Intercellular distribution of the plant hormone auxin largely depends on the polar subcellular distribution of the plasma membrane PIN-FORMED (PIN) auxin transporters. PIN polarity switches in response to different developmental and environmental signals have been shown to redirect auxin fluxes mediating certain developmental responses. PIN phosphorylation at different sites and by different kinases is crucial for PIN function. Here we investigate the role of PIN phosphorylation during gravitropic response. Loss- and gain-of-function mutants in PINOID and related kinases but not in D6PK kinase as well as mutations mimicking constitutive dephosphorylated or phosphorylated status of two clusters of predicted phosphorylation sites partially disrupted PIN3 phosphorylation and caused defects in gravitropic bending in roots and hypocotyls. In particular, they impacted PIN3 polarity rearrangements in response to gravity and during feed-back regulation by auxin itself. Thus PIN phosphorylation, besides regulating transport activity and apical-basal targeting, is also important for the rapid polarity switches in response to environmental and endogenous signals.

• MeSH
• Arabidopsis účinky léků   fyziologie   MeSH
• fosforylace MeSH
• gravitropismus * MeSH
• kořeny rostlin účinky léků   fyziologie   MeSH
• kyseliny indoloctové farmakologie   MeSH
• percepce tíhy MeSH
• polarita buněk * MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulátory růstu rostlin farmakologie   MeSH
• sekvence aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Plants adjust their growth according to gravity. Gravitropism involves gravity perception, signal transduction, and asymmetric growth response, with organ bending as a consequence [1]. Asymmetric growth results from the asymmetric distribution of the plant-specific signaling molecule auxin [2] that is generated by lateral transport, mediated in the hypocotyl predominantly by the auxin transporter PIN-FORMED3 (PIN3) [3-5]. Gravity stimulation polarizes PIN3 to the bottom sides of endodermal cells, correlating with increased auxin accumulation in adjacent tissues at the lower side of the stimulated organ, where auxin induces cell elongation and, hence, organ bending. A curvature response allows the hypocotyl to resume straight growth at a defined angle [6], implying that at some point auxin symmetry is restored to prevent overbending. Here, we present initial insights into cellular and molecular mechanisms that lead to the termination of the tropic response. We identified an auxin feedback on PIN3 polarization as underlying mechanism that restores symmetry of the PIN3-dependent auxin flow. Thus, two mechanistically distinct PIN3 polarization events redirect auxin fluxes at different time points of the gravity response: first, gravity-mediated redirection of PIN3-mediated auxin flow toward the lower hypocotyl side, where auxin gradually accumulates and promotes growth, and later PIN3 polarization to the opposite cell side, depleting this auxin maximum to end the bending. Accordingly, genetic or pharmacological interference with the late PIN3 polarization prevents termination of the response and leads to hypocotyl overbending. This observation reveals a role of auxin feedback on PIN polarity in the termination of the tropic response.

• MeSH
• Arabidopsis genetika   růst a vývoj   fyziologie   MeSH
• gravitropismus * MeSH
• kyseliny indoloctové metabolismus   MeSH
• percepce tíhy * MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• výhonky rostlin růst a vývoj   MeSH
• zpětná vazba fyziologická MeSH
• Publikační typ
• časopisecké články MeSH

Interplay between apicobasal cell polarity modules and the cytoskeleton is critical for differentiation and integrity of epithelia. However, this coordination is poorly understood at the level of gene regulation by transcription factors. Here, we establish the Drosophila activating transcription factor 3 (atf3) as a cell polarity response gene acting downstream of the membrane-associated Scribble polarity complex. Loss of the tumor suppressors Scribble or Dlg1 induces atf3 expression via aPKC but independent of Jun-N-terminal kinase (JNK) signaling. Strikingly, removal of Atf3 from Dlg1 deficient cells restores polarized cytoarchitecture, levels and distribution of endosomal trafficking machinery, and differentiation. Conversely, excess Atf3 alters microtubule network, vesicular trafficking and the partition of polarity proteins along the apicobasal axis. Genomic and genetic approaches implicate Atf3 as a regulator of cytoskeleton organization and function, and identify Lamin C as one of its bona fide target genes. By affecting structural features and cell morphology, Atf3 functions in a manner distinct from other transcription factors operating downstream of disrupted cell polarity.

• MeSH
• buněčná diferenciace MeSH
• chromatinová imunoprecipitace MeSH
• Drosophila melanogaster cytologie   genetika   MeSH
• endozomy metabolismus   MeSH
• geneticky modifikovaná zvířata MeSH
• imaginální disky cytologie   fyziologie   MeSH
• lamin typ A genetika   metabolismus   MeSH
• larva MeSH
• MAP kinasový signální systém MeSH
• nádorové supresorové proteiny genetika   metabolismus   MeSH
• nukleotidové motivy fyziologie   MeSH
• oči růst a vývoj   MeSH
• polarita buněk fyziologie   MeSH
• proteinkinasa C metabolismus   MeSH
• proteiny Drosophily genetika   metabolismus   MeSH
• transkripční faktor ATF3 genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Brain development is determined by neuronal differentiation including changes of cell polarity and asymetric grow- th of neuronal processes. Although, there are many unkown factors contributing to changes of lenght of neuronal cones, mounting experimental and review papers focus on changes of growth conus and role of axonal transport. In particular, mechanisms of actin/microtubule polymerisation and depolymerisation are important. Role of intracellu- lar calcium is also significant. Normal and properly timed changes of lenght of axons and dendrites are dependent on interaction of neurons and glia. Moreover, regeneration of injured axons is dependent on growth factors secre- ted from glial cells. The aim of the present study is characterisation of the most important mechanisms underlying changes of lenght of neurites.

• Klíčová slova
• kofilin,
• MeSH
• aktiny biosyntéza   MeSH
• axony fyziologie   MeSH
• dendrity fyziologie   MeSH
• dyneiny biosyntéza   fyziologie   MeSH
• lidé MeSH
• mikrotubuly fyziologie   MeSH
• morfogeneze MeSH
• mozková kůra růst a vývoj   MeSH
• myosiny biosyntéza   fyziologie   MeSH
• nervový růstový faktor MeSH
• nervový systém - fyziologické jevy MeSH
• neurity MeSH
• neuroglie cytologie   MeSH
• neurony fyziologie   MeSH
• růst MeSH
• synapse MeSH
• vápník zásobování a distribuce   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH

distribution of auxin within plant tissues is of great importance for developmental plasticity, including root gravitropic growth. Auxin flow is directed by the subcellular polar distribution and dynamic relocalisation of auxin transporters such as the PIN-FORMED (PIN) efflux carriers, which can be influenced by the main natural plant auxin indole-3-acetic acid (IAA). Anthranilic acid (AA) is an important early precursor of IAA and previously published studies with AA analogues have suggested that AA may also regulate PIN localisation. Using Arabidopsis thaliana as a model species, we studied an AA-deficient mutant displaying agravitropic root growth, treated seedlings with AA and AA analogues and transformed lines to over-produce AA while inhibiting its conversion to downstream IAA precursors. We showed that AA rescues root gravitropic growth in the AA-deficient mutant at concentrations that do not rescue IAA levels. Overproduction of AA affects root gravitropism without affecting IAA levels. Treatments with, or deficiency in, AA result in defects in PIN polarity and gravistimulus-induced PIN relocalisation in root cells. Our results revealed a previously unknown role for AA in the regulation of PIN subcellular localisation and dynamics involved in root gravitropism, which is independent of its better known role in IAA biosynthesis.

• MeSH
• Arabidopsis účinky léků   metabolismus   MeSH
• chinolony farmakologie   MeSH
• gravitropismus fyziologie   MeSH
• kořeny rostlin anatomie a histologie   účinky léků   růst a vývoj   fyziologie   MeSH
• kyseliny indoloctové chemie   metabolismus   MeSH
• mutace genetika   MeSH
• ortoaminobenzoáty chemie   metabolismus   farmakologie   MeSH
• polarita buněk * účinky léků   MeSH
• proteiny huseníčku metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Successful establishment and maintenance of cell polarity is crucial for many aspects of plant development, cellular morphogenesis, response to pathogen attack, and reproduction. Polar cell growth depends on integrating membrane and cell-wall dynamics with signal transduction pathways, changes in ion membrane transport, and regulation of vectorial vesicle trafficking and the dynamic actin cytoskeleton. In this review, we address the critical importance of protein-membrane crosstalk in the determination of plant cell polarity and summarize the role of membrane lipids, particularly minor acidic phospholipids, in regulation of the membrane traffic. We focus on the protein-membrane interface dynamics and discuss the current state of knowledge on three partially overlapping levels of descriptions. Finally, due to their multiscale and interdisciplinary nature, we stress the crucial importance of combining different strategies ranging from microscopic methods to computational modelling in protein-membrane studies.

• MeSH
• fyziologie rostlin * genetika   MeSH
• membránové lipidy metabolismus   MeSH
• membránové proteiny metabolismus   MeSH
• polarita buněk MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné proteiny metabolismus   MeSH
• signální transdukce * MeSH
• transport proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Cell polarity is crucial for the coordinated development of all multicellular organisms. In plants, this is exemplified by the PIN-FORMED (PIN) efflux carriers of the phytohormone auxin: The polar subcellular localization of the PINs is instructive to the directional intercellular auxin transport, and thus to a plethora of auxin-regulated growth and developmental processes. Despite its importance, the regulation of PIN polar subcellular localization remains poorly understood. Here, we have employed advanced live-cell imaging techniques to study the roles of microtubules and actin microfilaments in the establishment of apical polar localization of PIN2 in the epidermis of the Arabidopsis root meristem. We report that apical PIN2 polarity requires neither intact actin microfilaments nor microtubules, suggesting that the primary spatial cue for polar PIN distribution is likely independent of cytoskeleton-guided endomembrane trafficking.

• MeSH
• Arabidopsis cytologie   metabolismus   MeSH
• cytoskelet metabolismus   MeSH
• intracelulární prostor metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• transport proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND AND AIMS: The typical rootless linear shoots of aquatic carnivorous plants exhibit clear, steep polarity associated with very rapid apical shoot growth. The aim of this study was to determine how auxin and cytokinin contents are related to polarity and shoot growth in such plants. METHODS: The main auxin and cytokinin metabolites in separated shoot segments and turions of two carnivorous plants, Aldrovanda vesiculosa and Utricularia australis, were analysed using ultra-high-performance liquid chromatography coupled with triple quad mass spectrometry. KEY RESULTS: In both species, only isoprenoid cytokinins were identified. Zeatin cytokinins predominated in the apical parts, with their concentrations decreasing basipetally, and the trans isomer predominated in A. vesiculosa whereas the cis form was more abundant in U australis. Isopentenyladenine-type cytokinins, in contrast, increased basipetally. Conjugated cytokinin metabolites, the O-glucosides, were present at high concentrations in A. vesiculosa but only in minute amounts in U. australis. N(9)-glucoside forms were detected only in U. australis, with isopentenyladenine-9-glucoside (iP9G) being most abundant. In addition to free indole-3-acetic acid (IAA), indole-3-acetamide (IAM), IAA-aspartate (IAAsp), IAA-glutamate (IAGlu) and IAA-glycine (IAGly) conjugates were identified. CONCLUSIONS: Both species show common trends in auxin and cytokinin levels, the apical localization of the cytokinin biosynthesis and basipetal change in the ratio of active cytokinins to auxin, in favour of auxin. However, our detailed study of cytokinin metabolic profiles also revealed that both species developed different regulatory mechanisms of active cytokinin content; on the level of their degradation, in U. australis, or in the biosynthesis itself, in the case of A. vesiculosa Results indicate that the rapid turnover of these signalling molecules along the shoots is essential for maintaining the dynamic balance between the rapid polar growth and development of the apical parts and senescence of the older, basal parts of the shoots.

• MeSH
• cytokininy metabolismus   MeSH
• Droseraceae fyziologie   MeSH
• kyseliny indoloctové metabolismus   MeSH
• Magnoliopsida fyziologie   MeSH
• masožravci MeSH
• vodní organismy MeSH
• výhonky rostlin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

In many arthropods, there is a change in relative segment size during post-embryonic development, but how segment differential growth is produced is little known. A new dataset of the highest quality specimens of the 429 Myr old trilobite Aulacopleura koninckii provides an unparalleled opportunity to investigate segment growth dynamics and its control in an early arthropod. Morphometric analysis across nine post-embryonic stages revealed a growth gradient in the trunk of A. koninckii. We contrastively tested different growth models referable to two distinct hypotheses of growth control for the developing trunk: (i) a segment-specific control, with individual segments having differential autonomous growth progression, and (ii) a regional control, with segment growth depending on their relative position along the main axis. We show that the trunk growth pattern of A. koninckii was consistent with a regional growth control producing a continuous growth gradient that was stable across all developmental stages investigated. The specific posterior-to-anterior decaying shape of the growth gradient suggests it deriving from the linear transduction of a graded signal, similar to those commonly provided by morphogens. A growth control depending on a form of positional specification, possibly realized through the linear interpretation of a graded signal, may represent the primitive condition for arthropod differential growth along the main body axis, from which the diverse and generally more complex forms of growth control in subsequent arthropods have evolved.

• MeSH
• biologické modely * MeSH
• členovci anatomie a histologie   růst a vývoj   MeSH
• regresní analýza MeSH
• rozvržení tělního plánu fyziologie   MeSH
• tělesné váhy a míry MeSH
• zkameněliny * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• srovnávací studie MeSH
• Geografické názvy
• Česká republika MeSH

The apical-basal axis of the early plant embryo determines the body plan of the adult organism. To establish a polarized embryonic axis, plants evolved a unique mechanism that involves directional, cell-to-cell transport of the growth regulator auxin. Auxin transport relies on PIN auxin transporters, whose polar subcellular localization determines the flow directionality. PIN-mediated auxin transport mediates the spatial and temporal activity of the auxin response machinery that contributes to embryo patterning processes, including establishment of the apical (shoot) and basal (root) embryo poles. However, little is known of upstream mechanisms guiding the (re)polarization of auxin fluxes during embryogenesis. Here, we developed a model of plant embryogenesis that correctly generates emergent cell polarities and auxin-mediated sequential initiation of apical-basal axis of plant embryo. The model relies on two precisely localized auxin sources and a feedback between auxin and the polar, subcellular PIN transporter localization. Simulations reproduced PIN polarity and auxin distribution, as well as previously unknown polarization events during early embryogenesis. The spectrum of validated model predictions suggests that our model corresponds to a minimal mechanistic framework for initiation and orientation of the apical-basal axis to guide both embryonic and postembryonic plant development.

• MeSH
• biologické modely * MeSH
• biologický transport MeSH
• kyseliny indoloctové metabolismus   MeSH
• polarita buněk MeSH
• regulátory růstu rostlin metabolismus   MeSH
• rostlinné proteiny metabolismus   fyziologie   MeSH
• rozvržení tělního plánu MeSH
• semena rostlinná růst a vývoj   MeSH
• transportní proteiny metabolismus   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH