Partial characterization of SUVi, a new mammalian gene induced by UV-C andexpressed during the S phase of the cell cycle

By using a lacZ-based gene-trap approach, we identified a mammalian gene in duced by UV-C in a Chinese hamster ovary cell clone (Menichini P et al. [19 97]: Nucleic Acids Res 25:4803-4807). The activity of the encoded protein f used to a bacterial beta -galactosidase was followed through the hydrolysis of different p-galactosidase substrates. In this study we describe how the expression of this gene is modulated during the cell cycle and in response to UV-irradiation. We show that the beta -galactosidase activity was virtu ally undetectable in quiescent cells (G(0)), started to increase when cells progressed in G(1), and reached a maximum in mid-S phase, indicating a pos sible role of the endogenous protein during DNA synthesis. Following UV-irr adiation, besides a delay of the progression through the S phase, a twofold increase of the reporter protein activity in all phases of the cell cycle was observed. The partial sequence analysis showed that this gene, here nam ed SUVi (for S phase UV-inducible), contains a domain that is highly conser ved among different helicases. Together, these data suggest that the SUVi g ene could be involved in DNA synthesis, a process that takes place both in the S phase and in the processing of UV-induced damage. (C) 2001 Wiley-Liss , Inc.