Graves' disease (GD) is a thyroid-specific autoimmune disease with a high prevalence worldwide. The disease is primarily mediated by B cells, which produce autoantibodies against the ...thyroid-stimulating hormone receptor (TSHR), chronically stimulating it and leading to high levels of thyroid hormones in the body. Interest in characterizing the immune response in GD has motivated many phenotyping studies. The immunophenotype of the cells involved and the interplay between them and their secreted factors are crucial to understanding disease progression and future treatment options. T cell populations are markedly distinct, including increased levels of Th17 and follicular helper T cells (Tfh), while Treg cells appear to be impaired. Some B cells subsets are autoreactive, and anti-TSHR antibodies are the key disease-causing outcome of this interplay. Though some consensus across phenotyping studies will be discussed here, there are also complexities that are yet to be resolved. A better understanding of the immunophenotype of Graves' disease can lead to improved treatment strategies and novel drug targets.
Freezing triggers extracellular ice formation leading to cell dehydration and deformation during a freeze–thaw cycle. Many plant species increase their freezing tolerance during exposure to low, ...non‐freezing temperatures, a process termed cold acclimation. In addition, exposure to mild freezing temperatures after cold acclimation evokes a further increase in freezing tolerance (sub‐zero acclimation). Previous transcriptome and proteome analyses indicate that cell wall remodelling may be particularly important for sub‐zero acclimation. In the present study, we used a combination of immunohistochemical, chemical and spectroscopic analyses to characterize the cell walls of Arabidopsis thaliana and characterized a mutant in the XTH19 gene, encoding a xyloglucan endotransglucosylase/hydrolase (XTH). The mutant showed reduced freezing tolerance after both cold and sub‐zero acclimation, compared to the Col‐0 wild type, which was associated with differences in cell wall composition and structure. Most strikingly, immunohistochemistry in combination with 3D reconstruction of centres of rosette indicated that epitopes of the xyloglucan‐specific antibody LM25 were highly abundant in the vasculature of Col‐0 plants after sub‐zero acclimation but absent in the XTH19 mutant. Taken together, our data shed new light on the potential roles of cell wall remodelling for the increased freezing tolerance observed after low temperature acclimation.
xth19 mutant had reduced freezing tolerance after cold or sub‐zero acclimation. Microscopic and biochemical characterization of the cell wall indicated altered xyloglucan deposition in xth19 after sub‐zero acclimation showing the importance of cell wall remodelling for increased freezing tolerance.
Approximately 1% of plant proteins are predicted to be post‐translationally modified with a glycosylphosphatidylinositol (GPI) anchor that tethers the polypeptide to the outer leaflet of the plasma ...membrane. Whereas the synthesis and structure of GPI anchors is largely conserved across eukaryotes, the repertoire of functional domains present in the GPI‐anchored proteome has diverged substantially. In plants, this includes a large fraction of the GPI‐anchored proteome being further modified with plant‐specific arabinogalactan (AG) O‐glycans. The importance of the GPI‐anchored proteome to plant development is underscored by the fact that GPI biosynthetic null mutants exhibit embryo lethality. Mutations in genes encoding specific GPI‐anchored proteins (GAPs) further supports their contribution to diverse biological processes, occurring at the interface of the plasma membrane and cell wall, including signaling, cell wall metabolism, cell wall polymer cross‐linking, and plasmodesmatal transport. Here, we review the literature concerning plant GPI‐anchored proteins, in the context of their potential to act as molecular hubs that mediate interactions between the plasma membrane and the cell wall, and their potential to transduce the signal into the protoplast and, thereby, activate signal transduction pathways.
GPI anchors attach proteins to the outer leaflet of the plasma membrane. Although well characterised in mammals and yeast, less is known about the biosynthesis and structure of GPI anchors in plants. In this review, we cover the importance of plant GPI‐anchored proteins at the plasma membrane‐cell wall interface.
Plant cells are surrounded by highly dynamic cell walls that play important roles regulating aspects of plant development. Recent advances in visualization and measurement of cell wall properties ...have enabled accumulation of new data about wall architecture and biomechanics. This has resulted in greater understanding of the dynamics of cell wall deposition and remodeling. The cell wall is the first line of defense against different adverse abiotic and biotic environmental influences. Different abiotic stress conditions such as salinity, drought, and frost trigger production of Reactive Oxygen Species (ROS) which act as important signaling molecules in stress activated cellular responses. Detection of ROS by still-elusive receptors triggers numerous signaling events that result in production of different protective compounds or even cell death, but most notably in stress-induced cell wall remodeling. This is mediated by different plant hormones, of which the most studied are jasmonic acid and brassinosteroids. In this review we highlight key factors involved in sensing, signal transduction, and response(s) to abiotic stress and how these mechanisms are related to cell wall-associated stress acclimatization. ROS, plant hormones, cell wall remodeling enzymes and different wall mechanosensors act coordinately during abiotic stress, resulting in abiotic stress wall acclimatization, enabling plants to survive adverse environmental conditions.
Summary
Secondary cell walls (SCWs) in stem xylem vessel and fibre cells enable plants to withstand the enormous compressive forces associated with upright growth. It remains unclear if xylem vessel ...and fibre cells can directly sense mechanical stimuli and modify their SCW during development.
We provide evidence that Arabidopsis SCW‐specific Fasciclin‐Like Arabinogalactan‐proteins 11 (FLA11) and 12 (FLA12) are possible cell surface sensors regulating SCW development in response to mechanical stimuli. Plants overexpressing FLA11 (OE‐FLA11) showed earlier SCW development compared to the wild‐type (WT) and altered SCW properties that phenocopy WT plants under compression stress. By contrast, OE‐FLA12 stems showed higher cellulose content compared to WT plants, similar to plants experiencing tensile stress.
fla11, OE‐FLA11, fla12, and OE‐FLA12 plants showed altered SCW responses to mechanical stress compared to the WT. Quantitative polymerase chain reaction (qPCR) and RNA‐seq analysis revealed the up‐regulation of genes and pathways involved in stress responses and SCW synthesis and regulation. Analysis of OE‐FLA11 nst1 nst3 plants suggests that FLA11 regulation of SCWs is reliant on classical transcriptional networks.
Our data support the involvement of FLA11 and FLA12 in SCW sensing complexes to fine‐tune both the initiation of SCW development and the balance of lignin and cellulose synthesis/deposition in SCWs during development and in response to mechanical stimuli.
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