<i>Arabidopsis</i> Microtubule-Destabilizing Protein 25 Functions in Pollen Tube Growth by Severing Actin Filaments

Qin, Tao; Liu, Xiaomin; Li, Jiejie; Sun, Jingbo; Song, Lei; Mao, Tonglin

doi:10.1105/tpc.113.119768

Cited by 68 publications

(84 citation statements)

References 54 publications

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“…Arabidopsis augmin is composed of six subunits with homologs in animals and two plant-specific subunits that represent functional homologs of the animal coiled-coil protein AUG7 (At5g17620) and the MT-binding subunit AUG8 (At4g30710) (Hotta et al, 2012). Although augmin was initially identified as a gTuRC regulator that functions within the spindle of animal cells (Goshima et al, 2008), it is required for the MT-dependent MT nucleation that occurs in the spindle (Ho et al, 2011b), the phragmoplast (Ho et al, 2011b), and the interphase cortical MT array (Liu et al, 2014) of Arabidopsis cells.…”

Section: Mt Nucleationmentioning

confidence: 99%

Microtubules in Plants

Hashimoto

2015

The Arabidopsis Book

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Microtubules (MTs) are highly conserved polar polymers that are key elements of the eukaryotic cytoskeleton and are essential for various cell functions. αβ-tubulin, a heterodimer containing one structural GTP and one hydrolysable and exchangeable GTP, is the building block of MTs and is formed by the sequential action of several molecular chaperones. GTP hydrolysis in the MT lattice is mechanistically coupled with MT growth, thus giving MTs a metastable and dynamic nature. MTs adopt several distinct higher-order organizations that function in cell division and cell morphogenesis. Small molecular weight compounds that bind tubulin are used as herbicides and as research tools to investigate MT functions in plant cells. The de novo formation of MTs in cells requires conserved γ-tubulin-containing complexes and targeting/activating regulatory proteins that contribute to the geometry of MT arrays. Various MT regulators and tubulin modifications control the dynamics and organization of MTs throughout the cell cycle and in response to developmental and environmental cues. Signaling pathways that converge on the regulation of versatile MT functions are being characterized.

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Section: Mt Nucleationmentioning

confidence: 99%

Microtubules in Plants

Hashimoto

2015

The Arabidopsis Book

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“…Observation of a single actin filament lifetime, including elongation rate and depolymerizing rate, in living cells has been employed to study actin dynamics in vivo (Smertenko et al, 2010;Henty-Ridilla et al, 2013;Qin et al, 2014;Li et al, 2014;Li et al, 2015). To examine the actin filament dynamics in the guard cells of Col-0 and the ckl2 mutant, we performed time-lapse imaging using spinning disk confocal microscopy to determine single actin filament dynamics ( Figure 4A; Supplemental Movies 1 and 2).…”

Section: Ckl2 Regulates the Activity Of Actin Filament Severing In Gumentioning

confidence: 99%

“…To observe actin filament dynamic behavior, parameters including maximum filament lifetime, maximum filament length, elongation rate, severing frequency, and depolymerization rate with single actin filament turnover were calculated using Image J software as described previously (Henty et al, 2011;Qin et al, 2014).…”

Section: Confocal Laser Scanning Microscopy To Visualize Actin Filamementioning

confidence: 99%

CASEIN KINASE1-LIKE PROTEIN2 Regulates Actin Filament Stability and Stomatal Closure via Phosphorylation of Actin Depolymerizing Factor

et al. 2016

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The opening and closing of stomata are crucial for plant photosynthesis and transpiration. Actin filaments undergo dynamic reorganization during stomatal closure, but the underlying mechanism for this cytoskeletal reorganization remains largely unclear. In this study, we identified and characterized Arabidopsis thaliana casein kinase 1-like protein 2 (CKL2), which responds to abscisic acid (ABA) treatment and participates in ABA-and drought-induced stomatal closure. Although CKL2 does not bind to actin filaments directly and has no effect on actin assembly in vitro, it colocalizes with and stabilizes actin filaments in guard cells. Further investigation revealed that CKL2 physically interacts with and phosphorylates actin depolymerizing factor 4 (ADF4) and inhibits its activity in actin filament disassembly. During ABA-induced stomatal closure, deletion of CKL2 in Arabidopsis alters actin reorganization in stomata and renders stomatal closure less sensitive to ABA, whereas deletion of ADF4 impairs the disassembly of actin filaments and causes stomatal closure to be more sensitive to ABA. Deletion of ADF4 in the ckl2 mutant partially recues its ABA-insensitive stomatal closure phenotype. Moreover, Arabidopsis ADFs from subclass I are targets of CKL2 in vitro. Thus, our results suggest that CKL2 regulates actin filament reorganization and stomatal closure mainly through phosphorylation of ADF.

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“…In addition to RIC1, several actin regulators, such as VLN2, VLN5, MAP18, and MDP25, have been found to regulate pollen tube growth via actin filament severing activity in recent studies (Qu et al, 2013;Zhu et al, 2013;Qin et al, 2014). MAP18 is involved in regulating the growth direction of pollen tubes but has little effect on elongation rate.…”

Section: Actin Severing By Various Proteins May Contribute To Positivmentioning

confidence: 99%

“…They have also been demonstrated to promote actin turnover and facilitate the construction of actin collars/fringes (Qu et al, 2013). As a negative regulator of tube elongation, MDP25 is a PM-associated protein that is released from the PM in the apex (where high concentrations of Ca 2+ exist) and destabilizes actin filaments in the cytosol at a subapical region of pollen tubes (Qin et al, 2014). Here, we report another negative regulator, RIC1, which regulates the abundance and oscillatory amplitude of fine F-actin in pollen tube tips, most likely by severing F-actin at both the apical PM and in the cytosol and capping the barbed ends of actin filaments.…”

Section: Actin Severing By Various Proteins May Contribute To Positivmentioning

confidence: 99%

Arabidopsis RIC1 Severs Actin Filaments at the Apex to Regulate Pollen Tube Growth

et al. 2015

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Pollen tubes deliver sperms to the ovule for fertilization via tip growth. The rapid turnover of F-actin in pollen tube tips plays an important role in this process. In this study, we demonstrate that Arabidopsis thaliana RIC1, a member of the ROP-interactive CRIB motif-containing protein family, regulates pollen tube growth via its F-actin severing activity. Knockout of RIC1 enhanced pollen tube elongation, while overexpression of RIC1 dramatically reduced tube growth. Pharmacological analysis indicated that RIC1 affected F-actin dynamics in pollen tubes. In vitro biochemical assays revealed that RIC1 directly bound and severed F-actin in the presence of Ca2+ in addition to interfering with F-actin turnover by capping F-actin at the barbed ends. In vivo, RIC1 localized primarily to the apical plasma membrane (PM) of pollen tubes. The level of RIC1 at the apical PM oscillated during pollen tube growth. The frequency of F-actin severing at the apex was notably decreased in ric1-1 pollen tubes but was increased in pollen tubes overexpressing RIC1. We propose that RIC1 regulates F-actin dynamics at the apical PM as well as the cytosol by severing F-actin and capping the barbed ends in the cytoplasm, establishing a novel mechanism that underlies the regulation of pollen tube growth.

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Arabidopsis Microtubule-Destabilizing Protein 25 Functions in Pollen Tube Growth by Severing Actin Filaments

Cited by 68 publications

References 54 publications

Microtubules in Plants

Microtubules in Plants

CASEIN KINASE1-LIKE PROTEIN2 Regulates Actin Filament Stability and Stomatal Closure via Phosphorylation of Actin Depolymerizing Factor

Arabidopsis RIC1 Severs Actin Filaments at the Apex to Regulate Pollen Tube Growth

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