A striking finding from whole-genome sequences is the
amount of information we are missing on gene function. For
example, although Drosophila is arguably the
best-understood multi-cellular organism (and a proven
model system for human diseases), mutations with readily
detectable phenotypes have been isolated for only about
15% of the more than 15,000 annotated fly genes.
Our lack of information on the majority of genes (the
"phenotype gap") does not indicate that the genes have no
functions. Instead, it suggests that we have been unable
to either assay their roles experimentally and/or resolve
an issue of functional redundancy. In addition, our
understanding of many genes for which we have some
information is limited by pleiotropy, whereby the earlier
function of a gene prevents analysis of functions that
occur later in development.
How do we systematically learn more information about
all genes? Using transgenic RNAi, it is now possible to
disrupt the activity of single genes with a spatial and
temporal resolution that is impossible or exceedingly
difficult to achieve using classical genetic methods.
With the backing of the NIH/NIGMS, the Drosophila
Transgenic RNAi Project, or TRiP, has the goal to generate
6,250 transgenic RNAi lines designed to fill in the
phenotype gap and help researchers overcome issues
associated with pleiotropy. Specifically, we are using a
new approach for transgenic RNAi that relies on
phiC31-targeted integration combined with the Gal4/UAS
system. In this way, conditional and tissue-specific
expression of hairpin constructs in Drosophila will be
generated.
All validated transgenic fly lines will be made
available to the entire community through the Bloomington
Drosophila Stock Center (BDSC). The collection will be
invaluable to address a myriad of questions in biology and
medicine, including but not limited to cell biology,
signal transduction and cancer, the etiology of congenital
malformations, neurodegeneration, and behavior.
A pilot project supported by the HHMI/Janelia Farm
Visitor Program between the laboratories of N. Perrimon,
C. Zuker and G. Rubin has generated nearly 1,250 hairpin
lines. See the page TRiP
Stocks to learn target dates for availability at
BDSC. At the same time--and thanks to the NIH/NIGMS
award--the TRiP will continue production and transfer of
RNAi lines to BDSC during the four years of NIH/NIGMS
support.
Genes to be targeted are selected based on the BDSC
mandate of one mutation per gene, the needs of screeners
at the Drosophila RNAi Screening Center (DRSC), and the
needs of the Drosophila community for in vivo phenotypic
analyses. The resource will be housed in the TRiP facility
at Harvard Medical School (production and for screening)
and transferred on a regular schedule to the BDSC (for
distribution).
