CLIP-170-Dependent Capture of Membrane Organelles by Microtubules Initiates Minus-End Directed Transport

Abstract

Summary Cytoplasmic microtubules (MTs) continuously grow and shorten at free plus ends. During mitosis, this dynamic behavior allows MTs to capture chromosomes to initiate their movement to the spindle poles, however, the role of MT dynamics in capturing organelles for transport in interphase cells has not been demonstrated. Here we used Xenopus melanophores to test the hypothesis that MT dynamics significantly contribute to the efficiency of MT minus-end directed transport of membrane organelles. We demonstrated that initiation of transport of membrane-bounded melanosomes (pigment granules) to the cell center involves their capture by MT plus ends, and that inhibition of MT dynamics or loss of the MT plus-end tracking protein CLIP-170 from MT tips dramatically inhibits pigment aggregation. We conclude that MT dynamics are required for the initiation of MT transport of membrane organelles in interphase cells, and that +TIPs such as CLIP-170 play an important role in this process.

The microtubule plus-end localization ofAspergillusdynein is important for dynein–early-endosome interaction but not for dynein ATPase activation

“…In fungi and higher eukaryotic cells, dynein and kinesin might bind to the same vesicle or to each other directly, and vesicles along a microtubule often undergo bidirectional movement, which could be achieved by tug-of-war between kinesin and dynein or by other regulatory strategies (Ma and Chisholm, 2002;Ligon et al, 2004;Ha et al, 2008;Muller et al, 2008;Shubeita et al, 2008;Soppina et al, 2009;Ally et al, 2009;Hendricks et al, 2010). Nevertheless, the dynamic microtubule plus-end represents a cargo-loading site not only in fungi but also in higher eukaryotic cells (Vaughan et al, 2002;Lenz et al, 2006;Lomakin et al, 2009). Moreover, plus-end localization of dynein and its regulators such as dynactin and LIS1 has been found not only in fungi but also in mammalian cells (Valetti et al, 1999;Vaughan et al, 1999;Vaughan et al, 2002;Han et al, 2001;Ma and Chisholm, 2002;Coquelle et al, 2002;Lee et al, 2003;Sheeman et al, 2003;Lenz et al, 2006;Vogel et al, 2009).…”

Microtubule +TIPs at a glance

“…Dam1, CLIP-170, CLASPs, dynein (for a review, see Maiato et al, 2004) -and participate in the extension of endoplasmic reticulum tubules together with growing microtubule ends (STIM1) (Grigoriev et al, 2008). +TIPs also contribute to loading cargo for minus-enddirected microtubule transport (dynactin, CLIP-170) (Lomakin et al, 2009;Vaughan et al, 2002) and in transporting microtubule ends along other microtubules to promote organization of specialized microtubule arrays, such as mitotic spindles (Goshima et al, 2005) and bipolar microtubule bundles in fission yeast (Janson et al, 2007).…”

Phosphorylation of CLIP-170 by LRRK1 regulates EGFR trafficking by promoting recruitment of p150Glued to MT plus-ends

“…Because +TIPs have been proposed to promote the initial interaction of membranous organelles with microtubules (Pierre et al, 1992;Vaughan et al, 2002), Glued , localized at the plus ends, have been implicated in the initiation of dynein-mediated retrograde transport along microtubules (Vaughan et al, 1999). Consistent with this, CLIP-170 has been shown recently to be involved in the capture of melanosomes for minus-end-directed transport along microtubules in Xenopus melanophores (Lomakin et al, 2009). In addition, plus-end-associated p150…”

“…What is the target of LRRK1 phosphorylation that mediates this process? In a previous screen for LRRK1-binding proteins, we identified CLIP-170, a protein that is involved in dynein-mediated processes (Galjart, 2005;Wu et al, 2006;Akhmanova and Steinmetz, 2008;Lomakin et al, 2009;Hanafusa et al, 2011;Moughamian et al, 2013). We therefore examined the possibility that LRRK1 might regulate the motility of EGFRcontaining endosomes by phosphorylating CLIP-170.…”