PKA activation bypasses the requirement for UNC-31 in the docking of dense core vesicles from C. elegans neurons

Neuron. 2007 Nov 21;56(4):657-69. doi: 10.1016/j.neuron.2007.09.015.


The nematode C. elegans provides a powerful model system for exploring the molecular basis of synaptogenesis and neurotransmission. However, the lack of direct functional assays of release processes has largely prevented an in depth understanding of the mechanism of vesicular exocytosis and endocytosis in C. elegans. We address this technical limitation by developing direct electrophysiological assays, including membrane capacitance and amperometry measurements, in primary cultured C. elegans neurons. In addition, we have succeeded in monitoring the docking and fusion of single dense core vesicles (DCVs) employing total internal reflection fluorescence microscopy. With these approaches and mutant perturbation analysis, we provide direct evidence that UNC-31 is required for the docking of DCVs at the plasma membrane. Interestingly, the defect in DCV docking caused by UNC-31 mutation can be fully rescued by PKA activation. We also demonstrate that UNC-31 is required for UNC-13-mediated augmentation of DCV exocytosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans / ultrastructure
  • Caenorhabditis elegans Proteins / metabolism*
  • Calcium-Binding Proteins / metabolism*
  • Carrier Proteins
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Enzyme Activation / physiology
  • Exocytosis / physiology
  • Green Fluorescent Proteins
  • Intracellular Membranes / metabolism
  • Membrane Fusion / physiology
  • Nervous System / metabolism*
  • Nervous System / ultrastructure
  • Neurons / metabolism*
  • Neurons / ultrastructure
  • Neurosecretion / physiology
  • Neurotransmitter Agents / metabolism
  • Secretory Vesicles / metabolism*
  • Secretory Vesicles / ultrastructure
  • Serotonin / metabolism
  • Synaptic Membranes / metabolism
  • Synaptic Transmission / physiology


  • Caenorhabditis elegans Proteins
  • Calcium-Binding Proteins
  • Carrier Proteins
  • Neurotransmitter Agents
  • UNC-31 protein, C elegans
  • phorbol ester binding protein
  • Green Fluorescent Proteins
  • Serotonin
  • Cyclic AMP-Dependent Protein Kinases