Search results for "SIGNALISATION"
showing 10 items of 20 documents
Plasma membrane sterol complexation, generated by filipin, triggers signaling responses in tobacco cells
2010
International audience; The effects of changes in plasma membrane (PM) sterol lateral organization and availability on the control of signaling pathways have been reported in various animal systems, but rarely assessed in plant cells. In the present study, the pentaene macrolide antibiotic filipin III, commonly used in animal systems as a sterol sequestrating agent, was applied to tobacco cells. We show that filipin can be used at a non-lethal concentration that still allows an homogeneous labeling of the plasma membrane and the formation of filipin-sterol complexes at the ultrastructural level. This filipin concentration triggers a rapid and transient NADPH oxidase-dependent production of …
7-ketocholesterol and 7β-hydroxycholesterol: in vitro and animal models used to characterize their activities and to identify molecules preventing th…
2020
International audience; Oxysterols are molecules derived by the oxidation of cholesterol and can be formed either by auto-oxidation, enzymatically or by both processes. Among the oxysterols formed by auto-oxidation, 7-ketocholesterol and 7beta-hydroxycholesterol are the main forms generated. These oxysterols, formed endogenously and brought in large quantities by certain foods, have major cytotoxic properties. They are powerful inducers of oxidative stress, inducing dysfunction of organelles (mitochondria, lysosomes and peroxisomes) that can cause cell death. These molecules are often identified in increased amounts in common pathological states such as cardiovascular diseases, certain eye …
Characterization of grapevine defense reactions and identification of elicitors : the endopolygalacturonase 1 from Botrytis cinerea, an avirulence fu…
2002
The fight against grapevine pathogens is mainly carried out by pesticides, the continued use of which is harmful to the environment and the health of users and consumers. The main organizations in charge of viticulture set as a priority the research and use of alternatives to chemical control. However, the genetic improvement of the vine is prohibited in AOC vineyards to preserve the varietal typicity, partly responsible for the quality of the wines. In addition, research undertaken some fifteen years ago reveals that plants have their own immune defenses, which they activate on contact with the microorganisms they recognize via molecules called elicitors. In this context, the objective of …
Type-2 histones deacetylases and cryptogein-induced cell death in tabacco
2011
Cryptogein, which is secreted by the oomycete Phytophthora cryptogea, is a proteinaceous elicitor of plant defense reactions that activates a set of signaling events leading to the hypersensitive response and to systemic acquired resistance. Although the early cytosolic signaling events induced by cryptogein are well described, the only nuclear events characterized to date are the variations in free calcium concentrations and defense-related gene expression. The characterization of the activation of cytosolic protein kinases, including WIPK and SIPK, by phosphorylation in response to cryptogein highlights the key-role played by posttranslational modifications in cryptogein-induced signaling…
Gènes fongiques liés au calcium impliqués dans la mycorhize à arbuscules
2012
Fluctuations in intracellular (Ca2+) calcium levels generate signaling events and regulate different cellular processes. Whilst the implication of Ca2+ in plant cell responses during arbuscular mycorrhiza (AM) interactions is well documented, nothing is known about the regulation or role of this secondary meesenger in the fungal symbiont. The molecular basis of fungal calcium homeostasis in the AM symbiosis was analyzed by investigating the expression of Ca2+-related fungal genes. In a first study, G. mosseae genes putatively encoding a MAP3k-like protein kinase (Gm2) and a P-type ATPase (Gm152) were investigated. Both Ca2+-related genes were up-regulated by A. sinicum root exudates, sugges…
Identification of the cell-wall derived xyloglucan as a new damage-associated molecular pattern (DAMP) eliciting plant immunity in Vitis vinifera and…
2018
Activation of the plant immune responses requires recognition of common pathogen-associated molecular pattern (PAMP) by their cognate pattern recognition receptors (PRR). Chitin, a major component of fungal cell walls, is a well-known PAMP that triggers defense responses in several mammal and plant species.In the first part of this study, we show that two chitooligosaccharides, chitin and chitosan, act as PAMPs in grapevine (Vitis vinifera) as they elicit immune signaling events, defense gene expression, and resistance against pathogens. These two PAMPs are active in grapevine suggesting that at least one perception system exists. Phylogenetic analysis clearly distinguished three V. vinifer…
Caracterisation of the mecanisms regulating membrane structuration modifications induced during defense response signalisation in plants
2020
Spatial distribution of pasma membranes (PM) components is tightly regulated to provide the cell an optimal physiological state. The level of order degree is a suitable parameter to study PM organization, reflecting the intensity of interactions taking place between PM components and so the level of their packing. During our work, we used the environment sensitive probe di-4-ANEPPDHQ to assess the level of order degree of tobacco BY-2 cells PM in different situations: during the time-course of cell regeneration and in the particular case of an elicitation by cryptogein.We measured that the level of order degree of PM is modulated during the slow process of cell regeneration. This regulation…
Identification of the Weevil immune genes and their expression in the bacteriome tissue
2008
Abstract Background Persistent infections with mutualistic intracellular bacteria (endosymbionts) are well represented in insects and are considered to be a driving force in evolution. However, while pathogenic relationships have been well studied over the last decades very little is known about the recognition of the endosymbionts by the host immune system and the mechanism that limits their infection to the bacteria-bearing host tissue (the bacteriome). Results To study bacteriome immune specificity, we first identified immune-relevant genes of the weevil Sitophilus zeamais by using suppressive subtractive hybridization (SSH) and then analyzed their full-length coding sequences obtained b…
Functional characterisation of the first HSP110 inhibitors.
2023
Heat shock proteins are molecular chaperones highly expressed in haematological malignancies. My laboratory has shown that the heat shock protein HSP110 is a new and important therapeutic target In colorectal cancer and in non-Hodgkin's lymphoma. As there were no existing inhibitors of HSP110, a screening strategy of a chemical library was carried out and allowed the identification of two molecules capable of specifically inhibiting the chaperone activity of HSP110. My thesis objective was to characterise and functionally validate these newly identified molecules in diffuse large cell B lymphomas. I have shown that one of these molecules limits the interaction of HSP110 with the SYK signall…
Towards visual urban scene understanding for autonomous vehicle path tracking using GPS positioning data.
2019
This PhD thesis focuses on developing a path tracking approach based on visual perception and localization in urban environments. The proposed approach comprises two systems. The first one concerns environment perception. This task is carried out using deep learning techniques to automatically extract 2D visual features and use them to learn in order to distinguish the different objects in the driving scenarios. Three deep learning techniques are adopted: semantic segmentation to assign each image pixel to a class, instance segmentation to identify separated instances of the same class and, image classification to further recognize the specific labels of the instances. Here our system segme…