Formins are evolutionarily conserved multi-domain proteins participating in the control of both actin and microtubule dynamics. Angiosperm formins form two evolutionarily distinct families, Class I and Class II, with class-specific domain layouts. The model plant Arabidopsis thaliana has 21 formin-encoding loci, including 10 Class II members. In this study, we analyze the subcellular localization of two A. thaliana Class II formins exhibiting typical domain organization, the so far uncharacterized formin AtFH13 (At5g58160) and its distant homolog AtFH14 (At1g31810), previously reported to bind microtubules. Fluorescent protein-tagged full length formins and their individual domains were transiently expressed in Nicotiana benthamiana leaves under the control of a constitutive promoter and their subcellular localization (including co-localization with cytoskeletal structures and the endoplasmic reticulum) was examined using confocal microscopy. While the two formins exhibit distinct and only partially overlapping localization patterns, they both associate with microtubules via the conserved formin homology 2 (FH2) domain and with the periphery of the endoplasmic reticulum, at least in part via the N-terminal PTEN (Phosphatase and Tensin)-like domain. Surprisingly, FH2 domains of AtFH13 and AtFH14 can form heterodimers in the yeast two-hybrid assay-a first case of potentially biologically relevant formin heterodimerization mediated solely by the FH2 domain.

• MeSH
• Arabidopsis genetika   metabolismus   MeSH
• dimerizace MeSH
• endoplazmatické retikulum metabolismus   MeSH
• exprese genu MeSH
• forminy genetika   metabolismus   MeSH
• mikrotubuly metabolismus   MeSH
• proteinové domény MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• rekombinantní proteiny genetika   metabolismus   MeSH
• tabák metabolismus   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH

The cytoskeleton plays a central part in spatial organization of the plant cytoplasm, including the endomebrane system. However, the mechanisms involved are so far only partially understood. Formins (FH2 proteins), a family of evolutionarily conserved proteins sharing the FH2 domain whose dimer can nucleate actin, mediate the co-ordination between actin and microtubule cytoskeletons in multiple eukaryotic lineages including plants. Moreover, some plant formins contain transmembrane domains and participate in anchoring cytoskeletal structures to the plasmalemma, and possibly to other membranes. Direct or indirect membrane association is well documented even for some fungal and metazoan formins lacking membrane insertion motifs, and FH2 proteins have been shown to associate with endomembranes and modulate their dynamics in both fungi and metazoans. Here we summarize the available evidence suggesting that formins participate in membrane trafficking and endomembrane, especially ER, organization also in plants. We propose that, despite some methodological pitfalls inherent to in vivo studies based on (over)expression of truncated and/or tagged proteins, formins are beginning to emerge as candidates for the so far somewhat elusive link between the plant cytoskeleton and the endomembrane system.

• MeSH
• intracelulární membrány metabolismus   MeSH
• mikrofilamenta metabolismus   MeSH
• proteiny asociované s mikrotubuly chemie   genetika   metabolismus   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• proteiny huseníčku chemie   genetika   metabolismus   MeSH
• rostlinné buňky metabolismus   MeSH
• transport proteinů MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy 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

Profilin 1 is a crucial actin regulator, interacting with monomeric actin and several actin-binding proteins controlling actin polymerization. Recently, it has become evident that this profilin isoform associates with microtubules via formins and interferes with microtubule elongation at the cell periphery. Recruitment of microtubule-associated profilin upon extensive actin polymerizations, for example, at the cell edge, enhances microtubule growth, indicating that profilin contributes to the coordination of actin and microtubule organization. Here, we provide further evidence for the profilin-microtubule connection by demonstrating that it also functions in centrosomes where it impacts on microtubule nucleation.

• MeSH
• aktiny metabolismus   MeSH
• Caco-2 buňky MeSH
• centrozom metabolismus   MeSH
• forminy metabolismus   MeSH
• genový knockout MeSH
• lidé MeSH
• melanom experimentální metabolismus   patologie   MeSH
• mikrofilamentové proteiny metabolismus   MeSH
• mikrotubuly metabolismus   MeSH
• myši MeSH
• nádory kůže metabolismus   patologie   MeSH
• polymerizace MeSH
• profiliny genetika   metabolismus   MeSH
• signální transdukce genetika   MeSH
• transfekce MeSH
• tubulin metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• membránové proteiny genetika   chemie   MeSH
• molekulární sekvence - údaje MeSH
• peptidy genetika   chemie   klasifikace   MeSH
• rostlinné proteiny genetika   chemie   klasifikace   MeSH

Formins are evolutionarily conserved eukaryotic proteins engaged in actin nucleation and other aspects of cytoskeletal organization. Angiosperms have two formin clades with multiple paralogs; typical plant Class I formins are integral membrane proteins that can anchor cytoskeletal structures to membranes. For the main Arabidopsis housekeeping Class I formin, FH1 (At3g25500), plasmalemma localization was documented in heterologous expression and overexpression studies. We previously showed that loss of FH1 function increases cotyledon epidermal pavement cell shape complexity via modification of actin and microtubule organization and dynamics. Here, we employ transgenic Arabidopsis expressing green fluorescent protein-tagged FH1 (FH1-GFP) from its native promoter to investigate in vivo behavior of this formin using advanced microscopy techniques. The fusion protein is functional, since its expression complements the fh1 loss-of-function mutant phenotype. Accidental overexpression of FH1-GFP results in a decrease in trichome branch number, while fh1 mutation has the opposite effect, indicating a general role of this formin in controlling cell shape complexity. Consistent with previous reports, FH1-GFP associates with membranes. However, the protein exhibits surprising actin- and secretory pathway-dependent dynamic localization and relocates between cellular endomembranes and the plasmalemma during cell division and differentiation in root tissues, with transient tonoplast localization at the transition/elongation zones border. FH1-GFP also accumulates in actin-rich regions of cortical cytoplasm and associates with plasmodesmata in both the cotyledon epidermis and root tissues. Together with previous reports from metazoan systems, this suggests that formins might have a shared (ancestral or convergent) role at cell-cell junctions.

• MeSH
• Arabidopsis cytologie   metabolismus   MeSH
• cytoskelet genetika   metabolismus   MeSH
• kořeny rostlin cytologie   metabolismus   MeSH
• plazmodesmy fyziologie   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

Plant cell growth and morphogenesis depend on remodelling of both actin and microtubule cytoskeletons. AtFH1 (At5g25500), the main housekeeping Arabidopsis formin, is targeted to membranes and known to nucleate and bundle actin. The effect of mutations in AtFH1 on root development and cytoskeletal dynamics was examined. Consistent with primarily actin-related formin function, fh1 mutants showed increased sensitivity to the actin polymerization inhibitor latrunculin B (LatB). LatB-treated mutants had thicker, shorter roots than wild-type plants. Reduced cell elongation and morphological abnormalities were observed in both trichoblasts and atrichoblasts. Fluorescently tagged cytoskeletal markers were used to follow cytoskeletal dynamics in wild-type and mutant plants using confocal microscopy and VAEM (variable-angle epifluorescence microscopy). Mutants exhibited more abundant but less dynamic F-actin bundles and more dynamic microtubules than wild-type seedlings. Treatment of wild-type seedlings with a formin inhibitor, SMIFH2, mimicked the root growth and cell expansion phenotypes and cytoskeletal structure alterations observed in fh1 mutants. The results suggest that besides direct effects on actin organization, the in vivo role of AtFH1 also includes modulation of microtubule dynamics, possibly mediated by actin-microtubule cross-talk.

• MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   MeSH
• kořeny rostlin genetika   růst a vývoj   metabolismus   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• mikrofilamenta genetika   metabolismus   MeSH
• mikrotubuly genetika   metabolismus   MeSH
• mutace * MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Plant cell morphogenesis involves concerted rearrangements of microtubules and actin microfilaments. We previously reported that FH1, the main Arabidopsis thaliana housekeeping Class I membrane-anchored formin, contributes to actin dynamics and microtubule stability in rhizodermis cells. Here we examine the effects of mutations affecting FH1 (At3g25500) on cell morphogenesis and above-ground organ development in seedlings, as well as on cytoskeletal organization and dynamics, using a combination of confocal and variable angle epifluorescence microscopy with a pharmacological approach. Homozygous fh1 mutants exhibited cotyledon epinasty and had larger cotyledon pavement cells with more pronounced lobes than the wild type. The pavement cell shape alterations were enhanced by expression of the fluorescent microtubule marker GFP-microtubule-associated protein 4 (MAP4). Mutant cotyledon pavement cells exhibited reduced density and increased stability of microfilament bundles, as well as enhanced dynamics of microtubules. Analogous results were also obtained upon treatments with the formin inhibitor SMIFH2 (small molecule inhibitor of formin homology 2 domains). Pavement cell shape in wild-type (wt) and fh1 plants in some situations exhibited a differential response towards anti-cytoskeletal drugs, especially the microtubule disruptor oryzalin. Our observations indicate that FH1 participates in the control of microtubule dynamics, possibly via its effects on actin, subsequently influencing cell morphogenesis and macroscopic organ development.

• MeSH
• aktiny metabolismus   MeSH
• Arabidopsis cytologie   účinky léků   metabolismus   MeSH
• biologické markery metabolismus   MeSH
• biologické modely MeSH
• cytoskelet účinky léků   metabolismus   MeSH
• fluorescence MeSH
• klathrin metabolismus   MeSH
• kotyledon účinky léků   metabolismus   MeSH
• membránové proteiny metabolismus   MeSH
• mikrofilamenta účinky léků   metabolismus   MeSH
• mikrotubuly účinky léků   metabolismus   MeSH
• mutace genetika   MeSH
• proteiny huseníčku metabolismus   MeSH
• semenáček účinky léků   růst a vývoj   metabolismus   MeSH
• thioketony farmakologie   MeSH
• tvar buňky * účinky léků   MeSH
• uracil analogy a deriváty   farmakologie   MeSH
• zelené fluorescenční proteiny metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Actin-associated proteins regulate multiple cellular processes, including proliferation and differentiation, but the molecular mechanisms underlying these processes are unclear. Here, we report that the actin-binding protein filamin A (FlnA) physically interacts with the actin-nucleating protein formin 2 (Fmn2). Loss of FlnA and Fmn2 impairs proliferation, thereby generating multiple embryonic phenotypes, including microcephaly. FlnA interacts with the Wnt co-receptor Lrp6. Loss of FlnA and Fmn2 impairs Lrp6 endocytosis, downstream Gsk3β activity, and β-catenin accumulation in the nucleus. The proliferative defect in Flna and Fmn2 null neural progenitors is rescued by inhibiting Gsk3β activity. Our findings thus reveal a novel mechanism whereby actin-associated proteins regulate proliferation by mediating the endocytosis and transportation of components in the canonical Wnt pathway. Moreover, the Fmn2-dependent signaling in this pathway parallels that seen in the non-canonical Wnt-dependent regulation of planar cell polarity through the Formin homology protein Daam. These studies provide evidence for integration of actin-associated processes in directing neuroepithelial proliferation.

• MeSH
• beta-katenin metabolismus   MeSH
• buněčná diferenciace MeSH
• buněčná membrána fyziologie   MeSH
• buněčné linie MeSH
• endocytóza fyziologie   MeSH
• filaminy genetika   metabolismus   MeSH
• HEK293 buňky MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• kinasa glykogensynthasy 3beta antagonisté a inhibitory   metabolismus   MeSH
• LDL receptor related protein 6 metabolismus   MeSH
• lidé MeSH
• mikrocefalie genetika   MeSH
• mikrofilamentové proteiny genetika   metabolismus   MeSH
• myši knockoutované MeSH
• myši MeSH
• proliferace buněk genetika   fyziologie   MeSH
• proteiny Wnt metabolismus   MeSH
• signální dráha Wnt fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Age-associated memory decline is due to variable combinations of genetic and environmental risk factors. How these risk factors interact to drive disease onset is currently unknown. Here we begin to elucidate the mechanisms by which post-traumatic stress disorder (PTSD) at a young age contributes to an increased risk to develop dementia at old age. We show that the actin nucleator Formin 2 (Fmn2) is deregulated in PTSD and in Alzheimer's disease (AD) patients. Young mice lacking the Fmn2 gene exhibit PTSD-like phenotypes and corresponding impairments of synaptic plasticity, while the consolidation of new memories is unaffected. However, Fmn2 mutant mice develop accelerated age-associated memory decline that is further increased in the presence of additional risk factors and is mechanistically linked to a loss of transcriptional homeostasis. In conclusion, our data present a new approach to explore the connection between AD risk factors across life span and provide mechanistic insight to the processes by which neuropsychiatric diseases at a young age affect the risk for developing dementia.

• MeSH
• demence epidemiologie   genetika   psychologie   MeSH
• dospělí MeSH
• fenotyp MeSH
• jaderné proteiny genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mikrofilamentové proteiny genetika   MeSH
• myši knockoutované MeSH
• myši MeSH
• neuroplasticita genetika   MeSH
• paměť fyziologie   MeSH
• posttraumatická stresová porucha komplikace   epidemiologie   genetika   MeSH
• rizikové faktory MeSH
• stárnutí genetika   fyziologie   MeSH
• studie případů a kontrol MeSH
• věk při počátku nemoci MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH