Abstract
We studied the opening mechanism of Ca(2+)-permeable channels formed with mouse transient receptor potential type 5 (mTRP5) using Xenopus oocytes. After stimulation of coexpressed muscarinic M(1) receptors with acetylcholine (ACh) in a Ca(2+)-free solution, switching to 2 mM Ca(2+)-containing solution evoked a large Cl(-) current, which reflects the opening of endogenous Ca(2+)-dependent Cl(-) channels following Ca(2+) entry through the expressed channels. The ACh-evoked response was not affected by a depletion of Ca(2+) store with thapsigargin but was inhibited by preinjection of antisense oligodeoxynucleotides (ODNs) to G(q), G(11), or both. The mTRP5 channel response was also induced by a direct activation of G proteins with injection of guanosine 5'-3-O-(thio)triphosphate (GTP gamma S). The ACh- and GTP gamma S-evoked responses were inhibited by either pretreatment with a phospholipase C inhibitor, U73122, or an inositol-1,4,5-trisphosphate (IP(3)) receptor inhibitor, xestospongin C (XeC). An activation of IP(3) receptors with injection of adenophostin A (AdA) evoked the mTRP5 channel response in a dose-dependent manner. The AdA-evoked response was not suppressed by preinjection of antisense ODNs to G(q/11) or U73122 but was suppressed by either preinjection of XeC or a peptide mimicking the IP(3) binding domain of Xenopus IP(3) receptor. These findings suggest that the activation of IP(3) receptor is essential for the opening of mTRP5 channels, and that neither G proteins, phosphoinositide metabolism, nor depletion of the Ca(2+) store directly modifies the IP(3) receptor-linked opening of mTRP5 channels.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetylcholine / metabolism
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Adenosine / analogs & derivatives*
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Adenosine / pharmacology
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Allosteric Regulation
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Animals
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Calcium / deficiency
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Calcium / metabolism
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Calcium Channel Agonists / pharmacology
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Calcium Channels / drug effects
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Calcium Channels / metabolism*
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Calcium Channels / physiology
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Cation Transport Proteins*
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Electrophysiology
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Estrenes / pharmacology
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GTP-Binding Protein alpha Subunits, Gq-G11
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GTP-Binding Proteins / metabolism*
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Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
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Heterotrimeric GTP-Binding Proteins / antagonists & inhibitors
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Heterotrimeric GTP-Binding Proteins / genetics
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Inositol 1,4,5-Trisphosphate / metabolism
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Inositol 1,4,5-Trisphosphate Receptors
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Macrocyclic Compounds
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Mice
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Nuclear Proteins / antagonists & inhibitors
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Nuclear Proteins / genetics
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Oligodeoxyribonucleotides, Antisense / pharmacology
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Oocytes / drug effects
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Oocytes / physiology
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Oxazoles / pharmacology
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Peptides / chemical synthesis
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Peptides / chemistry
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Peptides / pharmacology
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Phosphodiesterase Inhibitors / pharmacology
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Protein Serine-Threonine Kinases
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Pyrrolidinones / pharmacology
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Receptor, Muscarinic M1
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Receptors, Cytoplasmic and Nuclear / antagonists & inhibitors
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Receptors, Cytoplasmic and Nuclear / metabolism*
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Receptors, Muscarinic / metabolism
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TRPC Cation Channels
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Type C Phospholipases / antagonists & inhibitors
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Type C Phospholipases / metabolism
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Xenopus laevis
Substances
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Calcium Channel Agonists
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Calcium Channels
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Cation Transport Proteins
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Estrenes
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ITPR1 protein, human
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Inositol 1,4,5-Trisphosphate Receptors
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Macrocyclic Compounds
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Nuclear Proteins
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Oligodeoxyribonucleotides, Antisense
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Oxazoles
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Peptides
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Phosphodiesterase Inhibitors
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Pyrrolidinones
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Receptor, Muscarinic M1
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Receptors, Cytoplasmic and Nuclear
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Receptors, Muscarinic
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TRPC Cation Channels
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TRPC5 protein, human
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Trpc5 protein, mouse
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xestospongin A
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1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
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adenophostin A
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Guanosine 5'-O-(3-Thiotriphosphate)
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Inositol 1,4,5-Trisphosphate
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Protein Serine-Threonine Kinases
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STK19 protein, human
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Type C Phospholipases
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GTP-Binding Proteins
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GTP-Binding Protein alpha Subunits, Gq-G11
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Heterotrimeric GTP-Binding Proteins
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Adenosine
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Acetylcholine
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Calcium