Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text (PDF, 662K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by LeBrasseur, N. Search for Related Content PubMed Articles by LeBrasseur, N. Social Bookmarking                            What's this?

Dividing via miRNA

Fewer oocytes are produced in flies lacking Dicer-1 activity (bottom). RUOHOLA-BAKER/MACMILLAN

Stem cells use the miRNA pathway to drive mitosis forward through a stage when other cells would stall, according to results from Steven Hatfield, Halyna Shcherbata, Hannele Ruohola-Baker (University of Washington, Seattle, WA), and colleagues.

The remarkable ability of stem cells to divide relentlessly while surrounding cells are quiescent is key to their function. Stems cells have been noted to express specific miRNAs, suggesting that translational inhibition by these small RNAs might be involved. Ruohola-Baker's group now shows that Dicer-1, the enzyme that makes miRNAs, is required for the strong proliferative capability of germline stem cells (GSCs) in flies.Compared with the wild type, mutant GSCs lacking Dicer-1 were blocked at the G1-to-S transition. Cyclin E, which normally drives cells into S phase, was high in the mutant GSCs. But Dacapo, a cyclin E inhibitor, was also elevated. As a result of the reduced GSC proliferation, female mutants made only 20% of the normal number of eggs. Egg production could be partially rescued in the Dicer-1 mutants by reducing Dacapo levels.

As Dacapo has several putative miRNA-binding sites in its 3' UTR, the authors suspect that these miRNAs normally down-regulate Dacapo in GSCs, when other cell types become quiescent. The group is now testing whether the relevant miRNAs inhibit the translation of a reporter linked to the Dacapo 3' UTR. Other stem cells, and possibly even cancer cells, might use a similar strategy to proliferate beyond the norm.

Reference:

Hatfield, S.D., et al. 2005. Nature. doi:10.1038/nature03816.

Nicole LeBrasseur

lebrasn{at}rockefeller.edu

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This Article Full Text (PDF, 662K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by LeBrasseur, N. Search for Related Content PubMed Articles by LeBrasseur, N. Social Bookmarking                            What's this?