A selection system for human apoptosis inhibitors using yeast

Abstract

Apoptosis is a regulated series of events which leads to the death and elimination of mammalian cells during development or in disease control. It is regulated in part by members of the Bcl-2 family of genes. Some of these stimulate cell death, while others prevent it. Expression of one of these death inducers, Bax-alpha (Bax), in the yeast Saccharomyces cerevisiae induces growth arrest and subsequently can cause cell death. Proteins of the Bcl-2 family that are known to inhibit apoptosis in mammalian cells overcome Bax-induced growth arrest in yeast. We describe here a system for isolation of human genes that are able to overcome Bax sensitivity in yeast. Two novel proteins, identified with this system, have been named 'Bax antagonists selected in saccharomyces' (BASS). These proteins not only overcome toxicity of Bax in yeast but also protect mammalian cells from apoptosis that is induced by staurosporine or Bax overexpression. We find that BASS2 is the more effective of the two genes.