Bix3: Transcription Factor and Apoptotic Regulator

Science's STKE  02 Sep 2003:
Vol. 2003, Issue 198, pp. tw340-TW340
DOI: 10.1126/stke.2003.198.tw340

The Bix family of homeobox-containing proteins are transcriptional regulators involved in early embryonic development. Trindade et al. report that misexpression of Bix3 by microinjection of RNA into Xenopus embryos causes different phenotypes from Bix1, with Bix3 causing cell disaggregation, stimulation of a different gene profile, and cellular apoptosis. Injection of antisense oligonucleotides that inhibited both Bix1 and Bix3 also stimulated apoptosis; however, only Bix3 rescued the embryos from increased cell death, suggesting that the effect was due to loss of Bix3. Apoptosis-inducing activity of Bix3 did not correlate with transcriptional activation activity based on analysis of mutants or deletion constructs. If the C-terminal 25 residues of Bix1 were deleted, then this truncated version of Bix1 could also promote embryonic apoptosis. Thus, Bix proteins may be dual-functional proteins with roles in transcriptional regulation and cell survival.

M. Trindade, N. Messenger, C. Papin, D. Grimmer, L. Fairclough, M. Tada, J. C. Smith, Regulation of apoptosis in the Xenopus embryo by Bix3. Development 130, 4611-4622 (2003). [Abstract] [Full Text]