The Experts below are selected from a list of 2184 Experts worldwide ranked by ideXlab platform

Robert D Burgoyne - One of the best experts on this subject based on the ideXlab platform.

  • Neuronal Calcium Sensor 1 binds the d2 dopamine receptor and g protein coupled receptor kinase 1 grk1 peptides using different modes of interactions
    Journal of Biological Chemistry, 2015
    Co-Authors: Sravan R Pandalaneni, Lee P Haynes, Robert D Burgoyne, Vijaykumar Karuppiah, Muhammad Saleem, Olga Mayans, Jeremy P Derrick, Lu-yun Lian
    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.

  • mutations that disrupt phoxb interaction with the Neuronal Calcium Sensor hpcal1 impede cellular differentiation in neuroblastoma
    Oncogene, 2014
    Co-Authors: Quan Zhong, Ling Teng, Namrata Bhatnagar, William Luther, Lee P Haynes, Bandana Sharma, Wenchao Wang, Xin Zhang, Robert D Burgoyne
    Abstract:

    Mutations that disrupt PHOXB interaction with the Neuronal Calcium Sensor HPCAL1 impede cellular differentiation in neuroblastoma

  • Identification of key structural elements for Neuronal Calcium Sensor-1 function in the regulation of the temperature-dependency of locomotion in C. elegans
    Molecular brain, 2013
    Co-Authors: Victoria M. Martin, Lee P Haynes, James R. Johnson, Jeff W. Barclay, Robert D Burgoyne
    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.

  • Understanding the physiological roles of the Neuronal Calcium Sensor proteins
    Molecular Brain, 2012
    Co-Authors: Robert D Burgoyne, Lee P Haynes
    Abstract:

    Calcium signalling plays a crucial role in the control of Neuronal function and plasticity. Changes in Neuronal Ca^2+ concentration are detected by Ca^2+-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.

  • Neuronal Calcium Sensor-1 Regulation of Calcium Channels, Secretion, and Neuronal Outgrowth
    Cellular and molecular neurobiology, 2010
    Co-Authors: Jamie L Weiss, Hui Hui, Robert D Burgoyne
    Abstract:

    Calcium (Ca2+) is an important intracellular messenger underlying cell physiology. Ca2+ channels are the main entry route for Ca2+ into excitable cells, and regulate processes such as neurotransmitter release and Neuronal outgrowth. Neuronal Calcium Sensor-1 (NCS-1) is a member of the Calmodulin superfamily of EF-hand Ca2+ sensing proteins residing in the subfamily of NCS proteins. NCS-1 was originally discovered in Drosophila as an overexpression mutant (Frequenin), having an increased frequency of Ca2+-evoked neurotransmission. NCS-1 is N-terminally myristoylated, can bind intracellular membranes, and has a Ca2+ affinity of 0.3 μM. Over 10 years ago it was discovered that NCS-1 overexpression enhances Ca2+-evoked secretion in bovine adrenal chromaffin cells. The mechanism was unclear, but there was no apparent direct effect on the exocytotic machinery. It was revealed, again in chromaffin cells, that NCS-1 regulates voltage-gated Ca2+ channels (Cavs) in G-Protein Coupled Receptor (GPCR) signaling pathways. This work in chromaffin cells highlighted NCS-1 as an important modulator of neurotransmission. NCS-1 has since been shown to regulate and/or directly interact with many proteins including Cavs (P/Q, N, and L), TRPC1/5 channels, GPCRs, IP3R, and PI4 kinase type IIIβ. NCS-1 also affects Neuronal outgrowth having roles in learning and memory affecting both short- and long-term synaptic plasticity. It is not known if NCS-1 affects neurotransmission and synaptic plasticity via its effect on PIP2 levels, and/or via a direct interaction with Ca2+ channels or their signaling complexes. This review gives a historical account of NCS-1 function, examining contributions from chromaffin cells, PC12 cells and other models, to describe how NCS-1’s regulation of Ca2+ channels allows it to exert its physiological effects.

Andreas Jeromin - One of the best experts on this subject based on the ideXlab platform.

  • Membrane binding of Neuronal Calcium Sensor-1 (NCS1).
    Colloids and surfaces. B Biointerfaces, 2015
    Co-Authors: Samuel Lemire, Andreas Jeromin, Elodie Boisselier
    Abstract:

    Neuronal Calcium Sensor-1 (NCS1) belongs to the family of Neuronal Calcium Sensor (NCS) proteins. NCS1 is composed of four EF-hand motifs and an N-terminal myristoylation. However, the presence of a Calcium-myristoyl switch in NCS1 and its role in the membrane binding are controversial. The model of Langmuir lipid monolayers is thus used to mimic the cell membrane in order to characterize the membrane interactions of NCS1. Two binding parameters are calculated from monolayer measurements: the maximum insertion pressure, up to which protein binding is energetically favorable, and the synergy, reporting attractive or repulsive interactions with the lipid monolayers. Binding membrane measurements performed in the presence of myristoylated NCS1 reveal better binding interactions for phospholipids composed of phosphoethanolamine polar head groups and unsaturated fatty acyl chains. In the absence of Calcium, the membrane binding measurements are drastically modified and suggest that the protein is more strongly bound to the membrane. Indeed, the binding of Calcium by three EF-hand motifs of NCS1 leads to a conformation change. NCS1 arrangement at the membrane could thus be reshuffled for better interactions with its substrates. The N-terminal peptide of NCS1 is composed of two amphiphilic helices involved in the membrane interactions of NCS1. Moreover, the presence of the myristoyl group has a weak influence on the membrane binding of NCS1 suggesting the absence of a Calcium-myristoyl switch mechanism in this protein. The myristoylation could thus have a structural role required in the folding/unfolding of NCS1 which is essential to its multiple biological functions.

  • Neuronal Calcium Sensor-1 enhancement of InsP3 receptor activity is inhibited by therapeutic levels of lithium
    The Journal of clinical investigation, 2006
    Co-Authors: Christina Schlecker, Yogendra Sharma, Andreas Jeromin, Brenda Degray, Wolfgang Boehmerle, Anurag Varshney, Klara Szigeti-buck, Barbara E. Ehrlich
    Abstract:

    Regulation and dysregulation of intracellular Calcium (Ca2+) signaling via the inositol 1,4,5-trisphosphate receptor (InsP3R) has been linked to many cellular processes and pathological conditions. In the present study, addition of Neuronal Calcium Sensor-1 (NCS-1), a high-affinity, low-capacity, Calcium-binding protein, to purified InsP3R type 1 (InsP3R1) increased the channel activity in both a Calcium-dependent and -independent manner. In intact cells, enhanced expression of NCS-1 resulted in increased intracellular Calcium release upon stimulation of the phosphoinositide signaling pathway. To determine whether InsP3R1/NCS-1 interaction could be functionally relevant in bipolar disorders, conditions in which NCS-1 is highly expressed, we tested the effect of lithium, a salt widely used for treatment of bipolar disorders. Lithium inhibited the enhancing effect of NCS-1 on InsP3R1 function, suggesting that InsP3R1/NCS-1 interaction is an essential component of the pathomechanism of bipolar disorder.

  • Localization of Neuronal Calcium Sensor-1 at the adult and developing rat neuromuscular junction
    Journal of neuroscience research, 2005
    Co-Authors: Neus Garcia, Andreas Jeromin, Maria A. Lanuza, Nuria Besalduch, Manel M. Santafé, Josep Tomàs
    Abstract:

    Neuronal Calcium Sensor (NCS-1; frequenin) is a Calcium-binding protein involved in the regulation of neurotransmission in the central and peripheral nervous systems from insects to vertebrates. This study reports the localization of NCS-1 immunoreactivity, by Western blotting and immunohistochemistry, at the adult and developing postnatal rat neuromuscular junction. Our confocal immunofluorescence results on the wholemount muscle and on semithin cross-sections are indicative of the localization of NCS-1 to motor axon terminals. There is no evidence of immunoreactivity in the postsynaptic side of the neuromuscular junctions or teloglial Schwann cells. These results suggest that NCS-1 is involved in the formation and function of presynaptic nerve terminal part of the neuromuscular junction during synaptogenesis and in adult mammals. V C 2005 Wiley-Liss, Inc.

  • Neuronal Calcium Sensor-1 facilitates Neuronal exocytosis through phosphatidylinositol 4-kinase.
    Journal of neurochemistry, 2005
    Co-Authors: Qian Zheng, John C. Roder, Joseph A. Bobich, Jolanta Vidugiriene, Susanne C Mcfadden, Fairwell Thomas, Andreas Jeromin
    Abstract:

    This work tested the theory that Neuronal Calcium Sensor-1 (NCS-1) has effects on neurotransmitter release beyond its actions on membrane channels. We used nerve-ending preparations where membrane channels are bypassed through membrane permeabilization made by mechanical disruption or streptolysin-O. Nerve ending NCS-1 and phosphatidylinositol 4-kinase (PI4K) are largely or entirely particulate, so their concentrations in nerve endings remain constant after breaching the membrane. Exogenous, myristoylated NCS-1 stimulated nerve ending phosphatidylinositol 4-phosphate [PI(4)P] synthesis, but non-myristoylated-NCS-1 did not. The N-terminal peptide of NCS-1 interfered with PI(4)P synthesis, and with spontaneous and Ca(2+)-evoked release of both [(3)H]-norepinephrine (NA) and [(14)C]-glutamate (glu) in a concentration-dependent manner. An antibody raised against the N-terminal of NCS-1 inhibited perforated nerve ending PI(4)P synthesis, but the C-terminal antibody had no effects. Antibodies against the N- and C-termini of NCS-1 caused significant increases in mini/spontaneous/stimulation-independent release of [(3)H]-NA from perforated nerve endings, but had no effect on [(14)C]-glu release. These results support the idea that NCS-1 facilitates nerve ending neurotransmitter release and phosphoinositide production via PI4K and localizes these effects to the N-terminal of NCS-1. Combined with previous work on the regulation of channels by NCS-1, the data are consistent with the hypothesis that a NCS-1-PI4K (NP, neuropotentiator) complex may serve as an essential linker between lipid and protein metabolism to regulate membrane traffic and co-ordinate it with ion fluxes and plasticity in the nerve ending.

  • n terminal myristoylation regulates Calcium induced conformational changes in Neuronal Calcium Sensor 1
    Journal of Biological Chemistry, 2004
    Co-Authors: Andreas Jeromin, John C. Roder, Kandala V. R. Chary, Dasari Muralidhar, Malavika Nair Parameswaran, Thomas Fairwell, Suzanne Scarlata, Louisa Dowal, Sourajit M Mustafi, Yogendra Sharma
    Abstract:

    Neuronal Calcium Sensor-1 (NCS-1), a Ca(2+)-binding protein, plays an important role in the modulation of neurotransmitter release and phosphatidylinositol signaling pathway. It is known that the physiological activity of NCS-1 is governed by its myristoylation. Here, we present the role of myristoylation of NSC-1 in governing Ca(2+) binding and Ca(2+)-induced conformational changes in NCS-1 as compared with the role in the nonmyristoylated protein. The (45)Ca binding and isothermal titration calorimetric data show that myristoylation increases the degree of cooperativity; thus, the myristoylated NCS-1 binds Ca(2+) more strongly (with three Ca(2+) binding sites) than the non-myristoylated one (with two Ca(2+) binding sites). Both forms of protein show different conformational features in far-UV CD when titrated with Ca(2+). Large conformational changes were seen in the near-UV CD with more changes in the case of nonmyristoylated protein than the myristoylated one. Although the changes in the far-UV CD upon Ca(2+) binding were not seen in E120Q mutant (disabling EF-hand 3), the near-UV CD changes in conformation also were not influenced by this mutation. The difference in the binding affinity of myristoylated and non-myristoylated proteins to Ca(2+) also was reflected by Trp fluorescence. Collisional quenching by iodide showed more inaccessibility of the fluorophore in the myristoylated protein. Mg(2+)-induced changes in near-UV CD are different from Ca(2+)-induced changes, indicating ion selectivity. 8-Anilino-1-naphthalene sulfonic acid binding data showed solvation of the myristoyl group in the presence of Ca(2+), which could be attributed to the myristoyl-dependent conformational changes in NCS-1. These results suggest that myristoylation influences the protein conformation and Ca(2+) binding, which might be crucial for its physiological functions.

James B. Ames - One of the best experts on this subject based on the ideXlab platform.

  • Dimerization of Neuronal Calcium Sensor Proteins
    Frontiers Media S.A., 2018
    Co-Authors: James B. Ames
    Abstract:

    Neuronal Calcium Sensor (NCS) proteins are EF-hand containing Ca2+ binding proteins that regulate Sensory signal transduction. Many NCS proteins (recoverin, GCAPs, neurocalcin and visinin-like protein 1 (VILIP1)) form functional dimers under physiological conditions. The dimeric NCS proteins have similar amino acid sequences (50% homology) but each bind to and regulate very different physiological targets. Retinal recoverin binds to rhodopsin kinase and promotes Ca2+-dependent desensitization of light-excited rhodopsin during visual phototransduction. The guanylyl cyclase activating proteins (GCAP1–5) each bind and activate retinal guanylyl cyclases (RetGCs) in light-adapted photoreceptors. VILIP1 binds to membrane targets that modulate Neuronal secretion. Here, I review atomic-level structures of dimeric forms of recoverin, GCAPs and VILIP1. The distinct dimeric structures in each case suggest that NCS dimerization may play a role in modulating specific target recognition. The dimerization of recoverin and VILIP1 is Ca2+-dependent and enhances their membrane-targeting Ca2+-myristoyl switch function. The dimerization of GCAP1 and GCAP2 facilitate their binding to dimeric RetGCs and may allosterically control the Ca2+-dependent activation of RetGCs

  • Structural diversity of Neuronal Calcium Sensor proteins and insights for activation of retinal guanylyl cyclase by GCAP1.
    Frontiers in molecular neuroscience, 2014
    Co-Authors: Sunghyuk Lim, Alexander M. Dizhoor, James B. Ames
    Abstract:

    Neuronal Calcium Sensor (NCS) proteins, a sub-branch of the calmodulin superfamily, are expressed in the brain and retina where they transduce Calcium signals and are genetically linked to degenerative diseases. The amino acid sequences of NCS proteins are highly conserved but their physiological functions are quite different. Retinal recoverin controls Ca(2) (+)-dependent inactivation of light-excited rhodopsin during phototransduction, guanylyl cyclase activating proteins 1 and 2 (GCAP1 and GCAP2) promote Ca(2) (+)-dependent activation of retinal guanylyl cyclases, and Neuronal frequenin (NCS-1) modulates synaptic activity and Neuronal secretion. Here we review the molecular structures of myristoylated forms of NCS-1, recoverin, and GCAP1 that all look very different, suggesting that the attached myristoyl group helps to refold these highly homologous proteins into different three-dimensional folds. Ca(2) (+)-binding to both recoverin and NCS-1 cause large protein conformational changes that ejects the covalently attached myristoyl group into the solvent exterior and promotes membrane targeting (Ca(2) (+)-myristoyl switch). The GCAP proteins undergo much smaller Ca(2) (+)-induced conformational changes and do not possess a Ca(2) (+)-myristoyl switch. Recent structures of GCAP1 in both its activator and Ca(2) (+)-bound inhibitory states will be discussed to understand structural determinants that control their Ca(2) (+)-dependent activation of retinal guanylyl cyclases.

  • 1H, 13C, and 15N Chemical Shift Assignments of Neuronal Calcium Sensor Protein, Hippocalcin
    Biomolecular NMR assignments, 2012
    Co-Authors: James B. Ames
    Abstract:

    Hippocalcin, a member of the Neuronal Calcium Sensor (NCS) subclass of the calmodulin superfamily, serves as an important Calcium Sensor for the slow afterhyperpolarizing (sAHP) current in the hippocampus, which underlies some forms of learning and memory. Hippocalcin is also a Calcium Sensor for hippocampal long-term depression (LTD) and genetically linked to neurodegenerative diseases. We report NMR chemical shift assignments of Ca2+-free hippocalcin (BMRB no. 18627).

  • molecular structure and target recognition of Neuronal Calcium Sensor proteins
    Biochimica et Biophysica Acta, 2012
    Co-Authors: James B. Ames
    Abstract:

    Abstract Background Neuronal Calcium Sensor (NCS) proteins, a sub-branch of the calmodulin superfamily, are expressed in the brain and retina where they transduce Calcium signals and are genetically linked to degenerative diseases. The amino acid sequences of NCS proteins are highly conserved but their physiological functions are quite distinct. Retinal recoverin and guanylate cyclase activating proteins (GCAPs) both serve as Calcium Sensors in retinal rod cells, Neuronal frequenin (NCS1) modulate synaptic activity and Neuronal secretion, K+ channel interacting proteins (KChIPs) regulate ion channels to control Neuronal excitability, and DREAM (KChIP3) is a transcriptional repressor that regulates Neuronal gene expression. Scope of review Here we review the molecular structures of myristoylated forms of NCS1, recoverin, and GCAP1 that all look very different, suggesting that the sequestered myristoyl group helps to refold these highly homologous proteins into very different structures. The molecular structure of NCS target complexes have been solved for recoverin bound to rhodopsin kinase, NCS-1 bound to phosphatidylinositol 4-kinase, and KChIP1 bound to A-type K+ channels. Major conclusions We propose the idea that N-terminal myristoylation is critical for shaping each NCS family member into a unique structure, which upon Ca2 +-induced extrusion of the myristoyl group exposes a unique set of previously masked residues, thereby exposing a distinctive ensemble of hydrophobic residues to associate specifically with a particular physiological target. This article is part of a Special Issue entitled Biochemical, biophysical and genetic approaches to intracellular Calcium signaling.

  • molecular structure and target recognition of Neuronal Calcium Sensor proteins
    Frontiers in Molecular Neuroscience, 2012
    Co-Authors: James B. Ames, Mitsuhiko Ikura
    Abstract:

    Neuronal Calcium Sensor (NCS) proteins, a sub-branch of the calmodulin superfamily, are expressed in the brain and retina where they transduce Calcium signals and are genetically linked to degenerative diseases. The amino acid sequences of NCS proteins are highly conserved but their physiological functions are quite distinct. Retinal recoverin and guanylate cyclase activating proteins (GCAPs) both serve as Calcium Sensors in retinal rod cells, Neuronal frequenin (NCS1) modulates synaptic activity and Neuronal secretion, K+ channel interacting proteins (KChIPs) regulate ion channels to control Neuronal excitability, and DREAM (KChIP3) is a transcriptional repressor that regulates Neuronal gene expression. Here we review the molecular structures of myristoylated forms of NCS1, recoverin, and GCAP1 that all look very different, suggesting that the sequestered myristoyl group helps to refold these highly homologous proteins into very different structures. The molecular structure of NCS target complexes have been solved for recoverin bound to rhodopsin kinase, NCS-1 bound to phosphatidylinositol 4-kinase, and KChIP1 bound to A-type K+ channels. We propose that N-terminal myristoylation is critical for shaping each NCS family member into a different structure, which upon Ca2+-induced extrusion of the myristoyl group exposes a unique set of previously masked residues that interact with a particular physiological target.

John C. Roder - One of the best experts on this subject based on the ideXlab platform.

  • Mice lacking Neuronal Calcium Sensor-1 show social and cognitive deficits.
    Behavioural brain research, 2019
    Co-Authors: John Georgiou, Ariel Avila, Kathleen Trought, Ho-suk Mun, Meggie Hodgson, Panayiotis Servinis, John C. Roder, Graham L. Collingridge, Albert H.c. Wong
    Abstract:

    Neuronal Calcium Sensor-1 or Frequenin is a Calcium Sensor widely expressed in the nervous system, with roles in neurotransmission, neurite outgrowth, synaptic plasticity, learning, and motivated behaviours. Neuronal Calcium Sensor-1 has been implicated in neuropsychiatric disorders including autism spectrum disorder, schizophrenia, and bipolar disorder. However, the role of Neuronal Calcium Sensor-1 in behavioural phenotypes and brain changes relevant to autism spectrum disorder have not been evaluated. We show that Neuronal Calcium Sensor-1 deletion in the mouse leads to a mild deficit in social approach and impaired displaced object recognition without affecting social interactions, behavioural flexibility, spatial reference memory, anxiety-like behaviour, or Sensorimotor gating. Morphologically, Neuronal Calcium Sensor-1 deletion leads to increased dendritic arbour complexity in the frontal cortex. At the level of hippocampal synaptic plasticity, Neuronal Calcium Sensor-1 deletion leads to a reduction in long-term potentiation in the dentate gyrus, but not area Cornu Ammonis 1. Metabotropic glutamate receptor-induced long-term depression was unaffected in both dentate and Cornu Ammonis 1. These studies identify roles for Neuronal Calcium Sensor-1 in specific subregions of the brain including a phenotype relevant to neuropsychiatric disorders.

  • Neuronal Calcium Sensor-1 deletion in the mouse decreases motivation and dopamine release in the nucleus accumbens.
    Behavioural brain research, 2015
    Co-Authors: Rafael K. Varaschin, Caleb J Browne, Joanna Hermainski, Bernard Le Foll, Olaf Pongs, Fang Liu, Louis-eric Trudeau, John C. Roder
    Abstract:

    Calcium Sensors detect intracellular Calcium changes and interact with downstream targets to regulate many functions. Neuronal Calcium Sensor-1 (NCS-1) or Frequenin is widely expressed in the nervous system, and involved in neurotransmission, synaptic plasticity and learning. NCS-1 interacts with and regulates dopamine D2 receptor (D2R) internalization and is implicated in disorders like schizophrenia and substance abuse. However, the role of NCS-1 in behaviors dependent on dopamine signaling in the striatum, where D2R is most highly expressed, is unknown. We show that Ncs-1 deletion in the mouse decreases willingness to work for food. Moreover, Ncs-1 knockout mice have significantly lower activity-dependent dopamine release in the nucleus accumbens core in acute slice recordings. In contrast, food preference, responding for conditioned reinforcement, ability to represent changes in reward value, and locomotor response to amphetamine are not impaired. These studies identify novel roles for NCS-1 in regulating activity-dependent striatal dopamine release and aspects of motivated behavior.

  • Neuronal Calcium Sensor-1 modulation of optimal Calcium level for neurite outgrowth
    Development (Cambridge England), 2007
    Co-Authors: Kwokyin Hui, John C. Roder, Guang-he Fei, Bechara J. Saab, Zhong-ping Feng
    Abstract:

    Neurite extension and branching are affected by activity-dependent modulation of intracellular Ca2+, such that an optimal window of [Ca2+] is required for outgrowth. Our understanding of the molecular mechanisms regulating this optimal [Ca2+]i remains unclear. Taking advantage of the large growth cone size of cultured primary neurons from pond snail Lymnaea stagnalis combined with dsRNA knockdown, we show that Neuronal Calcium Sensor-1 (NCS-1) regulates neurite extension and branching, and activity-dependent Ca2+ signals in growth cones. An NCS-1 C-terminal peptide enhances only neurite branching and moderately reduces the Ca2+ signal in growth cones compared with dsRNA knockdown. Our findings suggest that at least two separate structural domains in NCS-1 independently regulate Ca2+ influx and neurite outgrowth, with the C-terminus specifically affecting branching. We describe a model in which NCS-1 regulates cytosolic Ca2+ around the optimal window level to differentially control neurite extension and branching.

  • Neuronal Calcium Sensor-1 facilitates Neuronal exocytosis through phosphatidylinositol 4-kinase.
    Journal of neurochemistry, 2005
    Co-Authors: Qian Zheng, John C. Roder, Joseph A. Bobich, Jolanta Vidugiriene, Susanne C Mcfadden, Fairwell Thomas, Andreas Jeromin
    Abstract:

    This work tested the theory that Neuronal Calcium Sensor-1 (NCS-1) has effects on neurotransmitter release beyond its actions on membrane channels. We used nerve-ending preparations where membrane channels are bypassed through membrane permeabilization made by mechanical disruption or streptolysin-O. Nerve ending NCS-1 and phosphatidylinositol 4-kinase (PI4K) are largely or entirely particulate, so their concentrations in nerve endings remain constant after breaching the membrane. Exogenous, myristoylated NCS-1 stimulated nerve ending phosphatidylinositol 4-phosphate [PI(4)P] synthesis, but non-myristoylated-NCS-1 did not. The N-terminal peptide of NCS-1 interfered with PI(4)P synthesis, and with spontaneous and Ca(2+)-evoked release of both [(3)H]-norepinephrine (NA) and [(14)C]-glutamate (glu) in a concentration-dependent manner. An antibody raised against the N-terminal of NCS-1 inhibited perforated nerve ending PI(4)P synthesis, but the C-terminal antibody had no effects. Antibodies against the N- and C-termini of NCS-1 caused significant increases in mini/spontaneous/stimulation-independent release of [(3)H]-NA from perforated nerve endings, but had no effect on [(14)C]-glu release. These results support the idea that NCS-1 facilitates nerve ending neurotransmitter release and phosphoinositide production via PI4K and localizes these effects to the N-terminal of NCS-1. Combined with previous work on the regulation of channels by NCS-1, the data are consistent with the hypothesis that a NCS-1-PI4K (NP, neuropotentiator) complex may serve as an essential linker between lipid and protein metabolism to regulate membrane traffic and co-ordinate it with ion fluxes and plasticity in the nerve ending.

  • n terminal myristoylation regulates Calcium induced conformational changes in Neuronal Calcium Sensor 1
    Journal of Biological Chemistry, 2004
    Co-Authors: Andreas Jeromin, John C. Roder, Kandala V. R. Chary, Dasari Muralidhar, Malavika Nair Parameswaran, Thomas Fairwell, Suzanne Scarlata, Louisa Dowal, Sourajit M Mustafi, Yogendra Sharma
    Abstract:

    Neuronal Calcium Sensor-1 (NCS-1), a Ca(2+)-binding protein, plays an important role in the modulation of neurotransmitter release and phosphatidylinositol signaling pathway. It is known that the physiological activity of NCS-1 is governed by its myristoylation. Here, we present the role of myristoylation of NSC-1 in governing Ca(2+) binding and Ca(2+)-induced conformational changes in NCS-1 as compared with the role in the nonmyristoylated protein. The (45)Ca binding and isothermal titration calorimetric data show that myristoylation increases the degree of cooperativity; thus, the myristoylated NCS-1 binds Ca(2+) more strongly (with three Ca(2+) binding sites) than the non-myristoylated one (with two Ca(2+) binding sites). Both forms of protein show different conformational features in far-UV CD when titrated with Ca(2+). Large conformational changes were seen in the near-UV CD with more changes in the case of nonmyristoylated protein than the myristoylated one. Although the changes in the far-UV CD upon Ca(2+) binding were not seen in E120Q mutant (disabling EF-hand 3), the near-UV CD changes in conformation also were not influenced by this mutation. The difference in the binding affinity of myristoylated and non-myristoylated proteins to Ca(2+) also was reflected by Trp fluorescence. Collisional quenching by iodide showed more inaccessibility of the fluorophore in the myristoylated protein. Mg(2+)-induced changes in near-UV CD are different from Ca(2+)-induced changes, indicating ion selectivity. 8-Anilino-1-naphthalene sulfonic acid binding data showed solvation of the myristoyl group in the presence of Ca(2+), which could be attributed to the myristoyl-dependent conformational changes in NCS-1. These results suggest that myristoylation influences the protein conformation and Ca(2+) binding, which might be crucial for its physiological functions.

Xose M. Dopazo - One of the best experts on this subject based on the ideXlab platform.

  • Targeting the Neuronal Calcium Sensor DREAM with small-molecules for Huntington’s disease treatment
    Scientific reports, 2019
    Co-Authors: Alejandro López-hurtado, Diego A. Peraza, Pilar Cercós, Laura Lagartera, Paz Gonzalez, Xose M. Dopazo, Rosario Herranz, Teresa González, Mercedes Martín-martínez, Britt Mellström
    Abstract:

    DREAM, a Neuronal Calcium Sensor protein, has multiple cellular roles including the regulation of Ca2+ and protein homeostasis. We recently showed that reduced DREAM expression or blockade of DREAM activity by repaglinide is neuroprotective in Huntington’s disease (HD). Here we used structure-based drug design to guide the identification of IQM-PC330, which was more potent and had longer lasting effects than repaglinide to inhibit DREAM in cellular and in vivo HD models. We disclosed and validated an unexplored ligand binding site, showing Tyr118 and Tyr130 as critical residues for binding and modulation of DREAM activity. IQM-PC330 binding de-repressed c-fos gene expression, silenced the DREAM effect on KV4.3 channel gating and blocked the ATF6/DREAM interaction. Our results validate DREAM as a valuable target and propose more effective molecules for HD treatment.

  • targeting the Neuronal Calcium Sensor dream with small molecules for huntington s disease treatment
    Scientific Reports, 2019
    Co-Authors: Diego A. Peraza, Pilar Cercós, Laura Lagartera, Paz Gonzalez, Xose M. Dopazo, Alejandro Lopezhurtado
    Abstract:

    DREAM, a Neuronal Calcium Sensor protein, has multiple cellular roles including the regulation of Ca2+ and protein homeostasis. We recently showed that reduced DREAM expression or blockade of DREAM activity by repaglinide is neuroprotective in Huntington’s disease (HD). Here we used structure-based drug design to guide the identification of IQM-PC330, which was more potent and had longer lasting effects than repaglinide to inhibit DREAM in cellular and in vivo HD models. We disclosed and validated an unexplored ligand binding site, showing Tyr118 and Tyr130 as critical residues for binding and modulation of DREAM activity. IQM-PC330 binding de-repressed c-fos gene expression, silenced the DREAM effect on KV4.3 channel gating and blocked the ATF6/DREAM interaction. Our results validate DREAM as a valuable target and propose more effective molecules for HD treatment.

  • Inhibition of the Neuronal Calcium Sensor DREAM Modulates Presenilin-2 Endoproteolysis
    Frontiers Media S.A., 2018
    Co-Authors: Alejandro López-hurtado, Paz Gonzalez, Xose M. Dopazo, Britt Mellström, Rocío Naranjo
    Abstract:

    Deregulated intracellular Ca2+ and protein homeostasis underlie synaptic dysfunction and are common features in neurodegenerative diseases. DREAM, also known as calsenilin or KChIP-3, is a multifunctional Ca2+ binding protein of the Neuronal Calcium Sensor superfamily with specific functions through protein-DNA and protein-protein interactions. Small-molecules able to bind DREAM, like the anti-diabetic drug repaglinide, disrupt some of the interactions with other proteins and modulate DREAM activity on Kv4 channels or on the processing of activating transcription factor 6 (ATF6). Here, we show the interaction of endogenous DREAM and presenilin-2 (PS2) in mouse brain and, using DREAM deficient mice or transgenic mice overexpressing a dominant active DREAM (daDREAM) mutant in the brain, we provide genetic evidence of the role of DREAM in the endoproteolysis of endogenous PS2. We show that repaglinide disrupts the interaction between DREAM and the C-terminal PS2 fragment (Ct-PS2) by coimmunoprecipitation assays. Exposure to sub-micromolar concentrations of repaglinide reduces the levels of Ct-PS2 fragment in N2a neuroblastoma cells. These results suggest that the interaction between DREAM and PS2 may represent a new target for modulation of PS2 processing, which could have therapeutic potential in Alzheimer’s disease (AD) treatment