TIP maker and TIP marker; EB1 as a master controller of microtubule plus ends

Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
The Journal of Cell Biology (Impact Factor: 9.69). 11/2005; 171(2):197-200. DOI: 10.1083/jcb.200509150
Source: PubMed

ABSTRACT The EB1 protein is a member of the exciting and enigmatic family of microtubule (MT) tip-tracking proteins. EB1 acts as an exquisite marker of dynamic MT plus ends in some cases, whereas in others EB1 is thought to directly dictate the behavior of the plus ends. How EB1 differentiates between these two roles remains unclear; however, a growing list of interactions between EB1 and other MT binding proteins suggests there may be a single mechanism. Adding another layer of complexity to these interactions, two studies published in this issue implicate EB1 in cross-talk between mitotic MTs and between MTs and actin filaments (Goshima et al., p. 229; Wu et al., p. 201). These results raise the possibility that EB1 is a central player in MT-based transport, and that the activity of MT-binding proteins depends on their ability or inability to interact with EB1.

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Available from: Kevin Vaughan, Jun 22, 2015
    • "EB1 localizes to the microtubule plus end, at least in part, by recognizing the nucleotide state of tubulin in the microtubule lattice [Zanic et al., 2009; Maurer et al., 2011, 2012]. There is evidence that the EB1 N-terminal domain binds to the microtubule preferentially through interactions with the GTP-rich cap, whereas the C-terminal domain acts as a microtubule tip localization signal and enables binding to many other 1TIPs [Hayashi and Ikura, 2003; Vaughan, 2005; Honnappa et al., 2009; Zanic et al., 2009]. EB1 impacts numerous biological functions including the suppression of microtubule dynamic instability [Manna et al., 2008], regulation of microtubule dynamics and chromosomal stability [Leterrier et al., 2011], as well as maintenance of cell polarity through activation of protein kinase C [Schober et al., 2012]. "
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    ABSTRACT: Using the nonhydrolyzable GTP analog GMPCPP and the slowly hydrolyzable GTPγS, we polymerize microtubules that recapitulate the end binding behavior of the plus end interacting protein (+TIP) EB1 along their entire length, and use these to investigate the impact of EB1 binding on microtubule mechanics. To measure the stiffness of single filaments, we use a spectral analysis method to determine the ensemble of shapes adopted by a freely diffusing, fluorescently-labeled microtubule. We find that the presence of EB1 can stiffen microtubules in a manner that depends on the hydrolysis state of the tubulin-bound nucleotide, as well as the presence of the small-molecule stabilizer paclitaxel. We find that the magnitude of the EB1-induced stiffening is not proportional to the EB1-microtubule binding affinity, suggesting that the stiffening effect does not arise purely from an increase in the total amount of bound EB1. Additionally, we find that EB1 binds cooperatively to microtubules in manner that depends on tubulin-bound nucleotide state. © 2014 Wiley Periodicals, Inc.
    Cytoskeleton 09/2014; 71(9). DOI:10.1002/cm.21190 · 3.01 Impact Factor
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    • "A large number of +TIPs have been identified, and some of them are found in widely diverged species, suggesting that they regulate a basic, evolutionarily conserved component of the dynamic instability process (Bisgrove et al., 2004). For example, Arabidopsis has functional homologs of end binding protein 1 (EB1) and cytoplasmic linker-associated protein 1 (CLASP1), which were first identified in human cells (Chan et al., 2003; Mathur et al., 2003; Galjart, 2005; Vaughan, 2005; Ambrose et al., 2007; Kirik et al., 2007; Bisgrove et al., 2008; Komaki et al., 2010). Other +TIPs, such as SPIRAL1 (SPR1), are found only in plants (Nakajima et al., 2004, 2006; Sedbrook et al., 2004). "
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    ABSTRACT: The dynamic instability of cortical microtubules (MTs) (i.e., their ability to rapidly alternate between phases of growth and shrinkage) plays an essential role in plant growth and development. In addition, recent studies have revealed a pivotal role for dynamic instability in the response to salt stress conditions. The salt stress response includes a rapid depolymerization of MTs followed by the formation of a new MT network that is believed to be better suited for surviving high salinity. Although this initial depolymerization response is essential for the adaptation to salt stress, the underlying molecular mechanism has remained largely unknown. Here, we show that the MT-associated protein SPIRAL1 (SPR1) plays a key role in salt stress-induced MT disassembly. SPR1, a microtubule stabilizing protein, is degraded by the 26S proteasome, and its degradation rate is accelerated in response to high salinity. We show that accelerated SPR1 degradation is required for a fast MT disassembly response to salt stress and for salt stress tolerance.
    The Plant Cell 09/2011; 23(9):3412-27. DOI:10.1105/tpc.111.089920 · 9.58 Impact Factor
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    • "eb1 triple-mutants exhibit only mild phenotypes associated with root responses to touch and gravity (Bisgrove et al. 2008). EB1 proteins associate with plus ends of MTs where they regulate polymerization rates (Tirnauer et al. 2004), they serve as integrators of protein complex assembly at MT plus ends (Vaughan 2005), and they facilitate the delivery of proteins to specific sites at the cortex (Canman et al. 2003). To date, the significance of EB1 localization at the PPB is not resolved, although reports on a subtype of EB1c in Arabidopsis suggest some function in spindle formation (Komaki et al. 2010). "
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    ABSTRACT: Coordinated cell divisions and cell expansion are the key processes that command growth in all organisms. The orientation of cell divisions and the direction of cell expansion are critical for normal development. Symmetric divisions contribute to proliferation and growth, while asymmetric divisions initiate pattern formation and differentiation. In plants these processes are of particular importance since their cells are encased in cellulosic walls that determine their shape and lock their position within tissues and organs. Several recent studies have analyzed the relationship between cell shape and patterns of symmetric cell division in diverse organisms and employed biophysical and mathematical considerations to develop computer simulations that have allowed accurate prediction of cell division patterns. From these studies, a picture emerges that diverse biological systems follow simple universal rules of geometry to select their division planes and that the microtubule cytoskeleton takes a major part in sensing the geometric information and translates this information into a specific division outcome. In plant cells, the division plane is selected before mitosis, and spatial information of the division plane is preserved throughout division by the presence of reference molecules at a distinct region of the plasma membrane, the cortical division zone. The recruitment of these division zone markers occurs multiple times by several mechanisms, suggesting that the cortical division zone is a highly dynamic region.
    Protoplasma 05/2011; 249(2):239-53. DOI:10.1007/s00709-011-0289-y · 3.17 Impact Factor
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