The establishment of polarity and provision of spatial cues in the embryo are prerequisites for the development of a complex multicellular organism. These requirements are essentially problems of localization, or how to position morphogens or spatial cues non randomly in a cell or group of cells. The long term goal of this application is to understand one prominent example of the localization phenomenon, that of the bicoid morphogen. The bicoid gene is largely responsible for anterior body patterning in the Drosophila embryo. Appropriate spatial deployment of the bicoid protein morphogen in the anterior of the embryo relies on the prelocalization of bicoid mRNA to the anterior pole of the egg during oogenesis. Similar mRNA prelocalizations are involved in deployment of other patterning molecules; additional prominent examples come from both Drosophila and Xenopus.
The specific aims of this application fall into two related areas. First, we will continue our identification and characterization of the cis-acting elements within the bicoid mRNA that direct its localization. One previously identified element, BLEI, will be scrutinized in detail. A collection of mutated forms of BLEI will be constructed by in vitro DNA manipulations. These will be tested by a rapid in vitro assay for binding to an ovarian protein, pi 15, that binds specifically to wild-type BLEI and is a strong candidate to act in bicoid mRNA localization. Some of the same BLEI mutants will be tested for their abilities to direct localization in vivo using transgenic fly strains. From the behavior of the BLEI mutants we hope to learn how BLEI acts in localization. BLEI does not direct all stages of localization, and so we will attempt to identify and define the missing localization elements, monitoring the localization properties of mutants lacking parts of the bicoid mRNA other than BLEI. The second direction of the work is to isolate and characterize trans-acting factors involved in bicoid mRNA localization. Efforts will initially be directed towards two protein factors. One is the previously mentioned ovarian BLEI-binding protein. We will purify the protein and clone the gene that encodes it. Molecular and genetic characterization of the gene will be undertaken to explore its role in localization, with the eventual aim of asking what molecules it contacts in addition to bicoid mRNA. The other protein factor is the product of the exuperantia gene, which we have cloned. Because our results suggest that exu protein makes interactions with other proteins, we will use a yeast screening system to identify and isolate those proteins. Collectively, this work will provide a strong foundation for understanding how bicoid mRNA is localized.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM042612-07
Application #
2181518
Study Section
Genetics Study Section (GEN)
Project Start
1989-07-01
Project End
1998-06-30
Budget Start
1995-07-01
Budget End
1996-06-30
Support Year
7
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Stanford University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305
Snee, Mark J; Macdonald, Paul M (2009) Bicaudal C and trailer hitch have similar roles in gurken mRNA localization and cytoskeletal organization. Dev Biol 328:434-44
Snee, Mark J; Macdonald, Paul M (2009) Dynamic organization and plasticity of sponge bodies. Dev Dyn 238:918-30
Geng, Cuiyun; Macdonald, Paul M (2007) Identification of genes that influence gurken expression. Fly (Austin) 1:259-67
Geng, Cuiyun; Macdonald, Paul M (2006) Imp associates with squid and Hrp48 and contributes to localized expression of gurken in the oocyte. Mol Cell Biol 26:9508-16
Snee, Mark J; Arn, Eric A; Bullock, Simon L et al. (2005) Recognition of the bcd mRNA localization signal in Drosophila embryos and ovaries. Mol Cell Biol 25:1501-10
Arn, Eric A; Cha, Byeong J; Theurkauf, William E et al. (2003) Recognition of a bicoid mRNA localization signal by a protein complex containing Swallow, Nod, and RNA binding proteins. Dev Cell 4:41-51
Macdonald, P M; Kerr, K (1998) Mutational analysis of an RNA recognition element that mediates localization of bicoid mRNA. Mol Cell Biol 18:3788-95
Dubowy, J; Macdonald, P M (1998) Localization of mRNAs to the oocyte is common in Drosophila ovaries. Mech Dev 70:193-5
Macdonald, P M; Kerr, K (1997) Redundant RNA recognition events in bicoid mRNA localization. RNA 3:1413-20
Luk, S K; Kilpatrick, M; Kerr, K et al. (1994) Components acting in localization of bicoid mRNA are conserved among Drosophila species. Genetics 137:521-30

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