Human T Cell L-Plastin Bundles Actin Filaments in a Calcium Dependent Manner1

Namba, Yoshiharu; Ito, Masaya; Zu, Youli; Shigesada, Katsuya; Maruyama, Kosçak

doi:10.1093/oxfordjournals.jbchem.a123929

Cited by 136 publications

(148 citation statements)

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“…Calcium insensitivity was also reported for chicken fimbrin (Bretscher, 1981) and S. pombe Fim1p (Nakano et al, 2001). By contrast, plastins from mammalian cells (Namba et al, 1992;Lin et al, 1994) and Dictyostelium (Prassler et al, 1997) have been shown to be calcium sensitive. Another study reported that a fimbrin-like protein from T. pyriformis lacks EF-hand domains (Watanabe et al, 2000).…”

Section: Fim5 Is a Bona Fide Actin Bundling Factormentioning

confidence: 78%

ArabidopsisFIMBRIN5, an Actin Bundling Factor, Is Required for Pollen Germination and Pollen Tube Growth

et al. 2010

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Actin cables in pollen tubes serve as molecular tracks for cytoplasmic streaming and organelle movement and are formed by actin bundling factors like villins and fimbrins. However, the precise mechanisms by which actin cables are generated and maintained remain largely unknown. Fimbrins comprise a family of five members in Arabidopsis thaliana. Here, we characterized a fimbrin isoform, Arabidopsis FIMBRIN5 (FIM5). Our results show that FIM5 is required for the organization of actin cytoskeleton in pollen grains and pollen tubes, and FIM5 loss-of-function associates with a delay of pollen germination and inhibition of pollen tube growth. FIM5 decorates actin filaments throughout pollen grains and tubes. Actin filaments become redistributed in fim5 pollen grains and disorganized in fim5 pollen tubes. Specifically, actin cables protrude into the extreme tips, and their longitudinal arrangement is disrupted in the shank of fim5 pollen tubes. Consequently, the pattern and velocity of cytoplasmic streaming were altered in fim5 pollen tubes. Additionally, loss of FIM5 function rendered pollen germination and tube growth hypersensitive to the actin-depolymerizing drug latrunculin B. In vitro biochemical analyses indicated that FIM5 exhibits actin bundling activity and stabilizes actin filaments. Thus, we propose that FIM5 regulates actin dynamics and organization during pollen germination and tube growth via stabilizing actin filaments and organizing them into higher-order structures.

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Section: Fim5 Is a Bona Fide Actin Bundling Factormentioning

confidence: 78%

ArabidopsisFIMBRIN5, an Actin Bundling Factor, Is Required for Pollen Germination and Pollen Tube Growth

et al. 2010

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“…It is known that increased calcium concentrations negatively regulate the actin-bundling activity of LCP1 (46). It has been recently shown that LCP1 contains a switch helix structure that, in the presence of calcium, tightly binds to EF-hand motifs (47).…”

Section: Discussionmentioning

confidence: 99%

Angiotensin II regulates phosphorylation of actin‐associated proteins in human podocytes

et al. 2017

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Within the kidney, angiotensin II (AngII) targets different cell types in the vasculature, tubuli, and glomeruli. An important part of the renal filtration barrier is composed of podocytes with their actin-rich foot processes. In this study, we used stable isotope labeling with amino acids in cell culture coupled to mass spectrometry to characterize relative changes in the phosphoproteome of human podocytes in response to short-term treatment with AngII. In 4 replicates, we identified a total of 17,956 peptides that were traceable to 2081 distinct proteins. Bioinformatic analyses revealed that among the increasingly phosphorylated peptides are predominantly peptides that are related to actin filaments, cytoskeleton, lamellipodia, mammalian target of rapamycin, and MAPK signaling. Among others, this screening approach highlighted the increased phosphorylation of actin-bundling protein, L-plastin (LCP1). AngII-dependent phosphorylation of LCP1 in cultured podocytes was mediated by the kinases ERK, p90 ribosomal S6 kinase, PKA, or PKC. LCP1 phosphorylation increased filopodia formation. In addition, treatment with AngII led to LCP1 redistribution to the cell margins, membrane ruffling, and formation of lamellipodia. Our data highlight the importance of AngII-triggered actin cytoskeleton-associated signal transduction in

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“…In addition, it seems to interact more tightly with certain actin binding proteins that may function at the leading edge of crawling cells. Ezrin (19), profilin (20), thymosin ␤ 4 (21), and L-plastin (22) bind more strongly to ␤-actin than ␣-actin. A capping protein, ␤-cap 73, may cap the barbed end in an isoform-specific manner (23).…”

Section: Discussionmentioning

confidence: 99%

The physiological significance of β-actin mRNA localization in determining cell polarity and directional motility

Shestakova

Singer²,

Condeelis³

2001

Proc. Natl. Acad. Sci. U.S.A.

192

181

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␤-actin mRNA is localized near the leading edge in several cell types, where actin polymerization is actively promoting forward protrusion. The localization of the ␤-actin mRNA near the leading edge is facilitated by a short sequence in the 3 untranslated region, the ''zip code.'' Localization of the mRNA at this region is important physiologically. Treatment of chicken embryo fibroblasts with antisense oligonucleotides complementary to the localization sequence (zip code) in the 3 untranslated region leads to delocalization of ␤-actin mRNA, alteration of cell phenotype, and a decrease in cell motility. To determine the components of this process responsible for the change in cell behavior after ␤-actin mRNA delocalization, the Dynamic Image Analysis System was used to quantify movement of cells in the presence of sense and antisense oligonucleotides to the zip code. It was found that net path length and average speed of antisense-treated cells were significantly lower than in sense-treated cells. Total path length and the velocity of protrusion of antisense-treated cells were not affected compared with those of control cells. These results suggest that a decrease in persistence of direction of movement and not in velocity results from treatment of cells with zip codedirected antisense oligonucleotides. To test this, direct analysis of directionality was performed on antisense-treated cells and showed a decrease in directionality (net path͞total path) and persistence of movement. Less directional movement of antisensetreated cells correlated with a unpolarized and discontinuous distribution of free barbed ends of actin filaments and of ␤-actin protein. These results indicate that delocalization of ␤-actin mRNA results in delocalization of nucleation sites and ␤-actin protein from the leading edge followed by loss of cell polarity and directional movement.Dynamic Image Analysis System ͉ directionality ͉ antisense oligonucleotides

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Human T Cell L-Plastin Bundles Actin Filaments in a Calcium Dependent Manner1

Cited by 136 publications

References 0 publications

ArabidopsisFIMBRIN5, an Actin Bundling Factor, Is Required for Pollen Germination and Pollen Tube Growth

ArabidopsisFIMBRIN5, an Actin Bundling Factor, Is Required for Pollen Germination and Pollen Tube Growth

Angiotensin II regulates phosphorylation of actin‐associated proteins in human podocytes

The physiological significance of β-actin mRNA localization in determining cell polarity and directional motility

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