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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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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Nature Neuroscience - July 2014

miR-92a regulates translation and synaptic incorporation of GluA1 containing AMPA receptors during homeostatic scaling
Nat Neurosci. 201
4
- Jul 13. doi: 10.1038/nn.3762. [Epub ahead of print]

Mathieu Letellier1,2,*, Sara Elramah1,2,*, Magali Mondin1,2,*, Anaïs Soula1,2, Andrew Penn1,2, Daniel Choquet1,2, Marc Landry1,2, Olivier Thoumine1,2,$, Alexandre Favereaux1,2,$

miR-92a-favereauxMicroRNAs (miRNAs) are small non-coding RNAs that inhibit protein translation by binding to the 3′ untranslated region (3′ UTR) of target mRNAs. miRNAs are abundant in the brain, with the challenge being to identify their roles and targets in specific neuronal functions. Homeostatic synaptic scaling is a form of plasticity by which neurons make compensatory adjustments to the strength of excitatory synapses according to their activity level. Notably, postsynaptic AMPA receptors (AMPARs), which are the major effectors of communication at glutamatergic synapses, are upregulated following activity blockade. In a well-characterized procedure, treatment of hippocampal neurons with tetrodotoxin (TTX, to prevent action potentials) and AP5 (to further block NMDA receptor–mediated miniature synaptic transmission) increases the expression of GluA1 homomeric AMPARs through local translation of GluA1 mRNAs present in dendrites.
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NATURE - June 2014

The cancer glycocalyx mechanically primes integrin-mediated growth and survival
Nature 2014 -
doi:10.1038/nature13535

Matthew J. Paszek, Christopher C. DuFort, Olivier Rossier, Russell Bainer, Janna K. Mouw, Kamil Godula, Jason E. Hudak, Jonathon N. Lakins, Amanda C. Wijekoon, Luke Cassereau, Matthew G. Rubashkin, Mark J. Magbanua, Kurt S. Thorn, Michael W. Davidson, Hope S. Rugo, John W. Park, Daniel A. Hammer, Grégory Giannone, Carolyn R. Bertozzi, Valerie M. Weaver

thumb_mucine2014Malignancy is associated with altered expression of glycans and glycoproteins that contribute to the cellular glycocalyx. We constructed a glycoprotein expression signature, which revealed that metastatic tumors upregulate expression of bulky glycoproteins. A computational model predicted that these glycoproteins would influence transmembrane receptor spatial organization and function. We tested this prediction by investigating whether a bulky glycocalyx promotes a tumor phenotype by increasing integrin adhesion and signaling. Data revealed that a bulky glycocalyx facilitates integrin clustering by funneling active integrins into adhesions and altering integrin state by applying tension to matrix-bound integrins, independent of actomyosin contractility. Expression of large tumor-associated glycoproteins in non-transformed mammary cells promoted focal adhesion assembly and facilitated integrin-dependent growth factor signaling to support cell growth and survival. Clinical studies revealed that large glycoproteins are abundantly expressed on circulating tumor cells from patients with advanced disease. Thus, a bulky glycocalyx is a feature of tumor cells that could foster metastasis by mechanically enhancing cell surface receptor function.

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The Journal of Neuroscience - April 2014

Stimulated emission depletion (STED) microscopy reveals nanoscale defects in the developmental trajectory of dendritic spine morphogenesis in a mouse model of fragile X syndrome
The Journal of Neuroscience, April 30, 2014
34(18):6405–6412

Lasani S. Wijetunge, Julie Angibaud, Andreas Frick, Peter C. Kind, and U. Valentin Nägerl

thumb_fmr-vn-2014Dendritic spines are basic units of neuronal information processing and their structure is closely reflected in their function. Defects in synaptic development are common in neurodevelopmental disorders, making detailed knowledge of age-dependent changes in spine morphology essential for understanding disease mechanisms. However, little is known about the functionally important fine morphological structures, such as spine necks, due to the limited spatial resolution of conventional light microscopy.
Using stimulated emission depletion microscopy (STED), we examined spine morphology at the nanoscale during normal development in mice, and tested the hypothesis that it is impaired in a mouse model of fragile X syndrome (FXS). In contrast to common belief, we find that, in normal development, spine heads become smaller, while their necks become wider and shorter, indicating that synapse compartmentalization decreases substantially with age. In the mouse model of FXS, this developmental trajectory is largely intact, with only subtle differences that are dependent on age and brain region.
Together, our findings challenge current dogmas of both normal spine development as well as spine dysgenesis in FXS, highlighting the importance of super-resolution imaging approaches for elucidating structure–function relationships of dendritic spines.

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