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Spatiotemporal dynamics of transport in the squid giant axon : competition between cargo motor receptors, JIP-1, APP-C, and negative charge

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/17453

Spatiotemporal dynamics of transport in the squid giant axon : competition between cargo motor receptors, JIP-1, APP-C, and negative charge

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Title: Spatiotemporal dynamics of transport in the squid giant axon : competition between cargo motor receptors, JIP-1, APP-C, and negative charge
Author: Seamster, Pamela
Advisor(s): Bearer, Elaine
Committee Member(s): Bearer, Elaine
Koch, Steve
Lidke, Diane
Shuttleworth, Bill
Steinberg, Stan
Department: University of New Mexico. Biomedical Sciences Graduate Program
Subject: Axonal Transport, JIP-1, APP-C
LC Subject(s): Axonal transport.
Neurons--Physiology.
Squids--Nervous system.
Squids--Physiology.
Kinesin.
Degree Level: Masters
Abstract: Transport of membrane-­bound organelles is critical to neuronal cell function yet mechanisms hitching vesicles to transport machinery remain elusive. Here we test whether jun-­‐kinase interacting protein (JIP-­‐1), a peripheral membrane scaffolding protein that binds kinesin light chain, is sufficient to mediate cargo transport in axons and study its competition with amyloid precursor protein cytoplasmic domain (APP-­‐C) and negative charge, also known motor receptors. Fluorescent beads (100 nm diameter) exhibit sequence-­‐specific fast anterograde transport (0.46μm/s instantaneous velocity) in the squid giant axon when conjugated to a 14-­‐ amino acid synthetic peptide derived from the carboxyl terminus of JIP-­‐1. JIP-­‐1-­‐ beads have statistically significant faster velocities, longer run lengths, and fewer pauses of shorter durations than APP-­‐C or negatively charged beads by cumulative probability analyses of thousands of motile beads compared by a nonparametric K-­‐S test, with a P=0.004. In competition experiments negatively charged beads gradually cease moving when co-­‐injected with either APP-­‐C or JIP-­‐1 beads, which sustain 90% motility. Co-­‐injection of APP-­‐C and JIP-­‐1 beads decreases each bead's propensity to move initially. At later time points JIP-­‐1-­‐beads recover frequency without further decreasing APP-­‐C moves, suggesting JIP-­‐1 recruits motors from a cryptic pool not accessible to APP-­‐C. Soluble JIP-­‐1 peptide inhibits JIP-­‐1 beads, with smaller effects on APP-­‐C and negatively charged beads. Thus the hierarchy for recruitment of transport machinery is JIP>APP>negative charge. Organelle transport may in part be regulated through the numbers, types and affinities of motor receptors displayed on each organelle's cytoplasmic surface.
Graduation Date: December 2011
URI: http://hdl.handle.net/1928/17453


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