title: Neuronal calcium sensor-1 facilitates neuronal exocytosis through phosphatidylinositol 4-kinase.
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.
authors.affiliation: Department of Chemistry, Texas Christian University, Fort Worth, Texas, USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zheng
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Bobich
authors.forename: Jolanta
authors.initials: J
authors.lastname: Vidugiriene
authors.forename: Susanne C
authors.initials: SC
authors.lastname: McFadden
authors.forename: Fairwell
authors.initials: F
authors.lastname: Thomas
authors.forename: John
authors.initials: J
authors.lastname: Roder
authors.forename: Andreas
authors.initials: A
authors.lastname: Jeromin
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology*; D002540:Cerebral Cortex / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D005260:Female; D008297:Male; D009411:Nerve Endings / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology*; D051580:Neuronal Calcium-Sensor Proteins; D009474:Neurons / Q000737:chemistry*; D009479:Neuropeptides; D018377:Neurotransmitter Agents / Q000737:chemistry / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000096:biosynthesis / Q000737:chemistry; D018129:Phosphatidylinositol Phosphates / Q000096:biosynthesis / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism
chemical_list: D000906:Antibodies; D002135:Calcium-Binding Proteins; D009419:Nerve Tissue Proteins; D051580:Neuronal Calcium-Sensor Proteins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D010446:Peptide Fragments; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; C101464:frequenin calcium sensor proteins; C037178:phosphatidylinositol 4-phosphate; D019870:1-Phosphatidylinositol 4-Kinase; D002118:Calcium