Rho GTPase Integrating Morphogenesis and Gene Expression in Metamorphosis

Science's STKE  24 Feb 2004:
Vol. 2004, Issue 221, pp. tw70-TW70
DOI: 10.1126/stke.2212004TW70

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 like Drosophila, the destruction of larval tissues and their replacement with adult forms is triggered by the steroid hormone 20-hydroxyecdysone. Surely, there must be other factors that help coordinate transcriptional regulation with the wholesale tissue restructuring that must take place, and new work by Chen et al. implicates signaling through LIM-kinase, a protein kinase regulated by the small guanosine triphosphatase Rho. Rho modulates cell shape by regulating actin polymerization, and these changes affect transcription mediated by the serum response factor (SRF) transcription factor. Chen et al. analyzed genetic interactions in Drosophila to show that 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. In cultured Drosophila SL2 cells, the authors demonstrated a cell autonomous requirement for 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.

G.-C. Chen, P. Gajowniczek, J. Settleman, Rho-LIM kinase signaling regulates ecdysone-induced gene expression and morphogenesis during Drosophila metamorphosis. Curr. Biol. 14, 309-313 (2004). [Online Journal]