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 & Dopamine. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

Transcriptional Repression by RING Finger Protein TIF1β That Interacts with the KRAB Repressor Domain of KOX1

Abstract: Many of the vertebrate zinc finger factors of the Kruppel type (C2H2 zinc fingers) contain in their N-terminus a conserved sequence referred to as the KRAB (Kruppel-associated box) domain that, when tethered to DNA, efficiently represses transcription. Using the yeast two-hybrid system, we have isolated an 835 amino acid RING finger (C3HC4 zinc finger) protein, TIF1 beta (also named KAP-1), that specifically interacts with the KRAB domain of the human zinc finger factor KOX1/ZNF10. TIF1 beta, TIF1 alpha, PML and efp belong to a characteristic subgroup of RING finger proteins that contain one or two other Cys/His-rich clusters (B boxes) and a putative coiled-coil in addition to the classical C3HC4 RING finger motif (RBCC configuration). Like TIF1 alpha, TIF1 beta also contains an additional Cys/His cluster (PHD finger) and a bromo-related domain. When tethered to DNA, TIF1 beta can repress transcription in transiently transfected mammalian cells both from promoter-proximal and remote (enhancer) positions, similarly to the KRAB domain itself. We propose that TIF1 beta is a mediator of the transcriptional repression exerted by the KRAB domain.

Spontaneous activation of [FeFe]-hydrogenases by an inorganic [2Fe] active site mimic

Abstract: Hydrogenases catalyze the formation of hydrogen. The cofactor ('H-cluster') of [FeFe]-hydrogenases consists of a [4Fe-4S] cluster bridged to a unique [2Fe] subcluster whose biosynthesis in vivo requires hydrogenase-specific maturases. Here we show that a chemical mimic of the [2Fe] subcluster can reconstitute apo-hydrogenase to full activity, independent of helper proteins. The assembled H-cluster is virtually indistinguishable from the native cofactor. This procedure will be a powerful tool for developing new artificial H₂-producing catalysts.

Brain macrophages synthesize interleukin-1 and interleukin-1 mRNAs in vitro.

Abstract: Amoeboid microglial cells (brain macrophages) were purified from early post-natal mouse brain cultures. The percentage of cells stained with an anti-Mac-1 antibody was greater than 95%. Stimulation of these brain macrophages by lipopolysaccharides induced the synthesis of interleukin-1 (IL-1), which, in part, remained associated with the cell surface and, in part, was released into the culture medium. In contrast, pure primary astrocyte cultures and cell lines of transformed or immortalised astrocytes did not synthesise significant amounts of IL-1, demonstrating that amoeboid microglia and not astrocytes synthesise IL-1 in vitro. These physiological data were confirmed by RNA hybridisation studies showing that, on LPS treatment, brain macrophages synthesise significant amounts of IL-1 alpha and IL-1 beta mRNAs.

Reference Frames for Spatial Cognition: Different Brain Areas are Involved in Viewer-, Object-, and Landmark-Centered Judgments About Object Location

Abstract: Functional magnetic resonance imaging was used to compare the neural correlates of three different types of spatial coding, which are implicated in crucial cognitive functions of our everyday life, such as visuomotor coordination and orientation in topographical space. By manipulating the requested spatial reference during a task of relative distance estimation, we directly compared viewer-centered, object-centered, and landmark-centered spatial coding of the same realistic 3-D information. Common activation was found in bilateral parietal, occipital, and right frontal premotor regions. The retrosplenial and ventromedial occipital–temporal cortex (and parts of the parietal and occipital cortex) were significantly more activated during the landmark-centered condition. The ventrolateral occipital–temporal cortex was particularly involved in object-centered coding. Results strongly demonstrate that viewer-centered (egocentric) coding is restricted to the dorsal stream and connected frontal regions, whereas a coding centered on external references requires both dorsal and ventral regions, depending on the reference being a movable object or a landmark.

Human consciousness is supported by dynamic complex patterns of brain signal coordination

Abstract: Adopting the framework of brain dynamics as a cornerstone of human consciousness, we determined whether dynamic signal coordination provides specific and generalizable patterns pertaining to conscious and unconscious states after brain damage. A dynamic pattern of coordinated and anticoordinated functional magnetic resonance imaging signals characterized healthy individuals and minimally conscious patients. The brains of unresponsive patients showed primarily a pattern of low interareal phase coherence mainly mediated by structural connectivity, and had smaller chances to transition between patterns. The complex pattern was further corroborated in patients with covert cognition, who could perform neuroimaging mental imagery tasks, validating this pattern’s implication in consciousness. Anesthesia increased the probability of the less complex pattern to equal levels, validating its implication in unconsciousness. Our results establish that consciousness rests on the brain’s ability to sustain rich brain dynamics and pave the way for determining specific and generalizable fingerprints of conscious and unconscious states.