Molecular Biology Faculty
Elizabeth R. Gavis
Schultz Lab, 416
Lab (609) 258-1770
RNA localization and translational regulation during development in Drosophila
Localization of proteins to particular subcellular domains is fundamental to the generation of asymmetry during development and to the polarization of differentiated cells. Many cell types employ localized translation of mRNAs to ensure restricted accumulation of proteins. As a model system, my laboratory studies the Drosophila nanos mRNA, whose localized translation is essential for patterning of the anterior-posterior body axis during embryonic development.
Two post-transcriptional mechanisms, intracellular mRNA localization and translational control, are coupled to produce Nanos protein solely in the posterior of the embryo. Localization of nanos RNA to the posterior pole of the oocyte/embryo is required to activate nanos translation, producing a gradient of Nanos protein that directs abdominal development. However, since only a subset of nanos mRNA is localized, translational repression of unlocalized nanos mRNA is essential to restrict synthesis of Nanos protein to the posterior and prevent deleterious effects of Nanos on head and thorax development.
Our goal is to understand the mechanisms of nanos mRNA localization and translational regulation, and how the two are linked. We have identified both a complex cis-acting mRNA localization signal and a translational control element (TCE) within the nanos 3' untranslated region (3'UTR). The TCE consists of two stem-loops: one stem-loop mediates repression during oogenesis while the other mediates repression during embryogenesis. Through both genetic screens and biochemical assays, we are now beginning to identify cellular factors that recognize these cis-acting sequences. Characterization of these factors will enable us to determine how mRNAs are targeted and transported to their destinations, how they are stabley anchored, and how their translation is regulated during this process. We have found that the TCE and associated factors interfere with a late step in the translation cycle. A similar mechanism may be used by microRNAs to repress translation of their targets. Detailed investigation of this mechanism is currently underway.
To investigate nanos localization at the cell biological level, we have applied a method for in vivo labeling of mRNAs with GFP. The ability to visualize GFP-labeled nanos mRNA in living oocytes has permitted dynamic analysis of RNA localization in real time and determination of the cytoskeletal requirements for localization and anchoring. We have recently extended these studies to bicoid mRNA, whose localization to the anterior of the oocyte appears to occur by a distinct mechanism.
Recent work has shown that nanos is required in a set of peripheral neurons for dendritic morphogenesis and that the TCE can mediate repression of nanos in these neurons. We are investigating whether nanos mRNA and protein are localized within the dendrites and how the TCE functions in this tissue. Based on ectopic expression studies showing that the TCE can function in several other tissues as well, we are attempting to identify additional mRNAs that are subject to TCE-mediated regulation.
Olesnicky EC, Bhogal B, Gavis ER. (2012) Combinatorial use of translational co-factors for cell type-specific regulation during neuronal morphogenesis in Drosophila. Dev Biol. 365: 208-218. PubMed
Sinsimer KS, Jain RA, Chatterjee S, Gavis ER. (2011) A late phase of germ plasm accumulation during Drosophila oogenesis requires Lost and Rumpelstiltskin. Development. 138: 3431-3440. PubMed
Andrews S, Snowflack DR, Clark IE, Gavis ER. (2011) Multiple mechanisms collaborate to repress nanos translation in the Drosophila ovary and embryo. RNA. 17: 967-977. PubMed
Lerit DA, Gavis ER. (2011) Transport of germ plasm on astral microtubules directs germ cell development in Drosophila. Curr Biol. 21: 439-448. PubMed
Becalska AN, Kim YR, Belletier NG, Lerit DA, Sinsimer KS, Gavis ER. (2011) Aubergine is a component of a nanos mRNA localization complex. Dev Biol. 349: 46-52. PubMed
Becalska AN, Gavis ER. (2010) Bazooka regulates microtubule organization and spatial restriction of germ plasm assembly in the Drosophila oocyte. Dev Biol. 340: 528-538. PubMed
Becalska AN, Gavis ER. (2009) Lighting up mRNA localization in Drosophila oogenesis. Development. 136: 2493-2503. PubMed
Kalifa Y, Armenti ST, Gavis ER. (2008) Glorund interactions in the regulation of gurken and oskar mRNAs. Dev Biol. 326: 68-74. PubMed
Weil TT, Parton R, Davis I, Gavis ER. (2008) Changes in bicoid mRNA anchoring highlight conserved mechanisms during the oocyte-to-embryo transition. Curr Biol. 18: 1055-1061. PubMed
Jain RA, Gavis ER. (2008) The Drosophila hnRNP M homolog Rumpelstiltskin regulates nanos mRNA localization. Development 135: 973-982. PubMed
Brechbiel JL, Gavis ER. (2008) Spatial regulation of nanos is required for tts function in dendrite morphogenesis. Curr Biol. 18: 745-750. PubMed
Jaramillo AM, Weil TT, Goodhouse J, Gavis ER, Schupbach T. (2008) The dynamics of fluorescently labeled endogenous gurken mRNA in Drosophila. J Cell Sci.121: 887-894. PubMed
Gavis ER, Chatterjee S, Ford NR, Wolff LJ. (2008) Dispensability of nanos mRNA localization for abdominal patterning but not for germ cell development. Mech Dev 125: 81-90. PubMed
Weil TT, Forrest KM, Gavis ER. (2006) Localization of bicoid mRNA in late oocytes is maintained by continual active transport. Dev Cell 11: 251-262. PubMed
Kalifa Y, Huang T, Rosen LN, Chatterjee S, Gavis ER. (2006) Glorund, a Drosophila hnRNP F/H homolog, is an ovarian repressor of nanos translation. Dev Cell 10, 291-301. PubMed
Duchow HK, Brechbiel JL, Chatterjee S, Gavis ER. (2005) The nanos translational control element represses translation in somatic cells by a Beared box-like motif. Dev Biol 282: 207-217. PubMed
Forrest KM, Clark IE, Jain RA, Gavis ER. (2004) Temporal complexity within a translational control element in the nanos mRNA. Development 131: 5849-5857. PubMed
Ye B, Petritsch C, Clark IE, Gavis ER, Jan LY, Jan YN. (2004) Nanos and pumilio are essential for dendrite morphogenesis in Drosophila peripheral neurons. Curr Biol 14: 314-321. PubMed
Forrest KM, Gavis ER. (2003) Live imaging of endogenous RNA reveals a diffusion and entrapment mechanism for nanos mRNA localization in Drosophila. Curr Biol 13: 1159-1168. PubMed
Bergsten SE, Huang T, Chatterjee S, Gavis ER. (2001) Recognition and long range interactions of a minimal RNA localization signal element. Development 128: 427-435. PubMed
Crucs S, Chatterjee S, Gavis ER. (2000) Overlapping but distinct RNA elements control translational repression and activation of nanos mRNA. Mol Cell 5: 457-467. PubMed
Clark I, Wyckoff D, Gavis ER. (2000) Synthesis of the posterior determinant Nanos is spatially restricted by a novel co-translational regulatory mechanism. Curr Biol 10: 1311-1314. PubMed
Bergsten SE, Gavis ER. (1999) Role for mRNA localization in translational activation but not spatial restriction of nanos RNA. Development 126: 659-659. PubMed