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Nakhe AY, Dadi PK, Kim J, Dickerson MT, Behera S, Dobson JR, Shrestha S, Cartailler JP, Sampson L, Magnuson MA, Jacobson DA. The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults. bioRxiv 2024:2023.06.20.545631. [PMID: 37546831 PMCID: PMC10401960 DOI: 10.1101/2023.06.20.545631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The gain-of-function mutation in the TALK-1 K + channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion (GSIS). The KCNK16 gene encoding TALK-1, is the most abundant and β-cell-restricted K + channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the mixed C57BL/6J:CD-1(ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K + currents resulting in blunted glucose-stimulated Ca 2+ entry and loss of glucose-induced Ca 2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impaired glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet hormone secretion during development. These data strongly suggest that TALK-1 is an islet-restricted target for the treatment of diabetes.
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Graff SM, Nakhe AY, Dadi PK, Dickerson MT, Dobson JR, Zaborska KE, Ibsen CE, Butterworth RB, Vierra NC, Jacobson DA. TALK-1-mediated alterations of β-cell mitochondrial function and insulin secretion impair glucose homeostasis on a diabetogenic diet. Cell Rep 2024; 43:113673. [PMID: 38206814 PMCID: PMC10961926 DOI: 10.1016/j.celrep.2024.113673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 11/08/2023] [Accepted: 01/01/2024] [Indexed: 01/13/2024] Open
Abstract
Mitochondrial Ca2+ ([Ca2+]m) homeostasis is critical for β-cell function and becomes disrupted during the pathogenesis of diabetes. [Ca2+]m uptake is dependent on elevations in cytoplasmic Ca2+ ([Ca2+]c) and endoplasmic reticulum Ca2+ ([Ca2+]ER) release, both of which are regulated by the two-pore domain K+ channel TALK-1. Here, utilizing a novel β-cell TALK-1-knockout (β-TALK-1-KO) mouse model, we found that TALK-1 limited β-cell [Ca2+]m accumulation and ATP production. However, following exposure to a high-fat diet (HFD), ATP-linked respiration, glucose-stimulated oxygen consumption rate, and glucose-stimulated insulin secretion (GSIS) were increased in control but not TALK1-KO mice. Although β-TALK-1-KO animals showed similar GSIS before and after HFD treatment, these mice were protected from HFD-induced glucose intolerance. Collectively, these data identify that TALK-1 channel control of β-cell function reduces [Ca2+]m and suggest that metabolic remodeling in diabetes drives dysglycemia.
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Affiliation(s)
- Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA; Department of Pharmacy and Pharmaceutical Sciences, Lipscomb University, Nashville, TN 37204, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jordyn R Dobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Chloe E Ibsen
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Regan B Butterworth
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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Dickerson MT, Dadi PK, Zaborska KE, Nakhe AY, Schaub CM, Dobson JR, Wright NM, Lynch JC, Scott CF, Robinson LD, Jacobson DA. G i/o protein-coupled receptor inhibition of beta-cell electrical excitability and insulin secretion depends on Na +/K + ATPase activation. Nat Commun 2022; 13:6461. [PMID: 36309517 PMCID: PMC9617941 DOI: 10.1038/s41467-022-34166-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 10/17/2022] [Indexed: 12/25/2022] Open
Abstract
Gi/o-coupled somatostatin or α2-adrenergic receptor activation stimulated β-cell NKA activity, resulting in islet Ca2+ fluctuations. Furthermore, intra-islet paracrine activation of β-cell Gi/o-GPCRs and NKAs by δ-cell somatostatin secretion slowed Ca2+ oscillations, which decreased insulin secretion. β-cell membrane potential hyperpolarization resulting from Gi/o-GPCR activation was dependent on NKA phosphorylation by Src tyrosine kinases. Whereas, β-cell NKA function was inhibited by cAMP-dependent PKA activity. These data reveal that NKA-mediated β-cell membrane potential hyperpolarization is the primary and conserved mechanism for Gi/o-GPCR control of electrical excitability, Ca2+ handling, and insulin secretion.
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Affiliation(s)
- Matthew T Dickerson
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Prasanna K Dadi
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Karolina E Zaborska
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Arya Y Nakhe
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Charles M Schaub
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Jordyn R Dobson
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Nicole M Wright
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Joshua C Lynch
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Claire F Scott
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - Logan D Robinson
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA
| | - David A Jacobson
- Molecular Physiology and Biophysics Department, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN, USA.
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Zaborska KE, Jordan KL, Thorson AS, Dadi PK, Schaub CM, Nakhe AY, Dickerson MT, Lynch JC, Weiss AJ, Dobson JR, Jacobson DA. Liraglutide increases islet Ca 2+ oscillation frequency and insulin secretion by activating hyperpolarization-activated cyclic nucleotide-gated channels. Diabetes Obes Metab 2022; 24:1741-1752. [PMID: 35546791 PMCID: PMC9843726 DOI: 10.1111/dom.14747] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [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] [Received: 12/06/2021] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 01/19/2023]
Abstract
AIM To determine whether hyperpolarization-activated cyclic nucleotide-gated (HCN) channels impact glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) modulation of islet Ca2+ handling and insulin secretion. METHODS The impact of liraglutide (GLP-1 analogue) on islet Ca2+ handling, HCN currents and insulin secretion was monitored with fluorescence microscopy, electrophysiology and enzyme immunoassays, respectively. Furthermore, liraglutide-mediated β-to-δ-cell cross-communication was assessed following selective ablation of either mouse islet δ or β cells. RESULTS Liraglutide increased β-cell Ca2+ oscillation frequency in mouse and human islets under stimulatory glucose conditions. This was dependent in part on liraglutide activation of HCN channels, which also enhanced insulin secretion. Similarly, liraglutide activation of HCN channels also increased β-cell Ca2+ oscillation frequency in islets from rodents exposed to a diabetogenic diet. Interestingly, liraglutide accelerated Ca2+ oscillations in a majority of islet δ cells, which showed synchronized Ca2+ oscillations equivalent to β cells; therefore, we assessed if either cell type was driving this liraglutide-mediated islet Ca2+ response. Although δ-cell loss did not impact liraglutide-mediated increase in β-cell Ca2+ oscillation frequency, β-cell ablation attenuated liraglutide-facilitated acceleration of δ-cell Ca2+ oscillations. CONCLUSION The data presented here show that liraglutide-induced stimulation of islet HCN channels augments Ca2+ oscillation frequency. As insulin secretion oscillates with β-cell Ca2+ , these findings have important implications for pulsatile insulin secretion that is probably enhanced by liraglutide activation of HCN channels and therapeutics that target GLP-1Rs for treating diabetes. Furthermore, these studies suggest that liraglutide as well as GLP-1-based therapies enhance δ-cell Ca2+ oscillation frequency and somatostatin secretion kinetics in a β-cell-dependent manner.
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Affiliation(s)
- Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Ariel S Thorson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Charles M Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Joshua C Lynch
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Adam J Weiss
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Jordyn R Dobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
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5
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Kuo T, Du W, Miyachi Y, Dadi PK, Jacobson DA, Segrè D, Accili D. Antagonistic epistasis of Hnf4α and FoxO1 metabolic networks through enhancer interactions in β-cell function. Mol Metab 2021; 53:101256. [PMID: 34048961 PMCID: PMC8225970 DOI: 10.1016/j.molmet.2021.101256] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 05/04/2021] [Accepted: 05/12/2021] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Genetic and acquired abnormalities contribute to pancreatic β-cell failure in diabetes. Transcription factors Hnf4α (MODY1) and FoxO1 are respective examples of these two components and act through β-cell-specific enhancers. However, their relationship is unclear. METHODS In this report, we show by genome-wide interrogation of chromatin modifications that ablation of FoxO1 in mature β-cells enriches active Hnf4α enhancers according to a HOMER analysis. RESULTS To model the functional significance of this predicted unusual enhancer utilization, we generated single and compound knockouts of FoxO1 and Hnf4α in β-cells. Single knockout of either gene impaired insulin secretion in mechanistically distinct fashions as indicated by their responses to sulfonylurea and calcium fluxes. Surprisingly, the defective β-cell secretory function of either single mutant in hyperglycemic clamps and isolated islets treated with various secretagogues was completely reversed in double mutants lacking FoxO1 and Hnf4α. Gene expression analyses revealed distinct epistatic modalities by which the two transcription factors regulate networks associated with reversal of β-cell dysfunction. An antagonistic network regulating glycolysis, including β-cell "disallowed" genes, and a synergistic network regulating protocadherins emerged as likely mediators of the functional restoration of insulin secretion. CONCLUSIONS The findings provide evidence of antagonistic epistasis as a model of gene/environment interactions in the pathogenesis of β-cell dysfunction.
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Affiliation(s)
- Taiyi Kuo
- Department of Medicine and Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, NY, USA.
| | - Wen Du
- Department of Medicine and Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Yasutaka Miyachi
- Department of Medicine and Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Daniel Segrè
- Department of Biology, Department of Biomedical Engineering, Department of Physics, Boston University, Boston, MA, USA
| | - Domenico Accili
- Department of Medicine and Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
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6
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Altman MK, Schaub CM, Dadi PK, Dickerson MT, Zaborska KE, Nakhe AY, Graff SM, Galletta TJ, Amarnath G, Thorson AS, Gu G, Jacobson DA. TRPM7 is a crucial regulator of pancreatic endocrine development and high-fat-diet-induced β-cell proliferation. Development 2021; 148:271182. [PMID: 34345920 DOI: 10.1242/dev.194928] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 07/20/2021] [Indexed: 12/31/2022]
Abstract
The melastatin subfamily of the transient receptor potential channels (TRPM) are regulators of pancreatic β-cell function. TRPM7 is the most abundant islet TRPM channel; however, the role of TRPM7 in β-cell function has not been determined. Here, we used various spatiotemporal transgenic mouse models to investigate how TRPM7 knockout influences pancreatic endocrine development, proliferation and function. Ablation of TRPM7 within pancreatic progenitors reduced pancreatic size, and α-cell and β-cell mass. This resulted in modestly impaired glucose tolerance. However, TRPM7 ablation following endocrine specification or in adult mice did not impact endocrine expansion or glucose tolerance. As TRPM7 regulates cell proliferation, we assessed how TRPM7 influences β-cell hyperplasia under insulin-resistant conditions. β-Cell proliferation induced by high-fat diet was significantly decreased in TRPM7-deficient β-cells. The endocrine roles of TRPM7 may be influenced by cation flux through the channel, and indeed we found that TRPM7 ablation altered β-cell Mg2+ and reduced the magnitude of elevation in β-cell Mg2+ during proliferation. Together, these findings revealed that TRPM7 controls pancreatic development and β-cell proliferation, which is likely due to regulation of Mg2+ homeostasis.
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Affiliation(s)
- Molly K Altman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Charles M Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Thomas J Galletta
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Gautami Amarnath
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA.,Molecular Neurophysiology, Institute of Applied Physiology, University of Ulm, 89081 Ulm, Germany
| | - Ariel S Thorson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
| | - Guoqiang Gu
- Vanderbilt Program in Developmental Biology, Vanderbilt Center for Stem Cell Biology, Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, 2213 Garland Ave., Nashville, TN 37232, USA
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7
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Graff SM, Johnson SR, Leo PJ, Dadi PK, Dickerson MT, Nakhe AY, McInerney-Leo AM, Marshall M, Zaborska KE, Schaub CM, Brown MA, Jacobson DA, Duncan EL. A KCNK16 mutation causing TALK-1 gain of function is associated with maturity-onset diabetes of the young. JCI Insight 2021; 6:138057. [PMID: 34032641 PMCID: PMC8410089 DOI: 10.1172/jci.insight.138057] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 05/12/2021] [Indexed: 11/17/2022] Open
Abstract
Maturity-onset diabetes of the young (MODY) is a heterogeneous group of monogenic disorders of impaired pancreatic β cell function. The mechanisms underlying MODY include β cell KATP channel dysfunction (e.g., KCNJ11 [MODY13] or ABCC8 [MODY12] mutations); however, no other β cell channelopathies have been associated with MODY to date. Here, we have identified a nonsynonymous coding variant in KCNK16 (NM_001135105: c.341T>C, p.Leu114Pro) segregating with MODY. KCNK16 is the most abundant and β cell-restricted K+ channel transcript, encoding the two-pore-domain K+ channel TALK-1. Whole-cell K+ currents demonstrated a large gain of function with TALK-1 Leu114Pro compared with TALK-1 WT, due to greater single-channel activity. Glucose-stimulated membrane potential depolarization and Ca2+ influx were inhibited in mouse islets expressing TALK-1 Leu114Pro with less endoplasmic reticulum Ca2+ storage. TALK-1 Leu114Pro significantly blunted glucose-stimulated insulin secretion compared with TALK-1 WT in mouse and human islets. These data suggest that KCNK16 is a previously unreported gene for MODY.
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Affiliation(s)
- Sarah M. Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Stephanie R. Johnson
- Department of Endocrinology, Queensland Children’s Hospital, South Brisbane, Queensland, Australia
- Translational Genomics Group, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Translational Research Institute, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
- Faculty of Medicine, University of Queensland, Herston, Queensland, Australia
| | - Paul J. Leo
- Translational Genomics Group, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Translational Research Institute, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Prasanna K. Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Matthew T. Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Arya Y. Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Aideen M. McInerney-Leo
- Dermatology Research Centre, Dermatology Research Centre, The University of Queensland Diamantina Institute, Brisbane, Queensland, Australia
| | - Mhairi Marshall
- Translational Genomics Group, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Translational Research Institute, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Karolina E. Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Charles M. Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Matthew A. Brown
- Guy’s and St Thomas’ NHS Foundation Trust and King’s College London NIHR Biomedical Research Centre, King’s College London, London, United Kingdom
| | - David A. Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Emma L. Duncan
- Faculty of Medicine, University of Queensland, Herston, Queensland, Australia
- Department of Twin Research & Genetic Epidemiology, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
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8
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Sanavia T, Huang C, Manduchi E, Xu Y, Dadi PK, Potter LA, Jacobson DA, Di Camillo B, Magnuson MA, Stoeckert CJ, Gu G. Temporal Transcriptome Analysis Reveals Dynamic Gene Expression Patterns Driving β-Cell Maturation. Front Cell Dev Biol 2021; 9:648791. [PMID: 34017831 PMCID: PMC8129579 DOI: 10.3389/fcell.2021.648791] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 03/15/2021] [Indexed: 12/12/2022] Open
Abstract
Newly differentiated pancreatic β cells lack proper insulin secretion profiles of mature functional β cells. The global gene expression differences between paired immature and mature β cells have been studied, but the dynamics of transcriptional events, correlating with temporal development of glucose-stimulated insulin secretion (GSIS), remain to be fully defined. This aspect is important to identify which genes and pathways are necessary for β-cell development or for maturation, as defective insulin secretion is linked with diseases such as diabetes. In this study, we assayed through RNA sequencing the global gene expression across six β-cell developmental stages in mice, spanning from β-cell progenitor to mature β cells. A computational pipeline then selected genes differentially expressed with respect to progenitors and clustered them into groups with distinct temporal patterns associated with biological functions and pathways. These patterns were finally correlated with experimental GSIS, calcium influx, and insulin granule formation data. Gene expression temporal profiling revealed the timing of important biological processes across β-cell maturation, such as the deregulation of β-cell developmental pathways and the activation of molecular machineries for vesicle biosynthesis and transport, signal transduction of transmembrane receptors, and glucose-induced Ca2+ influx, which were established over a week before β-cell maturation completes. In particular, β cells developed robust insulin secretion at high glucose several days after birth, coincident with the establishment of glucose-induced calcium influx. Yet the neonatal β cells displayed high basal insulin secretion, which decreased to the low levels found in mature β cells only a week later. Different genes associated with calcium-mediated processes, whose alterations are linked with insulin resistance and deregulation of glucose homeostasis, showed increased expression across β-cell stages, in accordance with the temporal acquisition of proper GSIS. Our temporal gene expression pattern analysis provided a comprehensive database of the underlying molecular components and biological mechanisms driving β-cell maturation at different temporal stages, which are fundamental for better control of the in vitro production of functional β cells from human embryonic stem/induced pluripotent cell for transplantation-based type 1 diabetes therapy.
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Affiliation(s)
- Tiziana Sanavia
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Chen Huang
- Vanderbilt Program in Developmental Biology, Department of Cell and Developmental Biology, Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN, United States.,Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX, United States
| | - Elisabetta Manduchi
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States.,Institute for Biomedical Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Yanwen Xu
- Vanderbilt Program in Developmental Biology, Department of Cell and Developmental Biology, Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Leah A Potter
- Vanderbilt Program in Developmental Biology, Department of Cell and Developmental Biology, Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Barbara Di Camillo
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Mark A Magnuson
- Vanderbilt Program in Developmental Biology, Department of Cell and Developmental Biology, Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN, United States.,Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Christian J Stoeckert
- Institute for Biomedical Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.,Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Guoqiang Gu
- Vanderbilt Program in Developmental Biology, Department of Cell and Developmental Biology, Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN, United States
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9
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Dickerson MT, Dadi PK, Butterworth RB, Nakhe AY, Graff SM, Zaborska KE, Schaub CM, Jacobson DA. Tetraspanin-7 regulation of L-type voltage-dependent calcium channels controls pancreatic β-cell insulin secretion. J Physiol 2020; 598:4887-4905. [PMID: 32790176 PMCID: PMC8095317 DOI: 10.1113/jp279941] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/20/2020] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Tetraspanin (TSPAN) proteins regulate many biological processes, including intracellular calcium (Ca2+ ) handling. TSPAN-7 is enriched in pancreatic islet cells; however, the function of islet TSPAN-7 has not been identified. Here, we characterize how β-cell TSPAN-7 regulates Ca2+ handling and hormone secretion. We find that TSPAN-7 reduces β-cell glucose-stimulated Ca2+ entry, slows Ca2+ oscillation frequency and decreases glucose-stimulated insulin secretion. TSPAN-7 controls β-cell function through a direct interaction with L-type voltage-dependent Ca2+ channels (CaV 1.2 and CaV 1.3), which reduces channel Ca2+ conductance. TSPAN-7 slows activation of CaV 1.2 and accelerates recovery from voltage-dependent inactivation; TSPAN-7 also slows CaV 1.3 inactivation kinetics. These findings strongly implicate TSPAN-7 as a key regulator in determining the set-point of glucose-stimulated Ca2+ influx and insulin secretion. ABSTRACT Glucose-stimulated insulin secretion (GSIS) is regulated by calcium (Ca2+ ) entry into pancreatic β-cells through voltage-dependent Ca2+ (CaV ) channels. Tetraspanin (TSPAN) transmembrane proteins control Ca2+ handling, and thus they may also modulate GSIS. TSPAN-7 is the most abundant islet TSPAN and immunostaining of mouse and human pancreatic slices shows that TSPAN-7 is highly expressed in β- and α-cells; however, the function of islet TSPAN-7 has not been determined. Here, we show that TSPAN-7 knockdown (KD) increases glucose-stimulated Ca2+ influx into mouse and human β-cells. Additionally, mouse β-cell Ca2+ oscillation frequency was accelerated by TSPAN-7 KD. Because TSPAN-7 KD also enhanced Ca2+ entry when membrane potential was clamped with depolarization, the effect of TSPAN-7 on CaV channel activity was examined. TSPAN-7 KD enhanced L-type CaV currents in mouse and human β-cells. Conversely, heterologous expression of TSPAN-7 with CaV 1.2 and CaV 1.3 L-type CaV channels decreased CaV currents and reduced Ca2+ influx through both channels. This was presumably the result of a direct interaction of TSPAN-7 and L-type CaV channels because TSPAN-7 coimmunoprecipitated with both CaV 1.2 and CaV 1.3 from primary human β-cells and from a heterologous expression system. Finally, TSPAN-7 KD in human β-cells increased basal (5.6 mM glucose) and stimulated (45 mM KCl + 14 mM glucose) insulin secretion. These findings strongly suggest that TSPAN-7 modulation of β-cell L-type CaV channels is a key determinant of β-cell glucose-stimulated Ca2+ entry and thus the set-point of GSIS.
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Affiliation(s)
- Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Regan B Butterworth
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Charles M Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
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Zaborska KE, Dadi PK, Dickerson MT, Nakhe AY, Thorson AS, Schaub CM, Graff SM, Stanley JE, Kondapavuluru RS, Denton JS, Jacobson DA. Lactate activation of α-cell K ATP channels inhibits glucagon secretion by hyperpolarizing the membrane potential and reducing Ca 2+ entry. Mol Metab 2020; 42:101056. [PMID: 32736089 PMCID: PMC7479281 DOI: 10.1016/j.molmet.2020.101056] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/17/2020] [Accepted: 07/24/2020] [Indexed: 12/20/2022] Open
Abstract
Objective Elevations in pancreatic α-cell intracellular Ca2+ ([Ca2+]i) lead to glucagon (GCG) secretion. Although glucose inhibits GCG secretion, how lactate and pyruvate control α-cell Ca2+ handling is unknown. Lactate enters cells through monocarboxylate transporters (MCTs) and is also produced during glycolysis by lactate dehydrogenase A (LDHA), an enzyme expressed in α-cells. As lactate activates ATP-sensitive K+ (KATP) channels in cardiomyocytes, lactate may also modulate α-cell KATP. Therefore, this study investigated how lactate signaling controls α-cell Ca2+ handling and GCG secretion. Methods Mouse and human islets were used in combination with confocal microscopy, electrophysiology, GCG immunoassays, and fluorescent thallium flux assays to assess α-cell Ca2+ handling, Vm, KATP currents, and GCG secretion. Results Lactate-inhibited mouse (75 ± 25%) and human (47 ± 9%) α-cell [Ca2+]i fluctuations only under low-glucose conditions (1 mM) but had no effect on β- or δ-cells [Ca2+]i. Glyburide inhibition of KATP channels restored α-cell [Ca2+]i fluctuations in the presence of lactate. Lactate transport into α-cells via MCTs hyperpolarized mouse (14 ± 1 mV) and human (12 ± 1 mV) α-cell Vm and activated KATP channels. Interestingly, pyruvate showed a similar KATP activation profile and α-cell [Ca2+]i inhibition as lactate. Lactate-induced inhibition of α-cell [Ca2+]i influx resulted in reduced GCG secretion in mouse (62 ± 6%) and human (43 ± 13%) islets. Conclusions These data demonstrate for the first time that lactate entry into α-cells through MCTs results in KATP activation, Vm hyperpolarization, reduced [Ca2+]i, and inhibition of GCG secretion. Thus, taken together, these data indicate that lactate either within α-cells and/or elevated in serum could serve as important modulators of α-cell function. Lactate reduces islet α-cell Ca2+ entry under low glucose conditions. Lactate does not alter β- or δ-cell Ca2+ handling under low glucose conditions. Lactate enters islet α-cells through monocarboxylate transporters. Lactate hyperpolarizes islet α-cell membrane potential by activating KATP channels. Lactate reduces mouse and human islet glucagon secretion.
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Affiliation(s)
- Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Ariel S Thorson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Charles M Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jade E Stanley
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Roy S Kondapavuluru
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jerod S Denton
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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11
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Kharade SV, Sanchez-Andres JV, Fulton MG, Shelton EL, Blobaum AL, Engers DW, Hofmann CS, Dadi PK, Lantier L, Jacobson DA, Lindsley CW, Denton JS. Structure-Activity Relationships, Pharmacokinetics, and Pharmacodynamics of the Kir6.2/SUR1-Specific Channel Opener VU0071063. J Pharmacol Exp Ther 2019; 370:350-359. [PMID: 31201216 PMCID: PMC6691189 DOI: 10.1124/jpet.119.257204] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/12/2019] [Indexed: 01/14/2023] Open
Abstract
Glucose-stimulated insulin secretion from pancreatic β-cells is controlled by ATP-regulated potassium (KATP) channels composed of Kir6.2 and sulfonylurea receptor 1 (SUR1) subunits. The KATP channel-opener diazoxide is FDA-approved for treating hyperinsulinism and hypoglycemia but suffers from off-target effects on vascular KATP channels and other ion channels. The development of more specific openers would provide critically needed tool compounds for probing the therapeutic potential of Kir6.2/SUR1 activation. Here, we characterize a novel scaffold activator of Kir6.2/SUR1 that our group recently discovered in a high-throughput screen. Optimization efforts with medicinal chemistry identified key structural elements that are essential for VU0071063-dependent opening of Kir6.2/SUR1. VU0071063 has no effects on heterologously expressed Kir6.1/SUR2B channels or ductus arteriole tone, indicating it does not open vascular KATP channels. VU0071063 induces hyperpolarization of β-cell membrane potential and inhibits insulin secretion more potently than diazoxide. VU0071063 exhibits metabolic and pharmacokinetic properties that are favorable for an in vivo probe and is brain penetrant. Administration of VU0071063 inhibits glucose-stimulated insulin secretion and glucose-lowering in mice. Taken together, these studies indicate that VU0071063 is a more potent and specific opener of Kir6.2/SUR1 than diazoxide and should be useful as an in vitro and in vivo tool compound for investigating the therapeutic potential of Kir6.2/SUR1 expressed in the pancreas and brain.
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Affiliation(s)
- Sujay V Kharade
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Juan Vicente Sanchez-Andres
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Mark G Fulton
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Elaine L Shelton
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Anna L Blobaum
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Darren W Engers
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Christopher S Hofmann
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Prasanna K Dadi
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Louise Lantier
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - David A Jacobson
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Craig W Lindsley
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Jerod S Denton
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
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Liu J, Banerjee A, Herring CA, Attalla J, Hu R, Xu Y, Shao Q, Simmons AJ, Dadi PK, Wang S, Jacobson DA, Liu B, Hodges E, Lau KS, Gu G. Neurog3-Independent Methylation Is the Earliest Detectable Mark Distinguishing Pancreatic Progenitor Identity. Dev Cell 2019; 48:49-63.e7. [PMID: 30620902 PMCID: PMC6327977 DOI: 10.1016/j.devcel.2018.11.048] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 08/26/2018] [Accepted: 11/29/2018] [Indexed: 12/15/2022]
Abstract
In the developing pancreas, transient Neurog3-expressing progenitors give rise to four major islet cell types: α, β, δ, and γ; when and how the Neurog3+ cells choose cell fate is unknown. Using single-cell RNA-seq, trajectory analysis, and combinatorial lineage tracing, we showed here that the Neurog3+ cells co-expressing Myt1 (i.e., Myt1+Neurog3+) were biased toward β cell fate, while those not simultaneously expressing Myt1 (Myt1-Neurog3+) favored α fate. Myt1 manipulation only marginally affected α versus β cell specification, suggesting Myt1 as a marker but not determinant for islet-cell-type specification. The Myt1+Neurog3+ cells displayed higher Dnmt1 expression and enhancer methylation at Arx, an α-fate-promoting gene. Inhibiting Dnmts in pancreatic progenitors promoted α cell specification, while Dnmt1 overexpression or Arx enhancer hypermethylation favored β cell production. Moreover, the pancreatic progenitors contained distinct Arx enhancer methylation states without transcriptionally definable sub-populations, a phenotype independent of Neurog3 activity. These data suggest that Neurog3-independent methylation on fate-determining gene enhancers specifies distinct endocrine-cell programs.
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Affiliation(s)
- Jing Liu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Amrita Banerjee
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Charles A Herring
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Jonathan Attalla
- Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Biochemistry and the Vanderbilt Genetic Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Ruiying Hu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Yanwen Xu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Qiujia Shao
- Center for AIDS Health Disparities Research, Department of Microbiology, Immunology and Physiology, Meharry Medical College, Nashville, TN 37208, USA
| | - Alan J Simmons
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Sui Wang
- Department of Ophthalmology, Mary M. and Sash A. Spencer Center for Vision Research, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Bindong Liu
- Center for AIDS Health Disparities Research, Department of Microbiology, Immunology and Physiology, Meharry Medical College, Nashville, TN 37208, USA
| | - Emily Hodges
- Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Biochemistry and the Vanderbilt Genetic Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Ken S Lau
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN 37232, USA.
| | - Guoqiang Gu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Program in Developmental Biology and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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Dickerson MT, Dadi PK, Altman MK, Verlage KR, Thorson AS, Jordan KL, Vierra NC, Amarnath G, Jacobson DA. Glucose-mediated inhibition of calcium-activated potassium channels limits α-cell calcium influx and glucagon secretion. Am J Physiol Endocrinol Metab 2019; 316:E646-E659. [PMID: 30694690 PMCID: PMC6482666 DOI: 10.1152/ajpendo.00342.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pancreatic α-cells exhibit oscillations in cytosolic Ca2+ (Ca2+c), which control pulsatile glucagon (GCG) secretion. However, the mechanisms that modulate α-cell Ca2+c oscillations have not been elucidated. As β-cell Ca2+c oscillations are regulated in part by Ca2+-activated K+ (Kslow) currents, this work investigated the role of Kslow in α-cell Ca2+ handling and GCG secretion. α-Cells displayed Kslow currents that were dependent on Ca2+ influx through L- and P/Q-type voltage-dependent Ca2+ channels (VDCCs) as well as Ca2+ released from endoplasmic reticulum stores. α-Cell Kslow was decreased by small-conductance Ca2+-activated K+ (SK) channel inhibitors apamin and UCL 1684, large-conductance Ca2+-activated K+ (BK) channel inhibitor iberiotoxin (IbTx), and intermediate-conductance Ca2+-activated K+ (IK) channel inhibitor TRAM 34. Moreover, partial inhibition of α-cell Kslow with apamin depolarized membrane potential ( Vm) (3.8 ± 0.7 mV) and reduced action potential (AP) amplitude (10.4 ± 1.9 mV). Although apamin transiently increased Ca2+ influx into α-cells at low glucose (42.9 ± 10.6%), sustained SK (38.5 ± 10.4%) or BK channel inhibition (31.0 ± 11.7%) decreased α-cell Ca2+ influx. Total α-cell Ca2+c was similarly reduced (28.3 ± 11.1%) following prolonged treatment with high glucose, but it was not decreased further by SK or BK channel inhibition. Consistent with reduced α-cell Ca2+c following prolonged Kslow inhibition, apamin decreased GCG secretion from mouse (20.4 ± 4.2%) and human (27.7 ± 13.1%) islets at low glucose. These data demonstrate that Kslow activation provides a hyperpolarizing influence on α-cell Vm that sustains Ca2+ entry during hypoglycemic conditions, presumably by preventing voltage-dependent inactivation of P/Q-type VDCCs. Thus, when α-cell Ca2+c is elevated during secretagogue stimulation, Kslow activation helps to preserve GCG secretion.
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Affiliation(s)
- Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Molly K Altman
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Kenneth R Verlage
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
- School of Medicine, Texas Tech University Health Sciences Center , Lubbock, Texas
- Department of Urology, Oregon Health and Science University , Portland, Oregon
| | - Ariel S Thorson
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
- Department of Neurobiology, Physiology and Behavior University of California , Davis, California
| | - Gautami Amarnath
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
- Experimental and Clinical Neurosciences, University of Regensburg , Regensburg , Germany
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
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14
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Hart NJ, Aramandla R, Poffenberger G, Fayolle C, Thames AH, Bautista A, Spigelman AF, Babon JAB, DeNicola ME, Dadi PK, Bush WS, Balamurugan AN, Brissova M, Dai C, Prasad N, Bottino R, Jacobson DA, Drumm ML, Kent SC, MacDonald PE, Powers AC. Cystic fibrosis-related diabetes is caused by islet loss and inflammation. JCI Insight 2018; 3:98240. [PMID: 29669939 PMCID: PMC5931120 DOI: 10.1172/jci.insight.98240] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/14/2018] [Indexed: 12/20/2022] Open
Abstract
Cystic fibrosis-related (CF-related) diabetes (CFRD) is an increasingly common and devastating comorbidity of CF, affecting approximately 35% of adults with CF. However, the underlying causes of CFRD are unclear. Here, we examined cystic fibrosis transmembrane conductance regulator (CFTR) islet expression and whether the CFTR participates in islet endocrine cell function using murine models of β cell CFTR deletion and normal and CF human pancreas and islets. Specific deletion of CFTR from murine β cells did not affect β cell function. In human islets, CFTR mRNA was minimally expressed, and CFTR protein and electrical activity were not detected. Isolated CF/CFRD islets demonstrated appropriate insulin and glucagon secretion, with few changes in key islet-regulatory transcripts. Furthermore, approximately 65% of β cell area was lost in CF donors, compounded by pancreatic remodeling and immune infiltration of the islet. These results indicate that CFRD is caused by β cell loss and intraislet inflammation in the setting of a complex pleiotropic disease and not by intrinsic islet dysfunction from CFTR mutation.
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Affiliation(s)
- Nathaniel J. Hart
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Radhika Aramandla
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Gregory Poffenberger
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Cody Fayolle
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Ariel H. Thames
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Austin Bautista
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Aliya F. Spigelman
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Jenny Aurielle B. Babon
- Department of Medicine, Division of Diabetes, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Megan E. DeNicola
- Department of Medicine, Division of Diabetes, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Prasanna K. Dadi
- School of Medicine, Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - William S. Bush
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, Ohio, USA
| | - Appakalai N. Balamurugan
- Center for Cellular Transplantation, Department of Surgery, Cardiovascular Innovation Institute, University of Louisville, Louisville, Kentucky, USA
| | - Marcela Brissova
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Chunhua Dai
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Nripesh Prasad
- Hudson Alpha Institute of Biotechnology, Huntsville, Alabama, USA
| | - Rita Bottino
- Allegheny Singer Research Institute, Pittsburgh, Pennsylvania, USA
| | - David A. Jacobson
- School of Medicine, Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Mitchell L. Drumm
- School of Medicine, Department of Genetics, Case Western Reserve University, Cleveland, Ohio, USA
| | - Sally C. Kent
- Department of Medicine, Division of Diabetes, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Patrick E. MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Alvin C. Powers
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- School of Medicine, Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
- VA Tennessee Valley Healthcare, Nashville, Tennessee, USA
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15
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Huang C, Walker EM, Dadi PK, Hu R, Xu Y, Zhang W, Sanavia T, Mun J, Liu J, Nair GG, Tan HYA, Wang S, Magnuson MA, Stoeckert CJ, Hebrok M, Gannon M, Han W, Stein R, Jacobson DA, Gu G. Synaptotagmin 4 Regulates Pancreatic β Cell Maturation by Modulating the Ca 2+ Sensitivity of Insulin Secretion Vesicles. Dev Cell 2018; 45:347-361.e5. [PMID: 29656931 PMCID: PMC5962294 DOI: 10.1016/j.devcel.2018.03.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 02/12/2018] [Accepted: 03/19/2018] [Indexed: 12/14/2022]
Abstract
Islet β cells from newborn mammals exhibit high basal insulin secretion and poor glucose-stimulated insulin secretion (GSIS). Here we show that β cells of newborns secrete more insulin than adults in response to similar intracellular Ca2+ concentrations, suggesting differences in the Ca2+ sensitivity of insulin secretion. Synaptotagmin 4 (Syt4), a non-Ca2+ binding paralog of the β cell Ca2+ sensor Syt7, increased by ∼8-fold during β cell maturation. Syt4 ablation increased basal insulin secretion and compromised GSIS. Precocious Syt4 expression repressed basal insulin secretion but also impaired islet morphogenesis and GSIS. Syt4 was localized on insulin granules and Syt4 levels inversely related to the number of readily releasable vesicles. Thus, transcriptional regulation of Syt4 affects insulin secretion; Syt4 expression is regulated in part by Myt transcription factors, which repress Syt4 transcription. Finally, human SYT4 regulated GSIS in EndoC-βH1 cells, a human β cell line. These findings reveal the role that altered Ca2+ sensing plays in regulating β cell maturation.
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Affiliation(s)
- Chen Huang
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Emily M Walker
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Ruiying Hu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Yanwen Xu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Wenjian Zhang
- China-Japan Friendship Hospital, Beijing 100029, P. R. China
| | - Tiziana Sanavia
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Jisoo Mun
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Jennifer Liu
- Diabetes Center, UCSF, San Francisco, CA 94143, USA
| | | | - Hwee Yim Angeline Tan
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Singapore, Singapore
| | - Sui Wang
- Department of Ophthalmology, Mary M. and Sash A. Spencer Center for Vision Research, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Mark A Magnuson
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Christian J Stoeckert
- Institute for Biomedical Informatics and Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | | | - Maureen Gannon
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Department of Medicine, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - Weiping Han
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Singapore, Singapore
| | - Roland Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA.
| | - Guoqiang Gu
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; Center for Stem Cell Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA; The Program of Developmental Biology, Vanderbilt University School of Medicine, Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN 37232, USA.
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16
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Vierra NC, Dickerson MT, Jordan KL, Dadi PK, Katdare KA, Altman MK, Milian SC, Jacobson DA. TALK-1 reduces delta-cell endoplasmic reticulum and cytoplasmic calcium levels limiting somatostatin secretion. Mol Metab 2018; 9:84-97. [PMID: 29402588 PMCID: PMC5870147 DOI: 10.1016/j.molmet.2018.01.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 01/19/2018] [Indexed: 01/17/2023] Open
Abstract
OBJECTIVE Single-cell RNA sequencing studies have revealed that the type-2 diabetes associated two-pore domain K+ (K2P) channel TALK-1 is abundantly expressed in somatostatin-secreting δ-cells. However, a physiological role for TALK-1 in δ-cells remains unknown. We previously determined that in β-cells, K+ flux through endoplasmic reticulum (ER)-localized TALK-1 channels enhances ER Ca2+ leak, modulating Ca2+ handling and insulin secretion. As glucose amplification of islet somatostatin release relies on Ca2+-induced Ca2+ release (CICR) from the δ-cell ER, we investigated whether TALK-1 modulates δ-cell Ca2+ handling and somatostatin secretion. METHODS To define the functions of islet δ-cell TALK-1 channels, we generated control and TALK-1 channel-deficient (TALK-1 KO) mice expressing fluorescent reporters specifically in δ- and α-cells to facilitate cell type identification. Using immunofluorescence, patch clamp electrophysiology, Ca2+ imaging, and hormone secretion assays, we assessed how TALK-1 channel activity impacts δ- and α-cell function. RESULTS TALK-1 channels are expressed in both mouse and human δ-cells, where they modulate glucose-stimulated changes in cytosolic Ca2+ and somatostatin secretion. Measurement of cytosolic Ca2+ levels in response to membrane potential depolarization revealed enhanced CICR in TALK-1 KO δ-cells that could be abolished by depleting ER Ca2+ with sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) inhibitors. Consistent with elevated somatostatin inhibitory tone, we observed significantly reduced glucagon secretion and α-cell Ca2+ oscillations in TALK-1 KO islets, and found that blockade of α-cell somatostatin signaling with a somatostatin receptor 2 (SSTR2) antagonist restored glucagon secretion in TALK-1 KO islets. CONCLUSIONS These data indicate that TALK-1 reduces δ-cell cytosolic Ca2+ elevations and somatostatin release by limiting δ-cell CICR, modulating the intraislet paracrine signaling mechanisms that control glucagon secretion.
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Affiliation(s)
- Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Ketaki A Katdare
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Molly K Altman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Sarah C Milian
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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17
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Dickerson MT, Bogart AM, Altman MK, Milian SC, Jordan KL, Dadi PK, Jacobson DA. Cytokine-mediated changes in K + channel activity promotes an adaptive Ca 2+ response that sustains β-cell insulin secretion during inflammation. Sci Rep 2018; 8:1158. [PMID: 29348619 PMCID: PMC5773563 DOI: 10.1038/s41598-018-19600-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/04/2018] [Indexed: 12/13/2022] Open
Abstract
Cytokines present during low-grade inflammation contribute to β-cell dysfunction and diabetes. Cytokine signaling disrupts β-cell glucose-stimulated Ca2+ influx (GSCI) and endoplasmic reticulum (ER) Ca2+ ([Ca2+]ER) handling, leading to diminished glucose-stimulated insulin secretion (GSIS). However, cytokine-mediated changes in ion channel activity that alter β-cell Ca2+ handling remain unknown. Here we investigated the role of K+ currents in cytokine-mediated β-cell dysfunction. Kslow currents, which control the termination of intracellular Ca2+ ([Ca2+]i) oscillations, were reduced following cytokine exposure. As a consequence, [Ca2+]i and electrical oscillations were accelerated. Cytokine exposure also increased basal islet [Ca2+]i and decreased GSCI. The effect of cytokines on TALK-1 K+ currents were also examined as TALK-1 mediates Kslow by facilitating [Ca2+]ER release. Cytokine exposure decreased KCNK16 transcript abundance and associated TALK-1 protein expression, increasing [Ca2+]ER storage while maintaining 2nd phase GSCI and GSIS. This adaptive Ca2+ response was absent in TALK-1 KO islets, which exhibited decreased 2nd phase GSCI and diminished GSIS. These findings suggest that Kslow and TALK-1 currents play important roles in altered β-cell Ca2+ handling and electrical activity during low-grade inflammation. These results also reveal that a cytokine-mediated reduction in TALK-1 serves an acute protective role in β-cells by facilitating increased Ca2+ content to maintain GSIS.
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Affiliation(s)
- Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Avery M Bogart
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.,Department of Biological Sciences, Ohio University, Athens, OH, USA
| | - Molly K Altman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Sarah C Milian
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
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18
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Vierra NC, Dadi PK, Milian SC, Dickerson MT, Jordan KL, Gilon P, Jacobson DA. TALK-1 channels control β cell endoplasmic reticulum Ca 2+ homeostasis. Sci Signal 2017; 10:10/497/eaan2883. [PMID: 28928238 DOI: 10.1126/scisignal.aan2883] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ca2+ handling by the endoplasmic reticulum (ER) serves critical roles in controlling pancreatic β cell function and becomes perturbed during the pathogenesis of diabetes. ER Ca2+ homeostasis is determined by ion movements across the ER membrane, including K+ flux through K+ channels. We demonstrated that K+ flux through ER-localized TALK-1 channels facilitated Ca2+ release from the ER in mouse and human β cells. We found that β cells from mice lacking TALK-1 exhibited reduced basal cytosolic Ca2+ and increased ER Ca2+ concentrations, suggesting reduced ER Ca2+ leak. These changes in Ca2+ homeostasis were presumably due to TALK-1-mediated ER K+ flux, because we recorded K+ currents mediated by functional TALK-1 channels on the nuclear membrane, which is continuous with the ER. Moreover, overexpression of K+-impermeable TALK-1 channels in HEK293 cells did not reduce ER Ca2+ stores. Reduced ER Ca2+ content in β cells is associated with ER stress and islet dysfunction in diabetes, and islets from TALK-1-deficient mice fed a high-fat diet showed reduced signs of ER stress, suggesting that TALK-1 activity exacerbated ER stress. Our data establish TALK-1 channels as key regulators of β cell ER Ca2+ and suggest that TALK-1 may be a therapeutic target to reduce ER Ca2+ handling defects in β cells during the pathogenesis of diabetes.
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Affiliation(s)
- Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Sarah C Milian
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Patrick Gilon
- Pôle d'endocrinologie, diabète et nutrition, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels 1200, Belgium
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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19
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Stancill JS, Cartailler JP, Clayton HW, O'Connor JT, Dickerson MT, Dadi PK, Osipovich AB, Jacobson DA, Magnuson MA. Chronic β-Cell Depolarization Impairs β-Cell Identity by Disrupting a Network of Ca 2+-Regulated Genes. Diabetes 2017; 66:2175-2187. [PMID: 28550109 PMCID: PMC5521870 DOI: 10.2337/db16-1355] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 05/17/2017] [Indexed: 12/18/2022]
Abstract
We used mice lacking Abcc8, a key component of the β-cell KATP-channel, to analyze the effects of a sustained elevation in the intracellular Ca2+ concentration ([Ca2+]i) on β-cell identity and gene expression. Lineage tracing analysis revealed the conversion of β-cells lacking Abcc8 into pancreatic polypeptide cells but not to α- or δ-cells. RNA-sequencing analysis of FACS-purified Abcc8-/- β-cells confirmed an increase in Ppy gene expression and revealed altered expression of more than 4,200 genes, many of which are involved in Ca2+ signaling, the maintenance of β-cell identity, and cell adhesion. The expression of S100a6 and S100a4, two highly upregulated genes, is closely correlated with membrane depolarization, suggesting their use as markers for an increase in [Ca2+]i Moreover, a bioinformatics analysis predicts that many of the dysregulated genes are regulated by common transcription factors, one of which, Ascl1, was confirmed to be directly controlled by Ca2+ influx in β-cells. Interestingly, among the upregulated genes is Aldh1a3, a putative marker of β-cell dedifferentiation, and other genes associated with β-cell failure. Taken together, our results suggest that chronically elevated β-cell [Ca2+]i in Abcc8-/- islets contributes to the alteration of β-cell identity, islet cell numbers and morphology, and gene expression by disrupting a network of Ca2+-regulated genes.
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Affiliation(s)
- Jennifer S Stancill
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
- Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
| | | | - Hannah W Clayton
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
- Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
| | - James T O'Connor
- Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Anna B Osipovich
- Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Mark A Magnuson
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
- Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
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20
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Dickerson MT, Vierra NC, Milian SC, Dadi PK, Jacobson DA. Osteopontin activates the diabetes-associated potassium channel TALK-1 in pancreatic β-cells. PLoS One 2017; 12:e0175069. [PMID: 28403169 PMCID: PMC5389796 DOI: 10.1371/journal.pone.0175069] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 03/20/2017] [Indexed: 12/17/2022] Open
Abstract
Glucose-stimulated insulin secretion (GSIS) relies on β-cell Ca2+ influx, which is modulated by the two-pore-domain K+ (K2P) channel, TALK-1. A gain-of-function polymorphism in KCNK16, the gene encoding TALK-1, increases risk for developing type-2 diabetes. While TALK-1 serves an important role in modulating GSIS, the regulatory mechanism(s) that control β-cell TALK-1 channels are unknown. Therefore, we employed a membrane-specific yeast two-hybrid (MYTH) assay to identify TALK-1-interacting proteins in human islets, which will assist in determining signaling modalities that modulate TALK-1 function. Twenty-one proteins from a human islet cDNA library interacted with TALK-1. Some of these interactions increased TALK-1 activity, including intracellular osteopontin (iOPN). Intracellular OPN is highly expressed in β-cells and is upregulated under pre-diabetic conditions to help maintain normal β-cell function; however, the functional role of iOPN in β-cells is poorly understood. We found that iOPN colocalized with TALK-1 in pancreatic sections and coimmunoprecipitated with human islet TALK-1 channels. As human β-cells express two K+ channel-forming variants of TALK-1, regulation of these TALK-1 variants by iOPN was assessed. At physiological voltages iOPN activated TALK-1 transcript variant 3 channels but not TALK-1 transcript variant 2 channels. Activation of TALK-1 channels by iOPN also hyperpolarized resting membrane potential (Vm) in HEK293 cells and in primary mouse β-cells. Intracellular OPN was also knocked down in β-cells to test its effect on β-cell TALK-1 channel activity. Reducing β-cell iOPN significantly decreased TALK-1 K+ currents and increased glucose-stimulated Ca2+ influx. Importantly, iOPN did not affect the function of other K2P channels or alter Ca2+ influx into TALK-1 deficient β-cells. These results reveal the first protein interactions with the TALK-1 channel and found that an interaction with iOPN increased β-cell TALK-1 K+ currents. The TALK-1/iOPN complex caused Vm hyperpolarization and reduced β-cell glucose-stimulated Ca2+ influx, which is predicted to inhibit GSIS.
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Affiliation(s)
- Matthew T. Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Nicholas C. Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sarah C. Milian
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Prasanna K. Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - David A. Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
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21
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Dadi PK, Vierra NC, Days E, Dickerson MT, Vinson PN, Weaver CD, Jacobson DA. Selective Small Molecule Activators of TREK-2 Channels Stimulate Dorsal Root Ganglion c-Fiber Nociceptor Two-Pore-Domain Potassium Channel Currents and Limit Calcium Influx. ACS Chem Neurosci 2017; 8:558-568. [PMID: 27805811 DOI: 10.1021/acschemneuro.6b00301] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The two-pore-domain potassium (K2P) channel TREK-2 serves to modulate plasma membrane potential in dorsal root ganglia c-fiber nociceptors, which tunes electrical excitability and nociception. Thus, TREK-2 channels are considered a potential therapeutic target for treating pain; however, there are currently no selective pharmacological tools for TREK-2 channels. Here we report the identification of the first TREK-2 selective activators using a high-throughput fluorescence-based thallium (Tl+) flux screen (HTS). An initial pilot screen with a bioactive lipid library identified 11-deoxy prostaglandin F2α as a potent activator of TREK-2 channels (EC50 ≈ 0.294 μM), which was utilized to optimize the TREK-2 Tl+ flux assay (Z' = 0.752). A HTS was then performed with 76 575 structurally diverse small molecules. Many small molecules that selectively activate TREK-2 were discovered. As these molecules were able to activate single TREK-2 channels in excised membrane patches, they are likely direct TREK-2 activators. Furthermore, TREK-2 activators reduced primary dorsal root ganglion (DRG) c-fiber Ca2+ influx. Interestingly, some of the selective TREK-2 activators such as 11-deoxy prostaglandin F2α were found to inhibit the K2P channel TREK-1. Utilizing chimeric channels containing portions of TREK-1 and TREK-2, the region of the TREK channels that allows for either small molecule activation or inhibition was identified. This region lies within the second pore domain containing extracellular loop and is predicted to play an important role in modulating TREK channel activity. Moreover, the selective TREK-2 activators identified in this HTS provide important tools for assessing human TREK-2 channel function and investigating their therapeutic potential for treating chronic pain.
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Affiliation(s)
- Prasanna K. Dadi
- Department
of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Nicholas C. Vierra
- Department
of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Emily Days
- Institute
of Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Matthew T. Dickerson
- Department
of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Paige N. Vinson
- Department
of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - C. David Weaver
- Department
of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - David A. Jacobson
- Department
of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
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22
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Zhu L, Almaça J, Dadi PK, Hong H, Sakamoto W, Rossi M, Lee RJ, Vierra NC, Lu H, Cui Y, McMillin SM, Perry NA, Gurevich VV, Lee A, Kuo B, Leapman RD, Matschinsky FM, Doliba NM, Urs NM, Caron MG, Jacobson DA, Caicedo A, Wess J. β-arrestin-2 is an essential regulator of pancreatic β-cell function under physiological and pathophysiological conditions. Nat Commun 2017; 8:14295. [PMID: 28145434 PMCID: PMC5296650 DOI: 10.1038/ncomms14295] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Accepted: 12/15/2016] [Indexed: 01/06/2023] Open
Abstract
β-arrestins are critical signalling molecules that regulate many fundamental physiological functions including the maintenance of euglycemia and peripheral insulin sensitivity. Here we show that inactivation of the β-arrestin-2 gene, barr2, in β-cells of adult mice greatly impairs insulin release and glucose tolerance in mice fed with a calorie-rich diet. Both glucose and KCl-induced insulin secretion and calcium responses were profoundly reduced in β-arrestin-2 (barr2) deficient β-cells. In human β-cells, barr2 knockdown abolished glucose-induced insulin secretion. We also show that the presence of barr2 is essential for proper CAMKII function in β-cells. Importantly, overexpression of barr2 in β-cells greatly ameliorates the metabolic deficits displayed by mice consuming a high-fat diet. Thus, our data identify barr2 as an important regulator of β-cell function, which may serve as a new target to improve β-cell function. Beta-arrestins have key roles in development and metabolic functions as euglycaemic control and insulin sentitivity. Here Zhu et al. show that beta-arrestin-2 regulates insulin secretion and glucose tolerance in mice by promoting CAMKII functions in beta cells.
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Affiliation(s)
- Lu Zhu
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Joana Almaça
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Hao Hong
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA.,Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China
| | - Wataru Sakamoto
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Mario Rossi
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Regina J Lee
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Huiyan Lu
- Mouse Transgenic Core Facility, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Yinghong Cui
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Sara M McMillin
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Nicole A Perry
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, USA
| | - Bryan Kuo
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, Bethesda, Maryland 20892, USA
| | - Richard D Leapman
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, Bethesda, Maryland 20892, USA
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennslvania 19104, USA
| | - Nicolai M Doliba
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennslvania 19104, USA
| | - Nikhil M Urs
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Marc G Caron
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Alejandro Caicedo
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
| | - Jürgen Wess
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
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23
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Golson ML, Dunn JC, Maulis MF, Dadi PK, Osipovich AB, Magnuson MA, Jacobson DA, Gannon M. Activation of FoxM1 Revitalizes the Replicative Potential of Aged β-Cells in Male Mice and Enhances Insulin Secretion. Diabetes 2015; 64:3829-38. [PMID: 26251404 PMCID: PMC4613976 DOI: 10.2337/db15-0465] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 07/26/2015] [Indexed: 12/11/2022]
Abstract
Type 2 diabetes incidence increases with age, while β-cell replication declines. The transcription factor FoxM1 is required for β-cell replication in various situations, and its expression declines with age. We hypothesized that increased FoxM1 activity in aged β-cells would rejuvenate proliferation. Induction of an activated form of FoxM1 was sufficient to increase β-cell mass and proliferation in 12-month-old male mice after just 2 weeks. Unexpectedly, at 2 months of age, induction of activated FoxM1 in male mice improved glucose homeostasis with unchanged β-cell mass. Cells expressing activated FoxM1 demonstrated enhanced glucose-stimulated Ca2+ influx, which resulted in improved glucose tolerance through enhanced β-cell function. Conversely, our laboratory has previously demonstrated that mice lacking FoxM1 in the pancreas display glucose intolerance or diabetes with only a 60% reduction in β-cell mass, suggesting that the loss of FoxM1 is detrimental to β-cell function. Ex vivo insulin secretion was therefore examined in size-matched islets from young mice lacking FoxM1 in β-cells. Foxm1-deficient islets indeed displayed reduced insulin secretion. Our studies reveal that activated FoxM1 increases β-cell replication while simultaneously enhancing insulin secretion and improving glucose homeostasis, making FoxM1 an attractive therapeutic target for diabetes.
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Affiliation(s)
- Maria L Golson
- VA Tennessee Valley Healthcare System, Nashville, TN Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN
| | - Jennifer C Dunn
- VA Tennessee Valley Healthcare System, Nashville, TN Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN
| | - Matthew F Maulis
- VA Tennessee Valley Healthcare System, Nashville, TN Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Anna B Osipovich
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN Vanderbilt Center for Stem Cell Biology, Vanderbilt University Medical Center, Nashville, TN
| | - Mark A Magnuson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN Vanderbilt Center for Stem Cell Biology, Vanderbilt University Medical Center, Nashville, TN
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Maureen Gannon
- VA Tennessee Valley Healthcare System, Nashville, TN Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
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24
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Vierra NC, Dadi PK, Jeong I, Dickerson M, Powell DR, Jacobson DA. Type 2 Diabetes-Associated K+ Channel TALK-1 Modulates β-Cell Electrical Excitability, Second-Phase Insulin Secretion, and Glucose Homeostasis. Diabetes 2015; 64:3818-28. [PMID: 26239056 PMCID: PMC4613978 DOI: 10.2337/db15-0280] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 07/22/2015] [Indexed: 12/11/2022]
Abstract
Two-pore domain K+ (K2P) channels play an important role in tuning β-cell glucose-stimulated insulin secretion (GSIS). The K2P channel TWIK-related alkaline pH-activated K2P (TALK)-1 is linked to type 2 diabetes risk through a coding sequence polymorphism (rs1535500); however, its physiological function has remained elusive. Here, we show that TALK-1 channels are expressed in mouse and human β-cells, where they serve as key regulators of electrical excitability and GSIS. We find that the rs1535500 polymorphism, which results in an alanine-to-glutamate substitution in the C-terminus of human TALK-1, increases channel activity. Genetic ablation of TALK-1 results in β-cell membrane potential depolarization, increased islet Ca2+ influx, and enhanced second-phase GSIS. Moreover, mice lacking TALK-1 channels are resistant to high-fat diet-induced elevations in fasting glycemia. These findings reveal TALK-1 channels as important modulators of second-phase insulin secretion and suggest a clinically relevant mechanism for rs1535500, which may increase type 2 diabetes risk by limiting GSIS.
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Affiliation(s)
- Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Imju Jeong
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Matthew Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | | | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
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25
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Dadi PK, Luo B, Vierra NC, Jacobson DA. TASK-1 Potassium Channels Limit Pancreatic α-Cell Calcium Influx and Glucagon Secretion. Mol Endocrinol 2015. [PMID: 25849724 DOI: 10.1210/me.2014‐1321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Glucose regulation of pancreatic α-cell Ca(2+) entry through voltage-dependent Ca(2+) channels is essential for normal glucagon secretion and becomes defective during the pathogenesis of diabetes mellitus. The 2-pore domain K(+) channel, TWIK-related acid-sensitive K(+) channel 1 (TASK-1), is an important modulator of membrane voltage and Ca(2+) entry. However, its role in α-cells has not been determined. Therefore, we addressed how TASK-1 channels regulate α-cell electrical activity, Ca(2+) entry, and glucagon secretion. We find that TASK-1 channels expressed in human and rodent α-cells are blocked by the TASK-1 channel inhibitor A1899. Alpha-cell 2-pore domain K(+) currents were also significantly reduced after ablation of mouse α-cell TASK-1 channels. Inhibition of TASK-1 channels with A1899 caused plasma membrane potential depolarization in both human and mouse α-cells, which resulted in increased electrical excitability. Moreover, ablation of α-cell TASK-1 channels increased α-cell electrical excitability under elevated glucose (11 mM) conditions compared with control α-cells. This resulted in significantly elevated α-cell Ca(2+) influx when TASK-1 channels were inhibited in the presence of high glucose (14 mM). However, there was an insignificant change in α-cell Ca(2+) influx after TASK-1 inhibition in low glucose (1 mM). Glucagon secretion from mouse and human islets was also elevated specifically in high (11 mM) glucose after acute TASK-1 inhibition. Interestingly, mice deficient for α-cell TASK-1 showed improvements in both glucose inhibition of glucagon secretion and glucose tolerance, which resulted from the chronic loss of α-cell TASK-1 currents. Therefore, these data suggest an important role for TASK-1 channels in limiting α-cell excitability and glucagon secretion during glucose stimulation.
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Affiliation(s)
- Prasanna K Dadi
- Department of Molecular Physiology and Biophysics (P.K.D., N.C.V., D.A.J.), Vanderbilt University, Nashville, Tennessee 37232-0615; and University of Oklahoma College of Medicine (B.L.), Oklahoma City, Oklahoma 73104-5042
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26
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Dadi PK, Luo B, Vierra NC, Jacobson DA. TASK-1 Potassium Channels Limit Pancreatic α-Cell Calcium Influx and Glucagon Secretion. Mol Endocrinol 2015; 29:777-87. [PMID: 25849724 DOI: 10.1210/me.2014-1321] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Glucose regulation of pancreatic α-cell Ca(2+) entry through voltage-dependent Ca(2+) channels is essential for normal glucagon secretion and becomes defective during the pathogenesis of diabetes mellitus. The 2-pore domain K(+) channel, TWIK-related acid-sensitive K(+) channel 1 (TASK-1), is an important modulator of membrane voltage and Ca(2+) entry. However, its role in α-cells has not been determined. Therefore, we addressed how TASK-1 channels regulate α-cell electrical activity, Ca(2+) entry, and glucagon secretion. We find that TASK-1 channels expressed in human and rodent α-cells are blocked by the TASK-1 channel inhibitor A1899. Alpha-cell 2-pore domain K(+) currents were also significantly reduced after ablation of mouse α-cell TASK-1 channels. Inhibition of TASK-1 channels with A1899 caused plasma membrane potential depolarization in both human and mouse α-cells, which resulted in increased electrical excitability. Moreover, ablation of α-cell TASK-1 channels increased α-cell electrical excitability under elevated glucose (11 mM) conditions compared with control α-cells. This resulted in significantly elevated α-cell Ca(2+) influx when TASK-1 channels were inhibited in the presence of high glucose (14 mM). However, there was an insignificant change in α-cell Ca(2+) influx after TASK-1 inhibition in low glucose (1 mM). Glucagon secretion from mouse and human islets was also elevated specifically in high (11 mM) glucose after acute TASK-1 inhibition. Interestingly, mice deficient for α-cell TASK-1 showed improvements in both glucose inhibition of glucagon secretion and glucose tolerance, which resulted from the chronic loss of α-cell TASK-1 currents. Therefore, these data suggest an important role for TASK-1 channels in limiting α-cell excitability and glucagon secretion during glucose stimulation.
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Affiliation(s)
- Prasanna K Dadi
- Department of Molecular Physiology and Biophysics (P.K.D., N.C.V., D.A.J.), Vanderbilt University, Nashville, Tennessee 37232-0615; and University of Oklahoma College of Medicine (B.L.), Oklahoma City, Oklahoma 73104-5042
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27
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Vierra N, Dadi PK, Ladak F, Jacobson DA. The Talk-1 C-Terminus is a Charge-Sensitive Module Regulating Channel Activity. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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28
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Dadi PK, Vierra NC, Jacobson DA. Pancreatic β-cell-specific ablation of TASK-1 channels augments glucose-stimulated calcium entry and insulin secretion, improving glucose tolerance. Endocrinology 2014; 155:3757-68. [PMID: 24932805 PMCID: PMC4164933 DOI: 10.1210/en.2013-2051] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [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: 11/19/2022]
Abstract
Calcium entry through voltage-dependent Ca(2+) channels (VDCCs) is required for pancreatic β-cell insulin secretion. The 2-pore-domain acid-sensitive potassium channel (TASK-1) regulates neuronal excitability and VDCC activation by hyperpolarizing the plasma membrane potential (Δψp); however, a role for pancreatic β-cell TASK-1 channels is unknown. Here we examined the influence of TASK-1 channel activity on the β-cell Δψp and insulin secretion during secretagogue stimulation. TASK-1 channels were found to be highly expressed in human and rodent islets and localized to the plasma membrane of β-cells. TASK-1-like currents of mouse and human β-cells were blocked by the potent TASK-1 channel inhibitor, A1899 (250nM). Although inhibition of TASK-1 currents did not influence the β-cell Δψp in the presence of low (2mM) glucose, A1899 significantly enhanced glucose-stimulated (14mM) Δψp depolarization of human and mouse β-cells. TASK-1 inhibition also resulted in greater secretagogue-stimulated Ca(2+) influx in both human and mouse islets. Moreover, conditional ablation of mouse β-cell TASK-1 channels reduced K2P currents, increased glucose-stimulated Δψp depolarization, and augmented secretagogue-stimulated Ca(2+) influx. The Δψp depolarization caused by TASK-1 inhibition resulted in a transient increase in glucose-stimulated mouse β-cell action potential (AP) firing frequency. However, secretagogue-stimulated β-cell AP duration eventually increased in the presence of A1899 as well as in β-cells without TASK-1, causing a decrease in AP firing frequency. Ablation or inhibition of mouse β-cell TASK-1 channels also significantly enhanced glucose-stimulated insulin secretion, which improved glucose tolerance. Conversely, TASK-1 ablation did not perturb β-cell Δψp, Ca(2+) influx, or insulin secretion under low-glucose conditions (2mM). These results reveal a glucose-dependent role for β-cell TASK-1 channels of limiting glucose-stimulated Δψp depolarization and insulin secretion, which modulates glucose homeostasis.
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Affiliation(s)
- Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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29
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Raphemot R, Swale DR, Dadi PK, Jacobson DA, Cooper P, Wojtovich AP, Banerjee S, Nichols CG, Denton JS. Direct activation of β-cell KATP channels with a novel xanthine derivative. Mol Pharmacol 2014; 85:858-65. [PMID: 24646456 DOI: 10.1124/mol.114.091884] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ATP-regulated potassium (KATP) channel complexes of inward rectifier potassium channel (Kir) 6.2 and sulfonylurea receptor (SUR) 1 critically regulate pancreatic islet β-cell membrane potential, calcium influx, and insulin secretion, and consequently, represent important drug targets for metabolic disorders of glucose homeostasis. The KATP channel opener diazoxide is used clinically to treat intractable hypoglycemia caused by excessive insulin secretion, but its use is limited by off-target effects due to lack of potency and selectivity. Some progress has been made in developing improved Kir6.2/SUR1 agonists from existing chemical scaffolds and compound screening, but there are surprisingly few distinct chemotypes that are specific for SUR1-containing KATP channels. Here we report the serendipitous discovery in a high-throughput screen of a novel activator of Kir6.2/SUR1: VU0071063 [7-(4-(tert-butyl)benzyl)-1,3-dimethyl-1H-purine-2,6(3H,7H)-dione]. The xanthine derivative rapidly and dose-dependently activates Kir6.2/SUR1 with a half-effective concentration (EC50) of approximately 7 μM, is more efficacious than diazoxide at low micromolar concentrations, directly activates the channel in excised membrane patches, and is selective for SUR1- over SUR2A-containing Kir6.1 or Kir6.2 channels, as well as Kir2.1, Kir2.2, Kir2.3, Kir3.1/3.2, and voltage-gated potassium channel 2.1. Finally, we show that VU0071063 activates native Kir6.2/SUR1 channels, thereby inhibiting glucose-stimulated calcium entry in isolated mouse pancreatic β cells. VU0071063 represents a novel tool/compound for investigating β-cell physiology, KATP channel gating, and a new chemical scaffold for developing improved activators with medicinal chemistry.
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Affiliation(s)
- Rene Raphemot
- Departments of Anesthesiology (R.R., D.R.S., S.B., J.S.D.), Pharmacology (R.R., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.) and Institutes of Chemical Biology (J.S.D.) and Global Health (J.S.D.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, University of Rochester Medical Center, Rochester, New York (A.P.W.); and Department of Cell Biology and Physiology (P.C., C.G.N.) and Center for the Investigation of Membrane Excitability Disorders (P.C., C.G.N.), Washington University School of Medicine in St. Louis, St. Louis, Missouri
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30
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Dadi PK, Vierra NC, Ustione A, Piston DW, Colbran RJ, Jacobson DA. Inhibition of pancreatic β-cell Ca2+/calmodulin-dependent protein kinase II reduces glucose-stimulated calcium influx and insulin secretion, impairing glucose tolerance. J Biol Chem 2014; 289:12435-45. [PMID: 24627477 DOI: 10.1074/jbc.m114.562587] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells is caused by Ca(2+) entry via voltage-dependent Ca(2+) channels. CaMKII is a key mediator and feedback regulator of Ca(2+) signaling in many tissues, but its role in β-cells is poorly understood, especially in vivo. Here, we report that mice with conditional inhibition of CaMKII in β-cells show significantly impaired glucose tolerance due to decreased GSIS. Moreover, β-cell CaMKII inhibition dramatically exacerbates glucose intolerance following exposure to a high fat diet. The impairment of islet GSIS by β-cell CaMKII inhibition is not accompanied by changes in either glucose metabolism or the activities of KATP and voltage-gated potassium channels. However, glucose-stimulated Ca(2+) entry via voltage-dependent Ca(2+) channels is reduced in islet β-cells with CaMKII inhibition, as well as in primary wild-type β-cells treated with a peptide inhibitor of CaMKII. The levels of basal β-cell cytoplasmic Ca(2+) and of endoplasmic reticulum Ca(2+) stores are also decreased by CaMKII inhibition. In addition, CaMKII inhibition suppresses glucose-stimulated action potential firing frequency. These results reveal that CaMKII is a Ca(2+) sensor with a key role as a feed-forward stimulator of β-cell Ca(2+) signals that enhance GSIS under physiological and pathological conditions.
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Affiliation(s)
- Prasanna K Dadi
- From the Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232
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31
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Pound LD, Oeser JK, O’Brien TP, Wang Y, Faulman CJ, Dadi PK, Jacobson DA, Hutton JC, McGuinness OP, Shiota M, O’Brien RM. G6PC2: a negative regulator of basal glucose-stimulated insulin secretion. Diabetes 2013; 62:1547-56. [PMID: 23274894 PMCID: PMC3636628 DOI: 10.2337/db12-1067] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Elevated fasting blood glucose (FBG) is associated with increased risk for the development of type 2 diabetes and cardiovascular-associated mortality. Genome-wide association studies (GWAS) have linked polymorphisms in G6PC2 with variations in FBG and body fat, although not insulin sensitivity or glucose tolerance. G6PC2 encodes an islet-specific, endoplasmic reticulum-resident glucose-6-phosphatase catalytic subunit. A combination of in situ perfused pancreas, in vitro isolated islet, and in vivo analyses were used to explore the function of G6pc2 in mice. G6pc2 deletion had little effect on insulin sensitivity and glucose tolerance, whereas body fat was reduced in female G6pc2 knockout (KO) mice on both a chow and high-fat diet, observations that are all consistent with human GWAS data. G6pc2 deletion resulted in a leftward shift in the dose-response curve for glucose-stimulated insulin secretion (GSIS). As a consequence, under fasting conditions in which plasma insulin levels were identical, blood glucose levels were reduced in G6pc2 KO mice, again consistent with human GWAS data. Glucose-6-phosphatase activity was reduced, whereas basal cytoplasmic calcium levels were elevated in islets isolated from G6pc2 KO mice. These data suggest that G6pc2 represents a novel, negative regulator of basal GSIS that acts by hydrolyzing glucose-6-phosphate, thereby reducing glycolytic flux.
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Affiliation(s)
- Lynley D. Pound
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - Tracy P. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - Yingda Wang
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - Chandler J. Faulman
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - Prasanna K. Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - David A. Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - John C. Hutton
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Aurora, Colorado
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - Masakazu Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee
- Corresponding author: Richard M. O’Brien,
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32
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Pound LD, Sarkar SA, Ustione A, Dadi PK, Shadoan MK, Lee CE, Walters JA, Shiota M, McGuinness OP, Jacobson DA, Piston DW, Hutton JC, Powell DR, O’Brien RM. The physiological effects of deleting the mouse SLC30A8 gene encoding zinc transporter-8 are influenced by gender and genetic background. PLoS One 2012; 7:e40972. [PMID: 22829903 PMCID: PMC3400647 DOI: 10.1371/journal.pone.0040972] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 06/18/2012] [Indexed: 11/18/2022] Open
Abstract
Objective The SLC30A8 gene encodes the islet-specific transporter ZnT-8, which is hypothesized to provide zinc for insulin-crystal formation. A polymorphic variant in SLC30A8 is associated with altered susceptibility to type 2 diabetes. Several groups have examined the effect of global Slc30a8 gene deletion but the results have been highly variable, perhaps due to the mixed 129SvEv/C57BL/6J genetic background of the mice studied. We therefore sought to remove the conflicting effect of 129SvEv-specific modifier genes. Methods The impact of Slc30a8 deletion was examined in the context of the pure C57BL/6J genetic background. Results Male C57BL/6J Slc30a8 knockout (KO) mice had normal fasting insulin levels and no change in glucose-stimulated insulin secretion (GSIS) from isolated islets in marked contrast to the ∼50% and ∼35% decrease, respectively, in both parameters observed in male mixed genetic background Slc30a8 KO mice. This observation suggests that 129SvEv-specific modifier genes modulate the impact of Slc30a8 deletion. In contrast, female C57BL/6J Slc30a8 KO mice had reduced (∼20%) fasting insulin levels, though this was not associated with a change in fasting blood glucose (FBG), or GSIS from isolated islets. This observation indicates that gender also modulates the impact of Slc30a8 deletion, though the physiological explanation as to why impaired insulin secretion is not accompanied by elevated FBG is unclear. Neither male nor female C57BL/6J Slc30a8 KO mice showed impaired glucose tolerance. Conclusions Our data suggest that, despite a marked reduction in islet zinc content, the absence of ZnT-8 does not have a substantial impact on mouse physiology.
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Affiliation(s)
- Lynley D. Pound
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States of America
| | - Suparna A. Sarkar
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Aurora, Colorado, United States of America
| | - Alessandro Ustione
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States of America
| | - Prasanna K. Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States of America
| | - Melanie K. Shadoan
- Lexicon Pharmaceuticals Incorporated, The Woodlands, Texas, United States of America
| | - Catherine E. Lee
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Aurora, Colorado, United States of America
| | - Jay A. Walters
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Aurora, Colorado, United States of America
| | - Masakazu Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States of America
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States of America
| | - David A. Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States of America
| | - David W. Piston
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States of America
| | - John C. Hutton
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Aurora, Colorado, United States of America
| | - David R. Powell
- Lexicon Pharmaceuticals Incorporated, The Woodlands, Texas, United States of America
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States of America
- * E-mail:
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Ahmad Z, Dadi PK, Elord J, Kady IO. Synthesis and evaluation of diphenol aldimines as inhibitors of <i>Escherichia coli</i> ATPase and cell growth. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/abc.2012.22019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chinnam N, Dadi PK, Sabri SA, Ahmad M, Kabir MA, Ahmad Z. Dietary bioflavonoids inhibit Escherichia coli ATP synthase in a differential manner. Int J Biol Macromol 2010; 46:478-86. [PMID: 20346967 DOI: 10.1016/j.ijbiomac.2010.03.009] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Revised: 03/16/2010] [Accepted: 03/17/2010] [Indexed: 12/11/2022]
Abstract
The aim of this study was to determine if the dietary benefits of bioflavonoids are linked to the inhibition of ATP synthase. We studied the inhibitory effect of 17 bioflavonoid compounds on purified F1 or membrane bound F1Fo E. coli ATP synthase. We found that the extent of inhibition by bioflavonoid compounds was variable. Morin, silymarin, baicalein, silibinin, rimantadin, amantidin, or, epicatechin resulted in complete inhibition. The most potent inhibitors on molar scale were morin (IC50 approximately 0.07 mM)>silymarin (IC50 approximately 0.11 mM)>baicalein (IC50 approximately 0.29 mM)>silibinin (IC50 approximately 0.34 mM)>rimantadin (IC50 approximately 2.0 mM)>amantidin (IC50 approximately 2.5 mM)>epicatechin (IC50 approximately 4.0 mM). Inhibition by hesperidin, chrysin, kaempferol, diosmin, apigenin, genistein, or rutin was partial in the range of 40-60% and inhibition by galangin, daidzein, or luteolin was insignificant. The main skeleton, size, shape, geometry, and position of functional groups on inhibitors played important role in the effective inhibition of ATP synthase. In all cases inhibition was found fully reversible and identical in both F1Fo membrane preparations and isolated purified F1. ATPase and growth assays suggested that the bioflavonoid compounds used in this study inhibited F1-ATPase as well as ATP synthesis nearly equally, which signifies a link between the beneficial effects of dietary bioflavonoids and their inhibitory action on ATP synthase.
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Affiliation(s)
- Nagababu Chinnam
- Department of Biological Sciences, Box 70703, East Tennessee State University, Johnson City, TN 37614, USA
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