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Original Research ARTICLE

Front. Neural Circuits, 03 November 2010 | http://dx.doi.org/10.3389/fncir.2010.00121

The Me31B DEAD-box helicase localizes to postsynaptic foci and regulates expression of a CaMKII reporter mRNA in dendrites of Drosophila olfactory projection neurons

  • 1 Smurfit Institute of Genetics and Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
  • 2 Department of Electronic and Electrical Engineering, Trinity College Dublin, Dublin, Ireland
  • 3 Department of Biological Sciences, University of Denver, Denver, CO, USA
  • 4 Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, USA
  • 5 Howard Hughes Medical Institute, University of Arizona, Tucson, AZ, USA

mRNP granules at adult central synapses are postulated to regulate local mRNA translation and synapse plasticity. However, they are very poorly characterized in vivo. Here, in Drosophila olfactory synapses, we present early observations and characterization of candidate synaptic mRNP particles, one of which contains a widely conserved, DEAD-box helicase, Me31B. In Drosophilas, Me31B is required for translational repression of maternal and miRNA-target mRNAs. A role in neuronal translational control is primarily suggested by Me31B’s localization, in cultured primary neurons, to neuritic mRNP granules that contain: (i) various translational regulators; (ii) CaMKII mRNA; and (iii) several P-body markers including the mRNA hydrolases, Dcp1, and Pcm/Xrn-1. In adult neurons, Me31B localizes to P-body like cytoplasmic foci/particles in neuronal soma. In addition it is present to synaptic foci that may lack RNA degradative enzymes and localize predominantly to dendritic elements of olfactory sensory and projection neurons (PNs). MARCM clones of PNs mutant for Me31B show loss of both Me31B and Dcp1-positive dendritic puncta, suggesting potential interactions between these granule types. In PNs, expression of validated hairpin-RNAi constructs against Me31B causes visible knockdown of endogenous protein, as assessed by the brightness and number of Me31B puncta. Knockdown of Me31B also causes a substantial elevation in observed levels of a translational reporter of CaMKII, a postsynaptic protein whose mRNA has been shown to be localized to PN dendrites and to be translationally regulated, at least in part through the miRNA pathway. Thus, neuronal Me31B is present in dendritic particles in vivo and is required for repression of a translationally regulated synaptic mRNA.

Keywords: Me13B, Drosophila, synaptic mRNPs, CamKII, translational control, olfactory circuitry

Citation: Hillebrand J, Pan K, Kokaram A, Barbee S, Parker R and Ramaswami M (2010) The Me31B DEAD-box helicase localizes to postsynaptic foci and regulates expression of a CaMKII reporter mRNA in dendrites of Drosophila olfactory projection neurons. Front. Neural Circuits 4:121. doi: 10.3389/fncir.2010.00121

Received: 30 April 2010; Accepted: 27 September 2010;
Published online: 03 November 2010.

Edited by:

Leslie B. Vosshall, Rockefeller University, USA

Reviewed by:

Michael A. Sutton, University of Michigan, USA
Kelsey Martin, University of California at Los Angeles, USA
Jason Dictenberg, Hunter College, USA

Copyright: © 2010 Hillebrand, Pan, Kokaram, Barbee, Parker and Ramaswami. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.

*Correspondence: Mani Ramaswami and Jens Hillebrand, Institute for Neuroscience, Trinity College Dublin, Lloyd Building, Dublin 2, Ireland. e-mail: mani@u.arizona.edu; jens.hillebrand@tcd.ie