73 research outputs found
Les protéines de choc thermique (heat shock proteins). I : Classification, structure, fonctions et implications dans les processus pathologiques
All living systems have evolved mechanisms to maintain homeostasis in the face of rapid environmental changes. When exposed to elevated temperatures, most of the cells activate the synthesis of a specific group of proteins called Heat Shock Proteins (Hsps). This heat shock response, under control of specific transcription factors, the Heat Shock factors (HSF), is an evolutionarily conserved mechanism, from bacteria to humans. Heat Shock Proteins are classified into families according to their molecular weight (Hsp 25, 40, 70, 90, 105). They play the role of molecular chaperones by binding and protecting other molecules (proteins, RNAs). The function of Hsp is to prevent accumulation of non-native proteins either by assisting proper folding of polypeptides or by driving them to proteosome pathway for degradation. Hsps are involved in various pathological processes that are accompanied by protein alterations such as chronic or degenerative diseases. This review describes structural and functional characteristics of the six main Hsps classes. It also focuses on their respective role in highly studied pathologies. The diversity of Hsps implications in these diseases explains that they became recently a strategic target in development of new therapeutic strategies.Tout organisme est dotĂ© de mĂ©canismes lui permettant de rĂ©sister Ă de brusques changements de son environnement. ExposĂ©es Ă une tempĂ©rature anormalement Ă©levĂ©e, la plupart des cellules activent lâexpression dâune classe particuliĂšre de protĂ©ines appelĂ©es les protĂ©ines de choc thermique (Heat Shock Proteins, Hsps). Cette rĂ©ponse cellulaire au choc thermique placĂ©e sous le contrĂŽle de facteurs de trans-cription spĂ©cifiques, les facteurs de choc thermique (Heat shock factor, HSF) est un mĂ©canisme conservĂ© au travers de lâĂ©volution depuis les bactĂ©ries jusquâĂ lâhomme. Les protĂ©ines de choc thermique qui sont divisĂ©es en familles dĂ©signĂ©es par leur masse molĂ©culaire (Hsp25, 40, 70, 90, 105) font partie des molĂ©-cules chaperons qui sâassocient Ă dâautres molĂ©cules (protĂ©ines, ARNs) et en protĂšgent la destinĂ©e. Le rĂŽle des Hsp est dâempĂȘcher lâaccumulation de protĂ©ines anormales en aidant Ă conformer correctement les polypeptides ou en les dirigeant vers le protĂ©osome qui les dĂ©truit. En tant que chaperons, les Hsp sont impliquĂ©es dans de nombreux processus pathologiques qui sâaccompagnent dâaltĂ©rations des protĂ©ines comme les maladies chroniques et dĂ©gĂ©nĂ©ratives. Cette revue dĂ©crit les spĂ©cificitĂ©s structurelles et fonc-tionnelles des six familles principales d'Hsp ainsi que leur intervention Ă diffĂ©rents niveaux dans les patho-logies les mieux Ă©tudiĂ©es. La multiplicitĂ© de l'implication des Hsp dans ces phĂ©nomĂšnes pathologiques les dĂ©signe comme cibles privilĂ©giĂ©es dans le dĂ©veloppement de nouvelles stratĂ©gies thĂ©rapeutiques
Interaction between APOE4 and herpes simplex virus type 1 in Alzheimer's disease
Introduction: Numerous results suggest the implication of infectious agents in the onset of Alzheimer's disease (AD).Methods: In the Bordeauxâ3C prospective cohort, we assessed the impact of herpes simplex virus type 1 (HSVâ1) infection on the incidence of AD according to apolipoprotein E (APOE) status, a genetic susceptibility factor. Cox models were performed to estimate the 10âyear risk of AD associated with antiâHSV antibodies in 1037 participants according to APOE4 status.Results: Among APOE4 carriers, subjects for whom the frequency of HSVâ1 reactivation is supposed to be high, that is, immunoglobulin M (IgM) positive or elevated levels of IgG, had an increased risk of AD with adjusted hazard ratios (HRs) of 3.68 (1.08â12.55) and 3.28 (1.19â9.03), respectively. No significant association was found in APOE4ânegative subjects.Discussion: These results, in accordance with a solid pathophysiological rationale, suggest a role for HSVâ1 in AD development among subjects with a genetic susceptibility factor, the APOE4 allele
Betacellulin inhibits osteogenic differentiation and stimulates proliferation through HIF-1α
Cellular signaling via epidermal growth factor (EGF) and EGF-like ligands can determine cell fate and behavior. Osteoblasts, which are responsible for forming and mineralizing osteoid, express EGF receptors and alter rates of proliferation and differentiation in response to EGF receptor activation. Transgenic mice over-expressing the EGF-like ligand betacellulin (BTC) exhibit increased cortical bone deposition; however, because the transgene is ubiquitously expressed in these mice, the identity of cells affected by BTC and responsible for increased cortical bone thickness remains unknown. We have therefore examined the influence of BTC upon mesenchymal stem cell (MSC) and pre-osteoblast differentiation and proliferation. BTC decreases the expression of osteogenic markers in both MSCs and pre-osteoblasts; interestingly, increases in proliferation require hypoxia-inducible factor-alpha (HIF-α), as an HIF antagonist prevents BTC-driven proliferation. Both MSCs and pre-osteoblasts express EGF receptors ErbB1, ErbB2, and ErbB3, with no change in expression under osteogenic differentiation. These are the first data that demonstrate an influence of BTC upon MSCs and the first to implicate HIF-α in BTC-mediated proliferation
La collection Paul Boulet et les anciennes découvertes archéologiques des environs du confluent de l'Aisne et de l'Oise
Doize RenĂ©e-L. La collection Paul Boulet et les anciennes dĂ©couvertes archĂ©ologiques des environs du confluent de l'Aisne et de l'Oise. In: Bulletin de la SociĂ©tĂ© prĂ©historique française. Ătudes et travaux, tome 62, n°1, 1965. pp. 245-252
Flûte préhistorique à patine tourbeuse
Doize Renée-L. Flûte préhistorique à patine tourbeuse. In: Bulletin de la Société préhistorique de France, tome 36, n°10, 1939. pp. 420-422
Les collections africaines du déparlement de préhistoire exotique du Musée d'ethnographie du Trocadéro. II Nouvelles recherches préhistoriques au Congo
Kelley Harper, Doize R.-L. Les collections africaines du déparlement de préhistoire exotique du Musée d'ethnographie du Trocadéro. II Nouvelles recherches préhistoriques au Congo. In: Journal de la Société des Africanistes, 1934, tome 4, fascicule 2. pp. 303-312
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