperglycemia and H2O2 decreased PI3K and pAKT in beta cells, but increased them in alpha cells. FoxO1 localizations and pFoxO1 expressions between alpha cells and beta cells were opposite. Proliferation of beta cells was decreased, but alpha cell proliferation was increased under hyperglycemia. Antioxidant enzymes including superoxide dismutase (SOD) and catalase were increased in beta cells and they were reversed with FoxO1 inhibitor treatment. Increased proliferation in alpha cells under hyperglycemia was attenuated with PI3K inhibitor. In conclusion, hyperglycemia increased alpha cell proliferation and glucagon contents which are opposite to beta cells. These differences may be related to contrasting PI3K/pAkt changes in both cells and subsequent FoxO1 modulation.
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Affiliation(s)
- Mi-Kyung Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea; Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, South Korea.
| | - Hyun Mi Shin
- Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, South Korea
| | - HyeSook Jung
- Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, South Korea
| | - EunJu Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Tae Kyoon Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Tae Nyun Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Min Jeong Kwon
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Soon Hee Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Byoung Doo Rhee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Jeong Hyun Park
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea; Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, South Korea
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Lee YS, Kobayashi M, Kikuchi O, Sasaki T, Yokota-Hashimoto H, Susanti VY, Ido Kitamura Y, Kitamura T. ATF3 expression is induced by low glucose in pancreatic α and β cells and regulates glucagon but not insulin gene transcription. Endocr J 2014; 61:85-90. [PMID: 24140652 DOI: 10.1507/endocrj.ej13-0383] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [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] [Indexed: 11/23/2022] Open
Abstract
The pancreas is critical for maintaining glucose homeostasis. Activating transcription factor 3 (ATF3) is an adaptive response transcription factor. There are major discrepancies in previous reports on pancreatic ATF3; therefore, its role in the pancreas is unclear. To better elucidate the role of ATF3 in the pancreas, we conducted in vitro studies using pancreatic α and β cell lines, and also evaluated the use of ATF3 antibodies for immunohistochemistry. We determined ATF3 expression was increased by low glucose and decreased by high glucose in both αTC-1.6 and βTC3 cells. We also showed that adenovirus-mediated ATF3 overexpression increased glucagon promoter activity and glucagon mRNA levels in αTC-1.6 cells; whereas, it had no effect on insulin promoter activity and insulin mRNA levels in βTC3 cells. Although immunostaining with the C-19 ATF3 antibody demonstrated predominant expression in α cells rather than β cells, ATF3 staining was still detected in ATF3 knockout mice as clearly as in control mice. On the other hand, another ATF3 antibody (H-90) detected ATF3 in both α cells and β cells, and was clearly diminished in ATF3 knockout mice. These results indicate that previous discrepancies in ATF3 expression patterns in the pancreas were caused by the varying specificities of the ATF3 antibodies used, and that ATF3 is actually expressed in both α cells and β cells.
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Affiliation(s)
- Yong-Soo Lee
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
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Kawamori D. [Dysregulation of glucagon secretion in diabetes and intra-islet insulin effect on alpha-cells]. Nihon Rinsho 2012; 70 Suppl 3:212-217. [PMID: 22768522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Dan Kawamori
- Department of Metabolic Medicine, Graduate School of Medicine/Medical Education Center, Faculty of Medicine, Osaka University
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Ito A, Ichiyanagi N, Ikeda Y, Hagiyama M, Inoue T, Kimura KB, Sakurai MA, Hamaguchi K, Murakami Y. Adhesion molecule CADM1 contributes to gap junctional communication among pancreatic islet α-cells and prevents their excessive secretion of glucagon. Islets 2012; 4:49-55. [PMID: 22513384 DOI: 10.4161/isl.18675] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Cell adhesion molecule-1 (CADM1) is a recently identified adhesion molecule of pancreatic islet α-cells that mediates nerve-α-cell interactions via trans-homophilic binding and serves anatomical units for the autonomic control of glucagon secretion. CADM1 also mediates attachment between adjacent α-cells. Since gap junctional intercellular communication (GJIC) among islet cells is essential for islet hormone secretion, we examined whether CADM1 promotes GJIC among α-cells and subsequently participates in glucagon secretion regulation. Dye transfer assays using αTC6 mouse α-cells, which endogenously express CADM1, supported this possibility; efficient cell-to-cell spread of gap junction-permeable dye was detected in clusters of αTC6 cells transfected with nonspecific, but not with CADM1-targeting, siRNA. Immunocytochemical analysis of connexin 36, a major component of the gap junction among αTC6 cells, revealed that it was localized exclusively to the cell membrane in CADM1-non-targeted αTC6 cells, but diffusely to the cytoplasm in CADM1-targeted cells. Next, we incubated CADM1-targeted and non-targeted αTC6 cells in a medium containing 1 mM glucose and 200 mM arginine for 30 min to induce glucagon secretion, and found that the targeted cells secreted three times more glucagon than did the non-targeted. We conducted similar experiments using pancreatic islets that were freshly isolated from wild-type and CADM1-knockout mice, and expressed glucagon secretion as ratios relative to baseline values. The increase in ratio was larger in CADM1-knockout islets than in wild-type islets. These results suggest that CADM1 may serve as a volume limiter of glucagon secretion by sustaining α-cell attachment necessary for efficient GJIC.
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Affiliation(s)
- Akihiko Ito
- Division of Molecular Pathology; Institute of Medical Science; University of Tokyo; Tokyo, Japan; Department of Pathology; Faculty of Medicine; Kinki University; Osaka, Japan
| | - Naoki Ichiyanagi
- Division of Molecular Pathology; Institute of Medical Science; University of Tokyo; Tokyo, Japan
| | - Yuki Ikeda
- Division of Molecular Pathology; Institute of Medical Science; University of Tokyo; Tokyo, Japan
| | - Man Hagiyama
- Division of Molecular Pathology; Institute of Medical Science; University of Tokyo; Tokyo, Japan; Department of Pathology; Faculty of Medicine; Kinki University; Osaka, Japan
| | - Takao Inoue
- Department of Pathology; Faculty of Medicine; Kinki University; Osaka, Japan
| | - Keiko B Kimura
- Division of Molecular Pathology; Institute of Medical Science; University of Tokyo; Tokyo, Japan
| | - Minami A Sakurai
- Department of Pathology; Faculty of Medicine; Kinki University; Osaka, Japan; Department of Molecular Genetics; Research Institute for Microbial Diseases; Osaka University; Osaka, Japan
| | - Kazuyuki Hamaguchi
- Department of Community Health and Gerontological Nursing; Faculty of Medicine; Oita University; Oita, Japan
| | - Yoshinori Murakami
- Division of Molecular Pathology; Institute of Medical Science; University of Tokyo; Tokyo, Japan
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Abstract
OBJECTIVES Intranuclear rodlets (INRs) are rod-shaped intranuclear inclusions that we have described in neurons of the human brain. We recently identified these structures in pancreatic islet cells. The objectives of this study are to describe the light microscopic features and cellular pattern of distribution of INRs in human pancreatic islet cells. METHODS Double immunofluorescence staining was performed on 5 human pancreatic tissue samples for the detection of class III beta tubulin (C3T) to detect INRs and for promyelocytic leukemia (PML) protein to examine the relationship between PML and INRs. RESULTS Intranuclear rodlets were detected in 22.99% of pancreatic B cells compared with only 3.11%, 1.80%, and 1.60% of A, D, and PP cells, respectively. Twenty-four percent of C3T-immunoreactive INRs showed partial or complete immunoreactivity for PML. Promyelocytic leukemia staining within the nuclei of B cells was confined to INRs and was not present in the typical PML bodies present in other cell types. Spatially, PML and C3T staining of islet cell INRs appeared to be mutually exclusive within individual INRs. CONCLUSIONS Intranuclear rodlets are present within the nuclei of pancreatic islet cells, where they reside predominantly but not exclusively in B cells. Immunoreactivity of B-cell INRs for PML suggests that the functional significance of INRs may be related to that of PML and/or PML bodies. Conversely, the exclusive localization of PML staining to INRs in B cells indicates that PML's function in B cells is selectively associated with INRs. The mutually exclusive pattern of PML and C3T staining suggests dynamic interactions between these 2 proteins in B-cell INRs. In light of evidence for the involvement of INRs and of PML bodies in disease, it will be of interest to investigate these structures in animal models of diabetes and in human diabetes.
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Affiliation(s)
- Wendy Prichett
- Centre for Cancer Therapeutics, The Ottawa Health Research Institute, Ottawa, Ontario, Canada
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Sahloul R, Yaqub N, Driscoll HK, Leidy JW, Parkash J, Matthews KA, Chertow BS. Noninsulinoma pancreatogenous hypoglycemia syndrome: quantitative and immunohistochemical analyses of islet cells for insulin, glucagon, somatostatin, and pancreatic and duodenal homeobox protein. Endocr Pract 2007; 13:187-93. [PMID: 17490935 DOI: 10.4158/ep.13.2.187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [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: 11/15/2022]
Abstract
OBJECTIVE To present a case of an elderly man with noninsulinoma pancreatogenous hypoglycemia syndrome (NIPHS) and to determine the pathogenesis of this syndrome. METHODS The pancreas of our patient with NIPHS was immunocytochemically stained for insulin-, glucagon-, and somatostatin-secreting cells and pancreatic and duodenal homeobox protein (PDX-1). The clinical findings and morphologic and immunocytochemical analyses of the islets of our patient are described, along with a review of related published reports. RESULTS A 78-year-old man presented with hyperinsulinemic hypoglycemia, with episodes unrelated to meals or fasting. An insulinoma could not be localized by preoperative imaging or by intraoperative ultrasonography or palpation. He underwent a 70% distal pancreatectomy. For assessment of the possibility that a nuclear transcription factor regulating islet beta-cell growth and development is overexpressed in this disease and is responsible for diffuse islet hyperfunction and proliferation of beta-cells, pancreatic sections from our patient were stained immunocytochemically for PDX-1, insulin, glucagon, and somatostatin. Morphologic findings were compared with pancreatic sections from normal control patients and normative data reported in the literature. Clinical findings and morphologic analyses were consistent with NIPHS. Islets were arranged in long clusters, both in the pancreatic tissue and in peripancreatic adipose tissue. Islets were small but increased in number, and insulin, glucagon, and somatostatin were present in the islets. The relative intensity of insulin staining was increased in our patient in comparison with that in the control patients, and PDX-1 was not overexpressed. CONCLUSION The etiopathogenesis of NIPHS in this patient involved (1) an increased number of islets with development of ectopic islets in the peripancreatic adipose tissue; (2) alpha- and delta- as well as beta-cell proliferation; and (3) an early step in the development of the islet not involving overexpression of PDX-1.
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Affiliation(s)
- Raghda Sahloul
- Section of Endocrinology and Metabolism, Department of Medicine, Marshall University, VA Medical Center Medical Service, Huntington, West Virginia 25701-3655, USA
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Buchanan CM, Malik AS, Cooper GJS. Direct visualisation of peptide hormones in cultured pancreatic islet alpha- and beta-cells by intact-cell mass spectrometry. Rapid Commun Mass Spectrom 2007; 21:3452-3458. [PMID: 17918213 DOI: 10.1002/rcm.3253] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The application of intact-cell mass spectrometry (ICM) by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry to achieve direct protein-profiling of bacterial species is now well established. However, this methodology has not to our knowledge been applied to the analysis of mammalian cells in routine culture. Here, we describe a novel application of ICM by which we have identified proteins in intact cells from two lines representative of pancreatic islet alpha- and beta-cells. Adherent alphaTC1 clone 9 and betaTC6 F7 cells were harvested into phosphate-buffered saline (PBS) using enzyme-free dissociation buffer before 1 microL of cell suspension was spotted onto MALDI plates. Cells were overlaid with sinapinic acid then washed with pure water before application of a final coat of sinapinic acid. Data in the 2000-20,000 m/z range were acquired in linear mode on a Voyager DE-Pro mass spectrometer. The proteins which ionised were composed in large part of peptide hormones (e.g. insulin and glucagon) known to be packaged into the secretory granules of the beta- and alpha-cells respectively. However, in addition to visualising the peptides expected to be associated with these cells, a mass consistent with oxyntomodulin was identified in the cultured alpha-cells, a finding not previously reported to our knowledge. In summary, this paper describes, for the first time, a rapid and direct method useful for identifying secretory products in intact endocrine cells.
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Affiliation(s)
- Christina M Buchanan
- School of Biological Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, Faculty of Science, University of Auckland, Private Bag 92-019, Auckland, New Zealand
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Yu M, Kasai K, Nagashima K, Torii S, Yokota-Hashimoto H, Okamoto K, Takeuchi T, Gomi H, Izumi T. Exophilin4/Slp2-a targets glucagon granules to the plasma membrane through unique Ca2+-inhibitory phospholipid-binding activity of the C2A domain. Mol Biol Cell 2006; 18:688-96. [PMID: 17182843 PMCID: PMC1783794 DOI: 10.1091/mbc.e06-10-0914] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Rab27a and Rab27b have recently been recognized to play versatile roles in regulating the exocytosis of secretory granules and lysosome-related organelles by using multiple effector proteins. However, the precise roles of these effector proteins in particular cell types largely remain uncharacterized, except for those in pancreatic beta cells and in melanocytes. Here, we showed that one of the Rab27a/b effectors, exophilin4/Slp2-a, is specifically expressed in pancreatic alpha cells, in contrast to another effector, granuphilin, in beta cells. Like granuphilin toward insulin granules, exophilin4 promotes the targeting of glucagon granules to the plasma membrane. Although the interaction of granuphilin with syntaxin-1a is critical for the targeting activity, exophilin4 does this primarily through the affinity of its C2A domain toward the plasma membrane phospholipids phosphatidylserine and phosphatidylinositol-4,5-bisphosphate. Notably, the binding activity to phosphatidylserine is inhibited by a physiological range of the Ca(2+) concentration attained after secretagogue stimulation, which presents a striking contrast to the Ca(2+)-stimulatory activity of the C2A domain of synaptotagmin I. Analyses of the mutant suggested that this novel Ca(2+)-inhibitory phospholipid-binding activity not only mediates docking but also modulates the subsequent fusion of the secretory granules.
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Affiliation(s)
- Miao Yu
- *Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; and
| | - Kazuo Kasai
- *Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; and
| | - Kazuaki Nagashima
- *Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; and
- Department of Neurology, Gunma University School of Medicine, Maebashi 371-8511, Japan
| | - Seiji Torii
- *Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; and
| | - Hiromi Yokota-Hashimoto
- *Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; and
| | - Koichi Okamoto
- Department of Neurology, Gunma University School of Medicine, Maebashi 371-8511, Japan
| | - Toshiyuki Takeuchi
- *Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; and
| | - Hiroshi Gomi
- *Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; and
| | - Tetsuro Izumi
- *Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; and
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Jacobson DA, Cho J, Landa LR, Tamarina NA, Roe MW, Buxbaum JD, Philipson LH. Downstream regulatory element antagonistic modulator regulates islet prodynorphin expression. Am J Physiol Endocrinol Metab 2006; 291:E587-95. [PMID: 16621893 DOI: 10.1152/ajpendo.00612.2005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calcium-binding proteins regulate transcription and secretion of pancreatic islet hormones. Here, we demonstrate neuroendocrine expression of the calcium-binding downstream regulatory element antagonistic modulator (DREAM) and its role in glucose-dependent regulation of prodynorphin (PDN) expression. DREAM is distributed throughout beta- and alpha-cells in both the nucleus and cytoplasm. As DREAM regulates neuronal dynorphin expression, we determined whether this pathway is affected in DREAM(-/-) islets. Under low glucose conditions, with intracellular calcium concentrations of <100 nM, DREAM(-/-) islets had an 80% increase in PDN message compared with controls. Accordingly, DREAM interacts with the PDN promoter downstream regulatory element (DRE) under low calcium (<100 nM) conditions, inhibiting PDN transcription in beta-cells. Furthermore, beta-cells treated with high glucose (20 mM) show increased cytoplasmic calcium (approximately 200 nM), which eliminates DREAM's interaction with the DRE, causing increased PDN promoter activity. As PDN is cleaved into dynorphin peptides, which stimulate kappa-opioid receptors expressed predominantly in alpha-cells of the islet, we determined the role of dynorphin A-(1-17) in glucagon secretion from the alpha-cell. Stimulation with dynorphin A-(1-17) caused alpha-cell calcium fluctuations and a significant increase in glucagon release. DREAM(-/-) islets also show elevated glucagon secretion in low glucose compared with controls. These results demonstrate that PDN transcription is regulated by DREAM in a calcium-dependent manner and suggest a role for dynorphin regulation of alpha-cell glucagon secretion. The data provide a molecular basis for opiate stimulation of glucagon secretion first observed over 25 years ago.
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