Pierre Weiss
French Institute of Health and Medical Research
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Featured researches published by Pierre Weiss.
Cellular and Molecular Life Sciences | 2011
Solmaz Khoshniat; Annabelle Bourgine; Marion Julien; Pierre Weiss; Jérôme Guicheux; Laurent Beck
Although considerable advances in our understanding of the mechanisms of phosphate homeostasis and skeleton mineralization have recently been made, little is known about the initial events involving the detection of changes in the phosphate serum concentrations and the subsequent downstream regulation cascade. Recent data has strengthened a long-established hypothesis that a phosphate-sensing mechanism may be present in various organs. Such a phosphate sensor would detect changes in serum or local phosphate concentration and would inform the body, the local environment, or the individual cell. This suggests that phosphate in itself could represent a signal regulating multiple factors necessary for diverse biological processes such as bone or vascular calcification. This review summarizes findings supporting the possibility that phosphate represents a signaling molecule, particularly in bone and cartilage, but also in other tissues. The involvement of various signaling pathways (ERK1/2), transcription factors (Fra-1, Runx2) and phosphate transporters (PiT1, PiT2) is discussed.
Bone | 2011
S. Khoshniat; A. Bourgine; M. Julien; M. Petit; P. Pilet; T. Rouillon; M. Masson; M. Gatius; Pierre Weiss; J. Guicheux; L. Beck
Inorganic phosphate (Pi) acts as a signaling molecule in bone-forming cells, affecting cell functions and gene expression. Particularly, Pi stimulates the expression of mineralization-associated genes such as matrix gla protein (MGP) and osteopontin (OPN) through the ERK1/2 pathway. With respect to the presence of elevated extracellular calcium and Pi levels during bone remodeling, we questioned whether calcium might play a role in the Pi-dependent effects in osteoblasts. We first showed by Western blot and real-time PCR that the concomitant presence of 10 mM Pi and 1.8 mM calcium is required to stimulate ERK1/2 phosphorylation and MGP/OPN genes expression. The mechanisms involved in the cellular effects of calcium in the presence of Pi were subsequently examined. Firstly, the use of the calcium-sensing receptor (CaSR) agonist gadolinium and the G-protein inhibitor pertussis toxin enabled us to determine that a CaSR mechanism is not involved in the Pi and calcium mediated cellular effects. By transmission electron microscopy, we next demonstrated that adding 10mM Pi to the culture medium containing 1.8mM calcium led to the formation calcium phosphate precipitates (CaPp). Moreover, treatment of osteoblasts with exogenous pre-synthesized CaPp stimulated ERK1/2 phosphorylation and MGP/OPN genes expression. In spite of high extracellular calcium and Pi concentrations, this stimulation was blunted in the presence of phosphocitrate, an inhibitor of crystal formation. Finally, we showed that despite that CaPp are not endocytosed, their effect on ERK1/2 phosphorylation and MGP/OPN genes expression were dependent on lipid rafts integrity. In summary, we showed that calcium is required for Pi-dependent ERK1/2 phosphorylation and regulation of mineralization-associated genes in osteoblasts and that its effect could originate from extracellular-related effects of CaPp that are dependent on the integrity of lipid rafts.
Archives of Oral Biology | 2011
A. Bourgine; L. Beck; S. Khoshniat; F. Wauquier; L. Oliver; E. Hue; B. Alliot-Licht; Pierre Weiss; J. Guicheux; Yohann Wittrant
OBJECTIVEnDental pathologies such as caries are the most prevalent disease worldwide with infectious and social complications. During the process of caries formation, the tooth is degraded and demineralization of enamel and dentine leads to the release of large amounts of inorganic phosphate (Pi) within dental tubuli. As Pi has been shown to induce apoptosis in skeletal cells, including osteoblasts and chondrocytes, we questioned whether high concentrations of Pi could affect odontoblast viability, proliferation and apoptosis.nnnDESIGNnUsing the odontoblast-like MO6-G3 cell line as a model, we used cell counting and MTS-based colorimetric assays to measure cell viability and proliferation. Apoptosis was assessed using Hoechst nuclei staining and detection of the early apoptotic markers annexin V and Apo2.7.nnnRESULTSnWe show for the first time that a high Pi concentration (7 mM) induced a decrease in odontoblast viability and proliferation together with a large increase in apoptosis. These effects were blunted in calcium-free medium, possibly due to the formation of calcium-phosphate crystals in the presence of high Pi concentrations.nnnCONCLUSIONnThis study contributes to clarifying the effect of Pi on odontoblast viability and apoptosis, which may improve our understanding of the role of Pi during caries formation.
Archive | 2004
Guy Daculsi; Pierre Weiss; Xavier Bourges
Archive | 2012
Pierre Weiss; Eva Mathieu; Jérôme Guicheux; Patricia Lemarchand
3rd TERMIS World congress | 2012
Gildas Réthoré; Cécile Boyer; Frank Boury; J-F. Tassin; Fan Xie; Brice Calvignac; Jérôme Guicheux; Pierre Weiss
Archive | 2009
Pierre Weiss; Jérôme Guicheux; Pierre Daculsi; Gaël Grimandi; Claire Vinatier
Archive | 2009
Pierre Weiss; Bideau Jean Le; Jan Recho; Ahmed Fatimi; Jérôme Guicheux
/data/revues/1297319X/00750006/08002297/ | 2009
Christophe Merceron; Claire Vinatier; Johann Clouet; Sylvia Colliec-Jouault; Pierre Weiss; Jérôme Guicheux
/data/revues/1297319X/00750006/08002297/ | 2009
Christophe Merceron; Claire Vinatier; Johann Clouet; Sylvia Colliec-Jouault; Pierre Weiss; Jérôme Guicheux