Background and Aim: The cytoskeleton plays an important role in the synthesis of plant cell walls. Both microtubules and actin cytoskeleton are known to be involved in the morphogenesis of plant cells through their role in cell wall building. The role of ARP2/3-nucleated actin cytoskeleton in the morphogenesis of cotyledon pavement cells has been described before. Seedlings of Arabidopsis mutants lacking a functional ARP2/3 complex display specific cell wall-associated defects. Methods: In three independent Arabidopsis mutant lines lacking subunits of the ARP2/3 complex, phenotypes associated with the loss of the complex were analysed throughout plant development. Organ size and anatomy, cell wall composition, and auxin distribution were investigated. Key Results: ARP2/3-related phenotype is associated with changes in cell wall composition, and the phenotype is manifested especially in mature tissues. Cell walls of mature plants contain less cellulose and a higher amount of homogalacturonan, and display changes in cell wall lignification. Vascular bundles of mutant inflorescence stems show a changed pattern of AUX1-YFP expression. Plants lacking a functional ARP2/3 complex have decreased basipetal auxin transport. Conclusions: The results suggest that the ARP2/3 complex has a morphogenetic function related to cell wall synthesis and auxin transport.

• MeSH
• Arabidopsis genetika   metabolismus   MeSH
• buněčná stěna metabolismus   MeSH
• komplex proteinů 2-3 souvisejících s aktinem genetika   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The Arabidopsis EH proteins (AtEH1/Pan1 and AtEH2/Pan1) are components of the endocytic TPLATE complex (TPC) which is essential for endocytosis. Both proteins are homologues of the yeast ARP2/3 complex activator, Pan1p. Here, we show that these proteins are also involved in actin cytoskeleton regulated autophagy. Both AtEH/Pan1 proteins localise to the plasma membrane and autophagosomes. Upon induction of autophagy, AtEH/Pan1 proteins recruit TPC and AP-2 subunits, clathrin, actin and ARP2/3 proteins to autophagosomes. Increased expression of AtEH/Pan1 proteins boosts autophagosome formation, suggesting independent and redundant pathways for actin-mediated autophagy in plants. Moreover, AtEHs/Pan1-regulated autophagosomes associate with ER-PM contact sites (EPCS) where AtEH1/Pan1 interacts with VAP27-1. Knock-down expression of either AtEH1/Pan1 or VAP27-1 makes plants more susceptible to nutrient depleted conditions, indicating that the autophagy pathway is perturbed. In conclusion, we identify the existence of an autophagy-dependent pathway in plants to degrade endocytic components, starting at the EPCS through the interaction among AtEH/Pan1, actin cytoskeleton and the EPCS resident protein VAP27-1.

• MeSH
• aktiny metabolismus   MeSH
• Arabidopsis metabolismus   ultrastruktura   MeSH
• autofagie MeSH
• autofagozomy metabolismus   ultrastruktura   MeSH
• biologické modely MeSH
• buněčná membrána metabolismus   ultrastruktura   MeSH
• endocytóza * MeSH
• endoplazmatické retikulum metabolismus   ultrastruktura   MeSH
• fylogeneze MeSH
• komplex proteinů 2-3 souvisejících s aktinem metabolismus   MeSH
• mikrofilamenta metabolismus   MeSH
• mikrofilamentové proteiny metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny metabolismus   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

VEGFR-2/Notch signalling regulates angiogenesis in part by driving the remodelling of endothelial cell junctions and by inducing cell migration. Here, we show that VEGF-induced polarized cell elongation increases cell perimeter and decreases the relative VE-cadherin concentration at junctions, triggering polarized formation of actin-driven junction-associated intermittent lamellipodia (JAIL) under control of the WASP/WAVE/ARP2/3 complex. JAIL allow formation of new VE-cadherin adhesion sites that are critical for cell migration and monolayer integrity. Whereas at the leading edge of the cell, large JAIL drive cell migration with supportive contraction, lateral junctions show small JAIL that allow relative cell movement. VEGFR-2 activation initiates cell elongation through dephosphorylation of junctional myosin light chain II, which leads to a local loss of tension to induce JAIL-mediated junctional remodelling. These events require both microtubules and polarized Rac activity. Together, we propose a model where polarized JAIL formation drives directed cell migration and junctional remodelling during sprouting angiogenesis.

• MeSH
• aktiny účinky léků   metabolismus   MeSH
• buněčná adheze MeSH
• CD antigeny účinky léků   metabolismus   MeSH
• cévní endotel MeSH
• endoteliální buňky pupečníkové žíly (lidské) MeSH
• endoteliální buňky účinky léků   metabolismus   fyziologie   MeSH
• fyziologická neovaskularizace účinky léků   fyziologie   MeSH
• kadheriny účinky léků   metabolismus   MeSH
• komplex proteinů 2-3 souvisejících s aktinem metabolismus   MeSH
• lehké řetězce myosinu metabolismus   MeSH
• lidé MeSH
• mezibuněčné spoje účinky léků   metabolismus   MeSH
• mikrotubuly účinky léků   metabolismus   MeSH
• modely kardiovaskulární MeSH
• pohyb buněk účinky léků   fyziologie   MeSH
• polarita buněk účinky léků   fyziologie   MeSH
• protein 2 související s aktinem metabolismus   MeSH
• protein 3 související s aktinem metabolismus   MeSH
• protein Wiskottova-Aldrichova syndromu metabolismus   MeSH
• pseudopodia účinky léků   metabolismus   fyziologie   MeSH
• rac proteiny vázající GTP metabolismus   MeSH
• receptor 2 pro vaskulární endoteliální růstový faktor metabolismus   MeSH
• remodelace cév MeSH
• rodina proteinů Wiskottova-Aldrichova syndromu metabolismus   MeSH
• signální transdukce MeSH
• srdeční myosiny metabolismus   MeSH
• vaskulární endoteliální růstový faktor A metabolismus   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

UNLABELLED: We used microarray profiling to investigate the direct effects of lenalidomide on gene expression in isolated CD14(+) monocytes from 6 patients with del(5q). Our data demonstrate that changes in genes involved the tumor necrosis factor (TNF) signaling pathway and the bone marrow stroma, suggesting that treatment with lenalidomide may help restore the damaged niche and suppress the TNF signaling pathway. BACKGROUND: Lenalidomide is an effective treatment for patients with del(5q) and myelodysplastic syndrome (MDS) The exact mechanism of lenalidomide function and its impact on the prognosis of patients is not known exactly. MATERIALS AND METHODS: We used gene expression profiling to study the effect of lenalidomide therapy in peripheral blood CD14(+) monocytes of 6 patients with del(5q) and MDS. RESULTS: After lenalidomide treatment, genes involved in the tumor necrosis factor (TNF) signaling pathway that were upregulated in the patients before treatment decreased to the healthy control baseline expression level. This change in gene expression, in conjunction with increased expression of repressed genes that affect the stem cell niche (ie, CXCR4 and CRTAP), may exert a positive effect on treated patients. In contrast, we found that increased expression of the ARPC1B gene may have a negative impact on the stability of patient remission. CONCLUSION: The observed changes in gene expression described here may contribute to the identification of pathways that are affected by lenalidomide, which may help to explain the effects of this drug.

• MeSH
• antigeny CD14 krev   genetika   metabolismus   MeSH
• chromozomální delece * MeSH
• exprese genu účinky léků   MeSH
• interleukin-1beta genetika   metabolismus   MeSH
• komplex proteinů 2-3 souvisejících s aktinem genetika   metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• lidské chromozomy, pár 5 * MeSH
• monocyty účinky léků   metabolismus   MeSH
• myelodysplastické syndromy farmakoterapie   genetika   metabolismus   MeSH
• nika kmenových buněk účinky léků   genetika   MeSH
• prognóza MeSH
• protoonkogenní proteiny c-jun genetika   metabolismus   MeSH
• senioři MeSH
• signální transdukce účinky léků   genetika   MeSH
• studie případů a kontrol MeSH
• thalidomid analogy a deriváty   terapeutické užití   MeSH
• TNF-alfa genetika   metabolismus   MeSH
• transkriptom účinky léků   MeSH
• upregulace účinky léků   genetika   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Development of the plant aerial organs epidermis involves a complex interplay of cytoskeletal rearrangements, membrane trafficking-dependent cell surface expansion, and intra- and intercellular signaling, resulting in a pattern of perfectly interlocking pavement cells. While recent detailed in vivo observations convincingly identify microtubules rather than actin as key players at the early stages of development of pavement cell lobes in Arabidopsis, mutations affecting the actin-nucleating ARP2/3 complex are long known to reduce pavement cell lobing, suggesting a central role for actin. We have now shown that functional impairment of the Arabidopsis formin FH1 enhances both microtubule dynamics and pavement cell lobing. While formins are best known for their ability to nucleate actin, many members of this old gene family now emerge as direct or indirect regulators of the microtubule cytoskeleton, and our findings suggest that they might co-ordinate action of the two cytoskeletal systems during pavement cell morphogenesis.

• MeSH
• Arabidopsis růst a vývoj   metabolismus   ultrastruktura   MeSH
• biologické modely MeSH
• cytoskelet metabolismus   fyziologie   ultrastruktura   MeSH
• membránové proteiny genetika   metabolismus   fyziologie   MeSH
• mikrotubuly metabolismus   fyziologie   ultrastruktura   MeSH
• multigenová rodina MeSH
• proteiny huseníčku genetika   metabolismus   fyziologie   MeSH
• rostlinné buňky metabolismus   ultrastruktura   MeSH
• signální transdukce MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The pentameric WASH complex facilitates endosomal protein sorting by activating Arp2/3, which in turn leads to the formation of F-actin patches specifically on the endosomal surface. It is generally accepted that WASH complex attaches to the endosomal membrane via the interaction of its subunit FAM21 with the retromer subunit VPS35. However, we observe the WASH complex and F-actin present on endosomes even in the absence of VPS35. We show that the WASH complex binds to the endosomal surface in both a retromer-dependent and a retromer-independent manner. The retromer-independent membrane anchor is directly mediated by the subunit SWIP. Furthermore, SWIP can interact with a number of phosphoinositide species. Of those, our data suggest that the interaction with phosphatidylinositol-3,5-bisphosphate (PI(3,5)P2 ) is crucial to the endosomal binding of SWIP. Overall, this study reveals a new role of the WASH complex subunit SWIP and highlights the WASH complex as an independent, self-sufficient trafficking regulator.

• MeSH
• aktiny * metabolismus   MeSH
• endozomy metabolismus   MeSH
• mikrofilamentové proteiny metabolismus   MeSH
• transport proteinů MeSH
• vezikulární transportní proteiny * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Although actin monomers polymerize into filaments in the cytoplasm, the form of actin in the nucleus remains elusive. We searched for the form and function of β-actin fused to nuclear localization signal and to enhanced yellow fluorescent protein (EN-actin). Our results reveal that EN-actin is either dispersed in the nucleoplasm (homogenous EN-actin) or forms bundled filaments in the nucleus (EN-actin filaments). Formation of such filaments was not connected with increased EN-actin levels. Among numerous actin-binding proteins tested, only cofilin is recruited to the EN-actin filaments. Overexpression of EN-actin causes increase in the nuclear levels of actin-related protein 3 (Arp3). Although Arp3, a member of actin nucleation complex Arp2/3, is responsible for EN-actin filament nucleation and bundling, the way cofilin affects nuclear EN-actin filaments dynamics is not clear. While cells with homogenous EN-actin maintained unaffected mitosis during which EN-actin re-localizes to the plasma membrane, generation of nuclear EN-actin filaments severely decreases cell proliferation and interferes with mitotic progress. The introduction of EN-actin manifests in two mitotic-inborn defects-formation of binucleic cells and generation of micronuclei-suggesting that cells suffer aberrant cytokinesis and/or impaired chromosomal segregation. In interphase, nuclear EN-actin filaments passed through chromatin region, but do not co-localize with either chromatin remodeling complexes or RNA polymerases I and II. Surprisingly presence of EN-actin filaments was connected with increase in the overall transcription levels in the S-phase by yet unknown mechanism. Taken together, EN-actin can form filaments in the nucleus which affect important cellular processes such as transcription and mitosis.

• MeSH
• aktiny metabolismus   MeSH
• bakteriální proteiny metabolismus   MeSH
• buněčné jádro metabolismus   MeSH
• faktory depolymerizující aktin MeSH
• genetická transkripce MeSH
• HEK293 buňky MeSH
• lidé MeSH
• luminescentní proteiny metabolismus   MeSH
• mikrofilamenta metabolismus   MeSH
• mitóza genetika   MeSH
• nádorové buněčné linie MeSH
• protein 3 související s aktinem biosyntéza   metabolismus   MeSH
• restrukturace chromatinu MeSH
• RNA-polymerasa I genetika   MeSH
• RNA-polymerasa II genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH