Editors' ChoiceTranscription factors

One Cubitus Equals Three Gli

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Science's STKE  12 Sep 2000:
Vol. 2000, Issue 49, pp. tw8
DOI: 10.1126/stke.2000.49.tw8

Aza-Blanc et al. expressed the three vertebrate Gli transcription factors in the wing of Drosophila in order to explore how the functions of these three proteins relate to the Drosophila Cubitus protein (Ci). Ci and Gli transcription factors are major mediators of signaling by Hedgehog (Hh), and they can have repressor or activator functions depending on the concentration of the Hh signal. The authors find through ectopic expression experiments that each of the Gli proteins has a subset of Ci functions: Gli1 is an Hh-regulated activator, Gli3 is an Hh-regulated repressor, and Gli2 has some activator and repressor functions. Supporting these results, cleaved forms similar to the Ci repressor form were only detected for ectopically expressed Gli2 and Gli3, and only Gli3 cleavage was regulated by Hh. The authors propose that Ci is a composite protein with multiple functions in a single polypeptide that may represent a mechanism by which a compact genome like that of Drosophila may still yield complexity of function.

Aza-Blanc, P., Line, H.Y., Ruiz i Altaba, A., and Kornberg, T.B. (2000) Expression of the vertebrate Gli proteins in Drosophila reveals a distribution of activator and repressor activities. Development 127: 4293-4301. [Online Journal]

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