1
|
Yang H, Wang S, Ye Y, Xie M, Li Y, Jin H, Li J, Gao L. GLP-1 preserves β cell function via improvement on islet insulin signaling in high fat diet feeding mice. Neuropeptides 2021; 85:102110. [PMID: 33307381 DOI: 10.1016/j.npep.2020.102110] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 11/17/2020] [Accepted: 11/18/2020] [Indexed: 10/22/2022]
Abstract
BACKGROUND Numerous studies have shown that Glucagon like peptide-1 (GLP-1) treatment can protect β cell function, but the exact mechanism remains unclear. We hypothesized that GLP-1 may protect β cell function via its action on insulin signaling pathway. METHODS Mice were fed with high fat diet (HFD, 20 weeks) in the presence or absence of GLP-1 receptor agonist (exenatide) treatment. The islet structure was demonstrated by HE staining. Immunofluorescence antibodies targeting insulin and glucagon were used to illustrate α and β cell distribution. The insulin and glucagon abundance was measured by ELISA using pancreatic homogenates. The molecules involved in insulin signaling pathway (IRc, IRS1, IRS2, mTOR) in islet were examined with immunohistochemistry and immunoblotting. The effect of IRS1 silencing on mTOR and apoptosis were examined on NIT cells(β cell line)with immunoblotting and flow cytometry. RESULTS HE and immunofluorescence staining demonstrated that the normal structure of islet was deformed in HFD mice but preserved by exenatide. Insulin and glucagon contents were increased in islet and blood stream of HFD mice (HFD vs. Control, p<0.05) but resumed by exenatide. Meanwhile the expressions of IRc, IRS-1, mTOR from insulin signaling pathway and β cell apoptosis in the pancreas were significantly reduced (p<0.05) by HFD but reversed by exenatide. CONCLUSION Exenatide improved insulin signaling pathway that was suppressed by HFD in mice islet. Our results reveal a novel mechanism of the protective effects of GLP-1 on β cell function.
Collapse
Affiliation(s)
- Heng Yang
- Department of Endocrinology, Renmin Hospital of Wuhan University, 430060, China
| | - Shuo Wang
- Department of Endocrinology, Renmin Hospital of Wuhan University, 430060, China
| | - Yingchun Ye
- Department of Endocrinology, Renmin Hospital of Wuhan University, 430060, China
| | - Min Xie
- Department of Endocrinology, Renmin Hospital of Wuhan University, 430060, China
| | - Yubin Li
- Department of Endocrinology, Renmin Hospital of Wuhan University, 430060, China
| | - Hong Jin
- Department of Endocrinology, Renmin Hospital of Wuhan University, 430060, China
| | - Jing Li
- Department of Endocrinology, Renmin Hospital of Wuhan University, 430060, China
| | - Ling Gao
- Department of Endocrinology, Renmin Hospital of Wuhan University, 430060, China.
| |
Collapse
|
2
|
Abstract
Diabetes develops due to deficient functional β cell mass, insulin resistance, or both. Yet, various challenges in understanding the mechanisms underlying diabetes development in vivo remain to be overcome owing to the lack of appropriate intravital imaging technologies. To meet these challenges, we have exploited the anterior chamber of the eye (ACE) as a novel imaging site to understand diabetes basics and clinics in vivo. We have developed a technology platform transplanting pancreatic islets into the ACE where they later on can be imaged non-invasively for long time. It turns out that the ACE serves as an optimal imaging site and provides implanted islets with an oxygen-rich milieu and an immune-privileged niche where they undergo optimal engraftment, rich vascularization and dense innervation, preserve organotypic features and live with satisfactory viability and functionality. The ACE technology has led to a series of significant observations. It enables in vivo microscopy of islet cytoarchitecture, function and viability in the physiological context and intravital imaging of a variety of pathological events such as autoimmune insulitis, defects in β cell function and mass and insulin resistance during diabetes development in a real-time manner. Furthermore, application of the ACE technology in humanized mice and non-human primates verifies translational and clinical values of the technology. In this article, we describe the ACE technology in detail, review accumulated knowledge gained by means of the ACE technology and delineate prospective avenues for the ACE technology.
Collapse
|
3
|
Boothe T, Lim GE, Cen H, Skovsø S, Piske M, Li SN, Nabi IR, Gilon P, Johnson JD. Inter-domain tagging implicates caveolin-1 in insulin receptor trafficking and Erk signaling bias in pancreatic beta-cells. Mol Metab 2016; 5:366-378. [PMID: 27110488 PMCID: PMC4837300 DOI: 10.1016/j.molmet.2016.01.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 01/18/2016] [Accepted: 01/25/2016] [Indexed: 01/04/2023] Open
Abstract
OBJECTIVE The role and mechanisms of insulin receptor internalization remain incompletely understood. Previous trafficking studies of insulin receptors involved fluorescent protein tagging at their termini, manipulations that may be expected to result in dysfunctional receptors. Our objective was to determine the trafficking route and molecular mechanisms of functional tagged insulin receptors and endogenous insulin receptors in pancreatic beta-cells. METHODS We generated functional insulin receptors tagged with pH-resistant fluorescent proteins between domains. Confocal, TIRF and STED imaging revealed a trafficking pattern of inter-domain tagged insulin receptors and endogenous insulin receptors detected with antibodies. RESULTS Surprisingly, interdomain-tagged and endogenous insulin receptors in beta-cells bypassed classical Rab5a- or Rab7-mediated endocytic routes. Instead, we found that removal of insulin receptors from the plasma membrane involved tyrosine-phosphorylated caveolin-1, prior to trafficking within flotillin-1-positive structures to lysosomes. Multiple methods of inhibiting caveolin-1 significantly reduced Erk activation in vitro or in vivo, while leaving Akt signaling mostly intact. CONCLUSIONS We conclude that phosphorylated caveolin-1 plays a role in insulin receptor internalization towards lysosomes through flotillin-1-positive structures and that caveolin-1 helps bias physiological beta-cell insulin signaling towards Erk activation.
Collapse
Affiliation(s)
- Tobias Boothe
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Gareth E Lim
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Haoning Cen
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Søs Skovsø
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Micah Piske
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Shu Nan Li
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Ivan R Nabi
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Patrick Gilon
- Pôle d'endocrinologie, diabète et nutrition, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | - James D Johnson
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada.
| |
Collapse
|
4
|
Berchtold LA, Prause M, Størling J, Mandrup-Poulsen T. Cytokines and Pancreatic β-Cell Apoptosis. Adv Clin Chem 2016; 75:99-158. [PMID: 27346618 DOI: 10.1016/bs.acc.2016.02.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The discovery 30 years ago that inflammatory cytokines cause a concentration, activity, and time-dependent bimodal response in pancreatic β-cell function and viability has been a game-changer in the fields of research directed at understanding inflammatory regulation of β-cell function and survival and the causes of β-cell failure and destruction in diabetes. Having until then been confined to the use of pathophysiologically irrelevant β-cell toxic chemicals as a model of β-cell death, researchers could now mimic endocrine and paracrine effects of the cytokine response in vitro by titrating concentrations in the low to the high picomolar-femtomolar range and vary exposure time for up to 14-16h to reproduce the acute regulatory effects of systemic inflammation on β-cell secretory responses, with a shift to inhibition at high picomolar concentrations or more than 16h of exposure to illustrate adverse effects of local, chronic islet inflammation. Since then, numerous studies have clarified how these bimodal responses depend on discrete signaling pathways. Most interest has been devoted to the proapoptotic response dependent upon mainly nuclear factor κ B and mitogen-activated protein kinase activation, leading to gene expressional changes, endoplasmic reticulum stress, and triggering of mitochondrial dysfunction. Preclinical studies have shown preventive effects of cytokine antagonism in animal models of diabetes, and clinical trials demonstrating proof of concept are emerging. The full clinical potential of anticytokine therapies has yet to be shown by testing the incremental effects of appropriate dosing, timing, and combinations of treatments. Due to the considerable translational importance of enhancing the precision, specificity, and safety of antiinflammatory treatments of diabetes, we review here the cellular, preclinical, and clinical evidence of which of the death pathways recently proposed in the Nomenclature Committee on Cell Death 2012 Recommendations are activated by inflammatory cytokines in the pancreatic β-cell to guide the identification of antidiabetic targets. Although there are still scarce human data, the cellular and preclinical studies point to the caspase-dependent intrinsic apoptosis pathway as the prime effector of inflammatory β-cell apoptosis.
Collapse
Affiliation(s)
| | - M Prause
- University of Copenhagen, Copenhagen, Denmark
| | - J Størling
- Copenhagen Diabetes Research Center, Beta Cell Biology Group, Copenhagen University Hospital Herlev, Herlev, Denmark
| | | |
Collapse
|
5
|
Pagesy P, Fardini Y, Nguyen TT, Lohmann M, Pierre-Eugene C, Tennagels N, Issad T. Effect of insulin analogues on phosphatidyl inositol-3 kinase/Akt signalling in INS-1 rat pancreatic derived β-cells. Arch Physiol Biochem 2016; 122:54-60. [PMID: 26707268 DOI: 10.3109/13813455.2015.1125364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
CONTEXT Insulin analogues are largely used for the treatment of diabetic patients, but concerns have been raised about their mitogenic/anti-apoptotic potential. It is therefore important to evaluate these analogues in different cell systems. OBJECTIVE The aim of this work was to establish the pharmacological profiles of insulin analogues towards PI-3 kinase/Akt pathway in INS-1 β-pancreatic cells. METHODS Bioluminescence Resonance Energy Transfer (BRET), in cell western and caspase 3/7 assays, was used to study the effects of ligands. RESULTS Among the five analogues evaluated, only glargine stimulated PI-3 kinase/Akt pathway with higher efficiency than insulin, whereas glargine's metabolite M1 was less efficient. However, glargine did not show higher anti-apoptotic efficiency than insulin. CONCLUSION Glargine was more efficient than insulin for the activation of PI-3 kinase/Akt pathway, but not for the inhibition of caspase 3/7 activity. Moreover, glargine's metabolite M1 displayed lower efficiency than insulin towards PI-3 kinase/Akt activation and caspase 3/7 inhibition.
Collapse
Affiliation(s)
- Patrick Pagesy
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| | - Yann Fardini
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| | - Tuyet Thu Nguyen
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| | | | - Cécile Pierre-Eugene
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| | | | - Tarik Issad
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| |
Collapse
|
6
|
Leibiger B, Moede T, Paschen M, Yunn NO, Lim JH, Ryu SH, Pereira T, Berggren PO, Leibiger IB. PI3K-C2α Knockdown Results in Rerouting of Insulin Signaling and Pancreatic Beta Cell Proliferation. Cell Rep 2015; 13:15-22. [PMID: 26387957 DOI: 10.1016/j.celrep.2015.08.058] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 07/20/2015] [Accepted: 08/20/2015] [Indexed: 11/26/2022] Open
Abstract
Insulin resistance is a syndrome that affects multiple insulin target tissues, each having different biological functions regulated by insulin. A remaining question is to mechanistically explain how an insulin target cell/tissue can be insulin resistant in one biological function and insulin sensitive in another at the same time. Here, we provide evidence that in pancreatic β cells, knockdown of PI3K-C2α expression results in rerouting of the insulin signal from insulin receptor (IR)-B/PI3K-C2α/PKB-mediated metabolic signaling to IR-B/Shc/ERK-mediated mitogenic signaling, which allows the β cell to switch from a highly glucose-responsive, differentiated state to a proliferative state. Our data suggest the existence of IR-cascade-selective insulin resistance, which allows rerouting of the insulin signal within the same target cell. Hence, factors involved in the rerouting of the insulin signal represent tentative therapeutic targets in the treatment of insulin resistance.
Collapse
Affiliation(s)
- Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Tilo Moede
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Meike Paschen
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Na-Oh Yunn
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
| | - Jong Hoon Lim
- Aptamer Initiative Program, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
| | - Sung Ho Ryu
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea; Aptamer Initiative Program, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea; Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
| | - Teresa Pereira
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden; Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 637 553, Singapore.
| | - Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden.
| |
Collapse
|
7
|
Li R, Yang M, Chu T. Controllability and observability of Boolean networks arising from biology. CHAOS (WOODBURY, N.Y.) 2015; 25:023104. [PMID: 25725640 DOI: 10.1063/1.4907708] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Boolean networks are currently receiving considerable attention as a computational scheme for system level analysis and modeling of biological systems. Studying control-related problems in Boolean networks may reveal new insights into the intrinsic control in complex biological systems and enable us to develop strategies for manipulating biological systems using exogenous inputs. This paper considers controllability and observability of Boolean biological networks. We propose a new approach, which draws from the rich theory of symbolic computation, to solve the problems. Consequently, simple necessary and sufficient conditions for reachability, controllability, and observability are obtained, and algorithmic tests for controllability and observability which are based on the Gröbner basis method are presented. As practical applications, we apply the proposed approach to several different biological systems, namely, the mammalian cell-cycle network, the T-cell activation network, the large granular lymphocyte survival signaling network, and the Drosophila segment polarity network, gaining novel insights into the control and/or monitoring of the specific biological systems.
Collapse
Affiliation(s)
- Rui Li
- Key Laboratory of Systems and Control, Institute of Systems Science, Chinese Academy of Sciences, Beijing 100190, China
| | - Meng Yang
- China Ship Development and Design Center, Wuhan 430064, China
| | - Tianguang Chu
- State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871, China
| |
Collapse
|
8
|
Abstract
Optical imaging is crucial for addressing fundamental problems in all areas of life science. With the use of confocal and two-photon fluorescence microscopy, complex dynamic structures and functions in a plethora of tissue and cell types have been visualized. However, the resolution of 'classical' optical imaging methods is poor due to the diffraction limit and does not allow resolution of the cellular microcosmos. On the other hand, the novel stimulated emission depletion (STED) microscopy technique, because of its targeted on/off-switching of fluorescence, is not hampered by a diffraction-limited resolution barrier. STED microscopy can therefore provide much sharper images, permitting nanoscale visualization by sequential imaging of individual-labelled biomolecules, which should allow previous findings to be reinvestigated and provide novel information. The aim of this review is to highlight promising developments in and applications of STED microscopy and their impact on unresolved issues in biomedical science.
Collapse
Affiliation(s)
- H Blom
- Science for Life Laboratory, Royal Institute of Technology, Stockholm, Sweden
| | | |
Collapse
|
9
|
Campbell C, Albert R. Stabilization of perturbed Boolean network attractors through compensatory interactions. BMC SYSTEMS BIOLOGY 2014; 8:53. [PMID: 24885780 PMCID: PMC4037934 DOI: 10.1186/1752-0509-8-53] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 04/22/2014] [Indexed: 02/02/2023]
Abstract
Background Understanding and ameliorating the effects of network damage are of significant interest, due in part to the variety of applications in which network damage is relevant. For example, the effects of genetic mutations can cascade through within-cell signaling and regulatory networks and alter the behavior of cells, possibly leading to a wide variety of diseases. The typical approach to mitigating network perturbations is to consider the compensatory activation or deactivation of system components. Here, we propose a complementary approach wherein interactions are instead modified to alter key regulatory functions and prevent the network damage from triggering a deregulatory cascade. Results We implement this approach in a Boolean dynamic framework, which has been shown to effectively model the behavior of biological regulatory and signaling networks. We show that the method can stabilize any single state (e.g., fixed point attractors or time-averaged representations of multi-state attractors) to be an attractor of the repaired network. We show that the approach is minimalistic in that few modifications are required to provide stability to a chosen attractor and specific in that interventions do not have undesired effects on the attractor. We apply the approach to random Boolean networks, and further show that the method can in some cases successfully repair synchronous limit cycles. We also apply the methodology to case studies from drought-induced signaling in plants and T-LGL leukemia and find that it is successful in both stabilizing desired behavior and in eliminating undesired outcomes. Code is made freely available through the software package BooleanNet. Conclusions The methodology introduced in this report offers a complementary way to manipulating node expression levels. A comprehensive approach to evaluating network manipulation should take an "all of the above" perspective; we anticipate that theoretical studies of interaction modification, coupled with empirical advances, will ultimately provide researchers with greater flexibility in influencing system behavior.
Collapse
Affiliation(s)
- Colin Campbell
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA.
| | | |
Collapse
|
10
|
Roppenser B, Kwon H, Canadien V, Xu R, Devreotes PN, Grinstein S, Brumell JH. Multiple host kinases contribute to Akt activation during Salmonella infection. PLoS One 2013; 8:e71015. [PMID: 23990921 PMCID: PMC3750030 DOI: 10.1371/journal.pone.0071015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 06/24/2013] [Indexed: 01/05/2023] Open
Abstract
SopB is a type 3 secreted effector with phosphatase activity that Salmonella employs to manipulate host cellular processes, allowing the bacteria to establish their intracellular niche. One important function of SopB is activation of the pro-survival kinase Akt/protein kinase B in the infected host cell. Here, we examine the mechanism of Akt activation by SopB during Salmonella infection. We show that SopB-mediated Akt activation is only partially sensitive to PI3-kinase inhibitors LY294002 and wortmannin in HeLa cells, suggesting that Class I PI3-kinases play only a minor role in this process. However, depletion of PI(3,4) P2/PI(3-5) P3 by expression of the phosphoinositide 3-phosphatase PTEN inhibits Akt activation during Salmonella invasion. Therefore, production of PI(3,4) P2/PI(3-5) P3 appears to be a necessary event for Akt activation by SopB and suggests that non-canonical kinases mediate production of these phosphoinositides during Salmonella infection. We report that Class II PI3-kinase beta isoform, IPMK and other kinases identified from a kinase screen all contribute to Akt activation during Salmonella infection. In addition, the kinases required for SopB-mediated activation of Akt vary depending on the type of infected host cell. Together, our data suggest that Salmonella has evolved to use a single effector, SopB, to manipulate a remarkably large repertoire of host kinases to activate Akt for the purpose of optimizing bacterial replication in its host.
Collapse
Affiliation(s)
- Bernhard Roppenser
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Hyunwoo Kwon
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Veronica Canadien
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Risheng Xu
- Department of Neuroscience, Johns Hopkins Medical School, Baltimore, Maryland, United States of America
| | - Peter N. Devreotes
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Sergio Grinstein
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - John H. Brumell
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Sickkids IBD Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| |
Collapse
|
11
|
Chowdhury A, Dyachok O, Tengholm A, Sandler S, Bergsten P. Functional differences between aggregated and dispersed insulin-producing cells. Diabetologia 2013; 56:1557-68. [PMID: 23604550 PMCID: PMC3671110 DOI: 10.1007/s00125-013-2903-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 03/12/2013] [Indexed: 11/27/2022]
Abstract
AIMS/HYPOTHESIS Beta cells situated in the islet of Langerhans respond more vigorously to glucose than do dissociated beta cells. Mechanisms for this discrepancy were studied by comparing insulin-producing MIN6 cells aggregated into pseudoislets with MIN6 monolayer cells and mouse and human islets. METHODS MIN6 monolayers, pseudoislets and mouse and human islets were exposed to glucose, α-ketoisocaproic acid (KIC), pyruvate, KIC plus glutamine and the phosphatidylinositol 3-kinase (PI3K) inhibitors LY294002 or wortmannin. Insulin secretion (ELISA), cytoplasmic Ca(2+) concentration ([Ca(2+)]c; microfluorometry), glucose oxidation (radiolabelling), the expression of genes involved in mitochondrial metabolism (PCR) and the phosphorylation of insulin receptor signalling proteins (western blotting) were measured. RESULTS Insulin secretory responses to glucose, pyruvate, KIC and glutamine were higher in pseudoislets than monolayers and comparable to those of human islets. Glucose oxidation and genes for mitochondrial metabolism were upregulated in pseudoislets compared with single cells and monolayers, respectively. Phosphorylation at the inhibitory S636/639 site of IRS-1 was significantly higher in monolayers and dispersed human and mouse cells than pseudoislets and intact human and mouse islets. PI3K inhibition only slightly attenuated glucose-stimulated insulin secretion from monolayers, but substantially reduced that from pseudoislets and human and mouse islets without suppressing the glucose-induced [Ca(2+)]c response. CONCLUSIONS/INTERPRETATION We propose that islet architecture is critical for proper beta cell mitochondrial metabolism and IRS-1 signalling, and that PI3K regulates insulin secretion at a step distal to the elevation of [Ca(2+)]c.
Collapse
Affiliation(s)
- A Chowdhury
- Department of Medical Cell Biology, Uppsala University, Box 571, 75123, Uppsala, Sweden.
| | | | | | | | | |
Collapse
|
12
|
N-Acyl taurines trigger insulin secretion by increasing calcium flux in pancreatic β-cells. Biochem Biophys Res Commun 2013; 430:54-9. [DOI: 10.1016/j.bbrc.2012.11.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 11/06/2012] [Indexed: 11/18/2022]
|
13
|
Redox homeostasis in pancreatic β cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:932838. [PMID: 23304259 PMCID: PMC3532876 DOI: 10.1155/2012/932838] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/30/2012] [Indexed: 12/20/2022]
Abstract
We reviewed mechanisms that determine reactive oxygen species (redox) homeostasis, redox information signaling and metabolic/regulatory function of autocrine insulin signaling in pancreatic β cells, and consequences of oxidative stress and dysregulation of redox/information signaling for their dysfunction. We emphasize the role of mitochondrion in β cell molecular physiology and pathology, including the antioxidant role of mitochondrial uncoupling protein UCP2. Since in pancreatic β cells pyruvate cannot be easily diverted towards lactate dehydrogenase for lactate formation, the respiration and oxidative phosphorylation intensity are governed by the availability of glucose, leading to a certain ATP/ADP ratio, whereas in other cell types, cell demand dictates respiration/metabolism rates. Moreover, we examine the possibility that type 2 diabetes mellitus might be considered as an inevitable result of progressive self-accelerating oxidative stress and concomitantly dysregulated information signaling in peripheral tissues as well as in pancreatic β cells. It is because the redox signaling is inherent to the insulin receptor signaling mechanism and its impairment leads to the oxidative and nitrosative stress. Also emerging concepts, admiting participation of redox signaling even in glucose sensing and insulin release in pancreatic β cells, fit in this view. For example, NADPH has been firmly established to be a modulator of glucose-stimulated insulin release.
Collapse
|
14
|
Siddle K. Molecular basis of signaling specificity of insulin and IGF receptors: neglected corners and recent advances. Front Endocrinol (Lausanne) 2012; 3:34. [PMID: 22649417 PMCID: PMC3355962 DOI: 10.3389/fendo.2012.00034] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 02/13/2012] [Indexed: 12/15/2022] Open
Abstract
Insulin and insulin-like growth factor (IGF) receptors utilize common phosphoinositide 3-kinase/Akt and Ras/extracellular signal-regulated kinase signaling pathways to mediate a broad spectrum of "metabolic" and "mitogenic" responses. Specificity of insulin and IGF action in vivo must in part reflect expression of receptors and responsive pathways in different tissues but it is widely assumed that it is also determined by the ligand binding and signaling mechanisms of the receptors. This review focuses on receptor-proximal events in insulin/IGF signaling and examines their contribution to specificity of downstream responses. Insulin and IGF receptors may differ subtly in the efficiency with which they recruit their major substrates (IRS-1 and IRS-2 and Shc) and this could influence effectiveness of signaling to "metabolic" and "mitogenic" responses. Other substrates (Grb2-associated binder, downstream of kinases, SH2Bs, Crk), scaffolds (RACK1, β-arrestins, cytohesins), and pathways (non-receptor tyrosine kinases, phosphoinositide kinases, reactive oxygen species) have been less widely studied. Some of these components appear to be specifically involved in "metabolic" or "mitogenic" signaling but it has not been shown that this reflects receptor-preferential interaction. Very few receptor-specific interactions have been characterized, and their roles in signaling are unclear. Signaling specificity might also be imparted by differences in intracellular trafficking or feedback regulation of receptors, but few studies have directly addressed this possibility. Although published data are not wholly conclusive, no evidence has yet emerged for signaling mechanisms that are specifically engaged by insulin receptors but not IGF receptors or vice versa, and there is only limited evidence for differential activation of signaling mechanisms that are common to both receptors. Cellular context, rather than intrinsic receptor activity, therefore appears to be the major determinant of whether responses to insulin and IGFs are perceived as "metabolic" or "mitogenic."
Collapse
Affiliation(s)
- Kenneth Siddle
- University of Cambridge Metabolic Research Laboratories and Department of Clinical Biochemistry, Institute of Metabolic Science, Addenbrooke's Hospital Cambridge, UK.
| |
Collapse
|
15
|
Abstract
Abstract The endocrine cells of the gastrointestinal (GI) tract and the pancreas, referred to as the enteroendocrine cells, secrete a large variety of peptides and amines that regulate functions of the digestive tract itself and of distant organs. Taken together, the enteroendocrine cells form the largest system of endocrine cells in the body, presently comprising 16 cell types. Many of them have been named after letters of the alphabet, but the names are only occasionally related to morphological or functional characteristics of the cell. In this review of the normal, adult, mammalian enteroendocrine cells, we summarize synonyms, functions, locations, structure, stored hormones/amines, receptors, and other cellular expressions. We propose that the enteroendocrine cells should be renamed after their most well-known hormone/amine and, when applicable, their anatomical location, with opportunities for future revisions.
Collapse
Affiliation(s)
- Herbert F Helander
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
| | | |
Collapse
|
16
|
Saadatpour A, Wang RS, Liao A, Liu X, Loughran TP, Albert I, Albert R. Dynamical and structural analysis of a T cell survival network identifies novel candidate therapeutic targets for large granular lymphocyte leukemia. PLoS Comput Biol 2011; 7:e1002267. [PMID: 22102804 PMCID: PMC3213185 DOI: 10.1371/journal.pcbi.1002267] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 09/22/2011] [Indexed: 11/18/2022] Open
Abstract
The blood cancer T cell large granular lymphocyte (T-LGL) leukemia is a chronic disease characterized by a clonal proliferation of cytotoxic T cells. As no curative therapy is yet known for this disease, identification of potential therapeutic targets is of immense importance. In this paper, we perform a comprehensive dynamical and structural analysis of a network model of this disease. By employing a network reduction technique, we identify the stationary states (fixed points) of the system, representing normal and diseased (T-LGL) behavior, and analyze their precursor states (basins of attraction) using an asynchronous Boolean dynamic framework. This analysis identifies the T-LGL states of 54 components of the network, out of which 36 (67%) are corroborated by previous experimental evidence and the rest are novel predictions. We further test and validate one of these newly identified states experimentally. Specifically, we verify the prediction that the node SMAD is over-active in leukemic T-LGL by demonstrating the predominant phosphorylation of the SMAD family members Smad2 and Smad3. Our systematic perturbation analysis using dynamical and structural methods leads to the identification of 19 potential therapeutic targets, 68% of which are corroborated by experimental evidence. The novel therapeutic targets provide valuable guidance for wet-bench experiments. In addition, we successfully identify two new candidates for engineering long-lived T cells necessary for the delivery of virus and cancer vaccines. Overall, this study provides a bird's-eye-view of the avenues available for identification of therapeutic targets for similar diseases through perturbation of the underlying signal transduction network. T-LGL leukemia is a blood cancer characterized by an abnormal increase in the abundance of a type of white blood cell called T cell. Since there is no known curative therapy for this disease, identification of potential therapeutic targets is of utmost importance. Experimental identification of manipulations capable of reversing the disease condition is usually a long, arduous process. Mathematical modeling can aid this process by identifying potential therapeutic interventions. In this work, we carry out a systematic analysis of a network model of T cell survival in T-LGL leukemia to get a deeper insight into the unknown facets of the disease. We identify the T-LGL status of 54 components of the system, out of which 36 (67%) are corroborated by previous experimental evidence and the rest are novel predictions, one of which we validate by follow-up experiments. By deciphering the structure and dynamics of the underlying network, we identify component perturbations that lead to programmed cell death, thereby suggesting several novel candidate therapeutic targets for future experiments.
Collapse
Affiliation(s)
- Assieh Saadatpour
- Department of Mathematics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Rui-Sheng Wang
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Aijun Liao
- Penn State Hershey Cancer Institute, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Xin Liu
- Penn State Hershey Cancer Institute, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Thomas P. Loughran
- Penn State Hershey Cancer Institute, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - István Albert
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Réka Albert
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
| |
Collapse
|
17
|
Fiume R, Ramazzotti G, Faenza I, Piazzi M, Bavelloni A, Billi AM, Cocco L. Nuclear PLCs affect insulin secretion by targeting PPARγ in pancreatic β cells. FASEB J 2011; 26:203-10. [PMID: 21974932 DOI: 10.1096/fj.11-186510] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Type 2 diabetes is a heterogeneous disorder caused by concomitant impairment of insulin secretion by pancreatic β cells and of insulin action in peripheral target tissues. Studies with inhibitors and agonists established a role for PLC in the regulation of insulin secretion but did not distinguish between effects due to nuclear or cytoplasmic PLC signaling pathways that act in a distinct fashion. We report that in MIN6 β cells, PLCβ1 localized in both nucleus and cytoplasm, PLCδ4 in the nucleus, and PLCγ1 in the cytoplasm. By silencing each isoform, we observed that they all affected glucose-induced insulin release both at basal and high glucose concentrations. To elucidate the molecular basis of PLC regulation, we focused on peroxisome proliferator-activated receptor-γ (PPARγ), a nuclear receptor transcription factor that regulates genes critical to β-cell maintenance and functions. Silencing of PLCβ1 and PLCδ4 resulted in a decrease in the PPARγ mRNA level. By means of a PPARγ-promoter-luciferase assay, the decrease could be attributed to a PLC action on the PPARγ-promoter region. The effect was specifically observed on silencing of the nuclear and not the cytoplasmic PLC. These findings highlight a novel pathway by which nuclear PLCs affect insulin secretion and identify PPARγ as a novel molecular target of nuclear PLCs.
Collapse
Affiliation(s)
- Roberta Fiume
- Department of Human Anatomy, University of Bologna, Bologna, Italy
| | | | | | | | | | | | | |
Collapse
|