Investigation of the interplay between SKP2, CDT1 and Geminin in cancer cells

Geminin has a dual role in the regulation of DNA replication: it inhibits replication factor CDT1 activity during the G2 phase of the cell cycle and promotes its accumulation at the G2/M transition. In this way Geminin prevents DNA re-replication during G2 phase and ensures that DNA replication is efficiently executed in the next S phase. CDT1 was shown to associate with SKP2, the substrate recognition factor of the SCF ubiquitin ligase complex. We investigated the interplay between these three proteins in cancer cell lines. We show that Geminin, CDT1 and SKP2 could possibly form a complex and propose the putative regions of CDT1 and Geminin involved in the binding. We also show that, despite the physical interaction, SKP2 depletion does not substantially affect CDT1 and Geminin protein levels. Moreover, we show that while Geminin and CDT1 levels fluctuate, SKP2 levels, differently than in normal cells, are almost steady during the cell cycle of the tested cancer cells.