Cell Biology

Life, Death, and microRNA

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Science  09 May 2003:
Vol. 300, Issue 5621, pp. 867-869
DOI: 10.1126/science.300.5621.867e

Tissue growth and patterning during development rely on coordinated control of cell proliferation and cell survival. Research from two independent groups now suggests that this relationship may involve microRNA (miRNA). These small regulatory RNAs (21 to 25 nucleotides) are posttranscriptional repressors of gene expression, but their specific functions across species are largely unknown.

Brennecke et al. show that the bantam gene encodes a miRNA that controls the development of eye and wing imaginal disc structures in Drosophila by stimulating cell proliferation. In vivo bantam expression was spatially regulated during development. This may be controlled by the secreted protein Wingless, linking a signaling morphogen known to control spatial patterning to cell proliferation and tissue formation. Furthermore, bantam repressed the apoptosis-inducing gene hid, blocking hid-induced cell death.

In a genetic screen for inhibitors of apoptosis in Drosophila, Xu et al. identified mir-14 as a miRNA that suppresses the cell death effects of several proapototic genes, including rpr, hid, and grim. A potential target site for mir-14 was identified in a transcript encoding Drice, an apoptotic effector caspase. Flies lacking mir-14 exhibited increased Drice expression and a reduced life-span.

Thus, miRNAs may represent a general regulatory mechanism of cell death during development.—LDC

Cell 113, 25 (2003); Curr. Biol. 13, 790 (2003).

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