The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Jonathan D. G. Jones - One of the best experts on this subject based on the ideXlab platform.
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Mutual potentiation of plant immunity by cell-surface and Intracellular Receptors
Nature, 2021Co-Authors: Bruno Pok Man Ngou, Hee-kyung Ahn, Pingtao Ding, Jonathan D. G. JonesAbstract:The plant immune system involves cell-surface Receptors that detect intercellular pathogen-derived molecules, and Intracellular Receptors that activate immunity upon detection of pathogen-secreted effector proteins that act inside the plant cell. Immunity mediated by surface Receptors has been extensively studied^ 1 , but that mediated by Intracellular Receptors has rarely been investigated in the absence of surface-receptor-mediated immunity. Furthermore, interactions between these two immune pathways are poorly understood. Here, by activating Intracellular Receptors without inducing surface-receptor-mediated immunity, we analyse interactions between these two distinct immune systems in Arabidopsis . Pathogen recognition by surface Receptors activates multiple protein kinases and NADPH oxidases, and we find that Intracellular Receptors primarily potentiate the activation of these proteins by increasing their abundance through several mechanisms. Likewise, the hypersensitive response that depends on Intracellular Receptors is strongly enhanced by the activation of surface Receptors. Activation of either immune system alone is insufficient to provide effective resistance against the bacterial pathogen Pseudomonas syringae . Thus, immune pathways activated by cell-surface and Intracellular Receptors in plants mutually potentiate to activate strong defences against pathogens. These findings reshape our understanding of plant immunity and have broad implications for crop improvement. In Arabidopsis , two distinct types of immunity—that mediated by cell-surface Receptors and that mediated by Intracellular Receptors—interact with and mutually enhance each other to provide effective defence against pathogens.
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Mutual Potentiation of Plant Immunity by Cell-surface and Intracellular Receptors
2020Co-Authors: Bruno Pok Man Ngou, Hee-kyung Ahn, Pingtao Ding, Jonathan D. G. JonesAbstract:The plant immune system involves cell-surface Receptors that detect intercellular pathogen-derived molecules, and Intracellular Receptors that activate immunity upon detection of pathogen-secreted effectors that act inside the plant cell. Surface receptor-mediated immunity has been extensively studied but in authentic interactions between plants and microbial pathogens, its presence impedes study of Intracellular receptor-mediated immunity alone. How these two immune pathways interact is poorly understood. Here, we reveal mutual potentiation between these two recognition-dependent defense pathways. Recognition by surface Receptors activates multiple protein kinases and NADPH oxidases, whereas Intracellular Receptors primarily elevate abundance of these proteins. Reciprocally, the Intracellular receptor-dependent hypersensitive cell death response is strongly enhanced by activation of surface Receptors. Activation of either immune system alone is insufficient to provide effective resistance against Pseudomonas syringae. Thus, immune pathways activated by cell-surface and Intracellular Receptors mutually potentiate to activate strong defense that thwarts pathogens. By studying the activation of Intracellular Receptors in the absence of surface receptor-mediated immunity, we have dissected the relationship between the two distinct immune systems. These findings reshape our understanding of plant immunity and have broad implications for crop improvement.
Daria Mochly-rosen - One of the best experts on this subject based on the ideXlab platform.
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Phospholipase C-gamma 1 binding to Intracellular Receptors for activated protein kinase C.
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Marie-helene Disatnik, G Carpenter, Sm Hernandez-sotomayor, G Jones, Daria Mochly-rosenAbstract:Abstract Phospholipase C-gamma 1 (PLC-gamma 1; EC 3.1.4.11) hydrolyzes phosphatidylinositol 4,5-bisphosphate to generate diacylglycerol and inositol 1,4,5-trisphosphate and is activated in response to growth factor stimulation and tyrosine phosphorylation. Concomitantly, the enzyme translocates from the cytosol to the particulate cell fraction. A similar process of activation-induced translocation from the cytosol to the cell particulate fraction has also been described for protein kinase C (PKC). We have previously shown that activated PKC binds to specific receptor proteins, Receptors for activated C kinase, or RACKs, of approximately 30 kDa. Here, we show that PLC-gamma 1 bound to these RACKs and inhibited subsequent PKC binding to RACKs. However, unlike PKC, the binding of PLC-gamma 1 to RACKs did not require phospholipids and calcium. After epidermal growth factor treatment of intact A-431 cells, the binding of PLC-gamma 1 to RACKs increased as compared with PLC-gamma 1 from control cells. This increase in PLC-gamma 1 binding to RACKs was due to the phosphorylation of PLC-gamma 1. Additional data indicated that PLC-gamma 1 binds to RACKs in solution; epidermal growth factor receptor-dependent PLC-gamma 1 phosphorylation and activation decreased in the presence of RACKs. It is possible that, in vivo, PLC-gamma 1 associates with RACKs or with other PLC-gamma 1-specific anchoring proteins in the particulate cell fraction. Since a PKC C2 homologous region is present in PLC-gamma 1, the C2 region may mediate the activation-induced translocation of the enzyme to the cell particulate fraction and the anchoring protein-PLC-gamma 1 complex may be the active translocated form of PLC-gamma 1.
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Inhibition of protein kinase C function by injection of Intracellular Receptors for the enzyme.
Biochemical and biophysical research communications, 1992Co-Authors: Bradley L. Smith, Daria Mochly-rosenAbstract:Abstract We tested the hypothesis that the translocation and function of protein kinase C (PKC) requires the binding of PKC to its Intracellular Receptors (RACKs), using insulin-induced maturation of Xenopus oocytes. We show that after exposure of oocytes to insulin, PKC translocated from the cytosol to the particulate fraction. PKC is also required for insulin-induced oocyte maturation: microinjection of a PKC inhibitory peptide delayed maturation. To determine whether translocation of PKC was a result of the binding of PKC to the RACKS in the particulate fraction, we microinjected purified rat brain RACKS into oocytes before insulin exposure. Microinjection of RACKS, but not inactive phosphorylated RACKS, inhibited PKC translocation and delayed oocyte maturation. These results suggest an in vivo role for RACKS in a function mediated by PKC.
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Intracellular Receptors for activated protein kinase C. Identification of a binding site for the enzyme.
The Journal of biological chemistry, 1991Co-Authors: Daria Mochly-rosen, Hanita Khaner, José A. López, Bradley L. SmithAbstract:Protein kinase C (PKC) isozymes comprise a family of cytosolic enzymes that translocate to different Intracellular sites on activation. We have recently characterized at least two Intracellular receptor proteins for PKC (termed RACKs for Receptors for activated C-kinase) in the Triton-insoluble material of the particulate fraction from neonatal rat heart. Here, we identify a sequence that appears to resemble the PKC binding site on these RACKs. A peptide (peptide I) with the sequence KGDYEKILVALCGGN bound PKC, and binding was markedly increased in the presence of PKC activators. Furthermore, peptide I inhibited PKC binding to RACKs in a dose-dependent manner. These data suggest that these RACKs have a common PKC binding sequence. Since peptide I inhibited PKC binding to RACKs in vitro, it may be a useful tool to inhibit PKC translocation and subsequent function in vivo.
J A García-sáinz - One of the best experts on this subject based on the ideXlab platform.
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Activated protein kinase C binds to Intracellular Receptors in rat hepatocytes.
Biochemical Journal, 1993Co-Authors: Martha Robles-flores, J A García-sáinzAbstract:The aim of this study was to identify in rat hepatocytes cellular polypeptides that bind protein kinase C (PKC) and may influence its activity and its compartmentation. At least seven proteins, with apparent M(r) values between 12,000 and 36,000, that behave like Receptors for Activated C-Kinase (RACKs) were found in the Triton-X-100-insoluble fraction of these cells; i.e. PKC bound to these polypeptides when it was in its active form. RACKS seem to be PKC substrates. Studies using isotype-specific PKC antibodies suggested some selectivity of RACKs, i.e. RACKs in the M(r) approximately 28,000-36,000 region bound PKC-alpha and PKC-beta in the presence of phosphatidylserine, diolein and Ca2+, whereas those of M(r) approximately 12,000-14,000 bound all isoforms studied, and, in contrast with the other RACKs, they did this even in the absence of Ca2+. Peptide I (KGDYEKILVALCGGN), which has a sequence suggested to be involved in the PKC-RACKs interaction [Mochly-Rosen, Khaner, Lopez and Smith (1991) J. Biol. Chem. 266, 14866-14868], inhibited PKC activity. Preincubation of RACKs with antisera directed against peptide I prevented PKC binding to them. The data suggest that peptide I blocks PKC binding to RACKs by two mechanisms: inhibition of PKC activity and competition with a putative binding site.
Jeanne Feger - One of the best experts on this subject based on the ideXlab platform.
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Vasopressin-induced changes in receptor-mediated endocytosis of asialoglycoprotein in rat hepatocytes.
Biology of the cell, 1991Co-Authors: Sophie Gil-falgon, Christophe Lamaze, Jeanne FegerAbstract:The ability of second messengers to modulate receptor-mediated endocytosis was studied on isolated rat hepatocytes. A 20-min preincubation with vasopressin was used as a modulation. We observed a 20% inactivation of both surface and Intracellular Receptors, with no change in the affinity of those remaining active. The internalization and dissociation of a synchronous wave of ligand was not affected, but its degradation was partially inhibited. Our observations suggest that second messengers such as Intracellular calcium and diacylglycerol play a complex role in the Intracellular trafficking associated with endocytosis.
M J Thornton - One of the best experts on this subject based on the ideXlab platform.
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Oestrogen functions in skin and skin appendages.
Expert Opinion on Therapeutic Targets, 2005Co-Authors: M J ThorntonAbstract:Oestrogens have significant effects on different cell types important in skin physiology, including the epidermal keratinocytes, dermal fibroblasts and melanocytes. In addition, they can also modulate skin appendages such as the hair follicle, the sebaceous gland and the apocrine glands. Oestrogens may also have important modulatory roles in events such as skin ageing, pigmentation, hair growth, sebum production and skin cancer. It is now recognised that oestrogens can modulate their actions via two distinct Intracellular Receptors (ERα and ERβ) or via cell surface Receptors, which activate specific second messenger signalling pathways. This paper highlights the effects of oestrogens on different components of the skin and reviews some of the more recent developments in terms of receptor expression and cell signalling pathways.
