Papers by Thierry Arnould
Regulators of G protein signaling (RGS) proteins accelerate the intrinsic GTPase activity of cert... more Regulators of G protein signaling (RGS) proteins accelerate the intrinsic GTPase activity of certain G␣ subunits and thereby modulate a number of G proteindependent signaling cascades. Currently, little is known about the regulation of RGS proteins themselves. We identified a short-lived RGS protein, RGS7, that is rapidly degraded through the proteasome pathway. The degradation of RGS7 is inhibited by interaction with a C-terminal domain of polycystin, the protein encoded by PKD1, a gene involved in autosomal-dominant polycystic kidney disease. Furthermore, membranous expression of C-terminal polycystin relocalized RGS7. Our results indicate that rapid degradation and interaction with integral membrane proteins are potential means of regulating RGS proteins.
Journal of Colloid and Interface Science, Apr 1, 2023
Biochemical Pharmacology, Apr 1, 2015
Eukaryotic cells developed strategies to detect and eradicate infections. The innate immune syste... more Eukaryotic cells developed strategies to detect and eradicate infections. The innate immune system, which is the first line of defence against invading pathogens, relies on the recognition of molecular patterns conserved among pathogens. Pathogen associated molecular pattern binding to pattern recognition receptor triggers the activation of several signalling pathways leading to the establishment of a pro-inflammatory state required to control the infection. In addition, pathogens evolved to subvert those responses (with passive and active strategies) allowing their entry and persistence in the host cells and tissues. Indeed, several bacteria actively manipulate immune system or interfere with the cell fate for their own benefit. One can imagine that bacterial effectors can potentially manipulate every single organelle in the cell. However, the multiple functions fulfilled by mitochondria especially their involvement in the regulation of innate immune response, make mitochondria a target of choice for bacterial pathogens as they are not only a key component of the central metabolism through ATP production and synthesis of various biomolecules but they also take part to cell signalling through ROS production and control of calcium homeostasis as well as the control of cell survival/programmed cell death. Furthermore, considering that mitochondria derived from an ancestral bacterial endosymbiosis, it is not surprising that a special connection does exist between this organelle and bacteria. In this review, we will discuss different mitochondrial functions that are affected during bacterial infection as well as different strategies developed by bacterial pathogens to subvert functions related to calcium homeostasis, maintenance of redox status and mitochondrial morphology.
The EMBO Journal, Jan 15, 2002
We characterized a new signaling pathway leading to the activation of cAMP-responsive element-bin... more We characterized a new signaling pathway leading to the activation of cAMP-responsive element-binding protein (CREB) in several cell lines affected by mitochondrial dysfunction. In vitro kinase assays, inhibitors of several kinase pathways and overexpression of a dominant-negative mutant for calcium/calmodulin kinase IV (CaMKIV), which blocks the activation of CREB, showed that CaMKIV is activated by a mitochondrial activity impairment. A high calcium concentration leading to the disruption of the protein interaction with protein phosphatase 2A explains CaMKIV activation in these conditions. Transcriptionally active phosphorylated CREB was also found in a r0 143B human osteosarcoma cell line and in a MERRF cybrid cell line mutated for tRNA Lys (A8344G). We also showed that phosphorylated CREB is involved in the proliferation defect induced by a mitochondrial dysfunction. Indeed, cell proliferation inhibition can be prevented by CaMKIV inhibition and CREB dominant-negative mutants. Finally, our data suggest that phosphorylated CREB recruits p53 tumor suppressor protein, modi®es its transcriptional activity and increases the expression of p21 Waf1/Cip1 , a p53-regulated cyclin-dependent kinase inhibitor.
An adaptive capacity of white adipose tissues is essential to match energy intake and expenditure... more An adaptive capacity of white adipose tissues is essential to match energy intake and expenditure. Part of this adaptation is driven by the enrollment of new adipocytes, a phenomenon referred to “adipogenesis”. Our current efforts are dedicated to the investigation of the putative role of the Sirtuin 3 (SIRT3), a NAD+-dependent deacetylase and master regulator of several mitochondrial functions, in the differentiation of preadipocytes in white adipocytes. This is of particular relevance as mitochondrial biogenesis and activation of oxidative metabolism are promoted by SIRT3 and are known to be required for proper adipogenic differentiation. Moreover, SIRT3 was already reported to be required for proper differentiation of various other cell types such as skeletal myocytes [1] and brown adipocytes [2]. White 3T3-L1 adipoblasts were differentiated in adipocytes in the presence or in the absence of SIRT3 (invalidation using CIRSPR/Cas9-DN technology) and the expression of SIRT3 as well as markers of its activity were analysed during a differentiation programme of 12 days. In addition, ROS production as well as respiration (Oxygraph-2k, ORBOROS Instruments Corp) in cells in the presence or in the absence of SIRT3 were studied. The results show that the expression of SIRT3 is induced during the differentiation programme. In addition, the absence of SIRT3 is reflected by a delay (but not the inhibition) of preadipocyte differentiation as demonstrated by a reduced content of triacylglycerols. We are currently investigating the underlying mechanisms that could postpone adipogenesis in the absence of the mitochondrial deacetylase such as modifications in reactive oxygen species production and putative alterations of OXPHOS that could connect SIRT3 to proper development of the adipose phenotype. In conclusion, we showed that SIRT3 activity accompanies the adipogenic programme of 3T3-L1 preadipocytes and that the enzyme plays an important role in the kinetics of the differentiation programme. The identification of SIRT-3 dependent mechanisms playing a role in the differentiation of preadipocytes is ongoing
Biochemical Pharmacology, Nov 1, 2019
Cell differentiation is a fundamental biological event in which a precursor stem cell is turning ... more Cell differentiation is a fundamental biological event in which a precursor stem cell is turning into a specialized somatic cell. It is thus crucial for the development, tissue turnover and regeneration in mammals. Among the numerous changes taking place in a cell during a differentiation programme, the biology of mitochondria, the central organelle mainly responsible for energy homeostasis and stress adaptation, is deeply modified. These modifications are now well recognized as taking an active part to the completion of the differentiation programme. Indeed, mitochondrial biogenesis and metabolic shift are observed during cell differentiation, adapting many syntheses, calcium homeostasis, ATP and reactive oxygen species production, to the needs. These mitochondrial functions are substantially regulated by the post-translational modifications of the mitochondrial proteins among which lysine acetylation is essential. This mitoacetylome is then globally controlled by the balance between spontaneous/enzymatically-catalysed protein acetylation and the NAD +-dependent deacetylation mediated by Sirtuin 3. This enzyme is now considered as a major regulator of the function of the organelle. Regarding the requirement of these mitochondrial adaptations, the subsequent growing interest for this enzyme recently extended to the investigation of the mechanisms driving cell differentiation. This review summarizes the currently available information about the significance of SIRT3 in cell differentiation in physio-pathological contexts. We also suggest a control of the differentiation-activated autophagy by SIRT3, a hypothesis supported by recent findings establishing a causal link between SIRT3 and autophagy. Eventually, an update on the present pharmacological modulators of SIRT3 in a context of cell differentiation is discussed.
PLOS Pathogens
Mitochondria fulfil a plethora of cellular functions ranging from energy production to regulation... more Mitochondria fulfil a plethora of cellular functions ranging from energy production to regulation of inflammation and cell death control. The fundamental role of mitochondria makes them a target of choice for invading pathogens, with either an intracellular or extracellular lifestyle. Indeed, the modulation of mitochondrial functions by several bacterial pathogens has been shown to be beneficial for bacterial survival inside their host. However, so far, relatively little is known about the importance of mitochondrial recycling and degradation pathways through mitophagy in the outcome (success or failure) of bacterial infection. On the one hand, mitophagy could be considered as a defensive response triggered by the host upon infection to maintain mitochondrial homeostasis. However, on the other hand, the pathogen itself may initiate the host mitophagy to escape from mitochondrial-mediated inflammation or antibacterial oxidative stress. In this review, we will discuss the diversity of...
Autophagy, 2023
Mitochondria are at the basis of various cellular functions ranging from metabolism and redox hom... more Mitochondria are at the basis of various cellular functions ranging from metabolism and redox homeostasis to inflammation and cell death regulation. Mitochondria therefore constitute an attractive target for invading pathogens to fulfil their infectious cycle. This involves the modulation to their advantage of mitochondrial metabolism and dynamics, including the controlled degradation of mitochondria through mitophagy. Mitophagy might for instance be beneficial for bacterial survival as it can clear bactericidal mitochondrial ROS produced by damaged organelle fragments from the intracellular niche. In the case of the bacterial pathogen Brucella abortus, mitophagy induction has another role in the intracellular lifecycle of the bacteria. Indeed, in our study, we showed that B. abortus triggers an iron-dependent BNIP3L-mediated mitophagy response required for proper bacterial egress and infection of neighboring cells. These results highlight the diversity of mitophagy processes that might be crucial for several stages of cellular infection.
The EMBO Journal, May 25, 2023
The facultative intracellular pathogen Brucella abortus interacts with several organelles of the ... more The facultative intracellular pathogen Brucella abortus interacts with several organelles of the host cell to reach its replicative niche inside the endoplasmic reticulum. However, little is known about the interplay between the intracellular bacteria and the host cell mitochondria. Here, we showed that B. abortus triggers substantive mitochondrial network fragmentation, accompanied by mitophagy and the formation of mitochondrial Brucella‐containing vacuoles during the late steps of cellular infection. Brucella‐induced expression of the mitophagy receptor BNIP3L is essential for these events and relies on the iron‐dependent stabilisation of the hypoxia‐inducible factor 1α. Functionally, BNIP3L‐mediated mitophagy appears to be advantageous for bacterial exit from the host cell as BNIP3L depletion drastically reduces the number of reinfection events. Altogether, these findings highlight the intricate link between Brucella trafficking and the mitochondria during host cell infection.
Insights in analytical electrochemistry, Sep 19, 2017
F ood allergies rise increasingly over the last decades. To protect themselves, food customers mu... more F ood allergies rise increasingly over the last decades. To protect themselves, food customers must exclude the allergenic food. Unfortunately, unintentional contaminations in finish products are still possible due to cross-contamination during food production, and food storage. To help producers, food laboratories developed methods for the protection of allergic customers. Most contaminations of food products by allergens are determined by enzyme-linked immunosorbent assay (ELISA). However, high-baked allergens in food products are sometimes hardly detected by ELISA. Ultra-high-performance liquid chromatography coupled to tandem mass spectrometry recently developed allows a highly specific and sensitive detection of processed allergens in food products. The establishment of a UHPLC-MS/MS method is expensive compared to ELISA method. Both methods present advantages and disadvantages, but, they are complementary. The guideline SMPR 2016.002, published in 2016, is dedicated for UHPLC-MS/MS methods. Food products selected in this guideline will be analyzed by ELISA and UHPLC-MS/MS and compared. This study will present the complementarity of UHPLC-MS/MS and ELISA method for a better use and comprehension of methods for the detection of allergens. Biography M Planque holds a Master's degree in Chemistry. She started her PhD in 2014 at CER Groupe (Health Department) and at the University of Namur in Belgium. She is currently working on the sensitive detection of allergens by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry.
Journal of Chromatography A, 2016
Food Chemistry, Dec 1, 2020
Mass spectrometry-based methods coupled with stable isotope dilution have become effective and wi... more Mass spectrometry-based methods coupled with stable isotope dilution have become effective and widely used methods for the detection and quantification of food allergens. Current methods target signature peptides resulting from proteolytic digestion of proteins of the allergenic ingredient. The choice of appropriate stable isotope-labelled internal standard is crucial, given the diversity of encountered food matrices which can affect sample preparation and analysis. We propose the use of concatemer, an artificial and stable isotope-labelled protein composed of several concatenated signature peptides as internal standard. With a comparative analysis of three matrices contaminated with four allergens (egg, milk, peanut, and hazelnut), the concatemer approach was found to offer advantages associated with the use of labelled proteins, ideal but unaffordable, and circumvent certain limitations of traditionally used synthetic peptides as internal standards. Although used in the proteomic field for more than a decade, concatemer strategy has not yet been applied for food analysis.
International Journal of Molecular Sciences, May 31, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
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Papers by Thierry Arnould