TACC3 is a microtubule plus end-tracking protein that promotes axon elongation and also regulates microtubule plus end dynamics in multiple embryonic cell types.
Bottom Line: Using high-resolution live-imaging data on tagged +TIPs, we show that TACC3 localizes to the extreme microtubule plus end, where it lies distal to the microtubule polymerization marker EB1 and directly overlaps with the microtubule polymerase XMAP215.TACC3 also plays a role in regulating XMAP215 stability and localizing XMAP215 to microtubule plus ends.Taken together, our results implicate TACC3 as a +TIP that functions with XMAP215 to regulate microtubule plus end dynamics.
Affiliation: Department of Biology, Boston College, Chestnut Hill, MA 02467.Show MeSH
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Mentions: First, we determined that manipulating overall TACC3 protein levels had a corresponding effect on XMAP215 protein levels in whole embryo lysates. As TACC3 levels were reduced, XMAP215 levels decreased (Figure 7A), whereas adding back TACC3 mRNA to the TACC3 KD rescued XMAP215 levels (Figure 7A). Consistently, overexpressing TACC3 led to increased levels of XMAP215 (Figure 7B). Furthermore, TACC3 levels appeared depend on XMAP215 as well, because reducing XMAP215 led to a reduction in TACC3 protein (Figure 7C). Of note, overexpressing TACC3 in the XMAP215 KD background partially rescued the reduction in XMAP215 levels (Figure 7C′), consistent with a function for TACC3 in stabilizing XMAP215 protein. Alternatively, because TACC3 is a known translation regulator (Stebbins-Boaz et al., 1999), TACC3 could be increasing XMAP215 levels by increasing its protein synthesis. However, increased XMAP215 levels also had a positive effect on TACC3 levels (Figure 7D).
Affiliation: Department of Biology, Boston College, Chestnut Hill, MA 02467.