Abstract
Ca2+ signals in neurons use specific temporal and spatial patterns to encode unambiguous information about crucial cellular functions. To understand the molecular basis for initiation and propagation of inositol 1,4,5-trisphosphate (InsP3)-mediated intracellular Ca2+ signals, we correlated the subcellular distribution of components of the InsP3 pathway with measurements of agonist-induced intracellular Ca2+ transients in cultured rat hippocampal neurons and pheochromocytoma cells. We found specialized domains with high levels of phosphatidylinositol-4-phosphate kinase (PIPKI) and chromogranin B (CGB), proteins acting synergistically to increase InsP3 receptor (InsP3R) activity and sensitivity. In contrast, Ca2+ pumps in the plasma membrane (PMCA) and sarco-endoplasmic reticulum as well as buffers that antagonize the rise in intracellular Ca2+ were distributed uniformly. By pharmacologically blocking phosphatidylinositol-4-kinase and PIPKI or disrupting the CGB-InsP3R interaction by transfecting an interfering polypeptide fragment, we produced major changes in the initiation site and kinetics of the Ca2+ signal. This study shows that a limited number of proteins can reassemble to form unique, spatially restricted signaling domains to generate distinctive signals in different regions of the same neuron. The finding that the subcellular location of initiation sites and protein microdomains was cell type specific will help to establish differences in spatiotemporal Ca2+ signaling in different types of neurons.
Publication types
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Comparative Study
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Calcium / metabolism*
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Calcium Channels / metabolism*
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Calcium Signaling / drug effects
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Calcium Signaling / physiology
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Calcium-Transporting ATPases / metabolism
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Carbachol / pharmacology
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Cation Transport Proteins / metabolism
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Cells, Cultured
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Cholinergic Agonists / pharmacology
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Dose-Response Relationship, Drug
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Drug Interactions
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Embryo, Mammalian
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Endoplasmic Reticulum / metabolism
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Enzyme Inhibitors / pharmacology
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Hippocampus / cytology
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Immunohistochemistry / methods
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Inositol 1,4,5-Trisphosphate Receptors
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Intracellular Space / drug effects
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Intracellular Space / metabolism*
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Methoxyhydroxyphenylglycol / analogs & derivatives
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Methoxyhydroxyphenylglycol / pharmacology
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Mitochondria / metabolism
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Nerve Growth Factor / pharmacology
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Neurons / cytology
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Neurons / drug effects
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Neurons / metabolism*
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Parvalbumins / metabolism
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Peptide Fragments / metabolism
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Plasma Membrane Calcium-Transporting ATPases
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Rats
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Receptors, Cytoplasmic and Nuclear / metabolism*
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Receptors, Metabotropic Glutamate / metabolism
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Sarcoplasmic Reticulum Calcium-Transporting ATPases
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Signal Transduction / drug effects
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Signal Transduction / physiology*
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Time Factors
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Transfection / methods
Substances
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Calcium Channels
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Cation Transport Proteins
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Cholinergic Agonists
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Enzyme Inhibitors
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Inositol 1,4,5-Trisphosphate Receptors
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Parvalbumins
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Peptide Fragments
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Receptors, Cytoplasmic and Nuclear
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Receptors, Metabotropic Glutamate
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metabotropic glutamate receptor type 1
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Methoxyhydroxyphenylglycol
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Carbachol
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Nerve Growth Factor
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Plasma Membrane Calcium-Transporting ATPases
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Sarcoplasmic Reticulum Calcium-Transporting ATPases
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Calcium-Transporting ATPases
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Calcium
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3,4-dihydroxyphenylglycol