Download full-text

Full-text

Available from: Fuad Bahram, Feb 13, 2014
2 Followers
 · 
311 Views
 · 
55 Downloads
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    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. DOI:10.1016/j.celrep.2015.06.029 · 8.36 Impact Factor
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    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 · 5.98 Impact Factor
  • Source
    • "To test for the co-localization of REST with 5mC and 5hmC in nuclei of retinal neurons, we applied an in situ proximity ligation assay (PLA) combining REST-specific with 5mC-or 5hmC-specific antibodies . PLA gives only a positive signal when 5mC or 5hmC and REST are in close proximity (<40 nm) (Sö derberg et al., 2006). We observed a positive PLA signal for both combinations , REST/5mC as well as REST/5hmC (Figure 5A). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Ten-eleven translocation hydroxylases (TET1-3) oxidize 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC). In neurons, increased 5hmC levels within gene bodies correlate positively with gene expression. The mechanisms controlling TET activity and 5hmC levels are poorly understood. In particular, it is not known how the neuronal TET3 isoform lacking a DNA-binding domain is targeted to the DNA. To identify factors binding to TET3, we screened for proteins that co-precipitate with TET3 from mouse retina and identified the transcriptional repressor REST as a highly enriched TET3-specific interactor. REST was able to enhance TET3 hydroxylase activity after co-expression and overexpression of TET3-activated transcription of REST target genes. Moreover, we found that TET3 also interacts with NSD3 and two other H3K36 methyltransferases and is able to induce H3K36 trimethylation. We propose a mechanism for transcriptional activation in neurons that involves REST-guided targeting of TET3 to the DNA for directed 5hmC generation and NSD3-mediated H3K36 trimethylation. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Cell Reports 04/2015; 120(2). DOI:10.1016/j.celrep.2015.03.020 · 8.36 Impact Factor
Show more