Dominant role of lipid rafts L-type calcium channel in activity-dependent potentiation of large dense-core vesicle exocytosis

J Neurochem. 2009 Jul;110(2):520-9. doi: 10.1111/j.1471-4159.2009.06148.x. Epub 2009 May 5.

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels, L-Type / physiology*
  • Cattle
  • Chromaffin Cells / cytology
  • Chromaffin Cells / drug effects
  • Chromaffin Cells / metabolism
  • Drug Synergism
  • Exocytosis / drug effects
  • Exocytosis / physiology*
  • Ion Channel Gating / drug effects
  • Ion Channel Gating / physiology
  • Membrane Microdomains / drug effects
  • Membrane Microdomains / physiology*
  • Secretory Vesicles / metabolism*

Substances

  • Calcium Channel Blockers
  • Calcium Channels, L-Type