A change in the selective translocation of the Kinesin-1 motor domain marks the initial specification of the axon.
We used the accumulation of constitutively active kinesin motor domains as a measure of where kinesins translocate in developing neurons. Throughout development, truncated Kinesin-3 accumulates at the tips of all neurites. In contrast, Kinesin-1 selectively accumulates in only a subset of neurites. Before neurons become polarized, truncated Kinesin-1 accumulates transiently in a single neurite. Coincident with axon specification, truncated Kinesin-1 accumulates only in the emerging axon and no longer appears in any other neurite. The translocation of Kinesin-1 along a biochemically distinct track leading to the nascent axon could ensure the selective delivery of Kinesin-1 cargoes to the axon and hence contribute to its molecular specification. Imaging YFP-tagged truncated Kinesin-1 provides the most precise definition to date of when neuronal polarity first emerges and allows visualization of the molecular differentiation of the axon in real time.
Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, Portland, Oregon 97239, USA.
Catherine
C
Jacobson
Bruce
B
Schnapp
Gary A
GA
Banker
D000818:Animals; D001370:Axonal Transport / Q000502:physiology*; D001369:Axons / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D006624:Hippocampus / Q000166:cytology; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008164:Luminescent Proteins; D020409:Molecular Motor Proteins / Q000502:physiology*; D016501:Neurites / Q000378:metabolism; D009474:Neurons / Q000166:cytology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D013997:Time Factors; D014162:Transfection / Q000379:methods
D015415:Biomarkers; D008164:Luminescent Proteins; D020409:Molecular Motor Proteins; D016547:Kinesins