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Fan G, Baker MR, Terry LE, Arige V, Chen M, Seryshev AB, Baker ML, Ludtke SJ, Yule DI, Serysheva II. Conformational motions and ligand-binding underlying gating and regulation in IP 3R channel. Nat Commun 2022; 13:6942. [PMID: 36376291 PMCID: PMC9663519 DOI: 10.1038/s41467-022-34574-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 10/28/2022] [Indexed: 11/16/2022] Open
Abstract
Inositol-1,4,5-trisphosphate receptors (IP3Rs) are activated by IP3 and Ca2+ and their gating is regulated by various intracellular messengers that finely tune the channel activity. Here, using single particle cryo-EM analysis we determined 3D structures of the nanodisc-reconstituted IP3R1 channel in two ligand-bound states. These structures provide unprecedented details governing binding of IP3, Ca2+ and ATP, revealing conformational changes that couple ligand-binding to channel opening. Using a deep-learning approach and 3D variability analysis we extracted molecular motions of the key protein domains from cryo-EM density data. We find that IP3 binding relies upon intrinsic flexibility of the ARM2 domain in the tetrameric channel. Our results highlight a key role of dynamic side chains in regulating gating behavior of IP3R channels. This work represents a stepping-stone to developing mechanistic understanding of conformational pathways underlying ligand-binding, activation and regulation of the channel.
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Affiliation(s)
- Guizhen Fan
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at The University of Texas Health Science Center at Houston, 6431, Fannin Street, Houston, TX, USA
| | - Mariah R Baker
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at The University of Texas Health Science Center at Houston, 6431, Fannin Street, Houston, TX, USA
| | - Lara E Terry
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA
| | - Vikas Arige
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA
| | - Muyuan Chen
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, USA
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Alexander B Seryshev
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at The University of Texas Health Science Center at Houston, 6431, Fannin Street, Houston, TX, USA
| | - Matthew L Baker
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at The University of Texas Health Science Center at Houston, 6431, Fannin Street, Houston, TX, USA
| | - Steven J Ludtke
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, USA
| | - David I Yule
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA.
| | - Irina I Serysheva
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at The University of Texas Health Science Center at Houston, 6431, Fannin Street, Houston, TX, USA.
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Research Progress on the Relationship Between Acute Pancreatitis and Calcium Overload in Acinar Cells. Dig Dis Sci 2019; 64:25-38. [PMID: 30284136 DOI: 10.1007/s10620-018-5297-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 09/01/2018] [Indexed: 02/07/2023]
Abstract
Acute pancreatitis is a human disease with multiple causes that leads to autodigestion of the pancreas. There is sufficient evidence to support the key role of sustained increase in cytosolic calcium concentrations in the early pathogenesis of the disease. To clarify the mechanism of maintaining calcium homeostasis in the cell and pathological processes caused by calcium overload would help to research directly targeted therapeutic agents. We will specifically review the following: intracellular calcium homeostasis and regulation, the occurrence of calcium overload in acinar cells, the role of calcium overload in the pathogenesis of AP, the treatment strategy proposed for calcium overload.
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3
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Eid AH, El-Yazbi AF, Zouein F, Arredouani A, Ouhtit A, Rahman MM, Zayed H, Pintus G, Abou-Saleh H. Inositol 1,4,5-Trisphosphate Receptors in Hypertension. Front Physiol 2018; 9:1018. [PMID: 30093868 PMCID: PMC6071574 DOI: 10.3389/fphys.2018.01018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 07/09/2018] [Indexed: 12/21/2022] Open
Abstract
Chronic hypertension remains a major cause of global mortality and morbidity. It is a complex disease that is the clinical manifestation of multiple genetic, environmental, nutritional, hormonal, and aging-related disorders. Evidence supports a role for vascular aging in the development of hypertension involving an impairment in endothelial function together with an alteration in vascular smooth muscle cells (VSMCs) calcium homeostasis leading to increased myogenic tone. Changes in free intracellular calcium levels ([Ca2+] i ) are mediated either by the influx of Ca2+ from the extracellular space or release of Ca2+ from intracellular stores, mainly the sarcoplasmic reticulum (SR). The influx of extracellular Ca2+ occurs primarily through voltage-gated Ca2+ channels (VGCCs), store-operated Ca2+ channels (SOC), and Ca2+ release-activated channels (CRAC), whereas SR-Ca2+ release occurs through inositol trisphosphate receptor (IP3R) and ryanodine receptors (RyRs). IP3R-mediated SR-Ca2+ release, in the form of Ca2+ waves, not only contributes to VSMC contraction and regulates VGCC function but is also intimately involved in structural remodeling of resistance arteries in hypertension. This involves a phenotypic switch of VSMCs as well as an alteration of cytoplasmic Ca2+ signaling machinery, a phenomena tightly related to the aging process. Several lines of evidence implicate changes in expression/function levels of IP3R isoforms in the development of hypertension, VSMC phenotypic switch, and vascular aging. The present review discusses the current knowledge of these mechanisms in an integrative approach and further suggests potential new targets for hypertension management and treatment.
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Affiliation(s)
- Ali H Eid
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar
| | - Ahmed F El-Yazbi
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Fouad Zouein
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Abdelilah Arredouani
- Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Qatar Foundation, Doha, Qatar
| | - Allal Ouhtit
- Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar
| | - Md M Rahman
- Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar
| | - Hatem Zayed
- Department of Biomedical Sciences, College of Health Sciences, Qatar University, Doha, Qatar
| | - Gianfranco Pintus
- Department of Biomedical Sciences, College of Health Sciences, Qatar University, Doha, Qatar
| | - Haissam Abou-Saleh
- Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar
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4
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Yoon MN, Kim MJ, Koong HS, Kim DK, Kim SH, Park HS. Ethanol suppresses carbamylcholine-induced intracellular calcium oscillation in mouse pancreatic acinar cells. Alcohol 2017; 63:53-59. [PMID: 28847382 DOI: 10.1016/j.alcohol.2017.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 03/23/2017] [Accepted: 03/23/2017] [Indexed: 12/31/2022]
Abstract
Oscillation of intracellular calcium levels is closely linked to initiating secretion of digestive enzymes from pancreatic acinar cells. Excessive alcohol consumption is known to relate to a variety of disorders in the digestive system, including the exocrine pancreas. In this study, we have investigated the role and mechanism of ethanol on carbamylcholine (CCh)-induced intracellular calcium oscillation in murine pancreatic acinar cells. Ethanol at concentrations of 30 and 100 mM reversibly suppressed CCh-induced Ca2+ oscillation in a dose-dependent manner. Pretreatment of ethanol has no effect on the store-operated calcium entry induced by 10 μM of CCh. Ethanol significantly reduced the initial calcium peak induced by low concentrations of CCh and therefore, the CCh-induced dose-response curve of the initial calcium peak was shifted to the right by ethanol pretreatment. Furthermore, ethanol significantly dose-dependently reduced inositol 1,4,5-trisphosphate-induced calcium release from the internal stores in permeabilized acinar cells. These results provide evidence that excessive alcohol intake could impair cytosolic calcium oscillation through inhibiting calcium release from intracellular stores in mouse pancreatic acinar cells.
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Affiliation(s)
- Mi Na Yoon
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Republic of Korea
| | - Min Jae Kim
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Republic of Korea
| | - Hwa Soo Koong
- Department of Dental Hygiene, College of Medical Science, Konyang University, Daejeon 35365, Republic of Korea
| | - Dong Kwan Kim
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Republic of Korea
| | - Se Hoon Kim
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Republic of Korea
| | - Hyung Seo Park
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Republic of Korea; Myunggok Medical Research Institute, Konyang University, Daejeon 35365, Republic of Korea.
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5
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Yoon MN, Kim DK, Kim SH, Park HS. Hydrogen peroxide attenuates refilling of intracellular calcium store in mouse pancreatic acinar cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2017; 21:233-239. [PMID: 28280417 PMCID: PMC5343057 DOI: 10.4196/kjpp.2017.21.2.233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 12/12/2016] [Accepted: 12/13/2016] [Indexed: 01/05/2023]
Abstract
Intracellular calcium (Ca2+) oscillation is an initial event in digestive enzyme secretion of pancreatic acinar cells. Reactive oxygen species are known to be associated with a variety of oxidative stress-induced cellular disorders including pancreatitis. In this study, we investigated the effect of hydrogen peroxide (H2O2) on intracellular Ca2+ accumulation in mouse pancreatic acinar cells. Perfusion of H2O2 at 300 µM resulted in additional elevation of intracellular Ca2+ levels and termination of oscillatory Ca2+ signals induced by carbamylcholine (CCh) in the presence of normal extracellular Ca2+. Antioxidants, catalase or DTT, completely prevented H2O2-induced additional Ca2+ increase and termination of Ca2+ oscillation. In Ca2+-free medium, H2O2 still enhanced CCh-induced intracellular Ca2+ levels and thapsigargin (TG) mimicked H2O2-induced cytosolic Ca2+ increase. Furthermore, H2O2-induced elevation of intracellular Ca2+ levels was abolished under sarco/endoplasmic reticulum Ca2+ ATPase-inactivated condition by TG pretreatment with CCh. H2O2 at 300 µM failed to affect store-operated Ca2+ entry or Ca2+ extrusion through plasma membrane. Additionally, ruthenium red, a mitochondrial Ca2+ uniporter blocker, failed to attenuate H2O2-induced intracellular Ca2+ elevation. These results provide evidence that excessive generation of H2O2 in pathological conditions could accumulate intracellular Ca2+ by attenuating refilling of internal Ca2+ stores rather than by inhibiting Ca2+ extrusion to extracellular fluid or enhancing Ca2+ mobilization from extracellular medium in mouse pancreatic acinar cells.
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Affiliation(s)
- Mi Na Yoon
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea
| | - Dong Kwan Kim
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea
| | - Se Hoon Kim
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea
| | - Hyung Seo Park
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea.; Myunggok Medical Research Institute, Konyang University, Daejeon 35365, Korea
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6
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Chandrasekhar R, Alzayady KJ, Wagner LE, Yule DI. Unique Regulatory Properties of Heterotetrameric Inositol 1,4,5-Trisphosphate Receptors Revealed by Studying Concatenated Receptor Constructs. J Biol Chem 2016; 291:4846-60. [PMID: 26755721 DOI: 10.1074/jbc.m115.705301] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Indexed: 02/02/2023] Open
Abstract
The ability of inositol 1,4,5-trisphosphate receptors (IP3R) to precisely initiate and generate a diverse variety of intracellular Ca(2+) signals is in part mediated by the differential regulation of the three subtypes (R1, R2, and R3) by key functional modulators (IP3, Ca(2+), and ATP). However, the contribution of IP3R heterotetramerization to Ca(2+) signal diversity has largely been unexplored. In this report, we provide the first definitive biochemical evidence of endogenous heterotetramer formation. Additionally, we examine the contribution of individual subtypes within defined concatenated heterotetramers to the shaping of Ca(2+) signals. Under conditions where key regulators of IP3R function are optimal for Ca(2+) release, we demonstrate that individual monomers within heteromeric IP3Rs contributed equally toward generating a distinct 'blended' sensitivity to IP3 that is likely dictated by the unique IP3 binding affinity of the heteromers. However, under suboptimal conditions where [ATP] were varied, we found that one subtype dictated the ATP regulatory properties of heteromers. We show that R2 monomers within a heterotetramer were both necessary and sufficient to dictate the ATP regulatory properties. Finally, the ATP-binding site B in R2 critical for ATP regulation was mutated and rendered non-functional to address questions relating to the stoichiometry of IP3R regulation. Two intact R2 monomers were sufficient to maintain ATP regulation in R2 homotetramers. In summary, we demonstrate that heterotetrameric IP3R do not necessarily behave as the sum of the constituent subunits, and these properties likely extend the versatility of IP3-induced Ca(2+) signaling in cells expressing multiple IP3R isoforms.
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Affiliation(s)
- Rahul Chandrasekhar
- From the Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642
| | - Kamil J Alzayady
- From the Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642
| | - Larry E Wagner
- From the Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642
| | - David I Yule
- From the Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642
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7
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Chandrasekhar R, Alzayady KJ, Yule DI. Using concatenated subunits to investigate the functional consequences of heterotetrameric inositol 1,4,5-trisphosphate receptors. Biochem Soc Trans 2015; 43:364-70. [PMID: 26009177 PMCID: PMC4677331 DOI: 10.1042/bst20140287] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP3Rs) are a family of ubiquitous, ER localized, tetrameric Ca2+ release channels. There are three subtypes of the IP3Rs (R1, R2, R3), encoded by three distinct genes, that share ∼60-70% sequence identity. The diversity of Ca2+ signals generated by IP3Rs is thought to be largely the result of differential tissue expression, intracellular localization and subtype-specific regulation of the three subtypes by various cellular factors, most significantly InsP3, Ca2+ and ATP. However, largely unexplored is the notion of additional signal diversity arising from the assembly of both homo and heterotetrameric InsP3Rs. In the present article, we review the biochemical and functional evidence supporting the existence of homo and heterotetrameric populations of InsP3Rs. In addition, we consider a strategy that utilizes genetically concatenated InsP3Rs to study the functional characteristics of heterotetramers with unequivocally defined composition. This approach reveals that the overall properties of IP3R are not necessarily simply a blend of the constituent monomers but that specific subtypes appear to dominate the overall characteristics of the tetramer. It is envisioned that the ability to generate tetramers with defined wild type and mutant subunits will be useful in probing fundamental questions relating to IP3R structure and function.
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MESH Headings
- Adenosine Triphosphate/chemistry
- Adenosine Triphosphate/metabolism
- Calcium Signaling/genetics
- Humans
- Inositol 1,4,5-Trisphosphate/chemistry
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/chemistry
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Protein Multimerization
- Protein Structure, Tertiary
- Structure-Activity Relationship
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8
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Shah SZA, Zhao D, Khan SH, Yang L. Regulatory Mechanisms of Endoplasmic Reticulum Resident IP3 Receptors. J Mol Neurosci 2015; 56:938-948. [PMID: 25859934 DOI: 10.1007/s12031-015-0551-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/23/2015] [Indexed: 11/25/2022]
Abstract
Dysregulated calcium signaling and accumulation of aberrant proteins causing endoplasmic reticulum stress are the early sign of intra-axonal pathological events in many neurodegenerative diseases, and apoptotic signaling is initiated when the stress goes beyond the maximum threshold level of endoplasmic reticulum. The fate of the cell to undergo apoptosis is controlled by Ca2(+) signaling and dynamics at the level of the endoplasmic reticulum. Endoplasmic reticulum resident inositol 1,4,5-trisphosphate receptors (IP3R) play a pivotal role in cell death signaling by mediating Ca2(+) flux from the endoplasmic reticulum into the cytosol and mitochondria. Hence, many prosurvival and prodeath signaling pathways and proteins affect Ca2(+) signaling by directly targeting IP3R channels, which can happen in an IP3R-isoform-dependent manner. Here, in this review, we summarize the regulatory mechanisms of inositol triphosphate receptors in calcium regulation and initiation of apoptosis during unfolded protein response.
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Affiliation(s)
- Syed Zahid Ali Shah
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Deming Zhao
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Sher Hayat Khan
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Lifeng Yang
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
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9
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Vervloessem T, Yule DI, Bultynck G, Parys JB. The type 2 inositol 1,4,5-trisphosphate receptor, emerging functions for an intriguing Ca²⁺-release channel. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1992-2005. [PMID: 25499268 DOI: 10.1016/j.bbamcr.2014.12.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/19/2022]
Abstract
The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) type 2 (IP3R2) is an intracellular Ca²⁺-release channel located on the endoplasmic reticulum (ER). IP3R2 is characterized by a high sensitivity to both IP3 and ATP and is biphasically regulated by Ca²⁺. Furthermore, IP3R2 is modulated by various protein kinases. In addition to its regulation by protein kinase A, IP3R2 forms a complex with adenylate cyclase 6 and is directly regulated by cAMP. Finally, in the ER, IP3R2 is less mobile than the other IP3R isoforms, while its functional properties appear dominant in heterotetramers. These properties make the IP3R2 a Ca²⁺ channel with exquisite properties for setting up intracellular Ca²⁺ signals with unique characteristics. IP3R2 plays a crucial role in the function of secretory cell types (e.g. pancreatic acinar cells, hepatocytes, salivary gland, eccrine sweat gland). In cardiac myocytes, the role of IP3R2 appears more complex, because, together with IP3R1, it is needed for normal cardiogenesis, while its aberrant activity is implicated in cardiac hypertrophy and arrhythmias. Most importantly, its high sensitivity to IP3 makes IP3R2 a target for anti-apoptotic proteins (e.g. Bcl-2) in B-cell cancers. Disrupting IP3R/Bcl-2 interaction therefore leads in those cells to increased Ca²⁺ release and apoptosis. Intriguingly, IP3R2 is not only implicated in apoptosis but also in the induction of senescence, another tumour-suppressive mechanism. These results were the first to unravel the physiological and pathophysiological role of IP3R2 and we anticipate that further progress will soon be made in understanding the function of IP3R2 in various tissues and organs.
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Affiliation(s)
- Tamara Vervloessem
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - David I Yule
- University of Rochester, Department of Pharmacology and Physiology, Rochester, NY, USA
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - Jan B Parys
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium.
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Akl H, Vervloessem T, Kiviluoto S, Bittremieux M, Parys JB, De Smedt H, Bultynck G. A dual role for the anti-apoptotic Bcl-2 protein in cancer: mitochondria versus endoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2240-52. [PMID: 24768714 DOI: 10.1016/j.bbamcr.2014.04.017] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/04/2014] [Accepted: 04/05/2014] [Indexed: 12/14/2022]
Abstract
Anti-apoptotic Bcl-2 contributes to cancer formation and progression by promoting the survival of altered cells. Hence, it is a prime target for novel specific anti-cancer therapeutics. In addition to its canonical anti-apoptotic role, Bcl-2 has an inhibitory effect on cell-cycle progression. Bcl-2 acts at two different intracellular compartments, the mitochondria and the endoplasmic reticulum (ER). At the mitochondria, Bcl-2 via its hydrophobic cleft scaffolds the Bcl-2-homology (BH) domain 3 (BH3) of pro-apoptotic Bcl-2-family members. Small molecules (like BH3 mimetics) can disrupt this interaction, resulting in apoptotic cell death in cancer cells. At the ER, Bcl-2 modulates Ca(2+) signaling, thereby promoting proliferation while increasing resistance to apoptosis. Bcl-2 at the ER acts via its N-terminal BH4 domain, which directly binds and inhibits the inositol 1,4,5-trisphosphate receptor (IP3R), the main intracellular Ca(2+)-release channel. Tools targeting the BH4 domain of Bcl-2 reverse Bcl-2's inhibitory action on IP3Rs and trigger pro-apoptotic Ca(2+) signaling in cancer B-cells, including chronic lymphocytic leukemia (CLL) cells and diffuse large B-cell lymphoma (DLBCL) cells. The sensitivity of DLBCL cells to BH4-domain targeting tools strongly correlated with the expression levels of the IP3R2 channel, the IP3R isoform with the highest affinity for IP3. Interestingly, bio-informatic analysis of a database of primary CLL patient cells also revealed a transcriptional upregulation of IP3R2. Finally, this review proposes a model, in which cancer cell survival depends on Bcl-2 at the mitochondria and/or the ER. This dependence likely will have an impact on their responses to BH3-mimetic drugs and BH4-domain targeting tools. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
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Affiliation(s)
- Haidar Akl
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Molecular and Cellular Medicine, Campus Gasthuisberg, O/N-I, Bus 802, Herestraat 49, BE-3000 Leuven, Belgium.
| | - Tamara Vervloessem
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Molecular and Cellular Medicine, Campus Gasthuisberg, O/N-I, Bus 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Santeri Kiviluoto
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Molecular and Cellular Medicine, Campus Gasthuisberg, O/N-I, Bus 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Mart Bittremieux
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Molecular and Cellular Medicine, Campus Gasthuisberg, O/N-I, Bus 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Jan B Parys
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Molecular and Cellular Medicine, Campus Gasthuisberg, O/N-I, Bus 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Humbert De Smedt
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Molecular and Cellular Medicine, Campus Gasthuisberg, O/N-I, Bus 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Molecular and Cellular Medicine, Campus Gasthuisberg, O/N-I, Bus 802, Herestraat 49, BE-3000 Leuven, Belgium.
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11
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Ivanova H, Vervliet T, Missiaen L, Parys JB, De Smedt H, Bultynck G. Inositol 1,4,5-trisphosphate receptor-isoform diversity in cell death and survival. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2164-83. [PMID: 24642269 DOI: 10.1016/j.bbamcr.2014.03.007] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/06/2014] [Accepted: 03/09/2014] [Indexed: 01/22/2023]
Abstract
Cell-death and -survival decisions are critically controlled by intracellular Ca(2+) homeostasis and dynamics at the level of the endoplasmic reticulum (ER). Inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) play a pivotal role in these processes by mediating Ca(2+) flux from the ER into the cytosol and mitochondria. Hence, it is clear that many pro-survival and pro-death signaling pathways and proteins affect Ca(2+) signaling by directly targeting IP3R channels, which can happen in an IP3R-isoform-dependent manner. In this review, we will focus on how the different IP3R isoforms (IP3R1, IP3R2 and IP3R3) control cell death and survival. First, we will present an overview of the isoform-specific regulation of IP3Rs by cellular factors like IP3, Ca(2+), Ca(2+)-binding proteins, adenosine triphosphate (ATP), thiol modification, phosphorylation and interacting proteins, and of IP3R-isoform specific expression patterns. Second, we will discuss the role of the ER as a Ca(2+) store in cell death and survival and how IP3Rs and pro-survival/pro-death proteins can modulate the basal ER Ca(2+) leak. Third, we will review the regulation of the Ca(2+)-flux properties of the IP3R isoforms by the ER-resident and by the cytoplasmic proteins involved in cell death and survival as well as by redox regulation. Hence, we aim to highlight the specific roles of the various IP3R isoforms in cell-death and -survival signaling. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
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Affiliation(s)
- Hristina Ivanova
- KU Leuven Lab. of Molecular and Cellular Signaling, Dept. of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I Box 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Tim Vervliet
- KU Leuven Lab. of Molecular and Cellular Signaling, Dept. of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I Box 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Ludwig Missiaen
- KU Leuven Lab. of Molecular and Cellular Signaling, Dept. of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I Box 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Jan B Parys
- KU Leuven Lab. of Molecular and Cellular Signaling, Dept. of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I Box 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Humbert De Smedt
- KU Leuven Lab. of Molecular and Cellular Signaling, Dept. of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I Box 802, Herestraat 49, BE-3000 Leuven, Belgium.
| | - Geert Bultynck
- KU Leuven Lab. of Molecular and Cellular Signaling, Dept. of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I Box 802, Herestraat 49, BE-3000 Leuven, Belgium.
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12
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Voronina S, Okeke E, Parker T, Tepikin A. How to win ATP and influence Ca(2+) signaling. Cell Calcium 2014; 55:131-8. [PMID: 24613709 DOI: 10.1016/j.ceca.2014.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 02/10/2014] [Accepted: 02/11/2014] [Indexed: 12/11/2022]
Abstract
This brief review discusses recent advances in studies of mitochondrial Ca(2+) signaling and considers how the relationships between mitochondria and Ca(2+) responses are shaped in secretory epithelial cells. Perhaps the more precise title of this review could have been "How to win ATP and influence Ca(2+) signaling in secretory epithelium with emphasis on exocrine secretory cells and specific focus on pancreatic acinar cells". But "brevity is a virtue" and the authors hope that many of the mechanisms discussed are general and applicable to other tissues and cell types. Among these mechanisms are mitochondrial regulation of Ca(2+) entry and the role of mitochondria in the formation of localized Ca(2+) responses. The roles of Ca(2+) signaling in the physiological adjustment of bioenergetics and in mitochondrial damage are also briefly discussed.
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Affiliation(s)
- Svetlana Voronina
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, The University of Liverpool, Crown Street, Liverpool L69 3BX, UK
| | - Emmanuel Okeke
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, The University of Liverpool, Crown Street, Liverpool L69 3BX, UK
| | - Tony Parker
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, The University of Liverpool, Crown Street, Liverpool L69 3BX, UK
| | - Alexei Tepikin
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, The University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
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13
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Haanes KA, Kowal JM, Arpino G, Lange SC, Moriyama Y, Pedersen PA, Novak I. Role of vesicular nucleotide transporter VNUT (SLC17A9) in release of ATP from AR42J cells and mouse pancreatic acinar cells. Purinergic Signal 2014; 10:431-40. [PMID: 24488439 DOI: 10.1007/s11302-014-9406-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 01/08/2014] [Indexed: 12/11/2022] Open
Abstract
ATP is released from cells in response to various stimuli. Our previous studies on pancreas indicated that pancreatic acini could be major stores of secreted ATP. In the present study, our aim was to establish the role of the vesicular nucleotide transporter (VNUT), SLC17A9, in storage and release of ATP. Freshly prepared acini from mice and AR42J rat acinar cells were used in this study. We illustrate that in AR42J cells, quinacrine (an ATP store marker) and Bodipy ATP (a fluorescent ATP analog) co-localized with VNUT-mCherry to vesicles/granules. Furthermore, in acini and AR42J cells, a marker of the zymogen granule membranes, Rab3D, and VNUT co-localized. Dexamethasone treatment of AR42J cells promoted formation of acinar structures, paralleled by increased amylase and VNUT expression, and increased ATP release in response to cholinergic stimulation. Mechanical stimulus (pressure) and cell swelling also induced ATP release, but this was not influenced by dexamethasone, most likely indicating different non-zymogen-related release mechanism. In conclusion, we propose that VNUT-dependent ATP release pathway is associated with agonist-induced secretion process and downstream purinergic signalling in pancreatic ducts.
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Affiliation(s)
- K A Haanes
- Department of Biology, Section Molecular Integrative Physiology, University of Copenhagen, August Krogh Building, Universitetsparken 13, Copenhagen, 2100, Denmark
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14
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Alzayady KJ, Wagner LE, Chandrasekhar R, Monteagudo A, Godiska R, Tall GG, Joseph SK, Yule DI. Functional inositol 1,4,5-trisphosphate receptors assembled from concatenated homo- and heteromeric subunits. J Biol Chem 2013; 288:29772-84. [PMID: 23955339 DOI: 10.1074/jbc.m113.502203] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Vertebrate genomes code for three subtypes of inositol 1,4,5-trisphosphate (IP3) receptors (IP3R1, -2, and -3). Individual IP3R monomers are assembled to form homo- and heterotetrameric channels that mediate Ca(2+) release from intracellular stores. IP3R subtypes are regulated differentially by IP3, Ca(2+), ATP, and various other cellular factors and events. IP3R subtypes are seldom expressed in isolation in individual cell types, and cells often express different complements of IP3R subtypes. When multiple subtypes of IP3R are co-expressed, the subunit composition of channels cannot be specifically defined. Thus, how the subunit composition of heterotetrameric IP3R channels contributes to shaping the spatio-temporal properties of IP3-mediated Ca(2+) signals has been difficult to evaluate. To address this question, we created concatenated IP3R linked by short flexible linkers. Dimeric constructs were expressed in DT40-3KO cells, an IP3R null cell line. The dimeric proteins were localized to membranes, ran as intact dimeric proteins on SDS-PAGE, and migrated as an ∼1100-kDa band on blue native gels exactly as wild type IP3R. Importantly, IP3R channels formed from concatenated dimers were fully functional as indicated by agonist-induced Ca(2+) release. Using single channel "on-nucleus" patch clamp, the channels assembled from homodimers were essentially indistinguishable from those formed by the wild type receptor. However, the activity of channels formed from concatenated IP3R1 and IP3R2 heterodimers was dominated by IP3R2 in terms of the characteristics of regulation by ATP. These studies provide the first insight into the regulation of heterotetrameric IP3R of defined composition. Importantly, the results indicate that the properties of these channels are not simply a blend of those of the constituent IP3R monomers.
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Affiliation(s)
- Kamil J Alzayady
- From the Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642
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15
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Akl H, Monaco G, La Rovere R, Welkenhuyzen K, Kiviluoto S, Vervliet T, Molgó J, Distelhorst CW, Missiaen L, Mikoshiba K, Parys JB, De Smedt H, Bultynck G. IP3R2 levels dictate the apoptotic sensitivity of diffuse large B-cell lymphoma cells to an IP3R-derived peptide targeting the BH4 domain of Bcl-2. Cell Death Dis 2013; 4:e632. [PMID: 23681227 PMCID: PMC3674349 DOI: 10.1038/cddis.2013.140] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Disrupting inositol 1,4,5-trisphosphate (IP3) receptor (IP3R)/B-cell lymphoma 2 (Bcl-2) complexes using a cell-permeable peptide (stabilized TAT-fused IP3R-derived peptide (TAT-IDPS)) that selectively targets the BH4 domain of Bcl-2 but not that of B-cell lymphoma 2-extra large (Bcl-Xl) potentiated pro-apoptotic Ca2+ signaling in chronic lymphocytic leukemia cells. However, the molecular mechanisms rendering cancer cells but not normal cells particularly sensitive to disrupting IP3R/Bcl-2 complexes are poorly understood. Therefore, we studied the effect of TAT-IDPS in a more heterogeneous Bcl-2-dependent cancer model using a set of ‘primed to death' diffuse large B-cell lymphoma (DL-BCL) cell lines containing elevated Bcl-2 levels. We discovered a large heterogeneity in the apoptotic responses of these cells to TAT-IDPS with SU-DHL-4 being most sensitive and OCI-LY-1 being most resistant. This sensitivity strongly correlated with the ability of TAT-IDPS to promote IP3R-mediated Ca2+ release. Although total IP3R-expression levels were very similar among SU-DHL-4 and OCI-LY-1, we discovered that the IP3R2-protein level was the highest for SU-DHL-4 and the lowest for OCI-LY-1. Strikingly, TAT-IDPS-induced Ca2+ rise and apoptosis in the different DL-BCL cell lines strongly correlated with their IP3R2-protein level, but not with IP3R1-, IP3R3- or total IP3R-expression levels. Inhibiting or knocking down IP3R2 activity in SU-DHL-4-reduced TAT-IDPS-induced apoptosis, which is compatible with its ability to dissociate Bcl-2 from IP3R2 and to promote IP3-induced pro-apoptotic Ca2+ signaling. Thus, certain chronically activated B-cell lymphoma cells are addicted to high Bcl-2 levels for their survival not only to neutralize pro-apoptotic Bcl-2-family members but also to suppress IP3R hyperactivity. In particular, cancer cells expressing high levels of IP3R2 are addicted to IP3R/Bcl-2 complex formation and disruption of these complexes using peptide tools results in pro-apoptotic Ca2+ signaling and cell death.
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Affiliation(s)
- H Akl
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
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16
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Orabi AI, Luo Y, Ahmad MU, Shah AU, Mannan Z, Wang D, Sarwar S, Muili KA, Shugrue C, Kolodecik TR, Singh VP, Lowe ME, Thrower E, Chen J, Husain SZ. IP3 receptor type 2 deficiency is associated with a secretory defect in the pancreatic acinar cell and an accumulation of zymogen granules. PLoS One 2012. [PMID: 23185258 PMCID: PMC3504040 DOI: 10.1371/journal.pone.0048465] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Acute pancreatitis is a painful, life-threatening disorder of the pancreas whose etiology is often multi-factorial. It is of great importance to understand the interplay between factors that predispose patients to develop the disease. One such factor is an excessive elevation in pancreatic acinar cell Ca2+. These aberrant Ca2+ elevations are triggered by release of Ca2+ from apical Ca2+ pools that are gated by the inositol 1,4,5-trisphosphate receptor (IP3R) types 2 and 3. In this study, we examined the role of IP3R type 2 (IP3R2) using mice deficient in this Ca2+ release channel (IP3R2−/−). Using live acinar cell Ca2+ imaging we found that loss of IP3R2 reduced the amplitude of the apical Ca2+ signal and caused a delay in its initiation. This was associated with a reduction in carbachol-stimulated amylase release and an accumulation of zymogen granules (ZGs). Specifically, there was a 2-fold increase in the number of ZGs (P<0.05) and an expansion of the ZG pool area within the cell. There was also a 1.6- and 2.6-fold increase in cellular amylase and trypsinogen, respectively. However, the mice did not have evidence of pancreatic injury at baseline, other than an elevated serum amylase level. Further, pancreatitis outcomes using a mild caerulein hyperstimulation model were similar between IP3R2−/− and wild type mice. In summary, IP3R2 modulates apical acinar cell Ca2+ signals and pancreatic enzyme secretion. IP3R-deficient acinar cells accumulate ZGs, but the mice do not succumb to pancreatic damage or worse pancreatitis outcomes.
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Affiliation(s)
- Abrahim I. Orabi
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Yuhuan Luo
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Mahwish U. Ahmad
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Ahsan U. Shah
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Zahir Mannan
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Dong Wang
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Sheharyar Sarwar
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Kamaldeen A. Muili
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Christine Shugrue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Thomas R. Kolodecik
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Vijay P. Singh
- Department of Internal Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Mark E. Lowe
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Edwin Thrower
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ju Chen
- Department of Molecular Pathology, University of California San Diego, San Diego, California, United States of America
| | - Sohail Z. Husain
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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17
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Voronina S, Tepikin A. Mitochondrial calcium in the life and death of exocrine secretory cells. Cell Calcium 2012; 52:86-92. [PMID: 22571865 DOI: 10.1016/j.ceca.2012.03.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 03/26/2012] [Accepted: 03/27/2012] [Indexed: 01/11/2023]
Abstract
The remarkable recent discoveries of the proteins mediating mitochondrial Ca(2+) transport (reviewed in this issue) provide an exciting opportunity to utilise this new knowledge to improve our fundamental understanding of relationships between Ca(2+) signalling and bioenergetics and, importantly, to improve the understanding of diseases in which Ca(2+) toxicity and mitochondrial malfunction play a crucial role. Ca(2+) is an important activator of exocrine secretion, a regulator of the bioenergetics of exocrine cells and a contributor to exocrine cell damage. Exocrine secretory cells, exocrine tissues and diseases affecting exocrine glands (like Sjögren's syndrome and acute pancreatitis) will, therefore, provide worthy research areas for the application of this new knowledge of the Ca(2+) transport mechanisms in mitochondria.
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Affiliation(s)
- Svetlana Voronina
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, The University of Liverpool, Crown Street, Liverpool L69 3BX, UK
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Wagner LE, Yule DI. Differential regulation of the InsP₃ receptor type-1 and -2 single channel properties by InsP₃, Ca²⁺ and ATP. J Physiol 2012; 590:3245-59. [PMID: 22547632 DOI: 10.1113/jphysiol.2012.228320] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
An elevation of intracellular Ca2+ levels as a result of InsP3 receptor (InsP3R) activity represents a ubiquitous signalling pathway controlling a wide variety of cellular events. InsP3R activity is tightly controlled by the levels of the primary ligands, InsP3, Ca2+ and ATP. Importantly, InsP3Rs are regulated by Ca2+ i in a biphasic manner. Ca2+ release through all InsP3R family members is also modulated dramatically by ATP, albeit with sub-type-specific properties. To ascertain if a common mechanism can account for ATP and Ca2+ regulation of these InsP3R family members, we examined the effects of [ATP] on the Ca2+ dependency of rat InsP3R-1 (rInsP3R-1) and mouse InsP3R-2 (mInsP3R-2) activity expressed in DT40-3KO cells. We used the on-nucleus patch clamp recording technique with various [ATP], [InsP3] and [Ca2+] in the patch pipette and measured single InsP3R channel activity in stably transfected DT40 cells. Under identical conditions, at saturating [InsP3] and [ATP], the activity of rInsP3R-1 and mInsP3R-2 was essentially identical in terms of single channel conductance, maximal achievable open probability (Po) and the [Ca2+] required for activation and inhibition of activity. However, in contrast to rInsP3R-1 at saturating [InsP3], the activity of mInsP3R-2 was unaffected by [ATP]. At lower [InsP3], ATP had dramatic effects on mInsP3R-2 Po, but unlike the rInsP3R-1, this did not occur by altering the relative Ca2+ dependency, but by simply increasing the maximally achievable Po at a particular [InsP3] and [Ca2+]. [InsP3] did not alter the biphasic regulation of activity by Ca2+ in either rInsP3R-1 or mInsP3R-2. Analysis of the single channel kinetics indicated that Ca2+ and ATP modulate the Po predominately by facilitating extended bursting activity of the channel but the underlying biophysical mechanism appears to be distinct for each receptor. Subtype-specific regulation of InsP3R channel activity probably contributes to the fidelity of Ca2+ signalling in cells expressing these receptor subtypes.
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Affiliation(s)
- Larry E Wagner
- Department of Pharmacology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY, USA
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19
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Genetic variation in the calcium/calmodulin-dependent protein kinase (CaMK) pathway is associated with antidepressant response in females. J Affect Disord 2012; 136:558-66. [PMID: 22119081 DOI: 10.1016/j.jad.2011.10.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 09/29/2011] [Accepted: 10/21/2011] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Antidepressant effects on monoamine neurotransmission may be influenced by genetic variation in intracellular signal transduction pathways, such as the cyclic adenosine monophosphate (cAMP)--protein kinase A (PKA) pathway, Ras-mitogen activated protein kinase (MAPK) pathway and calcium/calmodulin-dependent protein kinase (CaMK) pathway. The aims of this study were to examine the association of polymorphisms in candidate genes of these three signal transduction pathways with response to antidepressant treatment, and to determine the effects of, and interactions with, environment factors. METHODS We recruited 412 patients who met diagnosis criteria for major depressive disorder (MDD) (DSM-IV Axis I). 284 patients completed 8 weeks treatment with selective serotonin reuptake inhibitors (SSRIs) or serotonin and noradrenergic reuptake inhibitors (SNRIs). Severity of depression was measured with the Hamilton Depression Rating Scale (HDRS) before and after 8 weeks antidepressant treatment. 209 patients completed the Childhood Trauma Questionnaire, 28 item Short Form (CTQ-SF) which was used to evaluate childhood adverse events. 218 patients completed the Life Events Scale (LES) which were used to evaluate life stress before onset. 155 SNPs in 66 candidate genes were genotyping by Illumina GoldenGate, including 28 SNPs in 15 genes of cAMP-PKA pathway, 37 SNPs in 17 genes of Ras-MAPK pathway and 90 SNPs in 34 genes of CaMK pathway. The remission criterion was HDRS score equal to or less than 7. Single SNP and haplotype associations were analyzed by UNPHASED 3.3.13. Gene-environment interactions were analyzed by binary logistic regression with SPSS 11.0 software. RESULTS The rs2230372 SNP in ITPR2, rs2280272 in PRKCZ, rs17109671, and rs17109674 in PLCE1 were significant associated with remission, as were haplotypes in PRKCZ and PLCE1. All these positive associations were found in genes of the CaMK pathway, but not the cAMP-PKA or Ras-MAPK pathways. There were no significant differences in CTQ scores and LES scores between remitters and non-remitters. No significantly interactions between candidate genes and environment effects were observed. CONCLUSION The CaMK pathway may be important in determining antidepressant response. But recent adverse life events, childhood adversity, and interactions between candidate genes and environment factors appear not to influence short term antidepressant outcome.
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20
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Park HS, Betzenhauser MJ, Zhang Y, Yule DI. Regulation of Ca²⁺ release through inositol 1,4,5-trisphosphate receptors by adenine nucleotides in parotid acinar cells. Am J Physiol Gastrointest Liver Physiol 2012; 302:G97-G104. [PMID: 21960523 PMCID: PMC3345966 DOI: 10.1152/ajpgi.00328.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Secretagogue-stimulated intracellular Ca(2+) signals are fundamentally important for initiating the secretion of the fluid and ion component of saliva from parotid acinar cells. The Ca(2+) signals have characteristic spatial and temporal characteristics, which are defined by the specific properties of Ca(2+) release mediated by inositol 1,4,5-trisphosphate receptors (InsP(3)R). In this study we have investigated the role of adenine nucleotides in modulating Ca(2+) release in mouse parotid acinar cells. In permeabilized cells, the Ca(2+) release rate induced by submaximal [InsP(3)] was increased by 5 mM ATP. Enhanced Ca(2+) release was not observed at saturating [InsP(3)]. The EC(50) for the augmented Ca(2+) release was ∼8 μM ATP. The effect was mimicked by nonhydrolysable ATP analogs. ADP and AMP also potentiated Ca(2+) release but were less potent than ATP. In acini isolated from InsP(3)R-2-null transgenic animals, the rate of Ca(2+) release was decreased under all conditions but now enhanced by ATP at all [InsP(3)]. In addition the EC(50) for ATP potentiation increased to ∼500 μM. These characteristics are consistent with the properties of the InsP(3)R-2 dominating the overall features of InsP(3)R-induced Ca(2+) release despite the expression of all isoforms. Finally, Ca(2+) signals were measured in intact parotid lobules by multiphoton microscopy. Consistent with the release data, carbachol-stimulated Ca(2+) signals were reduced in lobules exposed to experimental hypoxia compared with control lobules only at submaximal concentrations. Adenine nucleotide modulation of InsP(3)R in parotid acinar cells likely contributes to the properties of Ca(2+) signals in physiological and pathological conditions.
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Affiliation(s)
- Hyung Seo Park
- University of Rochester Medical Center, Department of Pharmacology and Physiology, University of Rochester, Rochester, New York
| | - Matthew J. Betzenhauser
- University of Rochester Medical Center, Department of Pharmacology and Physiology, University of Rochester, Rochester, New York
| | - Yu Zhang
- University of Rochester Medical Center, Department of Pharmacology and Physiology, University of Rochester, Rochester, New York
| | - David I. Yule
- University of Rochester Medical Center, Department of Pharmacology and Physiology, University of Rochester, Rochester, New York
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21
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Kim JY, Lim DM, Park HS, Moon CI, Choi KJ, Lee SK, Baik HW, Park KY, Kim BJ. Exendin-4 Protects Against Sulfonylurea-Induced β-Cell Apoptosis. J Pharmacol Sci 2012; 118:65-74. [DOI: 10.1254/jphs.11072fp] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 11/08/2011] [Indexed: 10/14/2022] Open
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Choi KJ, Cho DS, Kim JY, Kim BJ, Lee KM, Kim SH, Kim DK, Kim SH, Park HS. Ca-induced Ca Release from Internal Stores in INS-1 Rat Insulinoma Cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2011; 15:53-9. [PMID: 21461241 DOI: 10.4196/kjpp.2011.15.1.53] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 02/14/2011] [Accepted: 02/16/2011] [Indexed: 12/23/2022]
Abstract
The secretion of insulin from pancreatic β-cells is triggered by the influx of Ca(2+) through voltage-dependent Ca(2+) channels. The resulting elevation of intracellular calcium ([Ca(2+)](i)) triggers additional Ca(2+) release from internal stores. Less well understood are the mechanisms involved in Ca(2+) mobilization from internal stores after activation of Ca(2+) influx. The mobilization process is known as calcium-induced calcium release (CICR). In this study, our goal was to investigate the existence of and the role of caffeine-sensitive ryanodine receptors (RyRs) in a rat pancreatic β-cell line, INS-1 cells. To measure cytosolic and stored Ca(2+), respectively, cultured INS-1 cells were loaded with fura-2/AM or furaptra/AM. [Ca(2+)](i) was repetitively increased by caffeine stimulation in normal Ca(2+) buffer. However, peak [Ca(2+)](i) was only observed after the first caffeine stimulation in Ca(2+) free buffer and this increase was markedly blocked by ruthenium red, a RyR blocker. KCl-induced elevations in [Ca(2+)](i) were reduced by pretreatment with ruthenium red, as well as by depletion of internal Ca(2+) stores using cyclopiazonic acid (CPA) or caffeine. Caffeine-induced Ca(2+) mobilization ceased after the internal stores were depleted by carbamylcholine (CCh) or CPA. In permeabilized INS-1 cells, Ca(2+) release from internal stores was activated by caffeine, Ca(2+), or ryanodine. Furthermore, ruthenium red completely blocked the CICR response in permeabilized cells. RyRs were widely distributed throughout the intracellular compartment of INS-1 cells. These results suggest that caffeine-sensitive RyRs exist and modulate the CICR response from internal stores in INS-1 pancreatic β-cells.
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Affiliation(s)
- Kyung Jin Choi
- Department of Physiology, College of Medicine, Konyang University, Daejeon 302-718, Korea
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Han J, Liu YQ. Suppressed glucose metabolism in acinar cells might contribute to the development of exocrine pancreatic insufficiency in streptozotocin-induced diabetic mice. Metabolism 2010; 59:1257-67. [PMID: 20051281 DOI: 10.1016/j.metabol.2009.11.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 11/13/2009] [Accepted: 11/23/2009] [Indexed: 01/30/2023]
Abstract
High prevalence of exocrine pancreatic insufficiency has been observed in diabetic patients. However, the underlying mechanisms are not well known. Reduced cytosolic Ca(2+) signals in pancreatic acinar cells may contribute to lower digestive enzyme secretion. It is well known that adenosine triphosphate (ATP) regulates cytosolic Ca(2+) signals in acinar cells; however, little is known as to whether diabetes impairs glucose metabolism that produces ATP in acinar cells. Streptozotocin (STZ)-induced diabetic C57BL/6 mouse model was used. Four weeks after being diabetic, pancreatic acinar cells were isolated; and amylase secretion and contents, glucose utilization and oxidation, the activities of several key enzymes for glucose metabolism, and ATP and nicotinamide adenine dinucleotide phosphate (reduced form) (NADPH) contents were determined. Compared with controls, diabetic mice had lower body weight. Cholecystokinin-8- and acetylcholine-stimulated amylase secretion was significantly impaired, and total amylase activity in acinar cells of STZ-diabetic mice was markedly reduced. Glucose utilization and oxidation were suppressed; measured enzyme activities for glucose metabolism and the ATP and NADPH contents were significantly reduced. These data indicate that glucose metabolism and ATP and NADPH productions are very important for maintaining acinar cell normal function. Reduction of ATP (reduces cytosolic Ca(2+) signals) and NADPH (reduces cell capability for antioxidative stress) productions may contribute to the development of exocrine pancreatic insufficiency in STZ-diabetic mice.
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Affiliation(s)
- Junying Han
- The Research Institute for Children, Children's Hospital, New Orleans, Louisiana 70118, USA
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24
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Low JT, Shukla A, Behrendorff N, Thorn P. Exocytosis, dependent on Ca2+ release from Ca2+ stores, is regulated by Ca2+ microdomains. J Cell Sci 2010; 123:3201-8. [PMID: 20736314 DOI: 10.1242/jcs.071225] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The relationship between the cellular Ca2+ signal and secretory vesicle fusion (exocytosis) is a key determinant of the regulation of the kinetics and magnitude of the secretory response. Here, we have investigated secretion in cells where the exocytic response is controlled by Ca2+ release from intracellular Ca2+ stores. Using live-cell two-photon microscopy that simultaneously records Ca2+signals and exocytic responses, we provide evidence that secretion is controlled by changes in Ca2+ concentration [Ca2+] in relatively large-volume microdomains. Our evidence includes: (1) long latencies (>2 seconds) between the rise in [Ca2+] and exocytosis, (2) observation of exocytosis all along the lumen and not clustered around Ca2+ release hot-spots, (3) high affinity (Kd=1.75 microM) Ca2+dependence of exocytosis, (4) significant reduction in exocytosis in the presence of cytosolic EGTA, (5) spatial exclusion of secretory granules from the cell membrane by the endoplasmic reticulum, and (6) inability of local Ca2+ responses to trigger exocytosis. These results strongly indicate that the control of exocytosis, triggered by Ca2+ release from stores, is through the regulation of cytosolic[Ca2+] within a microdomain.
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Affiliation(s)
- Jiun T Low
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD 4072, Australia
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25
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Betzenhauser MJ, Yule DI. Regulation of inositol 1,4,5-trisphosphate receptors by phosphorylation and adenine nucleotides. CURRENT TOPICS IN MEMBRANES 2010; 66:273-98. [PMID: 22353484 DOI: 10.1016/s1063-5823(10)66012-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
- Matthew J Betzenhauser
- Department of Physiology and Cellular Biophysics, Columbia University Medical School, New York City, New York, USA
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26
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Yule DI. Pancreatic acinar cells: molecular insight from studies of signal-transduction using transgenic animals. Int J Biochem Cell Biol 2010; 42:1757-61. [PMID: 20637894 DOI: 10.1016/j.biocel.2010.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 07/08/2010] [Indexed: 11/15/2022]
Abstract
Pancreatic acinar cells are classical exocrine gland cells. The apical regions of clusters of coupled acinar cells collectively form a lumen which constitutes the blind end of a tube created by ductal cells - a structure reminiscent of a "bunch of grapes". When activated by neural or hormonal secretagogues, pancreatic acinar cells are stimulated to secrete a variety of proteins. These proteins are predominately inactive digestive enzyme precursors called "zymogens". Acinar cell secretion is absolutely dependent on secretagogue-induced increases in intracellular free Ca(2+). The increase in [Ca(2+)](i) has precise temporal and spatial characteristics as a result of the exquisite regulation of the proteins responsible for Ca(2+) release, Ca(2+) influx and Ca(2+) clearance in the acinar cell. This brief review discusses recent studies in which transgenic animal models have been utilized to define in molecular detail the components of the Ca(2+) signaling machinery which contribute to these characteristics.
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Affiliation(s)
- David I Yule
- Department of Pharmacology and Physiology, University of Rochester Medical School, Rochester, NY 14642, USA. David
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Yule DI, Betzenhauser MJ, Joseph SK. Linking structure to function: Recent lessons from inositol 1,4,5-trisphosphate receptor mutagenesis. Cell Calcium 2010; 47:469-79. [PMID: 20510450 DOI: 10.1016/j.ceca.2010.04.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 04/21/2010] [Accepted: 04/22/2010] [Indexed: 12/12/2022]
Abstract
Great insight has been gained into the structure and function of the inositol 1,4,5 trisphosphate receptor (InsP(3)R) by studies employing mutagenesis of the cDNA encoding the receptor. Notably, early studies using this approach defined the key constituents required for InsP(3) binding in the N-terminus and the membrane spanning regions in the C-terminal domain responsible for channel formation, targeting and function. In this article we evaluate recent studies which have used a similar approach to investigate key residues underlying the in vivo modulation by select regulatory factors. In addition, we review studies defining the structural requirements in the channel domain which comprise the conduction pathway and are suggested to be involved in the gating of the channel.
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Affiliation(s)
- David I Yule
- Department of Pharmacology and Physiology, University of Rochester, NY, United States.
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28
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Voronina S, Barrow S, Simpson A, Gerasimenko O, da Silva Xavier G, Rutter G, Petersen O, Tepikin AV. Dynamic changes in cytosolic and mitochondrial ATP levels in pancreatic acinar cells. Gastroenterology 2010; 138:1976-87. [PMID: 20102715 PMCID: PMC6101211 DOI: 10.1053/j.gastro.2010.01.037] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2009] [Revised: 12/17/2009] [Accepted: 01/21/2010] [Indexed: 01/09/2023]
Abstract
BACKGROUND & AIMS Previous studies of pancreatic acinar cells characterized the effects of Ca(2+)-releasing secretagogues and substances, inducing acute pancreatitis on mitochondrial Ca(2+), transmembrane potential, and NAD(P)H, but dynamic measurements of the crucial intracellular adenosine triphosphate (ATP) levels have not been reported. Here we characterized the effects of these agents on ATP levels in the cytosol and mitochondria. METHODS ATP levels were monitored using cytosolic- or mitochondrial-targeted luciferases. RESULTS Inhibition of oxidative phosphorylation produced a substantial decrease in cytosolic ATP comparable to that induced by inhibition of glycolysis. Cholecystokinin-8 (CCK) increased cytosolic ATP in spite of accelerating ATP consumption. Acetylcholine, caerulein, and bombesin had similar effect. A bile acid, taurolithocholic acid 3-sulfate (TLC-S); a fatty acid, palmitoleic acid (POA); and palmitoleic acid ethyl ester (POAEE) reduced cytosolic ATP. The ATP decrease in response to these substances was observed in cells with intact or inhibited oxidative phosphorylation. TLC-S, POA, and POAEE reduced mitochondrial ATP, whereas physiological CCK increased mitochondrial ATP. Supramaximal CCK produced a biphasic response composed of a small initial decline followed by a stronger increase. CONCLUSIONS Both glycolysis and oxidative phosphorylation make substantial contributions to ATP production in acinar cells. Ca(2+)-releasing secretagogues increased ATP level in the cytosol and mitochondria of intact isolated cells. TLC-S, POA, and POAEE reduced cytosolic and mitochondrial ATP. When cells rely on nonoxidative ATP production, secretagogues as well as TLC-S, POA, and POAEE all diminish cytosolic ATP levels.
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Affiliation(s)
- Svetlana Voronina
- The Physiological Laboratory, School of Biomedical Sciences, The University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Stephanie Barrow
- The Physiological Laboratory, School of Biomedical Sciences, The University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Alec Simpson
- Department of Human Anatomy and Cell Biology, School of Biomedical Sciences, The University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Oleg Gerasimenko
- The Physiological Laboratory, School of Biomedical Sciences, The University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Gabriela da Silva Xavier
- Section of Cell Biology, Division of Medicine, Imperial College, London, Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, UK
| | - Guy Rutter
- Section of Cell Biology, Division of Medicine, Imperial College, London, Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, UK
| | - Ole Petersen
- The Physiological Laboratory, School of Biomedical Sciences, The University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Alexei V. Tepikin
- The Physiological Laboratory, School of Biomedical Sciences, The University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
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29
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Choi KJ, Kim KS, Kim SH, Kim DK, Park HS. Caffeine and 2-Aminoethoxydiphenyl Borate (2-APB) Have Different Ability to Inhibit Intracellular Calcium Mobilization in Pancreatic Acinar Cell. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2010; 14:105-11. [PMID: 20473382 DOI: 10.4196/kjpp.2010.14.2.105] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 04/15/2010] [Accepted: 04/20/2010] [Indexed: 01/10/2023]
Abstract
Inositol 1,4,5-trisphosphate receptors (InsP(3)Rs) modulate Ca(2+) release from intracellular Ca(2+) store and are extensively expressed in the membrane of endoplasmic/sarcoplasmic reticulum and Golgi. Although caffeine and 2-aminoethoxydiphenyl borate (2-APB) have been widely used to block InsP(3)Rs, the use of these is limited due to their multiple actions. In the present study, we examined and compared the ability of caffeine and 2-APB as a blocker of Ca(2+) release from intracellular Ca(2+) stores and Ca(2+) entry through store-operated Ca(2+) (SOC) channel in the mouse pancreatic acinar cell. Caffeine did not block the Ca(2+) entry, but significantly inhibited carbamylcholine (CCh)-induced Ca(2+) release. In contrast, 2-APB did not block CCh-induced Ca(2+) release, but remarkably blocked SOC-mediated Ca(2+) entry at lower concentrations. In permeabilized acinar cell, caffeine had an inhibitory effect on InsP(3)-induced Ca(2+) release, but 2-APB at lower concentration, which effectively blocked Ca(2+) entry, had no inhibitory action. At higher concentrations, 2-APB has multiple paradoxical effects including inhibition of InsP(3)-induced Ca(2+) release and direct stimulation of Ca(2+) release. Based on the results, we concluded that caffeine is useful as an inhibitor of InsP(3)R, and 2-APB at lower concentration is considered a blocker of Ca(2+) entry through SOC channels in the pancreatic acinar cell.
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Affiliation(s)
- Kyung Jin Choi
- Department of Physiology, College of Medicine, Konyang University, Daejeon 302-718, Korea
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30
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Abstract
PURPOSE OF REVIEW This review focuses on studies from the past year that have greatly advanced our understanding of molecular and cellular regulation of pancreatic acinar cell function. RECENT FINDINGS Recent advances focus on signals dictating pancreatic development, acinar cell fate, pancreatic growth, and secretion. Regeneration of acinar cells after pancreatitis depends on expression of embryonic signals in mature acinar cells. In this setting, acinar cells can also transdifferentiate into adipose cells. With the forced induction of certain early and endocrine-driving transcription factors, acinar cells can also transdifferentiate into beta-cells. There has also been an increased understanding of acinar-to-ductal metaplasia and the subsequent formation of pancreatic intraepithelial neoplasia lesions. Multiple proteins involved in secretion have been characterized, including small guanosine triphosphate-binding proteins, soluble N-ethylmaleimide-sensitive factor attachment proteins, and ion channels. SUMMARY These findings demonstrate the regenerative potential of the acinar cell to mitigate injurious states such as pancreatitis. The ability of acinar cells to transdifferentiate into beta-cells could potentially provide a treatment for diabetes. Finally, the results might be helpful in preventing malignant transformation events arising from the acinar cell. Developments in proteomics and computer modeling could expand our view of proteins mediating acinar cell function.
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Betzenhauser MJ, Wagner LE, Park HS, Yule DI. ATP regulation of type-1 inositol 1,4,5-trisphosphate receptor activity does not require walker A-type ATP-binding motifs. J Biol Chem 2009; 284:16156-16163. [PMID: 19386591 DOI: 10.1074/jbc.m109.006452] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ATP is known to increase the activity of the type-1 inositol 1,4,5-trisphosphate receptor (InsP3R1). This effect is attributed to the binding of ATP to glycine rich Walker A-type motifs present in the regulatory domain of the receptor. Only two such motifs are present in neuronal S2+ splice variant of InsP3R1 and are designated the ATPA and ATPB sites. The ATPA site is unique to InsP3R1, and the ATPB site is conserved among all three InsP3R isoforms. Despite the fact that both the ATPA and ATPB sites are known to bind ATP, the relative contribution of these two sites to the enhancing effects of ATP on InsP3R1 function is not known. We report here a mutational analysis of the ATPA and ATPB sites and conclude neither of these sites is required for ATP modulation of InsP3R1. ATP augmented InsP3-induced Ca2+ release from permeabilized cells expressing wild type and ATP-binding site-deficient InsP3R1. Similarly, ATP increased the single channel open probability of the mutated InsP3R1 to the same extent as wild type. ATP likely exerts its effects on InsP3R1 channel function via a novel and as yet unidentified mechanism.
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Affiliation(s)
- Matthew J Betzenhauser
- From the Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York 14642
| | - Larry E Wagner
- From the Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York 14642
| | - Hyung Seo Park
- From the Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York 14642; Department of Physiology, College of Medicine, Konyang University, Daejeon 302-718, South Korea
| | - David I Yule
- From the Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York 14642.
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32
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Walsh C, Barrow S, Voronina S, Chvanov M, Petersen OH, Tepikin A. Modulation of calcium signalling by mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1374-82. [PMID: 19344663 DOI: 10.1016/j.bbabio.2009.01.007] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2008] [Revised: 01/12/2009] [Accepted: 01/13/2009] [Indexed: 02/07/2023]
Abstract
In this review we will attempt to summarise the complex and sometimes contradictory effects that mitochondria have on different forms of calcium signalling. Mitochondria can influence Ca(2+) signalling indirectly by changing the concentration of ATP, NAD(P)H, pyruvate and reactive oxygen species - which in turn modulate components of the Ca(2+) signalling machinery i.e. buffering, release from internal stores, influx from the extracellular solution, uptake into cellular organelles and extrusion by plasma membrane Ca(2+) pumps. Mitochondria can directly influence the calcium concentration in the cytosol of the cell by importing Ca(2+) via the mitochondrial Ca(2+) uniporter or transporting Ca(2+) from the interior of the organelle into the cytosol by means of Na+/Ca(2+) or H+/Ca(2+) exchangers. Considerable progress in understanding the relationship between Ca(2+) signalling cascades and mitochondrial physiology has been accumulated over the last few years due to the development of more advanced optical techniques and electrophysiological approaches.
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Affiliation(s)
- Ciara Walsh
- Department of Physiology, School of Biomedical Sciences, The University of Liverpool, Crown Street, Liverpool L69 3BX, UK
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