1
|
Nugues C, Helassa N, Haynes LP. Mitosis, Focus on Calcium. Front Physiol 2022; 13:951979. [PMID: 35784871 PMCID: PMC9247304 DOI: 10.3389/fphys.2022.951979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 05/30/2022] [Indexed: 12/04/2022] Open
Abstract
The transformation of a single fertilised egg into an adult human consisting of tens of trillions of highly diverse cell types is a marvel of biology. The expansion is largely achieved by cell duplication through the process of mitosis. Mitosis is essential for normal growth, development, and tissue repair and is one of the most tightly regulated biological processes studied. This regulation is designed to ensure accurate segregation of chromosomes into each new daughter cell since errors in this process can lead to genetic imbalances, aneuploidy, that can lead to diseases including cancer. Understanding how mitosis operates and the molecular mechanisms that ensure its fidelity are therefore not only of significant intellectual value but provide unique insights into disease pathology. The purpose of this review is to revisit historical evidence that mitosis can be influenced by the ubiquitous second messenger calcium and to discuss this in the context of new findings revealing exciting new information about its role in cell division.
Collapse
Affiliation(s)
- Charlotte Nugues
- Department of Molecular Physiology and Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Nordine Helassa
- Department of Cardiovascular and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- *Correspondence: Nordine Helassa,
| | - Lee P. Haynes
- Department of Molecular Physiology and Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| |
Collapse
|
2
|
Prakash O, Held M, McCormick LF, Gupta N, Lian LY, Antonyuk S, Haynes LP, Thomas NL, Helassa N. CPVT-associated calmodulin variants N53I and A102V dysregulate Ca2+ signalling via different mechanisms. J Cell Sci 2022; 135:274029. [PMID: 34888671 PMCID: PMC8917356 DOI: 10.1242/jcs.258796] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 11/29/2021] [Indexed: 12/26/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited condition that can cause fatal cardiac arrhythmia. Human mutations in the Ca2+ sensor calmodulin (CaM) have been associated with CPVT susceptibility, suggesting that CaM dysfunction is a key driver of the disease. However, the detailed molecular mechanism remains unclear. Focusing on the interaction with the cardiac ryanodine receptor (RyR2), we determined the effect of CPVT-associated variants N53I and A102V on the structural characteristics of CaM and on Ca2+ fluxes in live cells. We provide novel data showing that interaction of both Ca2+/CaM-N53I and Ca2+/CaM-A102V with the RyR2 binding domain is decreased. Ca2+/CaM-RyR23583-3603 high-resolution crystal structures highlight subtle conformational changes for the N53I variant, with A102V being similar to wild type (WT). We show that co-expression of CaM-N53I or CaM-A102V with RyR2 in HEK293 cells significantly increased the duration of Ca2+ events; CaM-A102V exhibited a lower frequency of Ca2+ oscillations. In addition, we show that CaMKIIδ (also known as CAMK2D) phosphorylation activity is increased for A102V, compared to CaM-WT. This paper provides novel insight into the molecular mechanisms of CPVT-associated CaM variants and will facilitate the development of strategies for future therapies.
Collapse
Affiliation(s)
- Ohm Prakash
- Liverpool Centre for Cardiovascular Science, Department of Cardiovascular Science and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Marie Held
- Liverpool Centre for Cardiovascular Science, Department of Cardiovascular Science and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Liam F. McCormick
- Liverpool Centre for Cardiovascular Science, Department of Cardiovascular Science and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Nitika Gupta
- Department of Molecular Physiology and Cell Signalling, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Lu-Yun Lian
- Nuclear Magnetic Resonance Centre for Structural Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Svetlana Antonyuk
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Lee P. Haynes
- Department of Molecular Physiology and Cell Signalling, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - N. Lowri Thomas
- School of Pharmacy & Pharmaceutical Sciences, Cardiff University, Cardiff, Redwood Building, CF10 3NB, UK
| | - Nordine Helassa
- Liverpool Centre for Cardiovascular Science, Department of Cardiovascular Science and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK,Author for correspondence ()
| |
Collapse
|
3
|
Gupta N, McCormick LF, Haynes LP, Dart C, Helassa N. LQTS-Associated Mutants of Calmodulin Show Disrupted Interaction with L-Type Calcium Channels. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2296] [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: 10/25/2022] Open
|
4
|
Helassa N, Nugues C, Rajamanoharan D, Burgoyne RD, Haynes LP. A centrosome-localized calcium signal is essential for mammalian cell mitosis. FASEB J 2019; 33:14602-14610. [PMID: 31682764 PMCID: PMC6910830 DOI: 10.1096/fj.201901662r] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [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: 07/04/2019] [Accepted: 09/23/2019] [Indexed: 02/02/2023]
Abstract
Mitosis defects can lead to premature ageing and cancer. Understanding mitosis regulation therefore has important implications for human disease. Early data suggested that calcium (Ca2+) signals could influence mitosis, but these have hitherto not been observed in mammalian cells. Here, we reveal a prolonged yet spatially restricted Ca2+ signal at the centrosomes of actively dividing cells. Local buffering of the centrosomal Ca2+ signals, by flash photolysis of the caged Ca2+ chelator diazo-2-acetoxymethyl ester, arrests mitosis. We also provide evidence that this Ca2+ signal emanates from the endoplasmic reticulum. In summary, we characterize a unique centrosomal Ca2+ signal as a functionally essential input into mitosis.-Helassa, N., Nugues, C., Rajamanoharan, D., Burgoyne, R. D., Haynes, L. P. A centrosome-localized calcium signal is essential for mammalian cell mitosis.
Collapse
Affiliation(s)
- Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Charlotte Nugues
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Dayani Rajamanoharan
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Robert D. Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Lee P. Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| |
Collapse
|
5
|
Abstract
Calcium signaling in neurons as in other cell types can lead to varied changes in cellular function. Neuronal Ca2+ signaling processes have also become adapted to modulate the function of specific pathways over a wide variety of time domains and these can have effects on, for example, axon outgrowth, neuronal survival, and changes in synaptic strength. Ca2+ also plays a key role in synapses as the trigger for fast neurotransmitter release. Given its physiological importance, abnormalities in neuronal Ca2+ signaling potentially underlie many different neurological and neurodegenerative diseases. The mechanisms by which changes in intracellular Ca2+ concentration in neurons can bring about diverse responses is underpinned by the roles of ubiquitous or specialized neuronal Ca2+ sensors. It has been established that synaptotagmins have key functions in neurotransmitter release, and, in addition to calmodulin, other families of EF-hand-containing neuronal Ca2+ sensors, including the neuronal calcium sensor (NCS) and the calcium-binding protein (CaBP) families, play important physiological roles in neuronal Ca2+ signaling. It has become increasingly apparent that these various Ca2+ sensors may also be crucial for aspects of neuronal dysfunction and disease either indirectly or directly as a direct consequence of genetic variation or mutations. An understanding of the molecular basis for the regulation of the targets of the Ca2+ sensors and the physiological roles of each protein in identified neurons may contribute to future approaches to the development of treatments for a variety of human neuronal disorders.
Collapse
Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Hannah V McCue
- Centre for Genomic Research, University of Liverpool, Liverpool, United Kingdom
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| |
Collapse
|
6
|
Helassa N, Antonyuk SV, Lian LY, Haynes LP, Burgoyne RD. Biophysical and functional characterization of hippocalcin mutants responsible for human dystonia. Hum Mol Genet 2017; 26:2426-2435. [PMID: 28398555 PMCID: PMC5886089 DOI: 10.1093/hmg/ddx133] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [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: 01/18/2017] [Accepted: 03/29/2017] [Indexed: 11/13/2022] Open
Abstract
Dystonia is a neurological movement disorder that forces the body into twisting, repetitive movements or sometimes painful abnormal postures. With the advent of next-generation sequencing technologies, the homozygous mutations T71N and A190T in the neuronal calcium sensor (NCS) hippocalcin were identified as the genetic cause of primary isolated dystonia (DYT2 dystonia). However, the effect of these mutations on the physiological role of hippocalcin has not yet been elucidated. Using a multidisciplinary approach, we demonstrated that hippocalcin oligomerises in a calcium-dependent manner and binds to voltage-gated calcium channels. Mutations T71N and A190T in hippocalcin did not affect stability, calcium-binding affinity or translocation to cellular membranes (Ca2+/myristoyl switch). We obtained the first crystal structure of hippocalcin and alignment with other NCS proteins showed significant variability in the orientation of the C-terminal part of the molecule, the region expected to be important for target binding. We demonstrated that the disease-causing mutations did not affect the structure of the protein, however both mutants showed a defect in oligomerisation. In addition, we observed an increased calcium influx in KCl-depolarised cells expressing mutated hippocalcin, mostly driven by N-type voltage-gated calcium channels. Our data demonstrate that the dystonia-causing mutations strongly affect hippocalcin cellular functions which suggest a central role for perturbed calcium signalling in DYT2 dystonia.
Collapse
Affiliation(s)
- Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
| | - Svetlana V Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69?7ZB, UK and
| | - Lu-Yun Lian
- NMR Centre for Structural Biology, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69?7ZB, UK
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
| | - Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
| |
Collapse
|
7
|
Todd PAC, McCue HV, Haynes LP, Barclay JW, Burgoyne RD. Interaction of ARF-1.1 and neuronal calcium sensor-1 in the control of the temperature-dependency of locomotion in Caenorhabditis elegans. Sci Rep 2016; 6:30023. [PMID: 27435667 PMCID: PMC4951722 DOI: 10.1038/srep30023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 03/29/2016] [Accepted: 06/27/2016] [Indexed: 12/15/2022] Open
Abstract
Neuronal calcium sensor-1 (NCS-1) mediates changes in cellular function by regulating various target proteins. Many potential targets have been identified but the physiological significance of only a few has been established. Upon temperature elevation, Caenorhabditis elegans exhibits reversible paralysis. In the absence of NCS-1, worms show delayed onset and a shorter duration of paralysis. This phenotype can be rescued by re-expression of ncs-1 in AIY neurons. Mutants with defects in four potential NCS-1 targets (arf-1.1, pifk-1, trp-1 and trp-2) showed qualitatively similar phenotypes to ncs-1 null worms, although the effect of pifk-1 mutation on time to paralysis was considerably delayed. Inhibition of pifk-1 also resulted in a locomotion phenotype. Analysis of double mutants showed no additive effects between mutations in ncs-1 and trp-1 or trp-2. In contrast, double mutants of arf-1.1 and ncs-1 had an intermediate phenotype, consistent with NCS-1 and ARF-1.1 acting in the same pathway. Over-expression of arf-1.1 in the AIY neurons was sufficient to rescue partially the phenotype of both the arf-1.1 and the ncs-1 null worms. These findings suggest that ARF-1.1 interacts with NCS-1 in AIY neurons and potentially pifk-1 in the Ca(2+) signaling pathway that leads to inhibited locomotion at an elevated temperature.
Collapse
Affiliation(s)
- Paul A. C. Todd
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom
| | - Hannah V. McCue
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom
| | - Lee P. Haynes
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom
| | - Jeff W. Barclay
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom
| | - Robert D. Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom
| |
Collapse
|
8
|
Pandalaneni S, Karuppiah V, Saleem M, Haynes LP, Burgoyne RD, Mayans O, Derrick JP, Lian LY. Neuronal Calcium Sensor-1 Binds the D2 Dopamine Receptor and G-protein-coupled Receptor Kinase 1 (GRK1) Peptides Using Different Modes of Interactions. J Biol Chem 2015; 290:18744-56. [PMID: 25979333 PMCID: PMC4513130 DOI: 10.1074/jbc.m114.627059] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [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: 11/21/2014] [Indexed: 11/25/2022] Open
Abstract
Neuronal calcium sensor-1 (NCS-1) is the primordial member of the neuronal calcium sensor family of EF-hand Ca2+-binding proteins. It interacts with both the G-protein-coupled receptor (GPCR) dopamine D2 receptor (D2R), regulating its internalization and surface expression, and the cognate kinases GRK1 and GRK2. Determination of the crystal structures of Ca2+/NCS-1 alone and in complex with peptides derived from D2R and GRK1 reveals that the differential recognition is facilitated by the conformational flexibility of the C-lobe-binding site. We find that two copies of the D2R peptide bind within the hydrophobic crevice on Ca2+/NCS-1, but only one copy of the GRK1 peptide binds. The different binding modes are made possible by the C-lobe-binding site of NCS-1, which adopts alternative conformations in each complex. C-terminal residues Ser-178–Val-190 act in concert with the flexible EF3/EF4 loop region to effectively form different peptide-binding sites. In the Ca2+/NCS-1·D2R peptide complex, the C-terminal region adopts a 310 helix-turn-310 helix, whereas in the GRK1 peptide complex it forms an α-helix. Removal of Ser-178–Val-190 generated a C-terminal truncation mutant that formed a dimer, indicating that the NCS-1 C-terminal region prevents NCS-1 oligomerization. We propose that the flexible nature of the C-terminal region is essential to allow it to modulate its protein-binding sites and adapt its conformation to accommodate both ligands. This appears to be driven by the variability of the conformation of the C-lobe-binding site, which has ramifications for the target specificity and diversity of NCS-1.
Collapse
Affiliation(s)
- Sravan Pandalaneni
- From the NMR Centre for Structural Biology, Institute of Integrative Biology, and
| | - Vijaykumar Karuppiah
- From the NMR Centre for Structural Biology, Institute of Integrative Biology, and the Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, and
| | - Muhammad Saleem
- the Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, and
| | - Lee P Haynes
- the Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L37 4BY, United Kingdom
| | - Robert D Burgoyne
- the Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L37 4BY, United Kingdom
| | - Olga Mayans
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB
| | - Jeremy P Derrick
- the Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, and
| | - Lu-Yun Lian
- From the NMR Centre for Structural Biology, Institute of Integrative Biology, and
| |
Collapse
|
9
|
Rajamanoharan D, McCue HV, Burgoyne RD, Haynes LP. Modulation of phosphatidylinositol 4-phosphate levels by CaBP7 controls cytokinesis in mammalian cells. Mol Biol Cell 2015; 26:1428-39. [PMID: 25717182 PMCID: PMC4395124 DOI: 10.1091/mbc.e14-07-1243] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [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: 07/29/2014] [Accepted: 02/13/2015] [Indexed: 12/29/2022] Open
Abstract
For more than 25 years, lysosomes have been known to cluster at the intercellular bridge during cytokinesis, but why has remained a mystery. This study provides evidence that phosphoinositide metabolism is important for this clustering and that lysosome activity is required for cytokinesis. Calcium and phosphoinositide signaling regulate cell division in model systems, but their significance in mammalian cells is unclear. Calcium-binding protein-7 (CaBP7) is a phosphatidylinositol 4-kinaseIIIβ (PI4KIIIβ) inhibitor required during cytokinesis in mammalian cells, hinting at a link between these pathways. Here we characterize a novel association of CaBP7 with lysosomes that cluster at the intercellular bridge during cytokinesis in HeLa cells. We show that CaBP7 regulates lysosome clustering and that PI4KIIIβ is essential for normal cytokinesis. CaBP7 depletion induces lysosome mislocalization, extension of intercellular bridge lifetime, and cytokinesis failure. These data connect phosphoinositide and calcium pathways to lysosome localization and normal cytokinesis in mammalian cells.
Collapse
Affiliation(s)
- Dayani Rajamanoharan
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Hannah V McCue
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, United Kingdom
| |
Collapse
|
10
|
Burgoyne RD, Haynes LP. Sense and specificity in neuronal calcium signalling. Biochim Biophys Acta 2014; 1853:1921-32. [PMID: 25447549 PMCID: PMC4728190 DOI: 10.1016/j.bbamcr.2014.10.029] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 10/25/2014] [Accepted: 10/29/2014] [Indexed: 11/02/2022]
Abstract
Changes in the intracellular free calcium concentration ([Ca²⁺]i) in neurons regulate many and varied aspects of neuronal function over time scales from microseconds to days. The mystery is how a single signalling ion can lead to such diverse and specific changes in cell function. This is partly due to aspects of the Ca²⁺ signal itself, including its magnitude, duration, localisation and persistent or oscillatory nature. The transduction of the Ca²⁺ signal requires Ca²⁺binding to various Ca²⁺ sensor proteins. The different properties of these sensors are important for differential signal processing and determine the physiological specificity of Ca(2+) signalling pathways. A major factor underlying the specific roles of particular Ca²⁺ sensor proteins is the nature of their interaction with target proteins and how this mediates unique patterns of regulation. We review here recent progress from structural analyses and from functional analyses in model organisms that have begun to reveal the rules that underlie Ca²⁺ sensor protein specificity for target interaction. We discuss three case studies exemplifying different aspects of Ca²⁺ sensor/target interaction. This article is part of a special issue titled the 13th European Symposium on Calcium.
Collapse
Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom.
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom
| |
Collapse
|
11
|
Lian LY, Pandalaneni SR, Todd PAC, Martin VM, Burgoyne RD, Haynes LP. Demonstration of binding of neuronal calcium sensor-1 to the cav2.1 p/q-type calcium channel. Biochemistry 2014; 53:6052-62. [PMID: 25188201 PMCID: PMC4180279 DOI: 10.1021/bi500568v] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [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] [Indexed: 11/28/2022]
Abstract
In neurons, entry of extracellular calcium (Ca(2+)) into synaptic terminals through Cav2.1 (P/Q-type) Ca(2+) channels is the driving force for exocytosis of neurotransmitter-containing synaptic vesicles. This class of Ca(2+) channel is, therefore, pivotal during normal neurotransmission in higher organisms. In response to channel opening and Ca(2+) influx, specific Ca(2+)-binding proteins associate with cytoplasmic regulatory domains of the P/Q channel to modulate subsequent channel opening. Channel modulation in this way influences synaptic plasticity with consequences for higher-level processes such as learning and memory acquisition. The ubiquitous Ca(2+)-sensing protein calmodulin (CaM) regulates the activity of all types of mammalian voltage-gated Ca(2+) channels, including the P/Q class, by direct binding to specific regulatory motifs. More recently, experimental evidence has highlighted a role for additional Ca(2+)-binding proteins, particularly of the CaBP and NCS families in the regulation of P/Q channels. NCS-1 is a protein found from yeast to humans and that regulates a diverse number of cellular functions. Physiological and genetic evidence indicates that NCS-1 regulates P/Q channel activity, including calcium-dependent facilitation, although a direct physical association between the proteins has yet to be demonstrated. In this study, we aimed to determine if there is a direct interaction between NCS-1 and the C-terminal cytoplasmic tail of the Cav2.1 α-subunit. Using distinct but complementary approaches, including in vitro binding of bacterially expressed recombinant proteins, fluorescence spectrophotometry, isothermal titration calorimetry, nuclear magnetic resonance, and expression of fluorescently tagged proteins in mammalian cells, we show direct binding and demonstrate that CaM can compete for it. We speculate about how NCS-1/Cav2.1 association might add to the complexity of calcium channel regulation mediated by other known calcium-sensing proteins and how this might help to fine-tune neurotransmission in the mammalian central nervous system.
Collapse
Affiliation(s)
- Lu-Yun Lian
- NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool , Liverpool L69 3BX, U.K
| | | | | | | | | | | |
Collapse
|
12
|
Martin VM, Johnson JR, Haynes LP, Barclay JW, Burgoyne RD. Identification of key structural elements for neuronal calcium sensor-1 function in the regulation of the temperature-dependency of locomotion in C. elegans. Mol Brain 2013; 6:39. [PMID: 23981466 PMCID: PMC3765893 DOI: 10.1186/1756-6606-6-39] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [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: 07/31/2013] [Accepted: 08/24/2013] [Indexed: 11/10/2022] Open
Abstract
Background Intracellular Ca2+ regulates many aspects of neuronal function through Ca2+ binding to EF hand-containing Ca2+ sensors that in turn bind target proteins to regulate their function. Amongst the sensors are the neuronal calcium sensor (NCS) family of proteins that are involved in multiple neuronal signalling pathways. Each NCS protein has specific and overlapping targets and physiological functions and specificity is likely to be determined by structural features within the proteins. Common to the NCS proteins is the exposure of a hydrophobic groove, allowing target binding in the Ca2+-loaded form. Structural analysis of NCS protein complexes with target peptides has indicated common and distinct aspects of target protein interaction. Two key differences between NCS proteins are the size of the hydrophobic groove that is exposed for interaction and the role of their non-conserved C-terminal tails. Results We characterised the role of NCS-1 in a temperature-dependent locomotion assay in C. elegans and identified a distinct phenotype in the ncs-1 null in which the worms do not show reduced locomotion at actually elevated temperature. Using rescue of this phenotype we showed that NCS-1 functions in AIY neurons. Structure/function analysis introducing single or double mutations within the hydrophobic groove based on information from characterised target complexes established that both N- and C-terminal pockets of the groove are functionally important and that deletion of the C-terminal tail of NCS-1 did not impair its ability to rescue. Conclusions The current work has allowed physiological assessment of suggestions from structural studies on the key structural features that underlie the interaction of NCS-1 with its target proteins. The results are consistent with the notion that full length of the hydrophobic groove is required for the regulatory interactions underlying NCS-1 function whereas the C-terminal tail of NCS-1 is not essential. This has allowed discrimination between two potential modes of interaction of NCS-1 with its targets.
Collapse
Affiliation(s)
- Victoria M Martin
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, L69 3BX, UK.
| | | | | | | | | |
Collapse
|
13
|
Wang W, Zhong Q, Teng L, Bhatnagar N, Sharma B, Zhang X, Luther W, Haynes LP, Burgoyne RD, Vidal M, Volchenboum S, Hill DE, George RE. Mutations that disrupt PHOXB interaction with the neuronal calcium sensor HPCAL1 impede cellular differentiation in neuroblastoma. Oncogene 2013; 33:3316-24. [PMID: 23873030 DOI: 10.1038/onc.2013.290] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 04/17/2013] [Accepted: 05/26/2013] [Indexed: 12/14/2022]
Abstract
Heterozygous germline mutations in PHOX2B, a transcriptional regulator of sympathetic neuronal differentiation, predispose to diseases of the sympathetic nervous system, including neuroblastoma and congenital central hypoventilation syndrome (CCHS). Although the PHOX2B variants in CCHS largely involve expansions of the second polyalanine repeat within the C-terminus of the protein, those associated with neuroblastic tumors are nearly always frameshift and truncation mutations. To test the hypothesis that the neuroblastoma-associated variants exert their effects through loss or gain of protein-protein interactions, we performed a large-scale yeast two-hybrid screen using both wild-type (WT) and six different mutant PHOX2B proteins against over 10 000 human genes. The neuronal calcium sensor protein HPCAL1 (VILIP-3) exhibited strong binding to WT PHOX2B and a CCHS-associated polyalanine expansion mutant but only weakly or not at all to neuroblastoma-associated frameshift and truncation variants. We demonstrate that both WT PHOX2B and the neuroblastoma-associated R100L missense and the CCHS-associated alanine expansion variants induce nuclear translocation of HPCAL1 in a Ca(2+)-independent manner, while the neuroblastoma-associated 676delG frameshift and K155X truncation mutants impair subcellular localization of HPCAL1, causing it to remain in the cytoplasm. HPCAL1 did not appreciably influence the ability of WT PHOX2B to transactivate the DBH promoter, nor did it alter the decreased transactivation potential of PHOX2B variants in 293T cells. Abrogation of the PHOX2B-HPCAL1 interaction by shRNA knockdown of HPCAL1 in neuroblastoma cells expressing PHOX2B led to impaired neurite outgrowth with transcriptional profiles indicative of inhibited sympathetic neuronal differentiation. Our results suggest that certain PHOX2B variants associated with neuroblastoma pathogenesis, because of their inability to bind to key interacting proteins such as HPCAL1, may predispose to this malignancy by impeding the differentiation of immature sympathetic neurons.
Collapse
Affiliation(s)
- W Wang
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Q Zhong
- Center for Cancer Systems Biology (CCSB) and Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - L Teng
- Chicago Center for Childhood Cancer and Blood Diseases, the University of Chicago, Chicago, IL, USA
| | - N Bhatnagar
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - B Sharma
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - X Zhang
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, People's Republic of China
| | - W Luther
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - L P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - R D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - M Vidal
- Center for Cancer Systems Biology (CCSB) and Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - S Volchenboum
- Chicago Center for Childhood Cancer and Blood Diseases, the University of Chicago, Chicago, IL, USA
| | - D E Hill
- Center for Cancer Systems Biology (CCSB) and Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - R E George
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
14
|
McCue HV, Patel P, Herbert AP, Lian LY, Burgoyne RD, Haynes LP. Solution NMR structure of the Ca2+-bound N-terminal domain of CaBP7: a regulator of golgi trafficking. J Biol Chem 2012; 287:38231-43. [PMID: 22989873 PMCID: PMC3488092 DOI: 10.1074/jbc.m112.402289] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [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] [Indexed: 12/12/2022] Open
Abstract
Calcium-binding protein 7 (CaBP7) is a member of the calmodulin (CaM) superfamily that harbors two high affinity EF-hand motifs and a C-terminal transmembrane domain. CaBP7 has been previously shown to interact with and modulate phosphatidylinositol 4-kinase III-β (PI4KIIIβ) activity in in vitro assays and affects vesicle transport in neurons when overexpressed. Here we show that the N-terminal domain (NTD) of CaBP7 is sufficient to mediate the interaction of CaBP7 with PI4KIIIβ. CaBP7 NTD encompasses the two high affinity Ca2+ binding sites, and structural characterization through multiangle light scattering, circular dichroism, and NMR reveals unique properties for this domain. CaBP7 NTD binds specifically to Ca2+ but not Mg2+ and undergoes significant conformational changes in both secondary and tertiary structure upon Ca2+ binding. The Ca2+-bound form of CaBP7 NTD is monomeric and exhibits an open conformation similar to that of CaM. Ca2+-bound CaBP7 NTD has a solvent-exposed hydrophobic surface that is more expansive than observed in CaM or CaBP1. Within this hydrophobic pocket, there is a significant reduction in the number of methionine residues that are conserved in CaM and CaBP1 and shown to be important for target recognition. In CaBP7 NTD, these residues are replaced with isoleucine and leucine residues with branched side chains that are intrinsically more rigid than the flexible methionine side chain. We propose that these differences in surface hydrophobicity, charge, and methionine content may be important in determining highly specific interactions of CaBP7 with target proteins, such as PI4KIIIβ.
Collapse
Affiliation(s)
- Hannah V McCue
- Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | | | | | | | | | | |
Collapse
|
15
|
Haynes LP, McCue HV, Burgoyne RD. Evolution and functional diversity of the Calcium Binding Proteins (CaBPs). Front Mol Neurosci 2012; 5:9. [PMID: 22375103 PMCID: PMC3284769 DOI: 10.3389/fnmol.2012.00009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [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: 01/09/2012] [Accepted: 01/25/2012] [Indexed: 02/01/2023] Open
Abstract
The mammalian central nervous system (CNS) exhibits a remarkable ability to process, store, and transfer information. Key to these activities is the use of highly regulated and unique patterns of calcium signals encoded by calcium channels and decoded by families of specific calcium-sensing proteins. The largest family of eukaryotic calcium sensors is those related to the small EF-hand containing protein calmodulin (CaM). In order to maximize the usefulness of calcium as a signaling species and to permit the evolution and fine tuning of the mammalian CNS, families of related proteins have arisen that exhibit characteristic calcium binding properties and tissue-, cellular-, and sub-cellular distribution profiles. The Calcium Binding Proteins (CaBPs) represent one such family of vertebrate specific CaM like proteins that have emerged in recent years as important regulators of essential neuronal target proteins. Bioinformatic analyses indicate that the CaBPs consist of two subfamilies and that the ancestral members of these are CaBP1 and CaBP8. The CaBPs have distinct intracellular localizations based on different targeting mechanisms including a novel type-II transmembrane domain in CaBPs 7 and 8 (otherwise known as calneuron II and calneuron I, respectively). Recent work has led to the identification of new target interactions and possible functions for the CaBPs suggesting that they have multiple physiological roles with relevance for the normal functioning of the CNS.
Collapse
Affiliation(s)
- Lee P Haynes
- The Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool Liverpool, UK
| | | | | |
Collapse
|
16
|
Abstract
Calcium signalling plays a crucial role in the control of neuronal function and plasticity. Changes in neuronal Ca2+ concentration are detected by Ca2+-binding proteins that can interact with and regulate target proteins to modify their function. Members of the neuronal calcium sensor (NCS) protein family have multiple non-redundant roles in the nervous system. Here we review recent advances in the understanding of the physiological roles of the NCS proteins and the molecular basis for their specificity.
Collapse
Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
| | | |
Collapse
|
17
|
Lian LY, Pandalaneni SR, Patel P, McCue HV, Haynes LP, Burgoyne RD. Characterisation of the interaction of the C-terminus of the dopamine D2 receptor with neuronal calcium sensor-1. PLoS One 2011; 6:e27779. [PMID: 22114693 PMCID: PMC3218054 DOI: 10.1371/journal.pone.0027779] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [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: 09/12/2011] [Accepted: 10/25/2011] [Indexed: 11/19/2022] Open
Abstract
NCS-1 is a member of the neuronal calcium sensor (NCS) family of EF-hand Ca(2+) binding proteins which has been implicated in several physiological functions including regulation of neurotransmitter release, membrane traffic, voltage gated Ca(2+) channels, neuronal development, synaptic plasticity, and learning. NCS-1 binds to the dopamine D2 receptor, potentially affecting its internalisation and controlling dopamine D2 receptor surface expression. The D2 receptor binds NCS-1 via a short 16-residue cytoplasmic C-terminal tail. We have used NMR and fluorescence spectroscopy to characterise the interactions between the NCS-1/Ca(2+) and D2 peptide. The data show that NCS-1 binds D2 peptide with a K(d) of ∼14.3 µM and stoichiometry of peptide binding to NCS-1 of 2:1. NMR chemical shift mapping confirms that D2 peptide binds to the large, solvent-exposed hydrophobic groove, on one face of the NCS-1 molecule, with residues affected by the presence of the peptide spanning both the N and C-terminal portions of the protein. The NMR and mutagenesis data further show that movement of the C-terminal helix 11 of NCS-1 to fully expose the hydrophobic groove is important for D2 peptide binding. Molecular docking using restraints derived from the NMR chemical shift data, together with the experimentally-derived stoichiometry, produced a model of the complex between NCS-1 and the dopamine receptor, in which two molecules of the receptor are able to simultaneously bind to the NCS-1 monomer.
Collapse
Affiliation(s)
- Lu-Yun Lian
- NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- * E-mail: (LYL); (RDB)
| | - Sravan R. Pandalaneni
- NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Pryank Patel
- NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Hannah V. McCue
- The Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Lee P. Haynes
- The Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Robert D. Burgoyne
- The Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
- * E-mail: (LYL); (RDB)
| |
Collapse
|
18
|
McCue HV, Burgoyne RD, Haynes LP. Determination of the membrane topology of the small EF-hand Ca2+-sensing proteins CaBP7 and CaBP8. PLoS One 2011; 6:e17853. [PMID: 21445352 PMCID: PMC3062558 DOI: 10.1371/journal.pone.0017853] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [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: 12/22/2010] [Accepted: 02/10/2011] [Indexed: 11/19/2022] Open
Abstract
The CaBPs represent a subfamily of small EF-hand containing calcium (Ca(2+))-sensing proteins related to calmodulin that regulate key ion channels in the mammalian nervous system. In a recent bioinformatic analyses we determined that CaBP7 and CaBP8 form an evolutionarily distinct branch within the CaBPs (also known as the calneurons) a finding that is consistent with earlier observations characterising a putative C-terminal transmembrane (TM) spanning helix in each of these proteins which is essential for their sub-cellular targeting to the Golgi apparatus and constitutive secretory vesicles. The C-terminal position of the predicted TM-helix suggests that CaBP7 and CaBP8 could be processed in a manner analogous to tail-anchored integral membrane proteins which exhibit the ability to insert across membranes post-translationally. In this study we have investigated the topology of CaBP7 and CaBP8 within cellular membranes through a combination of trypsin protection and epitope accessibility analyses. Our results indicate that the TM-helices of CaBP7 and CaBP8 insert fully across membranes such that their extreme C-termini are luminal. The observed type-II membrane topology is consistent with processing of CaBP7 and CaBP8 as true tail-anchored proteins. This targeting mechanism is distinct from any other calmodulin related Ca(2+)-sensor and conceivably underpins unique physiological functions of these proteins.
Collapse
Affiliation(s)
- Hannah V. McCue
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, United Kingdom
| | - Robert D. Burgoyne
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, United Kingdom
| | - Lee P. Haynes
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| |
Collapse
|
19
|
Graham ME, Prescott GR, Johnson JR, Jones M, Walmesley A, Haynes LP, Morgan A, Burgoyne RD, Barclay JW. Structure-function study of mammalian Munc18-1 and C. elegans UNC-18 implicates domain 3b in the regulation of exocytosis. PLoS One 2011; 6:e17999. [PMID: 21445306 PMCID: PMC3061876 DOI: 10.1371/journal.pone.0017999] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [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: 09/13/2010] [Accepted: 02/22/2011] [Indexed: 11/19/2022] Open
Abstract
Munc18-1 is an essential synaptic protein functioning during multiple stages of the exocytotic process including vesicle recruitment, docking and fusion. These functions require a number of distinct syntaxin-dependent interactions; however, Munc18-1 also regulates vesicle fusion via syntaxin-independent interactions with other exocytotic proteins. Although the structural regions of the Munc18-1 protein involved in closed-conformation syntaxin binding have been thoroughly examined, regions of the protein involved in other interactions are poorly characterised. To investigate this we performed a random transposon mutagenesis, identifying domain 3b of Munc18-1 as a functionally important region of the protein. Transposon insertion in an exposed loop within this domain specifically disrupted Mint1 binding despite leaving affinity for closed conformation syntaxin and binding to the SNARE complex unaffected. The insertion mutation significantly reduced total amounts of exocytosis as measured by carbon fiber amperometry in chromaffin cells. Introduction of the equivalent mutation in UNC-18 in Caenorhabditis elegans also reduced neurotransmitter release as assessed by aldicarb sensitivity. Correlation between the two experimental methods for recording changes in the number of exocytotic events was verified using a previously identified gain of function Munc18-1 mutation E466K (increased exocytosis in chromaffin cells and aldicarb hypersensitivity of C. elegans). These data implicate a novel role for an exposed loop in domain 3b of Munc18-1 in transducing regulation of vesicle fusion independent of closed-conformation syntaxin binding.
Collapse
Affiliation(s)
- Margaret E. Graham
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Gerald R. Prescott
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - James R. Johnson
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Mathew Jones
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Alice Walmesley
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Lee P. Haynes
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Alan Morgan
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Robert D. Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Jeff W. Barclay
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| |
Collapse
|
20
|
Dovgan AV, Cherkas VP, Stepanyuk AR, Fitzgerald DJ, Haynes LP, Tepikin AV, Burgoyne RD, Belan PV. Decoding glutamate receptor activation by the Ca2+ sensor protein hippocalcin in rat hippocampal neurons. Eur J Neurosci 2010; 32:347-58. [PMID: 20704590 PMCID: PMC3069492 DOI: 10.1111/j.1460-9568.2010.07303.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [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] [Indexed: 11/27/2022]
Abstract
Hippocalcin is a Ca2+-binding protein that belongs to a family of neuronal Ca2+sensors and is a key mediator of many cellular functions including synaptic plasticity and learning. However, the molecular mechanisms involved in hippocalcin signalling remain illusive. Here we studied whether glutamate receptor activation induced by locally applied or synaptically released glutamate can be decoded by hippocalcin translocation. Local AMPA receptor activation resulted in fast hippocalcin-YFP translocation to specific sites within a dendritic tree mainly due to AMPA receptor-dependent depolarization and following Ca2+influx via voltage-operated calcium channels. Short local NMDA receptor activation induced fast hippocalcin-YFP translocation in a dendritic shaft at the application site due to direct Ca2+influx via NMDA receptor channels. Intrinsic network bursting produced hippocalcin-YFP translocation to a set of dendritic spines when they were subjected to several successive synaptic vesicle releases during a given burst whereas no translocation to spines was observed in response to a single synaptic vesicle release and to back-propagating action potentials. The translocation to spines required Ca2+influx via synaptic NMDA receptors in which Mg2+ block is relieved by postsynaptic depolarization. This synaptic translocation was restricted to spine heads and even closely (within 1–2 μm) located spines on the same dendritic branch signalled independently. Thus, we conclude that hippocalcin may differentially decode various spatiotemporal patterns of glutamate receptor activation into site- and time-specific translocation to its targets. Hippocalcin also possesses an ability to produce local signalling at the single synaptic level providing a molecular mechanism for homosynaptic plasticity.
Collapse
Affiliation(s)
- A V Dovgan
- Department of General Physiology of the Nervous System, Bogomoletz Institute of Physiology, Kiev, Ukraine
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Abstract
Calcium signaling in neurons as in other cell types mediates changes in gene expression, cell growth, development, survival, and cell death. However, neuronal Ca(2+) signaling processes have become adapted to modulate the function of other important pathways including axon outgrowth and changes in synaptic strength. Ca(2+) plays a key role as the trigger for fast neurotransmitter release. The ubiquitous Ca(2+) sensor calmodulin is involved in various aspects of neuronal regulation. The mechanisms by which changes in intracellular Ca(2+) concentration in neurons can bring about such diverse responses has, however, become a topic of widespread interest that has recently focused on the roles of specialized neuronal Ca(2+) sensors. In this article, we summarize synaptotagmins in neurotransmitter release, the neuronal roles of calmodulin, and the functional significance of the NCS and the CaBP/calneuron protein families of neuronal Ca(2+) sensors.
Collapse
Affiliation(s)
- Hannah V McCue
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, United Kingdom
| | | | | |
Collapse
|
22
|
Handley MTW, Lian LY, Haynes LP, Burgoyne RD. Structural and functional deficits in a neuronal calcium sensor-1 mutant identified in a case of autistic spectrum disorder. PLoS One 2010; 5:e10534. [PMID: 20479890 PMCID: PMC2866544 DOI: 10.1371/journal.pone.0010534] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [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: 03/11/2010] [Accepted: 04/15/2010] [Indexed: 11/18/2022] Open
Abstract
Neuronal calcium sensor-1 (NCS-1) is a Ca(2+) sensor protein that has been implicated in the regulation of various aspects of neuronal development and neurotransmission. It exerts its effects through interactions with a range of target proteins one of which is interleukin receptor accessory protein like-1 (IL1RAPL1) protein. Mutations in IL1RAPL1 have recently been associated with autism spectrum disorders and a missense mutation (R102Q) on NCS-1 has been found in one individual with autism. We have examined the effect of this mutation on the structure and function of NCS-1. From use of NMR spectroscopy, it appeared that the R102Q affected the structure of the protein particularly with an increase in the extent of conformational exchange in the C-terminus of the protein. Despite this change NCS-1(R102Q) did not show changes in its affinity for Ca(2+) or binding to IL1RAPL1 and its intracellular localisation was unaffected. Assessment of NCS-1 dynamics indicated that it could rapidly cycle between cytosolic and membrane pools and that the cycling onto the plasma membrane was specifically changed in NCS-1(R102Q) with the loss of a Ca(2+) -dependent component. From these data we speculate that impairment of the normal cycling of NCS-1 by the R102Q mutation could have subtle effects on neuronal signalling and physiology in the developing and adult brain.
Collapse
Affiliation(s)
- Mark T. W. Handley
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Lu-Yun Lian
- School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Lee P. Haynes
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Robert D. Burgoyne
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| |
Collapse
|
23
|
McCue HV, Haynes LP, Burgoyne RD. Bioinformatic analysis of CaBP/calneuron proteins reveals a family of highly conserved vertebrate Ca2+-binding proteins. BMC Res Notes 2010; 3:118. [PMID: 20426809 PMCID: PMC2873350 DOI: 10.1186/1756-0500-3-118] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [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: 03/17/2010] [Accepted: 04/28/2010] [Indexed: 11/18/2022] Open
Abstract
Background Ca2+-binding proteins are important for the transduction of Ca2+ signals into physiological outcomes. As in calmodulin many of the Ca2+-binding proteins bind Ca2+ through EF-hand motifs. Amongst the large number of EF-hand containing Ca2+-binding proteins are a subfamily expressed in neurons and retinal photoreceptors known as the CaBPs and the related calneuron proteins. These were suggested to be vertebrate specific but exactly which family members are expressed outside of mammalian species had not been examined. Findings We have carried out a bioinformatic analysis to determine when members of this family arose and the conserved aspects of the protein family. Sequences of human members of the family obtained from GenBank were used in Blast searches to identify corresponding proteins encoded in other species using searches of non-redundant proteins, genome sequences and mRNA sequences. Sequences were aligned and compared using ClustalW. Some families of Ca2+-binding proteins are known to show a progressive expansion in gene number as organisms increase in complexity. In contrast, the results for CaBPs and calneurons showed that a full complement of CaBPs and calneurons are present in the teleost fish Danio rerio and possibly in cartilaginous fish. These findings suggest that the entire family of genes may have arisen at the same time during vertebrate evolution. Certain members of the family (for example the short form of CaBP1 and calneuron 1) are highly conserved suggesting essential functional roles. Conclusions The findings support the designation of the calneurons as a distinct sub-family. While the gene number for CaBPs/calneurons does not increase, a distinctive evolutionary change in these proteins in vertebrates has been an increase in the number of splice variants present in mammals.
Collapse
Affiliation(s)
- Hannah V McCue
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
| | | | | |
Collapse
|
24
|
Abstract
Ca2+ plays a crucial role in the regulation of neuronal function. Recent work has revealed important functions for two families of neuronally expressed Ca2+ sensor proteins. These include roles in membrane traffic and in alterations in synaptic plasticity underlying changes in behaviour.
Collapse
Affiliation(s)
- Robert D Burgoyne
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool Crown Street, Liverpool, L69 3BX UK
| | | |
Collapse
|
25
|
Lur G, Haynes LP, Prior IA, Gerasimenko OV, Feske S, Petersen OH, Burgoyne RD, Tepikin AV. Ribosome-free terminals of rough ER allow formation of STIM1 puncta and segregation of STIM1 from IP(3) receptors. Curr Biol 2009; 19:1648-53. [PMID: 19765991 PMCID: PMC2887489 DOI: 10.1016/j.cub.2009.07.072] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 07/19/2009] [Accepted: 07/31/2009] [Indexed: 11/03/2022]
Abstract
Store-operated Ca(2+) entry is a ubiquitous mechanism that prevents the depletion of endoplasmic reticulum (ER) calcium. A reduction of ER calcium triggers translocation of STIM proteins, which serve as calcium sensors in the ER, to subplasmalemmal puncta where they interact with and activate Orai channels. In pancreatic acinar cells, inositol 1,4,5-trisphosphate (IP(3)) receptors populate the apical part of the ER. Here, however, we observe that STIM1 translocates exclusively to the lateral and basal regions following ER Ca(2+) loss. This finding is paradoxical because the basal and lateral regions of the acinar cells contain rough ER (RER); the size of the ribosomes that decorate RER is larger than the distance that can be spanned by a STIM-Orai complex, and STIM1 function should therefore not be possible. We resolve this paradox and characterize ribosome-free terminals of the RER that form junctions between the reticulum and the plasma membrane in the basal and lateral regions of the acinar cells. Our findings indicate that different ER compartments specialize in different calcium-handling functions (Ca(2+) release and Ca(2+) reloading) and that any potential interference between Ca(2+) release and Ca(2+) influx is minimized by the spatial separation of the two processes.
Collapse
Affiliation(s)
- Gyorgy Lur
- Department of Physiology, School of Biomedical Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | | | | | | | | | | | | | | |
Collapse
|
26
|
McCue HV, Burgoyne RD, Haynes LP. Membrane targeting of the EF-hand containing calcium-sensing proteins CaBP7 and CaBP8. Biochem Biophys Res Commun 2009; 380:825-31. [PMID: 19338761 PMCID: PMC2706317 DOI: 10.1016/j.bbrc.2009.01.177] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 01/25/2009] [Indexed: 11/17/2022]
Abstract
The CaBP family of EF-hand containing small Ca(2+)-binding proteins have recently emerged as important regulators of multiple targets essential to normal neuronal function in the mammalian central nervous system. Of particular interest are CaBP7 and CaBP8, abundantly expressed brain proteins that exhibit the greatest sequence divergence from other family members. In this study, we have analysed their sub-cellular localisations in a model neuronal (Neuro2A) cell line and show that both proteins exhibit a membrane distribution distinct from the other CaBPs and consistent with localisation to the trans-Golgi network (TGN). Furthermore, we show that their localisation to the TGN critically depends upon an unusual predicted C-terminal transmembrane domain that if deleted or disrupted has dramatic consequences for protein targeting. CaBP7 and 8, therefore, possess a targeting mechanism that is unique amongst the CaBPs that may contribute to differential functional Ca(2+)-sensing by these family members.
Collapse
|
27
|
Chvanov M, Walsh CM, Haynes LP, Voronina SG, Lur G, Gerasimenko OV, Barraclough R, Rudland PS, Petersen OH, Burgoyne RD, Tepikin AV. ATP depletion induces translocation of STIM1 to puncta and formation of STIM1-ORAI1 clusters: translocation and re-translocation of STIM1 does not require ATP. Pflugers Arch 2008; 457:505-17. [PMID: 18542992 PMCID: PMC2770109 DOI: 10.1007/s00424-008-0529-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [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: 03/11/2008] [Accepted: 05/08/2008] [Indexed: 12/27/2022]
Abstract
Depletion of the endoplasmic reticulum (ER) calcium store triggers translocation of stromal interacting molecule one (STIM1) to the sub-plasmalemmal region and formation of puncta—structures in which STIM1 interacts and activates calcium channels. ATP depletion induced the formation of STIM1 puncta in PANC1, RAMA37, and HeLa cells. The sequence of events triggered by inhibition of ATP production included a rapid decline of ATP, depletion of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and a slow calcium leak from the ER followed by formation of STIM1 puncta. STIM1 puncta induced by ATP depletion were co-localized with clusters of ORAI1 channels. STIM1–ORAI1 clusters that developed as a result of ATP depletion were very poor mediators of Ca2+ influx. Re-translocation of STIM1 from puncta back to the ER was observed during total ATP depletion. We can therefore conclude that STIM1 translocation and re-translocation as well as formation of STIM1–ORAI1 clusters occur in an ATP-independent fashion and under conditions of PI(4,5)P2 depletion.
Collapse
Affiliation(s)
- Michael Chvanov
- Department of Physiology, The University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
|
29
|
Fitzgerald DJ, Burgoyne RD, Haynes LP. Neuronal calcium sensor proteins are unable to modulate NFAT activation in mammalian cells. Biochim Biophys Acta Gen Subj 2007; 1780:240-8. [PMID: 18005668 PMCID: PMC2258317 DOI: 10.1016/j.bbagen.2007.10.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 10/01/2007] [Accepted: 10/18/2007] [Indexed: 12/18/2022]
Abstract
Calcium activated gene transcription through Nuclear Factor of Activated T-cells, (NFAT) proteins, is emerging as a ubiquitous mechanism for the control of important physiological processes. Of the five mammalian NFAT isoforms, transcriptional activities of NFATs 1-4 are stimulated by a calcium driven association between the ubiquitous phosphatase calcineurin and the calcium-sensing protein calmodulin. Published in vitro evidence has suggested that other members of the calmodulin super-family, in particular the neuronal calcium sensor (NCS) proteins, can similarly modulate calcineurin activity. In this study we have assessed the ability of NCS proteins to interact directly with calcineurin in vitro and report a specific if weak association between various NCS proteins and the phosphatase. In an extension to these analyses we have also examined the effects of over-expression of NCS-1 or NCS-1 mutants on calcineurin signalling in HeLa cells in experiments examining the dephosphorylation of an NFAT-GFP reporter construct as a readout of calcineurin activity. Results from these experiments indicate that NCS-1 was not able to detectably modulate calcineurin/NFAT signalling in a live mammalian cell system, findings that are consistent with the idea that calmodulin and not NCS-1 or other NCS family proteins is the physiologically relevant modulator of calcineurin activity.
Collapse
Affiliation(s)
- Daniel J Fitzgerald
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | | | | |
Collapse
|
30
|
Haynes LP, Sherwood MW, Dolman NJ, Burgoyne RD. Specificity, promiscuity and localization of ARF protein interactions with NCS-1 and phosphatidylinositol-4 kinase-III beta. Traffic 2007; 8:1080-92. [PMID: 17555535 PMCID: PMC2492389 DOI: 10.1111/j.1600-0854.2007.00594.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [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] [Indexed: 11/28/2022]
Abstract
ADP-ribosylation factor (ARF) proteins are involved in multiple intracellular vesicular transport pathways. Most studies have focused on the functions of ARF1 or ARF6 and little is known about the remaining ARF isoforms. Although the mammalian ARF proteins share a high degree of sequence identity, recent evidence has indicated that they may control distinct trafficking steps within cells. A unanswered issue is the degree of specificity of ARF family members for different interacting proteins. To investigate potential functional differences between the human ARF proteins, we have examined the localization of all human ARF isoforms and their interactions with two ARF1 binding proteins, neuronal calcium sensor-1 (NCS-1) and phosphatidylinositol-4 kinase-IIIbeta (PI4Kbeta). Use of a fluorescent protein fragment complementation method showed direct interactions between ARFs 1, 3, 5 and 6 with NCS-1 but at different intracellular locations in live HeLa cells. Photobleaching experiments indicated that complementation did not detect dynamic changes in protein interactions over short-time scales. A more specific interaction between ARFs 1/3 and PI4Kbeta was observed. Consistent with these latter findings ARF1 but not ARF5 or 6 enhanced the stimulatory effect of PI4Kbeta on regulated exocytosis, suggesting a specific role for class-I ARFs in the regulation of PI4Kbeta.
Collapse
Affiliation(s)
- Lee P Haynes
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Mark W. Sherwood
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Nick J Dolman
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Robert D Burgoyne
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| |
Collapse
|
31
|
Abstract
We have assessed the dynamics of the association of Rab3A and Rab27A with secretory granules at various stages of their life in PC12 cells. Endogenous Rab3A colocalised with the secretory granule marker secretogranin II (SGII) and expressed EGFP-Rab3A and ECFP-Rab27A colocalised with one another. The extent of colocalisation between EGFP-Rab3A or EGFP-Rab27 and SGII increased after longer times post transfection suggesting that these Rab proteins are preferentially recruited to newly synthesised granules. Following the release of immature secretory granules from the trans-Golgi network, Rab3A and Rab27A became associated with the immature granules after a lag period of around 20 minutes. Rab dynamics on granules were analysed in fluorescence recovery after photobleaching (FRAP) experiments. The recovery profile of EGFP-Rab27A was comparable to that of ppANF-EGFP, whereas the recovery profile of EGFP-Rab3A was significantly faster, indicating that Rab3A but not Rab27A might be rapidly exchanged between granules and cytosol. Inhibition of heat-shock protein 90 with 10 muM geldanamycin did not affect the exchange process or regulated exocytosis. Rab dynamics during stimulation with 300 muM ATP were analysed in live cells. Loss of granular ppANF-EGFP fluorescence was seen at the cell periphery after stimulation but only limited changes in EGFP-Rab3A and EGFP-Rab27A fluorescence was observed, indicating that the Rab proteins do not immediately dissociate or disperse on stimulation. The data suggest potentially distinct roles for Rab3A and Rab27A and we suggest that the finding that young secretory granules have a higher capacity for binding Rab3A and Rab27A is functionally important for preferential exocytosis from these granules.
Collapse
Affiliation(s)
- Mark T W Handley
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | | | | |
Collapse
|
32
|
Haynes LP, Fitzgerald DJ, Wareing B, O'Callaghan DW, Morgan A, Burgoyne RD. Analysis of the interacting partners of the neuronal calcium-binding proteins L-CaBP1, hippocalcin, NCS-1 and neurocalcin delta. Proteomics 2006; 6:1822-32. [PMID: 16470652 DOI: 10.1002/pmic.200500489] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [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] [Indexed: 11/07/2022]
Abstract
Intracellular Ca2+ signals are transduced by the binding of Ca2+ to sensor proteins, which subsequently modify the activity of their target proteins. Identification of these target proteins is, therefore, important for an understanding of cellular signalling processes. We have investigated the binding partners of four EF-hand Ca2+-binding proteins. Three proteins of the neuronal calcium sensor (NCS) family, hippocalcin, NCS-1 and neurocalcin delta were prepared as N-terminally tagged GST fusion proteins, and the less closely related protein L-CaBP1 was prepared in both N- and C-terminally tagged forms, the latter requiring generation of a new vector. Immobilised fusion proteins were used to purify binding partners from bovine brain cytosol and membrane extracts in the presence of 1 microM free Ca2+. Bound proteins were eluted with Ca2+-free and high-salt buffers and eluted proteins were identified by MALDI-MS and Western blotting. New protein targets detected included ARF1, Ca2+-dependent activator protein for secretion 1, cyclic nucleotide 3',5'-phosphodiesterase, the vacuolar ATPase, AP1 and AP2 complexes and the type I TGF-beta receptor. While certain of these interactions occurred with more than one of the Ca2+-binding proteins, others were found to be specific targets for particular Ca2+ sensors, and many of these did not overlap with known calmodulin-binding proteins. These findings provide new clues to the functional roles of the neuronal calcium sensor proteins.
Collapse
Affiliation(s)
- Lee P Haynes
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool, UK
| | | | | | | | | | | |
Collapse
|
33
|
Haynes LP, Thomas GMH, Burgoyne RD. Interaction of neuronal calcium sensor-1 and ADP-ribosylation factor 1 allows bidirectional control of phosphatidylinositol 4-kinase beta and trans-Golgi network-plasma membrane traffic. J Biol Chem 2004; 280:6047-54. [PMID: 15576365 DOI: 10.1074/jbc.m413090200] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified a novel Ca(2+)-dependent interaction between neuronal calcium sensor-1 (NCS-1) and the GTPase ARF1. Both of these proteins are localized to the Golgi complex, and both regulate phosphatidylinositol 4-kinase IIIbeta (PI(4)Kbeta). Spatial and temporal control of phosphatidylinositol 4-phosphate levels through activation of PI(4)Kbeta is important for the recruitment of trafficking complexes to the trans-Golgi network (TGN) and vesicular traffic from this organelle. The NCS-1-ARF1 interaction and its specificity have been demonstrated through in vitro binding assays, in vitro enzyme assay, and through functional cellular assays. We show that NCS-1 can exert bidirectional effects to activate PI(4)Kbeta on its own or inhibit the activation by ARF1. NCS-1 was shown to modulate the effects of expression of ARF mutants that disrupt Golgi morphology and to recruit GDP-loaded ARF to the Golgi complex in a Ca(2+)-dependent manner. We demonstrate antagonist effects of NCS-1 and ARF on constitutive and regulated exocytosis. The NCS-1-ARF1 interaction provides evidence for functional cross-talk between Ca(2+)-dependent and ARF-dependent pathways in TGN to plasma membrane traffic.
Collapse
Affiliation(s)
- Lee P Haynes
- Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown St., Liverpool L69 3BX, UK
| | | | | |
Collapse
|
34
|
Abstract
Many aspects of neuronal activity are regulated by Ca2+ signals. The transduction of temporally and spatially distinct Ca2+ signals requires the action of Ca2+-sensor proteins including various EF-hand-containing Ca2+-binding proteins. The neuronal Ca2+ sensor (NCS) protein family and the related Ca2+-binding proteins (CaBPs) have begun to emerge as key players in neuronal function. Many of these proteins are expressed predominantly or only in neurons, sometimes with cell-specific patterns of expression. Their ability to associate with membranes either constitutively or in response to elevated Ca2+ concentration allows the NCS proteins to discriminate between different spatial and temporal patterns of Ca2+ signals. Recent work has established several physiological roles of these proteins, including diverse actions on gene expression, ion channel function, membrane traffic of ion channels and receptors, and the control of apoptosis.
Collapse
Affiliation(s)
- Robert D Burgoyne
- The Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
| | | | | | | | | |
Collapse
|
35
|
Haynes LP, Tepikin AV, Burgoyne RD. Calcium-binding Protein 1 Is an Inhibitor of Agonist-evoked, Inositol 1,4,5-Trisphosphate-mediated Calcium Signaling. J Biol Chem 2004; 279:547-55. [PMID: 14570872 DOI: 10.1074/jbc.m309617200] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intracellular calcium signals are responsible for initiating a spectrum of physiological responses. The caldendrins/calcium-binding proteins (CaBPs) represent mammal-specific members of the CaM superfamily. CaBPs display a restricted pattern of expression in neuronal/retinal tissues, suggesting a specialized role in Ca2+ signaling in these cell types. Recently, it was reported that a splice variant of CaBP1 functionally interacts with inositol 1,4,5-trisphosphate (InsP3) receptors to elicit channel activation in the absence of InsP3 (Yang, J., McBride, S., Mak, D.-O. D., Vardi, N., Palczewski, K., Haeseleer, F., and Foskett, J. K. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 7711-7716). These data indicate a new mode of InsP3 receptor modulation and hence control of intracellular Ca2+ concentration ([Ca2+]i) in neuronal tissues. We have analyzed the biochemistry of the long form splice variant of CaBP1 (L-CaBP1) and show that, in vitro, a recombinant form of the protein is able to bind Ca2+ with high affinity and undergo a conformational change. We also describe the localization of endogenous and overexpressed L-CaBP1 in the model neuroendocrine PC12 cell system, where it was associated with the plasma membrane and Golgi complex in a myristoylation-dependent manner. Furthermore, we show that overexpressed L-CaBP1 is able to substantially suppress rises in [Ca2+]i in response to physiological agonists acting on purinergic receptors and that this inhibition is due in large part to blockade of release from intracellular Ca2+ stores. The related protein neuronal calcium sensor-1 was without effect on the [Ca2+]i responses to agonist stimulation. Measurement of [Ca2+] within the ER of permeabilized PC12 cells demonstrated that LCaBP1 directly inhibited InsP3-mediated Ca2+ release. Expression of L-CaBP1 also inhibited histamine-induced [Ca2+]i oscillations in HeLa cells. Together, these data suggest that L-CaBP1 is able to specifically regulate InsP3 receptor-mediated alterations in [Ca2+]i during agonist stimulation.
Collapse
Affiliation(s)
- Lee P Haynes
- The Physiological Laboratory, Crown Street, University of Liverpool, Liverpool L69 3BX, UK
| | | | | |
Collapse
|
36
|
Cheviet S, Coppola T, Haynes LP, Burgoyne RD, Regazzi R. The Rab-binding protein Noc2 is associated with insulin-containing secretory granules and is essential for pancreatic beta-cell exocytosis. Mol Endocrinol 2003; 18:117-26. [PMID: 14593078 DOI: 10.1210/me.2003-0300] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The small GTPases Rab3 and Rab27 are associated with secretory granules of pancreatic beta-cells and regulate insulin exocytosis. In this study, we investigated the role of Noc2, a potential partner of these two GTPases, in insulin secretion. In the beta-cell line INS-1E wild-type Noc2, Noc265E, and Noc258A, a mutant capable of interacting with Rab27 but not Rab3, colocalized with insulin-containing vesicles. In contrast, two mutants (Noc2138S,141S and Noc2154A,155A,156A) that bind neither Rab3 nor Rab27 did not associate with secretory granules and were uniformly distributed throughout the cell cytoplasm. Overexpression of wild-type Noc2, Noc265E, or Noc258A inhibited hormone secretion elicited by insulin secretagogues. In contrast, overexpression of the mutants not targeted to secretory granules was without effect. Silencing of the Noc2 gene by RNA interference led to a strong impairment in the capacity of INS-1E cells to respond to insulin secretagogues, indicating that appropriate levels of Noc2 are essential for pancreatic beta-cell exocytosis. The defect was already detectable in the early secretory phase (0-10 min) but was particularly evident during the sustained release phase (10-45 min). Protein-protein binding studies revealed that Noc2 is a potential partner of Munc13, a component of the machinery that controls vesicle priming and insulin exocytosis. These data suggest that Noc2 is involved in the recruitment of secretory granules at the plasma membrane possibly via the interaction with Munc13.
Collapse
Affiliation(s)
- Séverine Cheviet
- Institut de Biologie Cellulaire et de Morphologie, University of Lausanne, Switzerland
| | | | | | | | | |
Collapse
|
37
|
Abstract
The study of regulated exocytosis uniquely allows the direct measurement of intracellular membrane fusion events in real time. We have exploited this to examine factors that regulate not only the extent but also the dynamics of single fusion/release events. The general strategy used has been to assess exocytosis in transiently transfected PC12 or adrenal chromaffin cells. We aimed to design mutant constructs based on in vitro biochemistry, in some cases informed by knowledge of protein structure. Using this approach we have demonstrated an inhibitory role for the putative Rab3 effector Noc2 that requires interaction with Rab3. Using carbon-fibre amperometry on adrenal chromaffin cells, we have demonstrated regulation of the kinetics of single granule release events consistent with changes in fusion pore dynamics and switches between full fusion and 'kiss-and-run' fusion. These studies have demonstrated a late role for cysteine string protein in exocytosis. In addition, they have focused attention on a key role for Munc18 in the regulation of post-fusion events that affect fusion pore dynamics.
Collapse
Affiliation(s)
- R D Burgoyne
- The Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
| | | | | | | | | |
Collapse
|
38
|
Haynes LP, Evans GJ, Morgan A, Burgoyne RD. A direct inhibitory role for the Rab3-specific effector, Noc2, in Ca2+-regulated exocytosis in neuroendocrine cells. J Biol Chem 2001; 276:9726-32. [PMID: 11134008 DOI: 10.1074/jbc.m006959200] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rab proteins comprise a family of GTPases, conserved from yeast to mammals, which are integral components of membrane trafficking pathways. Rab3A is a neural/neuroendocrine-specific member of the Rab family involved in Ca(2+) -regulated exocytosis, where it functions in an inhibitory capacity controlling recruitment of secretory vesicles into a releasable pool at the plasma membrane. The effector by which Rab3A exerts its inhibitory effect is unclear as the Rab3A effectors Rabphilin and RIM have been excluded from for this role. One putative Rab3A effector in dense-core granule exocytosis is the cytosolic zinc finger protein, Noc2. We have established that overexpression of Noc2 in PC12 cells has a direct inhibitory effect upon Ca(2+)-triggered exocytosis in permeabilized cells. We demonstrate specific nucleotide-dependent binding of Noc2 to Rab3A and show that the inhibition of exocytosis is dependent upon this interaction since Rab3A binding-deficient mutants of Noc2 do not inhibit exocytosis. We propose that Noc2 may be a negative effector for Rab3A in regulated exocytosis of dense-core granules from endocrine cells.
Collapse
Affiliation(s)
- L P Haynes
- Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, United Kingdom
| | | | | | | |
Collapse
|
39
|
Haynes LP, Morgan A, Burgoyne RD. nSec-1 (munc-18) interacts with both primed and unprimed syntaxin 1A and associates in a dimeric complex on adrenal chromaffin granules. Biochem J 1999; 342 Pt 3:707-14. [PMID: 10477283 PMCID: PMC1220513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
The target-SNARE syntaxin 1A is an essential component of the core machinery required for regulated exocytosis (where SNARE is the soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor). Syntaxin 1A interacts with a variety of other proteins, two of which, N-ethylmaleimide-sensitive fusion protein (NSF) and alpha-soluble NSF attachment protein (alpha-SNAP) have been suggested to impart a conformational rearrangement on this protein during a reaction referred to as priming. We have studied the effect of the primed state on the binding properties of syntaxin 1A and we have confirmed that primed syntaxin 1A no longer associated with alpha-SNAP or its cognate vesicle-SNARE, vesicle-associated membrane protein (VAMP). Under such conditions, however, it retained the ability to bind to nSec-1. It has been demonstrated that nSec-1, a regulatory protein also involved in neuronal exocytosis, binds syntaxin 1A with high affinity in vitro, although evidence for this physical interaction occurring in vivo has proven elusive. We analysed the subcellular distribution of these two proteins in fractions from bovine adrenal medulla and detected syntaxin 1A and nSec-1 in both plasma membrane and chromaffin-granule fractions. Using a cross-linking approach with chromaffin-granule membranes we detected a putative dimeric complex composed of approx. 54% total granule membrane nSec-1 and approx. 30% total syntaxin 1A. The results of this study therefore suggest the possibility of nSec-1 interactions with primed syntaxin 1A and demonstrate a potentially significant interaction of syntaxin 1A and nSec-1 on the membranes of chromaffin granules.
Collapse
Affiliation(s)
- L P Haynes
- The Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | | | | |
Collapse
|
40
|
Abstract
N-Ethylmaleimide-sensitive factor (NSF) plays a key role in vesicular traffic by disassembling and priming SNARE proteins for their function in docking and fusion. We demonstrate that the ATPase activity of NSF is activated by alpha-soluble NSF attachment protein (alpha-SNAP) in a complex with syntaxin 1A. In addition, we show that a construct consisting of the H3 domain of syntaxin IA (GST-synt(195-263), which does not support NSF disassembly in the presence of MgATP gave a larger stimulation. NSF ATPase activation was specific and did not occur using mutant alpha-SNAPs unable to bind GST-synt or with mutated C-termini. We suggest that activation of NSF ATPase activity in the SNARE complex may be essential to allow SNARE priming.
Collapse
Affiliation(s)
- L P Haynes
- The Physiological Laboratory, University of Liverpool, UK
| | | | | | | |
Collapse
|