EB1 reveals mobile microtubule nucleation sites in Arabidopsis

Chan, Jordi; Calder, Grant; Doonan, John H.; Lloyd, Clive

doi:10.1038/ncb1057

Cited by 215 publications

(266 citation statements)

References 30 publications

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“…Using an in vitro model that provides good access to the cortex combined with the hook decoration of MTs, Tian et al (2004) demonstrated that the MTs in the cortical array are predominantly oriented in a mixed polarity. This organization is in agreement with opposing growth directionalities of green fluorescent protein (GFP)-labeled MTs observed in the cortical array (Chan et al, 2003;Shaw et al, 2003). In contrast, Dixit et al (2006) reported that ϳ70% of CMTs have the same polarity and that this polar arrangement of CMTs occurs simultaneously with the coalignment of CMTs.…”

Section: Introductionsupporting

confidence: 64%

Two Microtubule-associated Proteins of Arabidopsis MAP65s Promote Antiparallel Microtubule Bundling

Gaillard

Neumann

Damme

et al. 2008

MBoC

111

115

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The Arabidopsis MAP65s are a protein family with similarity to the microtubule-associated proteins PRC1/Ase1p that accumulate in the spindle midzone during late anaphase in mammals and yeast, respectively. Here we investigate the molecular and functional properties of AtMAP65-5 and improve our understanding of AtMAP65-1 properties. We demonstrate that, in vitro, both proteins promote the formation of a planar network of antiparallel microtubules. In vivo, we show that AtMAP65-5 selectively binds the preprophase band and the prophase spindle microtubule during prophase, whereas AtMAP65-1-GFP selectively binds the preprophase band but does not accumulate at the prophase spindle microtubules that coexists within the same cell. At later stages of mitosis, AtMAP65-1 and AtMAP65-5 differentially label the late spindle and phragmoplast. We present evidence for a mode of action for both proteins that involves the binding of monomeric units to microtubules that "zipper up" antiparallel arranged microtubules through the homodimerization of the N-terminal halves when adjacent microtubules encounter. INTRODUCTIONIn higher plant cells, interphase microtubules occur predominantly at the cell cortex as ordered bundles in close association with the plasma membrane. These so-called cortical microtubules (CMTs) play crucial roles in cell morphogenesis (Wasteneys and Fujita, 2006). In rapidly elongating cells, CMTs are linear bundles that are usually transversely oriented relative to the longest cell axis. When cell expansion slows down, the transverse organization is lost and CMTs become oblique (Lloyd, 1994;Dixit and Cyr, 2004). CMTs are highly dynamic and show higher (de)-polymerization rates than interphase mammalian microtubules (Shaw et al., 2003;Dixit et al., 2006). In contrast to animal and yeast microtubules (MTs), CMTs do not emanate from a well-defined nucleating center. Instead, the MT nucleation activity in interphase plant cells mostly occurs at dispersed sites along pre-existing MTs at the cell's cortex (Murata et al., 2005) in a ␥-tubulin-dependent manner (Pastuglia et al., 2006). This MT-dependent nucleation results in branching patterns of CMTs (Murata et al., 2005) that are subsequently resolved into coaligned CMTs. After nucleation, the majority of the MTs are released from their nucleation site, move in the cell cortex by a hybrid treadmilling mechanism leading to polymer interactions (Shaw et al., 2003), and are incorporated into bundles (Dixit and Cyr, 2004). Significantly, the CMT bundles are not anchored and consequently both MT ends are dynamic. Thus, the ordered patterns of CMT arrays are not correlated with the patterns of the CMT nucleation sites (Dixit et al., 2006) and depend on a yet-to-be-discovered mechanism.To accommodate for the transverse network observed in expanding cells, CMTs form bundles. How these bundles are organized is not clear, and for instance, the polarity of CMTs within bundles is not yet solved. Using an in vitro model that provides good access to the cortex combined with the hoo...

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Section: Introductionsupporting

confidence: 64%

Two Microtubule-associated Proteins of Arabidopsis MAP65s Promote Antiparallel Microtubule Bundling

Gaillard

Neumann

Damme

et al. 2008

MBoC

111

115

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“…Expression of AtEB1a:GFP has been reported to reveal the dynamic behavior of microtubules upon transgenic or transient expression in Arabidopsis, tobacco, and N. benthamiana cells (Chan et al, 2003;Mathur et al, 2003;Van Damme et al, 2004;Dixit et al, 2006;Brandner et al, 2008). However, transient coexpression of ABD2:GFP had no significant effect on microtubule polymerization (data not shown), indicating that microtubules are not affected by the inhibition of membrane movements induced by transient ABD2:GFP expression.…”

Section: Labeling Of Actin Filaments With Abd:gfpmentioning

confidence: 81%

“…To investigate whether ABD2:GFP expression may also affect microtubule dynamics, we expressed the Arabidopsis AtEB1a fused to GFP (AtEB1a:GFP; Chan et al, 2003). Expression of AtEB1a:GFP has been reported to reveal the dynamic behavior of microtubules upon transgenic or transient expression in Arabidopsis, tobacco, and N. benthamiana cells (Chan et al, 2003;Mathur et al, 2003;Van Damme et al, 2004;Dixit et al, 2006;Brandner et al, 2008).…”

Section: Labeling Of Actin Filaments With Abd:gfpmentioning

confidence: 99%

Inhibition of Tobacco Mosaic Virus Movement by Expression of an Actin-Binding Protein

et al. 2009

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The tobacco mosaic virus (TMV) movement protein (MP) required for the cell-to-cell spread of viral RNA interacts with the endoplasmic reticulum (ER) as well as with the cytoskeleton during infection. Whereas associations of MP with ER and microtubules have been intensely investigated, research on the role of actin has been rather scarce. We demonstrate that Nicotiana benthamiana plants transgenic for the actin-binding domain 2 of Arabidopsis (Arabidopsis thaliana) fimbrin (AtFIM1) fused to green fluorescent protein (ABD2:GFP) exhibit a dynamic ABD2:GFP-labeled actin cytoskeleton and myosin-dependent Golgi trafficking. These plants also support the movement of TMV. In contrast, both myosin-dependent Golgi trafficking and TMV movement are dominantly inhibited when ABD2:GFP is expressed transiently. Inhibition is mediated through binding of ABD2:GFP to actin filaments, since TMV movement is restored upon disruption of the ABD2:GFP-labeled actin network with latrunculin B. Latrunculin B shows no significant effect on the spread of TMV infection in either wild-type plants or ABD2:GFP transgenic plants under our treatment conditions. We did not observe any binding of MP along the length of actin filaments.Collectively, these observations demonstrate that TMV movement does not require an intact actomyosin system. Nevertheless, actin-binding proteins appear to have the potential to exert control over TMV movement through the inhibition of myosinassociated protein trafficking along the ER membrane.The mechanism by which plant viruses move from cell to cell and systemically to cause systemic infection has been the subject of intense studies (for review, see

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“…New MTs appear both in association with existing MTs and in areas devoid of MTs. Evidence for MT nucleation at cortical sites also comes from the observation that SPC98 (a component of the ␥-TuRC) and EB1 associate with newly formed MTs in the periphery of plant cells (Chan et al, 2003;Erhardt et al, 2002). MT polymerization sites marked by GFP-tagged EB1 associate with and dissociate from the cortex, which suggests that nucleating material constantly redistributes.…”

Section: Generation Of Noncentrosomal Mtsmentioning

confidence: 99%

Generation of noncentrosomal microtubule arrays

Bartolini

Gundersen

2006

Journal of Cell Science

226

219

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In most proliferating and migrating animal cells, the centrosome is the main site for microtubule (MT) nucleation and anchoring, leading to the formation of radial MT arrays in which MT minus ends are anchored at the centrosomes and plus ends extend to the cell periphery. By contrast, in most differentiated animal cell types, including muscle, epithelial and neuronal cells, as well as most fungi and vascular plant cells, MTs are arranged in noncentrosomal arrays that are non-radial. Recent studies suggest that these noncentrosomal MT arrays are generated by a three step process. The initial step involves formation of noncentrosomal MTs by distinct mechanisms depending on cell type: release from the centrosome, catalyzed nucleation at noncentrosomal sites or breakage of pre-existing MTs. The second step involves transport by MT motor proteins or treadmilling to sites of assembly. In the final step, the noncentrosomal MTs are rearranged into cell-type-specific arrays by bundling and/or capture at cortical sites, during which MTs acquire stability. Despite their relative stability, the final noncentrosomal MT arrays may still exhibit dynamic properties and in many cases can be remodeled.

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EB1 reveals mobile microtubule nucleation sites in Arabidopsis

Cited by 215 publications

References 30 publications

Two Microtubule-associated Proteins of Arabidopsis MAP65s Promote Antiparallel Microtubule Bundling

Two Microtubule-associated Proteins of Arabidopsis MAP65s Promote Antiparallel Microtubule Bundling

Inhibition of Tobacco Mosaic Virus Movement by Expression of an Actin-Binding Protein

Generation of noncentrosomal microtubule arrays

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