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Available from: Fuad Bahram, Feb 13, 2014
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    • "In this model, high RGS4 activity can limit diffusion of GTP-bound Ga i to <20 nm. This suggestion is supported by our proximity ligation assay data, which suggest preferential postsynaptic coupling of a2Rs/AMPARs and GABA B Rs/ NMDARs within 20 nm (Sö derberg et al., 2006). There is mounting anatomical evidence that synaptic proteins, including glutamate receptors, are organized into 70-to 80-nm clusters within the postsynaptic density (MacGillavry et al., 2013; Nair et al., 2013). "
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    ABSTRACT: A diverse array of neuromodulators governs cellular function in the prefrontal cortex (PFC) via the activation of G-protein-coupled receptors (GPCRs). However, these functionally diverse signals are carried and amplified by a relatively small assortment of intracellular second messengers. Here, we examine whether two distinct Gαi-coupled neuromodulators (norepinephrine and GABA) act as redundant regulators of glutamatergic synaptic transmission. Our results reveal that, within single dendritic spines of layer 5 pyramidal neurons, alpha-2 adrenergic receptors (α2Rs) selectively inhibit excitatory transmission mediated by AMPA-type glutamate receptors, while type B GABA receptors (GABABRs) inhibit NMDA-type receptors. We show that both modulators act via the downregulation of cAMP and PKA. However, by restricting the lifetime of active Gαi, RGS4 promotes the independent control of these two distinct target proteins. Our findings highlight a mechanism by which neuromodulatory microdomains can be established in subcellular compartments such as dendritic spines. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Cell Reports 07/2015; 69(2). DOI:10.1016/j.celrep.2015.06.029 · 8.36 Impact Factor
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    • "The proximity ligation assay confirmed their interaction. Indeed, this technique made it possible to detect closed epitopes separated by a maximum distance of around 30–40 nm [33], and finally strengthened the binding between both in their physiological context (Fig. 5). This heteromeric cytokine may be stabilized by its binding to the M-CSFR, as the molecular docking study proposed a new binding mode for this heteromeric cytokine to two isolated M-CSFR chains (Fig. 4D). "
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    ABSTRACT: Interleukin-34 (IL-34) is a newly-discovered homodimeric cytokine that regulates, like Macrophage Colony-Stimulating Factor (M-CSF), the differentiation of the myeloid lineage through M-CSF receptor (M-CSFR) signaling pathways. To date, both cytokines have been considered as competitive cytokines with regard to the M-CSFR. The aim of the present work was to study the functional relationships of these cytokines on cells expressing the M-CSFR. We demonstrate that simultaneous addition of M-CSF and IL-34 led to a specific activation pattern on the M-CSFR, with higher phosphorylation of the tyrosine residues at low concentrations. Similarly, both cytokines showed an additive effect on cellular proliferation or viability. In addition, BIAcore experiments demonstrated that M-CSF binds to IL-34, and molecular docking studies predicted the formation of a heteromeric M-CSF/IL-34 cytokine. A proximity ligation assay confirmed this interaction between the cytokines. Finally, co-expression of the M-CSFR and its ligands differentially regulated M-CSFR trafficking into the cell. This study establishes a new foundation for the understanding of the functional relationship between IL-34 and M-CSF, and gives a new vision for the development of therapeutic approaches targeting the IL-34/M-CSF/M-CSFR axis. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Cytokine 06/2015; 76(2). DOI:10.1016/j.cyto.2015.05.029 · 2.66 Impact Factor
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    • "The simplest interpretation of these data is that Tm5NM1- containing actin filaments are required for the interaction of pERK with Imp7. To test this, we used the Duolink in situ proximity ligation assay (PLA) to evaluate the interaction of Tm5NM1 with pERK and the effect of the Tm5NM1 KO on the ability of pERK to interact with Imp7 (Soderberg et al., 2006). pERK interacts with Tm5NM1 in a serum-responsive manner, with a significantly higher number of PLA signal dots in the WT MEFs after serum addition relative to serum-starved cells (Figure 8, A and C). "
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    ABSTRACT: ERK regulated cell proliferation requires multiple phosphorylation events catalysed first by MEK and then Casein Kinase 2 (CK2) followed by interaction with importin7 and subsequent nuclear translocation of pERK. We report that genetic manipulation of a core component of the actin filaments of cancer cells, the tropomyosin Tm5NM1, regulates the proliferation of normal cells both in vitro and in vivo. Mouse embryo fibroblasts (MEFs) lacking Tm5NM1, which have reduced proliferative capacity, are insensitive to inhibition of ERK by peptide and small molecule inhibitors indicating that ERK is unable to regulate proliferation of these knockout (KO) cells. Treatment of wild type MEFs with a CK2 inhibitor to block phosphorylation of the nuclear translocation signal in pERK resulted in greatly decreased cell proliferation and a significant reduction in the nuclear translocation of pERK. In contrast, Tm5NM1 KO MEFs which show reduced nuclear translocation of pERK were unaffected by inhibition of CK2. This suggested that it is nuclear translocation of CK2-phosphorylated pERK which regulates cell proliferation and this capacity is absent in Tm5NM1 KO cells. Proximity ligation assays confirmed a growth factor-stimulated interaction of pERK with Tm5NM1 and that the interaction of pERK with importin7 is greatly reduced in the Tm5NM1 KO cells. © 2015 by The American Society for Cell Biology.
    Molecular biology of the cell 05/2015; 26(13). DOI:10.1091/mbc.E14-10-1453 · 4.47 Impact Factor
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