RNAi in C. elegans is naturally systemic; gene silencing initiated in a single cell or tissue spreads, silencing that gene throughout the animal and its progeny. A C. elegans protein, SID-1, has been identified that is required for the systemic transmission of silencing information. SID- 1 is predicted to contain 11 integral membrane domains and a large extracellular domain suggesting that it may act as a channel or receptor for the uptake or transport of dsRNA. Furthermore, two mammalian genes have been identified with a similar overall predicted structure and extensive homology in the transmembrane domains. A second C. elegans integral membrane protein SID-2 is also required for uptake of silencing information. The goals of this proposal are to investigate the subcellular localization, structure, activity, and regulation of SID-1 and SID-2 and to begin to characterize mammalian SID-1 homologs. To determine whether either SID protein acts as a channel or receptor and to identify and characterize their presumed interactions with dsRNA, their transport activity will be investigated using nematode primary cell lines derived from wild-type and mutant embryos. To corroborate these findings, the transport activity of SID-1 and SID-2 expressed in heterologous systems will be assayed. The mouse SID-1 homologs will be expressed in nematodes and insect cell lines to determine whether they can complement sid-1 mutations or perform any of the functions of SID-1. Mouse embryonic stem cells will be characterized for expression of SID homologs and dsRNA uptake activity as well as cell-tocell spreading of silencing information. Finally, we will begin a functional analysis of the mouse homologs in ES cells and chimera embryos. These studies may have a direct impact on the treatment of human genetic disease and viral infection. RNAi has been shown to effectively inhibit HIV and polio infection and to disable oncogenes, returning cells to normal growth behavior. Although RNAi has been shown to be effective, a major obstacle remains delivery of dsRNA into human cells both in culture and in vivo.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM069891-04
Application #
7173262
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Carter, Anthony D
Project Start
2004-01-01
Project End
2008-07-31
Budget Start
2007-01-01
Budget End
2008-07-31
Support Year
4
Fiscal Year
2007
Total Cost
$279,904
Indirect Cost
Name
Harvard University
Department
Microbiology/Immun/Virology
Type
Schools of Arts and Sciences
DUNS #
082359691
City
Cambridge
State
MA
Country
United States
Zip Code
02138
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Shih, Joseph D; Fitzgerald, Michael C; Sutherlin, Marie et al. (2009) The SID-1 double-stranded RNA transporter is not selective for dsRNA length. RNA 15:384-90
Jose, Antony M; Smith, Jessica J; Hunter, Craig P (2009) Export of RNA silencing from C. elegans tissues does not require the RNA channel SID-1. Proc Natl Acad Sci U S A 106:2283-8
Whangbo, Jennifer S; Hunter, Craig P (2008) Environmental RNA interference. Trends Genet 24:297-305
Winston, William M; Sutherlin, Marie; Wright, Amanda J et al. (2007) Caenorhabditis elegans SID-2 is required for environmental RNA interference. Proc Natl Acad Sci U S A 104:10565-70
Jose, Antony M; Hunter, Craig P (2007) Transport of sequence-specific RNA interference information between cells. Annu Rev Genet 41:305-30
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Schott, Daniel H; Cureton, David K; Whelan, Sean P et al. (2005) An antiviral role for the RNA interference machinery in Caenorhabditis elegans. Proc Natl Acad Sci U S A 102:18420-4