Non-cell autonomous induction of apoptosis and loss of posterior structures by activation domain-specific interactions of Oct-1 in the Xenopus embryo

Abstract

Oct-1, a member of the POU family of transcription factors, is expressed at relatively high levels in ectodermal and mesodermal cell lineages during early Xenopus embryogenesis. Here we show that overexpression of Oct-1 induces programmed cell death concomitant with the loss of the posterior part of the body axis. Truncated Oct-1 variants, missing either the C-terminal or N-terminal transactivation domain, exhibit a different capacity to cause such developmental defects. Oct-1-induced cell death is rescued in unilaterally injected embryos by non-injected cells, indicative of the non-cell autonomous character of the developmental effects of Oct-1. This was confirmed by marker gene analysis, which showed a significant decrease in brachyuryexpression, suggesting that Oct-1 interferes with an FGF-type signalling pathway.