Subcellular Localization and Cell Cycle-Associated Expression of Human dUTPase Isoforms

The enzyme dUTPase plays a critical role in maintaining genomic integrity by preventing the misincorporation of uracil into DNA. Beyond the well-described nuclear (DUT-N) and mitochondrial (DUT-M) isoforms, two novel dUTPase isoforms (DUT-3 and DUT-4) have recently been identified in human cells; however, their subcellular localization and cell cycle-associated transcription profiles have not yet been characterized. Here, we demonstrate the localization patterns of all dUTPase isoforms in HCT116 cells, identifying the predominantly cytoplasmic DUT-3 and nuclear DUT-4, as well as the nuclear DUT-N and mitochondrial DUT-M. Moreover, we characterized the endogenous cell cycle-associated isoform-specific expression of dUTPase in human leukemia cell lines U937 and MOLT4. DUT-N exhibits the highest expression and is elevated during the G1/S transition, while DUT-M displays a similar expression pattern at lower levels. The novel DUT-3 isoform shows moderate changes, while DUT-4 shows low constitutive expression during the cell cycle. Our findings support the necessity of dUTPase availability throughout the cell cycle.