Human fertility protein PUMILIO2 interacts in vitro with testis mRNA encoding Cdc42 effector 3 (CEP3).

PUMILIO protein regulates translation of specific mRNAs in morphogenesis and in development of the germ-line of model organisms such as flies and worms. Given that a human homologue (PUMILIO2) was recently identified in the germ-line stem cells, the question was raised whether it regulates translation of fertility mRNAs similarly to Drosophila Pumilio. Here, we describe a candidate mRNA encoding Cdc42 effector protein 3 (CEP3), however, a function for this protein in reproduction has previously not been reported. We detected three CEP3 transcripts in the testis tissue including one which was highly expressed and testis specific by northern blotting. We found that CEP mRNA contains GUUGU (A) and AUUGUA (B) motifs (ABB) within the 3' untranslated region (3'UTR), which are also present in mRNA targets of Pumilio in Drosophila. Interaction of PUMILIO2 with the fragment of CEP3 transcript containing the ABB array was tested by mobility shift assay and we found that PUMILIO2 binds the 3' untranslated region of the CEP3 mRNA. These results support the hypothesis that CEP3 mRNA may be a target of PUMILIO2 protein in the human male gonad and be under translational control mediated by specific nucleotide motifs within the 3'UTR.