Integrating Morphogenesis and Metamorphosis

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Science  05 Mar 2004:
Vol. 303, Issue 5663, pp. 1441
DOI: 10.1126/science.303.5663.1441b

One of the most dramatic signaling events in biology is the developmental transition from larval to adult form in organisms that undergo metamorphosis. In insects such as Drosophila, the destruction of larval tissues and their replacement with adult forms is triggered by the steroid hormone 20-hydroxyecdysone. What other factors help coordinate transcriptional regulation with the wholesale tissue restructuring?

Chen et al. found that signaling through LIM-kinase (a protein kinase regulated by the small guanosine triphosphatase Rho) is involved in these transitions. Rho modulates cell shape by regulating actin polymerization, and these changes affect transcription mediated by the serum response factor (SRF) transcription factor. Rho works through LIM-kinase to modulate expression of ecdysone-regulated genes, including Stubble, a gene encoding a protease involved in remodeling of the extracellular matrix. Cultured Drosophila SL2 cells required Rho signaling through SRF to allow proper ecdysone-dependent gene expression. Rho thus appears to be well placed to coordinate tissue remodeling and gene expression through its effects on the cytoskeleton, the extracellular matrix, and ecdysone-dependent gene expression. — LBR

Curr. Biol. 14, 309 (2004).

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