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Neural Dev February 25, 2015; 10 3.

Differential requirement of F-actin and microtubule cytoskeleton in cue-induced local protein synthesis in axonal growth cones.

Piper M , Lee AC , van Horck FP , McNeilly H , Lu TB , Harris WA , Holt CE .

BACKGROUND: Local protein synthesis (LPS) via receptor-mediated signaling plays a role in the directional responses of axons to extrinsic cues. An intact cytoskeleton is critical to enact these responses, but it is not known whether the two major cytoskeletal elements, F-actin and microtubules, have any roles in regulating axonal protein synthesis. RESULTS: Here, we show that pharmacological disruption of either microtubules or actin filaments in growth cones blocks netrin-1-induced de novo synthesis of proteins, as measured by metabolic incorporation of labeled amino acids, implicating both elements in axonal synthesis. However, comparative analysis of the activated translation initiation regulator, eIF4E-BP1, revealed a striking difference in the point of action of the two elements: actin disruption completely inhibited netrin-1-induced eIF4E-BP1 phosphorylation while microtubule disruption had no effect. An intact F-actin, but not microtubule, cytoskeleton was also required for netrin-1-induced activation of the PI3K/Akt/mTOR pathway, upstream of translation initiation. Downstream of translation initiation, microtubules were required for netrin-1-induced activation of eukaryotic elongation factor 2 kinase (eEF2K) and eEF2. CONCLUSIONS: Taken together, our results show that while actin and microtubules are both crucial for cue-induced axonal protein synthesis, they serve distinct roles with F-actin being required for the initiation of translation and microtubules acting later at the elongation step.

PubMed ID: 25886013
PMC ID: PMC4350973
Article link: Neural Dev
Grant support: [+]

Species referenced: Xenopus
Genes referenced: actl6a akt1 ctrl eef2.2 eif4e mtor ntn1 pik3ca

Article Images: [+] show captions
References [+] :
Akiyama, Phosphatidylinositol 3-kinase facilitates microtubule-dependent membrane transport for neuronal growth cone guidance. 2010, Pubmed