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Naik AR, Formosa BJ, Pulvender RG, Liyanaarachchi AG, Jena BP. vH +-ATPase-induced intracellular acidification is critical to glucose-stimulated insulin secretion in beta cells. Histochem Cell Biol 2020; 153:279-285. [PMID: 31901974 DOI: 10.1007/s00418-019-01841-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/17/2019] [Indexed: 10/25/2022]
Abstract
Swelling of secretory vesicles is critical for the regulated release of intra-vesicular contents from cells during secretion. At the secretory vesicle membrane of the exocrine pancreas and neurons, GTP-binding G proteins, vH+-ATPase, potassium channels and AQP water channels, are among the players implicated in vesicle volume regulation. Here we report in the endocrine insulin-secreting MIN6 cells, the similar requirement of vH+-ATPase-mediated intracellular acidification on glucose-stimulated insulin release. MIN6 cells exposed to the vH+-ATPase inhibitor Bafilomycin A show decreased acidification of the cytosolic compartment that include insulin-carrying granules. Additionally, a loss of insulin granules near the cell plasma membrane following Bafilomycin A treatment, suggests impaired transport of insulin granules and consequent decrease in glucose-stimulated insulin secretion and accumulation of intracellular insulin. These results suggest that vH+-ATPase-mediated intracellular acidification is required for insulin secretion in beta cells.
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Affiliation(s)
- Akshata R Naik
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Brent J Formosa
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Rishika G Pulvender
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Asiri G Liyanaarachchi
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Bhanu P Jena
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA. .,NanoBioScience Institute, Wayne State University, Detroit, MI, 48201, USA. .,Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, 540 E. Canfield, 5245 Scott Hall, Detroit, MI, 48201, USA.
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2
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Stamenkovic M, Janjetovic K, Paunovic V, Ciric D, Kravic-Stevovic T, Trajkovic V. Comparative analysis of cell death mechanisms induced by lysosomal autophagy inhibitors. Eur J Pharmacol 2019; 859:172540. [DOI: 10.1016/j.ejphar.2019.172540] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 06/18/2019] [Accepted: 07/12/2019] [Indexed: 12/21/2022]
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Can exposure to environmental chemicals increase the risk of diabetes type 1 development? BIOMED RESEARCH INTERNATIONAL 2015; 2015:208947. [PMID: 25883945 PMCID: PMC4391693 DOI: 10.1155/2015/208947] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 09/14/2014] [Indexed: 01/09/2023]
Abstract
Type 1 diabetes mellitus (T1DM) is an autoimmune disease, where destruction of beta-cells causes insulin deficiency. The incidence of T1DM has increased in the last decades and cannot entirely be explained by genetic predisposition. Several environmental factors are suggested to promote T1DM, like early childhood enteroviral infections and nutritional factors, but the evidence is inconclusive. Prenatal and early life exposure to environmental pollutants like phthalates, bisphenol A, perfluorinated compounds, PCBs, dioxins, toxicants, and air pollutants can have negative effects on the developing immune system, resulting in asthma-like symptoms and increased susceptibility to childhood infections. In this review the associations between environmental chemical exposure and T1DM development is summarized. Although information on environmental chemicals as possible triggers for T1DM is sparse, we conclude that it is plausible that environmental chemicals can contribute to T1DM development via impaired pancreatic beta-cell and immune-cell functions and immunomodulation. Several environmental factors and chemicals could act together to trigger T1DM development in genetically susceptible individuals, possibly via hormonal or epigenetic alterations. Further observational T1DM cohort studies and animal exposure experiments are encouraged.
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Greene LM, Nolan DP, Regan-Komito D, Campiani G, Williams DC, Zisterer DM. Inhibition of late-stage autophagy synergistically enhances pyrrolo-1,5-benzoxazepine-6-induced apoptotic cell death in human colon cancer cells. Int J Oncol 2013; 43:927-35. [PMID: 23799546 DOI: 10.3892/ijo.2013.1989] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 04/23/2013] [Indexed: 11/06/2022] Open
Abstract
The pyrrolo-1,5-benzoxazepines (PBOXs) are a novel group of selective apoptotic agents displaying promising therapeutic potential in both ex vivo chemotherapy-refractory patient samples and in vivo murine carcinoma models. In this report, we present novel data concerning the induction of autophagy by the PBOXs in adenocarcinoma-derived colon cancer cells. Autophagy is a lysosome-dependent degradative pathway recently associated with chemotherapy. However, whether autophagy facilitates cell survival in response to chemotherapy or contributes to chemotherapy-induced cell death is highly controversial. Autophagy was identified by enhanced expression of LC3B-II, an autophagosome marker, an increase in the formation of acridine orange-stained cells, indicative of increased vesicle formation and electron microscopic confirmation of autophagic structures. The vacuolar H+ ATPase inhibitor bafilomycin-A1 (BAF-A1) inhibited vesicle formation and enhanced the apoptotic potential of PBOX-6. These findings suggest a cytoprotective role of autophagy in these cells following prolonged exposure to PBOX-6. Furthermore, BAF-A1 and PBOX-6 interactions were determined to be synergistic and caspase-dependent. Potentiation of PBOX-6-induced apoptosis by BAF-A1 was associated with a decrease in the levels of the anti-apoptotic protein, Mcl-1. The data provide evidence that autophagy functions as a survival mechanism in colon cancer cells to PBOX-6-induced apoptosis and a rationale for the use of autophagy inhibitors to further enhance PBOX‑6‑induced apoptosis in colon cancer.
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Affiliation(s)
- Lisa M Greene
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
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Nijholt DAT, Nölle A, van Haastert ES, Edelijn H, Toonen RF, Hoozemans JJM, Scheper W. Unfolded protein response activates glycogen synthase kinase-3 via selective lysosomal degradation. Neurobiol Aging 2013; 34:1759-71. [PMID: 23415837 DOI: 10.1016/j.neurobiolaging.2013.01.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 12/20/2012] [Accepted: 01/12/2013] [Indexed: 01/01/2023]
Abstract
The unfolded protein response (UPR) is a stress response that is activated upon disturbed homeostasis in the endoplasmic reticulum. In Alzheimer's disease, as well as in other tauopathies, the UPR is activated in neurons that contain early tau pathology. A recent genome-wide association study identified genetic variation in a UPR transducer as a risk factor for tauopathy, supporting a functional connection between UPR activation and tau pathology. Here we show that UPR activation increases the activity of the major tau kinase glycogen synthase kinase (GSK)-3 in vitro via a selective removal of inactive GSK-3 phosphorylated at Ser(21/9). We demonstrate that this is mediated by the autophagy/lysosomal pathway. In brain tissue from patients with different tauopathies, lysosomal accumulations of pSer(21/9) GSK-3 are found in neurons with markers for UPR activation. Our data indicate that UPR activation increases the activity of GSK-3 by a novel mechanism, the lysosomal degradation of the inactive pSer(21/9) GSK-3. This may provide a functional explanation for the close association between UPR activation and early tau pathology in neurodegenerative diseases.
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Affiliation(s)
- Diana A T Nijholt
- Department of Genome Analysis, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Meur G, Qian Q, da Silva Xavier G, Pullen TJ, Tsuboi T, McKinnon C, Fletcher L, Tavaré JM, Hughes S, Johnson P, Rutter GA. Nucleo-cytosolic shuttling of FoxO1 directly regulates mouse Ins2 but not Ins1 gene expression in pancreatic beta cells (MIN6). J Biol Chem 2011; 286:13647-56. [PMID: 21335550 PMCID: PMC3075709 DOI: 10.1074/jbc.m110.204248] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 02/14/2011] [Indexed: 01/26/2023] Open
Abstract
The Forkhead box transcription factor FoxO1 regulates metabolic gene expression in mammals. FoxO1 activity is tightly controlled by phosphatidylinositol 3-kinase (PI3K) signaling, resulting in its phosphorylation and nuclear exclusion. We sought here to determine the mechanisms involved in glucose and insulin-stimulated nuclear shuttling of FoxO1 in pancreatic β cells and its consequences for preproinsulin (Ins1, Ins2) gene expression. Nuclear-localized endogenous FoxO1 translocated to the cytosol in response to elevated glucose (3 versus 16.7 mM) in human islet β cells. Real-time confocal imaging of nucleo-cytosolic shuttling of a FoxO1-EGFP chimera in primary mouse and clonal MIN6 β cells revealed a time-dependent glucose-responsive nuclear export, also mimicked by exogenous insulin, and blocked by suppressing insulin secretion. Constitutively active PI3K or protein kinase B/Akt exerted similar effects, while inhibitors of PI3K, but not of glycogen synthase kinase-3 or p70 S6 kinase, blocked nuclear export. FoxO1 overexpression reversed the activation by glucose of pancreatic duodenum homeobox-1 (Pdx1) transcription. Silencing of FoxO1 significantly elevated the expression of mouse Ins2, but not Ins1, mRNA at 3 mM glucose. Putative FoxO1 binding sites were identified in the distal promoter of rodent Ins2 genes and direct binding of FoxO1 to the Ins2 promoter was demonstrated by chromatin immunoprecipitation. A 915-bp glucose-responsive Ins2 promoter was inhibited by constitutively active FoxO1, an effect unaltered by simultaneous overexpression of PDX1. We conclude that nuclear import of FoxO1 contributes to the suppression of Pdx1 and Ins2 gene expression at low glucose, the latter via a previously unsuspected and direct physical interaction with the Ins2 promoter.
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Affiliation(s)
- Gargi Meur
- From the Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Qingwen Qian
- From the Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Gabriela da Silva Xavier
- From the Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Timothy J. Pullen
- From the Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Takashi Tsuboi
- the Department of Life Sciences, University of Tokyo, Tokyo 153-8902, Japan
| | - Caroline McKinnon
- From the Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom
- the Henry Wellcome Laboratories for Integrated Cell Signalling and Department of Biochemistry, School of Medical Sciences, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Laura Fletcher
- the Henry Wellcome Laboratories for Integrated Cell Signalling and Department of Biochemistry, School of Medical Sciences, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Jeremy M. Tavaré
- the Henry Wellcome Laboratories for Integrated Cell Signalling and Department of Biochemistry, School of Medical Sciences, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Stephen Hughes
- the Nuffield Department of Surgery, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom, and
| | - Paul Johnson
- the Nuffield Department of Surgery, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom, and
| | - Guy A. Rutter
- From the Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom
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Hettiarachchi KD, Zimmet PZ, Danial NN, Myers MA. Transplacental exposure to the vacuolar-ATPase inhibitor bafilomycin disrupts survival signaling in β cells and delays neonatal remodeling of the endocrine pancreas. ACTA ACUST UNITED AC 2008; 60:295-306. [DOI: 10.1016/j.etp.2008.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Accepted: 02/15/2008] [Indexed: 12/31/2022]
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Lamb MM, Myers MA, Barriga K, Zimmet PZ, Rewers M, Norris JM. Maternal diet during pregnancy and islet autoimmunity in offspring. Pediatr Diabetes 2008; 9:135-41. [PMID: 18221424 DOI: 10.1111/j.1399-5448.2007.00311.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Recent studies on the etiology of type 1 diabetes mellitus (T1DM) suggest that the components of the infant diet are associated with islet autoimmunity (IA), a precursor of T1DM. The role of prenatal nutritional exposures has not been thoroughly investigated. METHODS The Diabetes Autoimmunity Study in the Young has enrolled newborns from 1993 to 2004 at increased risk for T1DM based on human leukocyte antigen (HLA) genotype and family history of T1DM. The child is tested for islet autoantibodies at 9 and 15 months, 2 yr, and annually thereafter. We conducted a cohort study of 642 subjects for whom a Willett food frequency questionnaire for the mother's third trimester diet was completed. A case is defined as a subject who tests positive for islet autoantibodies at two consecutive blood draws and is still positive (or diabetic) at last follow-up (n = 27). Maternal consumption frequencies of potatoes, other root vegetables, gluten-containing foods, non-gluten cereal grains, cow's milk and cow's milk products, fruits, vegetables, meat and poultry, and fish were analyzed in a survival analysis. RESULTS Adjusting for breast-feeding duration, age at first cereal introduction, ethnicity, HLA genotype, family history of T1DM, and total caloric intake, higher maternal intake of potatoes (hazard ratio for one standard deviation difference: 0.49, 95% confidence interval: 0.28-0.86) was associated with a delayed time to IA onset. No other food groups ingested during pregnancy were associated with IA in the child. CONCLUSIONS The composition of the maternal diet during pregnancy may play a role in the offspring's risk of development of IA and potentially T1DM.
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Affiliation(s)
- Molly M Lamb
- Department of Preventive Medicine and Biometrics, University of Colorado at Denver and Health Sciences Center, Denver, CO, USA
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García-Fortanet J, Murga J, Carda M, Marco JA, Matesanz R, Díaz JF, Barasoain I. The total synthesis and biological properties of the cytotoxic macrolide FD-891 and its non-natural (Z)-C12 isomer. Chemistry 2007; 13:5060-74. [PMID: 17516610 DOI: 10.1002/chem.200700342] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A total, stereoselective synthesis of the naturally occurring, cytotoxic macrolide FD-891 and of its non-natural (Z)-C12 isomer is described. Three fragments of the main carbon chain were stereoselectively prepared by using asymmetric aldol and allylation reactions as the key steps. The molecule was then assembled by using two Julia-Kocienski olefinations to connect the three fragments and a Yamaguchi reaction to close the macrolactone ring. Some specific biological properties (cytotoxicity, binding to tubulin) have been determined for both macrolides. The E configuration of the C12-C13 olefinic bond seems to be an important feature in determining the cytotoxicity but the precise biological mechanism of the latter still remains to be cleared.
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Affiliation(s)
- Jorge García-Fortanet
- Depart. de Q. Inorgánica y Orgánica, Univ. Jaume I, Avda. Sos Baynat s/n, 12071 Castellón, Spain
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