Improved reactive aldehyde, salt and cadmium tolerance of transgenic barley due to the expression of aldo–keto reductase genes

Under various stress conditions, plant cells are exposed to oxidative damage which triggers lipid peroxidation. Lipid peroxide breakdown products include protein crosslinking reactive aldehydes. These are highly damaging to living cells. Stress-protective aldo–keto reductase (AKR) enzymes are able to recognise and modify these molecules, reducing their toxicity. AKRs not only modify reactive aldehydes but may synthesize osmoprotective sugar alcohols as well. The role of these mixed function enzymes was investigated under direct reactive aldehyde, heavy metal and salt stress conditions. Transgenic barley (Hordeum vulgare L.) plants constitutively expressing AKR enzymes derived from either thale cress (Arabidopsis thaliana) (AKR4C9) or alfalfa (Medicago sativa) (MsALR) were studied. Not only AKR4C9 but MsALR expressing plants were also found to produce more sorbitol than the non-transgenic (WT) barley. Salinity tolerance of genetically modified (GM) plants improved, presumably as a consequence of the enhanced sorbitol content. The MsALR enzyme expressing line (called 51) exhibited almost no symptoms of salt stress. Furthermore, both transgenes were shown to increase reactive aldehyde (glutaraldehyde) tolerance. Transgenic plants also exhibited better cadmium tolerance compared to WT, which was considered to be an effect of the reduction of reactive aldehyde molecules. Transgenic barley expressing either thale cress or alfalfa derived enzyme showed improved heavy metal and salt tolerance. Both can be explained by higher detoxifying and sugar alcohol producing activity. Based on the presented data, we consider AKRs as very effective stress-protective enzymes and their genes provide promising tools in the improvement of crops through gene technology

Extracellular vesicles transmit epithelial growth factor activity in the intestinal stem cell niche.

Extracellular vesicles (EV) are membrane-surrounded vesicles that represent a novel way of intercellular communication by carrying biologically important molecules in a concentrated and protected form. The intestinal epithelium is continuously renewed by a small proliferating intestinal stem cell population (ISC), residing at the bottom of the intestinal crypts in a specific microenvironment, the stem cell niche. By using 3D mouse and human intestinal organoids, we show that intestinal fibroblast-derived EVs are involved in forming the ISC niche by transmitting Wnt and epidermal growth factor (EGF) activity. With a mouse model that expresses EGFP in the Lgr5+ ISCs we prove that loss in ISC number in the absence of EGF is prevented by fibroblast-derived EVs. Furthermore, we demonstrate that intestinal fibroblast-derived EVs carry EGF family members, such as amphiregulin. Mechanistically, blocking EV-bound amphiregulin inhibited the EV-induced survival of organoids. In contrast, EVs have no role in transporting R-Spondin, a critical niche factor amplifying Wnt signalling. Collectively, we prove the important role of fibroblast-derived EVs as a novel transmission mechanism of factors in the normal ISC niche. © AlphaMed Press 2019 SIGNIFICANCE STATEMENT: Intestinal stem cells (ISC) reside in a specific microenvironment in the intestinal epithelium, the ISC niche. Although they are critical in maintaining tissue integrity, the transmission of ISC niche factors is still not well known. Extracellular vesicles (EV) carry biologically active molecules in a membrane-surrounded form, thus, representing a novel way of intercellular communication. Here we provide evidence that fibroblast-derived EVs transport epidermal growth factor activity, one of the critical niche factors, by carrying amphiregulin, thus, they represent a novel way of intercellular signal transmission mechanism for normal ISCs

Nanotubes connecting B lymphocytes: High impact of differentiation-dependent lipid composition on their growth and mechanics

Nanotubes (NTs) are thin, long membranous structures forming novel, yet poorly known communication pathways between various cell types. Key mechanisms controlling their growth still remained poorly understood. Since NT-forming capacity of immature and mature B cells was found largely different, we investigated how lipid composition and molecular order of the membrane affect NT-formation. Screening B cell lines with various differentiation stages revealed that NT-growth linearly correlates with membrane ganglioside levels, while it shows maximum as a function of cholesterol level. NT-growth of B lymphocytes is promoted by raftophilic phosphatidylcholine and sphingomyelin species, various glycosphingolipids, and docosahexaenoic acid-containing inner leaflet lipids, through supporting membrane curvature, as demonstrated by comparative lipidomic analysis of mature versus immature B cell membranes. Targeted modification of membrane cholesterol and sphingolipid levels altered NT-forming capacity confirming these findings, and also highlighted that the actual lipid raft number may control NT-growth via defining the number of membrane-F-actin coupling sites. Atomic force microscopic mechano-manipulation experiments further proved that mechanical properties (elasticity or bending stiffness) of B cell NTs also depend on the actual membrane lipid composition. Data presented here highlight importance of the lipid side in controlling intercellular, nanotubular, regulatory communications in the immune system

Skin-homing CD8+ T cells preferentially express GPI-anchored peptidase inhibitor 16, an inhibitor of cathepsin K

This study sought to identify novel CD8+ T cell homing markers by studying acute graft versus host disease (aGvHD), typically involving increased T cell homing to the skin and gut. FACS-sorted skin-homing (CD8β+ /CLA+ ), gut-homing (CD8β+ /integrinβ7+ ), and reference (CD8β+ /CLA- /integrinβ7- ) T cells were compared in patients affected by cutaneous and/or gastrointestinal aGVHD. Microarray analysis, qPCR, and flow cytometry revealed increased expression of peptidase inhibitor 16 (PI16) in skin-homing CD8+ T cells. Robust association of PI16 with skin homing was confirmed in all types of aGvHD and in healthy controls, too. PI16 was not observed on CLA+ leukocytes other than T cells. Induction of PI16 expression on skin-homing T cells occurred independently of vitamin D3. Among skin-homing T cells, PI16 expression was most pronounced in memory-like CD45RO+ /CD127+ /CD25+ /CD69- /granzyme B- cells. PI16 was confined to the plasma membrane, was GPI-anchored, and was lost upon restimulation of memory CD8+ T cells. Loss of PI16 occurred by downregulation of PI16 transcription, and not by Phospholipase C (PLC)- or Angiotensin-converting enzyme (ACE)-mediated shedding, or by protein recycling. Inhibitor screening and pull-down experiments confirmed that PI16 inhibits cathepsin K, but may not bind to other skin proteases. These data link PI16 to skin-homing CD8+ T cells, and raise the possibility that PI16 may regulate cutaneous cathepsin K

Mast cell secretome: Soluble and vesicular components

Mast cells are multifunctional master cells implicated in both innate and adaptive immune responses. Their role has been best characterized in allergy and anaphylaxis; however, emerging evidences support their contribution to a wide variety of human diseases. Mast cells, being capable of both degranulation and subsequent recovery, have recently attracted substantial attention as also being rich sources of secreted extracellular vesicles (including exosomes and microvesicles). Along with secreted de novo synthesized soluble molecules and secreted preformed granules, the membrane-enclosed extracellular vesicles represent a previously unexplored part of the mast cell secretome. In this review article we summarize available data regarding the different soluble molecules and membrane-enclosed structures secreted by mast cells. Furthermore, we provide an overview of the release mechanisms including degranulation, piecemeal degranulation, transgranulation, and secretion of different types of extracellular vesicles. Finally, we aim to give a summary of the known biological functions associated with the different mast cell-derived secretion products. The increasingly recognized complexity of mast cell secretome may provide important novel clues to processes by which mast cells contribute to the development of different pathologies and are capable of orchestrating immune responses both in health and disease