Frédérique Gaits-Iacovoni

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The virulence factor IpgD, delivered into nonphagocytic cells by the type III secretion system of the pathogen Shigella flexneri, is a phosphoinositide 4-phosphatase generating phosphatidylinositol 5 monophosphate (PtdIns5P). We show that PtdIns5P is rapidly produced and concentrated at the entry foci of the bacteria, where it colocalises with(More)
PtdIns5P is a lipid messenger acting as a stress-response mediator in the nucleus, and known to maintain cell activation through traffic alterations upon bacterial infection. Here, we show that PtdIns5P regulates actin dynamics and invasion via recruitment and activation of the exchange factor Tiam1 and Rac1. Restricted Rac1 activation results from the(More)
Phosphoinositide 3-kinases (PI3Ks) are important signaling enzymes involved in the regulation of a number of critical cell functions. Significant progress has been made during the last few years in defining the implication of individual PI3K isoforms. The role of the class IA PI3Kβ in different cell types has only been recently uncovered by the use of(More)
The phosphoinositide metabolism that is highly controlled by a set of kinases, phosphatases and phospholipases leads to the production of several second messengers playing critical roles in intracellular signal transduction mechanisms. Recent discoveries have unraveled unexpected roles for the three phosphatidylinositol monophosphates, PtdIns(3)P,(More)
Phosphoinositides are minor constituents of cell membranes playing a critical role in the regulation of many cellular functions. Recent discoveries indicate that mutations in several phosphoinositide kinases and phosphatases generate imbalances in the levels of phosphoinositides, thereby leading to the development of human diseases. Although the roles of(More)
Phosphatidylinositol 5-phosphate (PtdIns5P), the least characterized among the three phosphatidylinositol monophosphates, is emerging as a bioactive lipid involved in the control of several cellular functions. Similar to PtdIns3P, it is present in low amounts in mammalian cells, and can be detected at the plasma membrane and endomembranes as well as in the(More)
Many anaplastic large cell lymphomas (ALCL) express the chimeric oncogene NPM-ALK, which drives malignant transformation and invasion. In this study, we show that NPM-ALK expression increases matrix metalloproteinase-9 (MMP-9) expression. Accordingly, we found that 100% of a large panel of ALK(+) ALCL biopsies examined were also MMP-9(+), in contrast to(More)
The physiologic roles of the class II phosphoinositide 3-kinases (PI3Ks) and their contributions to phosphatidylinositol 3-monophosphate (PI3P) and PI(3,4)P2 production remain elusive. Here we report that mice heterozygous for a constitutively kinase-dead PI3K-C2α display aberrant platelet morphology with an elevated number of barbell-shaped proplatelets, a(More)
Anaplastic large-cell lymphomas (ALCLs) bearing the t(2;5) translocation (ALK(+)ALCLs) are frequently characterized by skin colonization and associated with a poor prognosis. Using conditional transgenic models of anaplastic lymphoma kinase-positive (ALK(+)) lymphomas and human ALK(+)ALCL cell lines, in the present study, we show that high-mobility-group(More)
Obesity-associated inflammation contributes to the development of metabolic diseases. Although brite adipocytes have been shown to ameliorate metabolic parameters in rodents, their origin and differentiation remain to be characterized in humans. Native CD45-/CD34+/CD31- cells have been previously described as human adipocyte progenitors. Using two(More)