Dense core vesicle dynamics in Caenorhabditis elegans neurons and the role of kinesin UNC-104.
We have developed a model system in Caenorhabditis elegans to perform genetic and molecular analysis of peptidergic neurotransmission using green fluorescent protein (GFP)-tagged IDA-1. IDA-1 represents the nematode ortholog of the transmembrane proteins ICA512 and phogrin that are localized to dense core secretory vesicles (DCVs) of mammalian neuroendocrine tissues. IDA-1::GFP was expressed in a small subset of neurons and present in both axonal and dendritic extensions, where it was localized to small mobile vesicular elements that at the ultrastructural level corresponded to 50 nm electron-dense objects in the neuronal processes. The post-translational processing of IDA-1::GFP in transgenic worms was dependent on the neuropeptide proprotein convertase EGL-3, indicating that the protein was efficiently targeted to the peptidergic secretory pathway. Time-lapse epifluorescence microscopy of IDA-1::GFP revealed that DCVs moved in a saltatory and bidirectional manner. DCV velocity profiles exhibited multiple distinct peaks, suggesting the participation of multiple molecular motors with distinct properties. Differences between velocity profiles for axonal and dendritic processes furthermore suggested a polarized distribution of the molecular transport machinery. Study of a number of candidate mutants identified the kinesin UNC-104 (KIF1A) as the microtubule motor that is specifically responsible for anterograde axonal transport of DCVs at velocities of 1.6 microm/s-2.7 microm/s.
Zahn
Tobias R
TR
Barbara Davis Center for Childhood Diabetes and Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
Angleson
Joseph K
JK
MacMorris
Margaret A
MA
Domke
Erin
E
Hutton
John F
JF
Schwartz
Cindi
C
Hutton
John C
JC
D000818:Animals; D030801:Animals, Genetically Modified; D001324:Autoantigens; D001369:Axons / Q000378:metabolism; D001692:Biological Transport; D015153:Blotting, Western; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008954:Models, Biological; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism / Q000494:pharmacology; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D013997:Time Factors; D019076:Transgenes
D001324:Autoantigens; D029742:Caenorhabditis elegans Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C423186:UNC-104 protein, C elegans; D049452:Green Fluorescent Proteins; C516862:PTPRN protein, human; C102889:PTPRN2 protein, human; D017027:Protein Tyrosine Phosphatases; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D016547:Kinesins