Trk activation of the ERK1/2 kinase pathway stimulates intermediate chain phosphorylation and recruits cytoplasmic dynein to signaling endosomes for retrograde axonal transport.
Trk activation of the ERK1/2 kinase pathway stimulates intermediate chain phosphorylation and recruits cytoplasmic dynein to signaling endosomes for retrograde axonal transport.
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DOI：
10.1523/jneurosci.5599-11.2012
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发表时间：
2012-10-31
期刊：
影响因子：
--
通讯作者：
Pfister KK
中科院分区：
文献类型：
--
作者：
Mitchell DJ;Blasier KR;Jeffery ED;Ross MW;Pullikuth AK;Suo D;Park J;Smiley WR;Lo KW;Shabanowitz J;Deppmann CD;Trinidad JC;Hunt DF;Catling AD;Pfister KK
The retrograde transport of Trk containing endosomes from the axon to the cell body by cytoplasmic dynein is necessary for axonal and neuronal survival. We investigated the recruitment of dynein to signaling endosomes in rat embryonic neurons and PC12 cells. We identified a novel phospho-serine on the dynein intermediate chains (IC) and we observed a time-dependent neurotrophin-stimulated increase in intermediate chain phosphorylation on this site in both cell types. Pharmacological studies, over-expression of constitutively active MEK, and an in vitro assay with recombinant proteins demonstrated that the intermediate chains are phosphorylated by the MAP kinase ERK1/2, extracellular-signal-regulated kinase, a major downstream effector of Trk. Live cell imaging with fluorescently-tagged IC mutants demonstrated that the dephospho-mimic mutants had significantly reduced co-localization with Trk and Rab7, but not a mitochondrial marker. The phosphorylated intermediate chains were enriched on immuno-affinity purified Trk containing organelles. Inhibition of ERK reduced the amount of phospho-IC and the total amount of dynein that co-purified with the signaling endosomes. In addition, inhibition of ERK1/2 reduced the motility of Rab7 and TrkB containing endosomes and the extent of their co-localization with dynein in axons. NGF-dependent survival of sympathetic neurons was significantly reduced by the over-expression of the dephospho-mimic mutant IC-1B-S80A, but not WT IC-1B, further demonstrating the functional significance of phosphorylation on this site. These results demonstrate that neurotrophin binding to Trk initiates the recruitment of cytoplasmic dynein to signaling endosomes through ERK1/2 phosphorylation of intermediate chains for their subsequent retrograde transport in axons.
