The central importance of translational control by posttranslational modification has spurred major interest in regulatory pathways that control translation. One such pathway uniquely adds hypusine to eukaryotic initiation factor 5A (eIF5A), and thereby affects protein synthesis and subsequently cellular proliferation through an unknown mechanism. Using a novel conditional knockout mouse model and a Caenorhabditis elegans knockout model, we found an evolutionarily conserved role for the DOHH-mediated second step of hypusine synthesis in early embryonic development. At the cellular level we observed reduced proliferation and induction of senescence in 3T3 Dohh(-/-) cells as well as reduced capability for malignant transformation. Furthermore, by mass spectrometry we observed that deletion of DOHH results in an unexpected complete loss of hypusine modification. Our results provide new biological insight into the physiological roles of the second step of the hypusination of eIF5A. Moreover, the conditional mouse model presented here provides a powerful tool to manipulate hypusine modification in a temporal and spatial manner, both to analyze how this unique modification normally functions in vivo, as well as how it contributes to different pathological conditions.
