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Optics Express May 2022We propose a bi-layer transmissive metasurface to obtain linear-to-circular polarization conversion in a wideband. The unit cell of each metasurface layer, which has...
We propose a bi-layer transmissive metasurface to obtain linear-to-circular polarization conversion in a wideband. The unit cell of each metasurface layer, which has identical configuration, consists of a Jerusalem-cross-like resonator and a metal strip. A universal equivalent circuit model is employed to guide the design of the polarizer. By analyzing the circuit parameters of the equivalent circuit, four metal strips are symmetrically inserted in each unit cell to broaden the bandwidth of linear-to-circular polarization conversion. Numerical and experimental results show that the polarizer can convert a linearly polarized wave into a circularly polarized wave in a wideband from 6.1 GHz to 12.6 GHz. Compared to the reported designs, the proposed polarization converter has advantages of ultrathin thickness and ultrawideband, and hence can be used in many applications, such as antennas and remote sensors.
PubMed: 36221641
DOI: 10.1364/OE.460685 -
Cold Spring Harbor Perspectives in... Nov 2017Collective cell migration is paramount to morphogenesis and contributes to the pathogenesis of cancer. To migrate directionally and reach their site of destination,... (Review)
Review
Collective cell migration is paramount to morphogenesis and contributes to the pathogenesis of cancer. To migrate directionally and reach their site of destination, migrating cells must distinguish a front and a rear. In addition to polarizing individually, cell-cell interactions in collectively migrating cells give rise to a higher order of polarity, which allows them to move as a supracellular unit. Rather than just conferring adhesion, emerging evidence indicates that cadherin-based adherens junctions intrinsically polarize the cluster and relay mechanical signals to establish both intracellular and supracellular polarity. In this review, we discuss the various functions of adherens junctions in polarity of migrating cohorts.
Topics: Animals; Cell Adhesion; Cell Movement; Cell Polarity; Humans
PubMed: 28246177
DOI: 10.1101/cshperspect.a027854 -
PLoS Biology Oct 2018Apical-basal polarity is essential for the formation and function of epithelial tissues, whereas loss of polarity is a hallmark of tumours. Studies in Drosophila have...
Apical-basal polarity is essential for the formation and function of epithelial tissues, whereas loss of polarity is a hallmark of tumours. Studies in Drosophila have identified conserved polarity factors that define the apical (Crumbs, Stardust, Par-6, atypical protein kinase C [aPKC]), junctional (Bazooka [Baz]/Par-3), and basolateral (Scribbled [Scrib], Discs large [Dlg], Lethal [2] giant larvae [Lgl]) domains of epithelial cells. Because these conserved factors mark equivalent domains in diverse types of vertebrate and invertebrate epithelia, it is generally assumed that this system underlies polarity in all epithelia. Here, we show that this is not the case, as none of these canonical factors are required for the polarisation of the endodermal epithelium of the Drosophila adult midgut. Furthermore, like vertebrate epithelia but not other Drosophila epithelia, the midgut epithelium forms occluding junctions above adherens junctions (AJs) and requires the integrin adhesion complex for polarity. Thus, Drosophila contains two types of epithelia that polarise by fundamentally different mechanisms. This diversity of epithelial types may reflect their different developmental origins, junctional arrangement, or whether they polarise in an apical-basal direction or vice versa. Since knock-outs of canonical polarity factors in vertebrates often have little or no effect on epithelial polarity and the Drosophila midgut shares several common features with vertebrate epithelia, this diversity of polarity mechanisms is likely to be conserved in other animals.
Topics: Animals; Animals, Genetically Modified; Body Patterning; Cell Polarity; Digestive System; Drosophila Proteins; Drosophila melanogaster; Epithelial Cells; Epithelium; Female; Genes, Insect; Intercellular Junctions; Models, Biological
PubMed: 30339698
DOI: 10.1371/journal.pbio.3000041 -
BioRxiv : the Preprint Server For... Oct 2023Atypical protein kinase C (aPKC) is a major regulator of cell polarity. Acting in conjunction with Par6, Par3 and the small GTPase Cdc42, aPKC becomes asymmetrically...
Atypical protein kinase C (aPKC) is a major regulator of cell polarity. Acting in conjunction with Par6, Par3 and the small GTPase Cdc42, aPKC becomes asymmetrically localised and drives the polarisation of cells. aPKC activity is crucial for its own asymmetric localisation, suggesting a hitherto unknown feedback mechanism contributing to polarisation. Here we show in zygotes that the feedback relies on CDC-42 phosphorylation at serine 71 by aPKC, which in turn results in aPKC dissociation from CDC-42. The dissociated aPKC then associates with PAR-3 clusters, which are transported anteriorly by actomyosin-based cortical flow. Moreover, the turnover of aPKC-mediated CDC-42 phosphorylation regulates the organisation of the actomyosin cortex that drives aPKC asymmetry. Given the widespread role of aPKC and Cdc42 in cell polarity, this form of self-regulation of aPKC may be vital for the robust polarisation of many cell types.
PubMed: 38009101
DOI: 10.1101/2023.10.27.563985 -
Plant Communications Jan 2024The phytohormone auxin, and its directional transport through tissues, plays a fundamental role in the development of higher plants. This polar auxin transport...
The phytohormone auxin, and its directional transport through tissues, plays a fundamental role in the development of higher plants. This polar auxin transport predominantly relies on PIN-FORMED (PIN) auxin exporters. Hence, PIN polarization is crucial for development, but its evolution during the rise of morphological complexity in land plants remains unclear. Here, we performed a cross-species investigation by observing the trafficking and localization of endogenous and exogenous PINs in two bryophytes, Physcomitrium patens and Marchantia polymorpha, and in the flowering plant Arabidopsis thaliana. We confirmed that the GFP fusion did not compromise the auxin export function of all examined PINs by using a radioactive auxin export assay and by observing the phenotypic changes in transgenic bryophytes. Endogenous PINs polarize to filamentous apices, while exogenous Arabidopsis PINs distribute symmetrically on the membrane in both bryophytes. In the Arabidopsis root epidermis, bryophytic PINs have no defined polarity. Pharmacological interference revealed a strong cytoskeletal dependence of bryophytic but not Arabidopsis PIN polarization. The divergence of PIN polarization and trafficking is also observed within the bryophyte clade and between tissues of individual species. These results collectively reveal the divergence of PIN trafficking and polarity mechanisms throughout land plant evolution and the co-evolution of PIN sequence-based and cell-based polarity mechanisms.
Topics: Arabidopsis; Arabidopsis Proteins; Indoleacetic Acids; Plant Roots; Membrane Transport Proteins
PubMed: 37528584
DOI: 10.1016/j.xplc.2023.100669 -
International Journal of Molecular... Jul 2018Macrophages can polarize into two different states (M1 and M2), which play contrasting roles during pathogenesis or tissue damage. M1 polarized macrophages produce... (Review)
Review
Macrophages can polarize into two different states (M1 and M2), which play contrasting roles during pathogenesis or tissue damage. M1 polarized macrophages produce pro-inflammatory cytokines and mediators resulting in inflammation, while M2 macrophages have an anti-inflammatory effect. Secretion of appropriate cytokines and chemokines from macrophages can lead to the modification of the microenvironment for bridging innate and adaptive immune responses. Increasing evidence suggests that polarized macrophages are pivotal for disease progression, and the regulation of macrophage polarization may provide a new approach in therapeutic treatment of inflammation-related diseases, including cancer, obesity and metabolic diseases, fibrosis in organs, brain damage and neuron injuries, and colorectal disease. Polarized macrophages affect the microenvironment by secreting cytokines and chemokines while cytokines or mediators that are produced by resident cells or tissues may also influence macrophages behavior. The interplay of macrophages and other cells can affect disease progression, and therefore, understanding the activation of macrophages and the interaction between polarized macrophages and disease progression is imperative prior to taking therapeutic or preventive actions. Manipulation of macrophages can be an entry point for disease improvement, but the mechanism and potential must be understood. In this review, some advanced studies regarding the role of macrophages in different diseases, potential mechanisms involved, and intervention of drugs or phytochemicals, which are effective on macrophage polarization, will be discussed.
Topics: Animals; Cell Polarity; Cytokines; Humans; Inflammation; Macrophage Activation; Macrophages; Phytochemicals
PubMed: 30060570
DOI: 10.3390/ijms19082208 -
Cold Spring Harbor Perspectives in... Aug 2009During Drosophila development, neuroblasts divide to generate progeny with two different fates. One daughter cell self-renews to maintain the neuroblast pool, whereas... (Review)
Review
During Drosophila development, neuroblasts divide to generate progeny with two different fates. One daughter cell self-renews to maintain the neuroblast pool, whereas the other differentiates to populate the central nervous system. The difference in fate arises from the asymmetric distribution of proteins that specify either self-renewal or differentiation, which is brought about by their polarization into separate apical and basal cortical domains during mitosis. Neuroblast symmetry breaking is regulated by numerous proteins, many of which have only recently been discovered. The atypical protein kinase C (aPKC) is a broad regulator of polarity that localizes to the neuroblast apical cortical region and directs the polarization of the basal domain. Recent work suggests that polarity can be explained in large part by the mechanisms that restrict aPKC activity to the apical domain and those that couple asymmetric aPKC activity to the polarization of downstream factors. Polarized aPKC activity is created by a network of regulatory molecules, including Bazooka/Par-3, Cdc42, and the tumor suppressor Lgl, which represses basal recruitment. Direct phosphorylation by aPKC leads to cortical release of basal domain factors, preventing them from occupying the apical domain. In this framework, neuroblast polarity arises from a complex system that orchestrates robust aPKC polarity, which in turn polarizes substrates by coupling phosphorylation to cortical release.
Topics: Animals; Body Patterning; Cell Differentiation; Cell Division; Drosophila; Models, Biological; Neoplasms; Neurons; Protein Isoforms; Protein Kinase C; Spindle Apparatus; Stem Cells
PubMed: 20066083
DOI: 10.1101/cshperspect.a001388 -
ELife Dec 2022Grass stomata recruit lateral subsidiary cells (SCs), which are key to the unique stomatal morphology and the efficient plant-atmosphere gas exchange in grasses....
Grass stomata recruit lateral subsidiary cells (SCs), which are key to the unique stomatal morphology and the efficient plant-atmosphere gas exchange in grasses. Subsidiary mother cells (SMCs) strongly polarise before an asymmetric division forms a SC. Yet apart from a proximal polarity module that includes PANGLOSS1 (PAN1) and guides nuclear migration, little is known regarding the developmental processes that form SCs. Here, we used comparative transcriptomics of developing wild-type and SC-less leaves in the genetic model grass to identify novel factors involved in SC formation. This approach revealed BdPOLAR, which forms a novel, distal polarity domain in SMCs that is opposite to the proximal PAN1 domain. Both polarity domains are required for the formative SC division yet exhibit various roles in guiding pre-mitotic nuclear migration and SMC division plane orientation, respectively. Nonetheless, the domains are linked as the proximal domain controls polarisation of the distal domain. In summary, we identified two opposing polarity domains that coordinate the SC division, a process crucial for grass stomatal physiology.
Topics: Plant Stomata; Cell Division; Plant Leaves; Asymmetric Cell Division; Poaceae; Cell Polarity
PubMed: 36537077
DOI: 10.7554/eLife.79913 -
Current Opinion in Genetics &... Dec 2011Cell polarity is typically oriented by external cues such as cell-cell contacts, chemoattractants, or morphogen gradients. In the absence of such cues, however, many... (Review)
Review
Cell polarity is typically oriented by external cues such as cell-cell contacts, chemoattractants, or morphogen gradients. In the absence of such cues, however, many cells can spontaneously polarize in a random direction, suggesting the existence of an internal polarity-generating mechanism whose direction can be spatially biased by external cues. Spontaneous 'symmetry-breaking' polarization is likely to involve an autocatalytic process set off by small random fluctuations. Here we review recent work on the nature of the autocatalytic process in budding yeast and on the question of why polarized cells only develop a single 'front'.
Topics: Actins; Cell Differentiation; Cell Membrane; Cell Polarity; Models, Biological; Morphogenesis; Multigene Family; Saccharomycetales; Systems Biology; cdc42 GTP-Binding Protein, Saccharomyces cerevisiae
PubMed: 21955794
DOI: 10.1016/j.gde.2011.09.007 -
ELife Jun 2017Polarity is a shared feature of most cells. In epithelia, apical-basal polarity often coexists, and sometimes intersects with planar cell polarity (PCP), which orients...
Polarity is a shared feature of most cells. In epithelia, apical-basal polarity often coexists, and sometimes intersects with planar cell polarity (PCP), which orients cells in the epithelial plane. From a limited set of core building blocks (e.g. the Par complexes for apical-basal polarity and the Frizzled/Dishevelled complex for PCP), a diverse array of polarized cells and tissues are generated. This suggests the existence of little-studied tissue-specific factors that rewire the core polarity modules to the appropriate conformation. In sensory organ precursors (SOPs), the core PCP components initiate the planar polarization of apical-basal determinants, ensuring asymmetric division into daughter cells of different fates. We show that Meru, a RASSF9/RASSF10 homologue, is expressed specifically in SOPs, recruited to the posterior cortex by Frizzled/Dishevelled, and in turn polarizes the apical-basal polarity factor Bazooka (Par3). Thus, Meru belongs to a class of proteins that act cell/tissue-specifically to remodel the core polarity machinery.
Topics: Animals; Asymmetric Cell Division; Cell Polarity; Drosophila; Drosophila Proteins; Gene Expression Profiling; Gene Expression Regulation, Developmental; Vesicular Transport Proteins
PubMed: 28665270
DOI: 10.7554/eLife.25014