Regulation of cell fate in Caenorhabditis elegans by a novel cytoplasmic polyadenylation element binding protein

The fog-1 gene of Caenorhabditis elegans specifies that germ cells differen tiate as sperm rather than as oocytes. We cloned fog-1 through a combinatio n of transformation rescue experiments, RNA-mediated inactivation, and muta nt analyses. Our results show that fog-1 produces two transcripts, both of which are found in germ cells but not in the soma. Furthermore, two deletio n mutants alter these transcripts and are likely to eliminate fog-1 activit y. The larger transcript is expressed under the control of sex-determinatio n genes, is necessary for fog-1 activity, and is sufficient to rescue a fog -1 mutant. This transcript encodes a novel member of the CPEB family of RNA -binding proteins. Because CPEB proteins in Xenopus and Drosophila regulate gene expression at the level of translation, we propose that FOG-1 control s germ cell fates by regulating the translation of specific messenger RNAs. (C) 2001 Academic Press.