The nuclear concentration of kin17, a mouse protein that binds to curved DNA, increases during cell proliferation and after UV irradiation

UV-irradiation induces, in mammalian cells, the expression of a set ofgenes known as the 'UV-response', which may be reminiscent of the bacterialresponse, called SOS system. The multifunctional protein RecA controls theexpression of the SOS genes. We report the expression profile of a mousegene conserved among mammals, called Kin17, that codes a DNA-bindingprotein of undetermined biochemical activity and which shares epitopes withthe bacterial RecA protein. We demonstrate that the level of Kin17 RNA was5-fold higher in mid-S phase of serum- stimulated BALB/c 3T3 fibroblaststhan in quiescent cells. Cells in S- phase displayed a high level of kin17protein with a marked nuclear localisation. The maximal level of Kin17 RNAwas observed 18 h after serum stimulation, indicating that Kin17 gene is anew member of the late growth-related genes. The accumulation of kin17protein during cell proliferation follows the increase in Kin17 RNA andcorrelates with DNA synthesis, which suggests a possible role of kin17protein in a transaction related to DNA-replication. In quiescentfibroblasts, a 3- fold increase in Kin17 RNA was seen 13 h after UVirradiation. In parallel, kin17 protein accumulated in the nucleus, whichsuggests that it might be required after the stress produced by UVirradiation.