Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Receptor. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

In memory of consolidation

Abstract: How an animal learns, remembers, and uses information to guide adaptive behavior remains one of the most challenging questions in science today. Much progress was made in the twentieth century, and new tools available to neurobiological investigators have accelerated progress in the new century. Nevertheless, the road has been rocky and progress sometimes impeded by periodic polemic debates at a conceptual level. Retrospective examination of the nature of the divisive issues and how they were (or were not) resolved could help steer a new generation of investigators away from similar pitfalls and impasses. The same applies to scientists from other disciplines, recently joining in the “search for the engram,” who might not be aware of the vast literature generated, mainly by psychologists, in the middle decades of the last century. Our purpose here is not to furnish a complete review of this literature, but to provide a historical perspective for some of the unresolved issues that continue to be discussed within the context of the field of neurobiology of memory. For more general reviews, refer to McGaugh (2000) and Dudai (2004). Scientific investigation of memory processes was initiated at the end of the 19th century by psychologists in Germany, Ebbinghaus (1885) and then Mueller and Pilzecker (1900). Their studies of verbal learning and retention in human subjects led them to conclude that a memory trace was formed gradually over time after acquisition and they coined the term consolidation. Contemporary with this were the very influential clinical observations and theoretical elaborations of the French psychiatrist, Ribot (1882). From his studies of amnesic patients, he formulated “La loi de regression,” which simply notes that, as memories age, they become more resistant to trauma-induced amnesia.

Residual stresses in thin polymer films cause rupture and dominate early stages of dewetting.

Abstract: Residual stresses in thin polymer films cause rupture and dominate early stages of dewetting

Cellular retinol-binding protein I is essential for vitamin A homeostasis.

Abstract: The gene encoding cellular retinol (ROL, vitA)-binding protein type I (CRBPI) has been inactivated. Mutant mice fed a vitA-enriched diet are healthy and fertile. They do not present any of the congenital abnormalities related to retinoic acid (RA) deficiency, indicating that CRBPI is not indispensable for RA synthesis. However, CRBPI deficiency results in an approximately 50% reduction of retinyl ester (RE) accumulation in hepatic stellate cells. This reduction is due to a decreased synthesis and a 6-fold faster turnover, which are not related to changes in the levels of RE metabolizing enzymes, but probably reflect an impaired delivery of ROL to lecithin:retinol acyltransferase. CRBPI-null mice fed a vitA-deficient diet for 5 months fully exhaust their RE stores. Thus, CRBPI is indispensable for efficient RE synthesis and storage, and its absence results in a waste of ROL that is asymptomatic in vitA-sufficient animals, but leads to a severe syndrome of vitA deficiency in animals fed a vitA-deficient diet.

A new alternative mechanism in glioblastoma vascularization: tubular vasculogenic mimicry.

Abstract: Glioblastoma is one of the most angiogenic human tumours and endothelial proliferation is a hallmark of the disease. A better understanding of glioblastoma vasculature is needed to optimize anti-angiogenic therapy that has shown a high but transient efficacy. We analysed human glioblastoma tissues and found non-endothelial cell-lined blood vessels that were formed by tumour cells (vasculogenic mimicry of the tubular type). We hypothesized that CD133+ glioblastoma cells presenting stem-cell properties may express pro-vascular molecules allowing them to form blood vessels de novo. We demonstrated in vitro that glioblastoma stem-like cells were capable of vasculogenesis and endothelium-associated genes expression. Moreover, a fraction of these glioblastoma stem-like cells could transdifferentiate into vascular smooth muscle-like cells. We describe here a new mechanism of alternative glioblastoma vascularization and open a new perspective for the antivascular treatment strategy.

Transcription factor TFIID recruits factor CPSF for formation of 3′ end of mRNA

Abstract: Initiation of transcription by RNA polymerase II from a promoter region on DNA requires the assembly of several initiation factors to form a preinitiation complex. Assembly of this complex is initiated by the binding of the transcription factor TFIID, composed of the TATA-box binding protein (TBP) and TBP-associated factors (TAF[II]s), to the promoter. We have now characterized an immunopurified TFIID complex which we unexpectedly find contains the cleavage-polyadenylation specificity factor (CPSF), one of the factors required for formation of the 3' end of messenger RNA. CPSF is brought to the preinitiation complex by TFIID, but after transcription starts, CPSF dissociates from TFIID and becomes associated with the elongating polymerase. We also show that overexpression of recombinant TBP in HeLa cells decreases polyadenylation without affecting the correct initiation of transcription of the reporter gene. This indicates that, owing to incomplete assembly of TFIID on recombinant TBP, CPSF is not brought to the promoter and therefore polyadenylation becomes less efficient. Our observations have thus revealed a link between transcription initiation and elongation by RNA polymerase II and processing of the 3' end of mRNA.