title: Dominant role of lipid rafts L-type calcium channel in activity-dependent potentiation of large dense-core vesicle exocytosis.
abstract: Calcium influx triggers exocytosis by promoting vesicle fusion with the plasma membrane. However, different subtypes of voltage-gated calcium channel (VGCC) have distinct roles in exocytosis. We previously reported that repetitive stimulation induces activity-dependent potentiation (ADP) which represents the increase of neurotransmitter release. Here, we show that L-type VGCC have a dominant role in ADP of large dense-core vesicle (LDCV) exocytosis. Repetitive stimulation activating VGCC can induce ADP, whereas activation of bradykinin (BK) G protein-coupled receptors or purinergic P2X cation channels can not. L-type VGCC has the dominant role in ADP of LDCV exocytosis by regulating Protein Kinase C (PKC)-epsilon translocation and phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS), a target molecule of PKC-epsilon. We provide evidence that L-type VGCC, PKC-epsilon, and MARCKS, but not Q-type VGCC, are selectively located in lipid rafts. Also, PKC-epsilon translocation induced by L-type VGCC activation occurs in lipid rafts. Disruption of lipid rafts abolishes ADP of LDCV exocytosis and changes the fusion pore kinetics without affecting the first stimulation-induced exocytosis, showing that lipid rafts are involved in the potentiation process. Taken together, we suggest that L-type VGCC in lipid rafts selectively mediates ADP of LDCV exocytosis by regulating PKC-epsilon translocation and MARCKS phosphorylation.
authors.affiliation: Department of Life Science, Pohang University of Science and Technology, Korea.
authors.forename: Yongsoo
authors.initials: Y
authors.lastname: Park
authors.forename: Kyong-Tai
authors.initials: KT
authors.lastname: Kim
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000502:physiology*; D002417:Cattle; D019439:Chromaffin Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004357:Drug Synergism; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D021962:Membrane Microdomains / Q000187:drug effects / Q000502:physiology*; D022142:Secretory Vesicles / Q000378:metabolism*
chemical_list: D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type