A new center for interdisciplinary research in Neuroscience

Discern the infinitely small in order to grasp the complexity of the brain

The Institute for Interdisciplinary Neuroscience (IINS - UMR 5297) is a new research center that has officially opened its doors January 1st, 2011.
The IINS is part of the "Centre National de la Recherche Scientifique" & the "Université de Bordeaux".

The IINS unites researchers with diverse areas of expertise, and creates a highly synergistic environment to promote:

> The development of innovative methods and investigation tools, especially those based on molecular biology, physiology, optics, chemistry, physics and computer science.

> The application of such tools to push the boundaries of the study of molecular events underlying the activity of the brain. This will include studying the morpho-dynamic and functional properties of the nervous system to understand the complexity of its molecular assemblies and functions at an integrated level.

> The development of the Bordeaux Imaging Center, a core facility of service, training and R & D in cellular imaging of international stature to permit the transfer to the scientific community and industry of the tools developed in IINS.

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EMBO Journal – October 2014

Nanoscale segregation of actin nucleation and elongation factors determines dendritic spine protrusion
EMBO Journal
- October 2014 DOI
Anaël Chazeau, Amine Mehidi, Deepak Nair, Jérémie J. Gautier, Cécile Leduc, Ingrid Chamma, Frieda Kage, Adel Kechkar, Olivier Thoumine, Klemens Rottner, Daniel Choquet, Alexis Gautreau, Jean-Baptiste Sibarita and Grégory Giannone

Actin dynamics drive morphological remodeling of neuronal dendritic spines and changes in synaptic transmission. Yet, the spatiotemporal coordination of actin regulators in spines is unknown. Using single protein tracking and super‐resolution imaging, we revealed the nanoscale organization and dynamics of branched F‐actin regulators in spines. Branched F‐actin nucleation occurs at the PSD vicinity, while elongation occurs at the tip of finger‐like protrusions. This spatial segregation differs from lamellipodia where both branched F‐actin nucleation and elongation occur at protrusion tips. The PSD is a persistent confinement zone for IRSp53 and the WAVE complex, an activator of the Arp2/3 complex.

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Philos Trans R Soc B - September 2014

Dissecting tripartite synapses with STED microscopy

Philos Trans R Soc Lond B Biol Sci. 2014 Oct 19;369(1654). pii: 20130597. doi: 10.1098/rstb.2013.0597
Aude Panatier, Misa Arizono and U. Valentin Nägerl 

The concept of the tripartite synapse reflects the important role that astrocytic processes are thought to play in the function and regulation of neuronal synapses in the mammalian nervous system. However, aspects regarding the dynamic interplay between pre- and postsynaptic neuronal structures and their astrocytic partners remain to be explored. A major experimental hurdle has been the small physical size of the relevant glial and synaptic structures, leaving them largely out of reach for conventional light microscopic approaches such as confocal and two-photon microscopy. Hence, most of what we know about the organization of the tripartite synapse is based on electron microscopy, which does not lend itself to investigating dynamic events and which cannot be carried out in parallel with functional assays.

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Nature - August 2014

Sensory-evoked LTP driven by dendritic plateau potentials in vivo
Nature 2014 Aug 31. doi: 10.1038/nature13664
Gambino F, Pagès S, Kehayas V, Baptista D, Tatti R, Carleton A, Holtmaat A

Long-term synaptic potentiation (LTP) is thought to be a key process in cortical synaptic network plasticity and memory formation. Hebbian forms of LTP depend on strong postsynaptic depolarization, which in many models is generated by action potentials that propagate back from the soma into dendrites. However, local dendritic depolarization has been shown to mediate these forms of LTP as well. As pyramidal cells in supragranular layers of the somatosensory cortex spike infrequently, it is unclear which of the two mechanisms prevails for those cells in vivo. Using whole-cell recordings in the mouse somatosensory cortex in vivo, we demonstrate that rhythmic sensory whisker stimulation efficiently induces synaptic LTP in layer 2/3 (L2/3) pyramidal cells in the absence of somatic spikes. The induction of LTP depended on the occurrence of NMDAR (N-methyl-d-aspartate receptor)-mediated long-lasting depolarizations, which bear similarities to dendritic plateau potentials.

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The Journal of Neuroscience – August 2014

Recycling endosomes undergo rapid closure of a fusion pore on exocytosis in neuronal dendrites
The
Journal of Neuroscience, Aug 13, 2014. Featured article. 34(33):11106-18.
Damien Jullié, Daniel Choquet & David Perrais

Whether a neuron responds to extracellular signals such as guidance molecules, neurotrophins, and neurotransmitters depends on the amount and location of receptors for the signals in the neuron's plasma membrane. These are regulated by ongoing endocytosis, recycling, and exocytosis. Endocytosis of AMPA receptors, for example, reduces responses to presynaptic glutamate release, whereas reinserting the receptors via exocytosis increases synaptic strength. After insertion into the plasma membrane, receptors can either diffuse rapidly within the membrane (called “burst” exocytosis) or remain clustered at the insertion point (“display” exocytosis). Using pH-sensitive fluorescent molecules to track protein movements, Jullié et al. found that transferrin, glutamate, and adrenergic receptors underwent both types of exocytosis. Moreover, receptors that underwent display exocytosis were often locally reinternalized within a few seconds, suggesting the fusion pore rapidly opened and closed. Reinternalized receptors often remained near the plasma membrane for several seconds before they were exocytosed in either burst or display events or their fluorescence faded as the endosome acidified.

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