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Endocrinology - Hellerman |
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microRNA/RNAi |
| See Web links on RNA |
#4 Still hot. Science's breakthrough of 2002 kept scientists on the edge of their seats in 2003. Having sketched out the role played by miniature RNA molecules in modulating gene expression, this year biologists dove into the details, exploring how small RNAs orchestrate a cell's behavior and how harnessing their power could combat disease.
Interference. Mice injected with siRNAs (right) are
protected from liver disease (left).
CREDIT: E. SONG ET AL., NATURE MEDICINE
MicroRNAs, the runts of the RNA litter at about 22 nucleotides in length, were found to guide early development--from shaping plant leaves to mediating cell proliferation in fruit fly embryos. RNA interference (RNAi), which shuts down gene expression, also plays a critical role in development. Mice lacking an RNAi protein called Dicer lost swaths of stem cells and died before birth. Also this year, certain microRNAs in mice were found to help direct stem cells that create the embryo's blood cell system. Humans, meanwhile, are now thought to harbor as many as 255 genes that encode microRNAs--nearly 1% of the genes in the entire genome.
RNAi also proved its worth this year as a tool to screen hundreds or even thousands of genes. RNAi offers a quick and relatively easy way of systematically inhibiting RNA molecules with a complementary sequence, preventing them from synthesizing proteins. By squelching the RNA signal of one gene at a time, researchers are beginning to outline genetic networks that govern everything from a cell's morphology to its signaling systems.
Other RNA enthusiasts are recruiting small interfering RNAs (siRNAs), which are similar in size to their micro counterparts, in the fight against disease. They help power the RNAi machinery and thus are pros at controlling protein production--something that goes awry in many diseases. Researchers showed that siRNAs can ramp down proteins involved in HIV and protect mice from hepatitis by blocking a gene behind liver inflammation. The effort to pit these molecules against disease faces big challenges, however. Among them: getting siRNAs to the right genes and cells and steering them clear of the wrong ones.
| Jump to: Online extras on RNA Next runner-up: Single-molecule techniques Top of page |
| Papers and Articles |
| E. J. Finnegan and M. A. Matzke,
"The Small
RNA World," J. Cell Sci. 116, 4689 (2003)
C.-Z. Chen et al., "MicroRNAs Modulate Hematopoietic Lineage Differentiation," Science, published online 4 December 2003 (10.1126/science.1091903) J. F. Palatniket al., "Control of Leaf Morphogenesis by MicroRNAs," Nature 425, 257 (2003) E. Bernstein et al., "Dicer Is Essential for Mouse Development," Nature Genetics 35, 215 (2003) E. Wienholds et al., "The MicroRNA-Producing Enzyme Dicer1 Is Essential for Zebrafish Development," Nature Genetics 35, 217 (2003) J. Brennecke et al., "bantam Encodes a Developmentally Regulated MicroRNA that Controls Cell Proliferation and Regulates the Proapoptotic Gene hid in Drosophila," Cell 113, 25 (2003) J. C. Carrington and V. Ambros, "Role of MicroRNAs in Plant and Animal Development," Science 301, 336 (2003) M. Matzke and A.J. M. Matzke, "RNAi Extends Its Reach," Science 301, 1060 (2003) J. Couzin, "Mini RNA Molecules Shield Mouse Liver from Hepatitis," Science 299, 995 (2003) J. Couzin, "New Screen Nets 'Hedgehog' Genes," Science 299, 1961 (2003) |
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Last Modified: Sunday December 28 2003
