Construction and characterization of ribonuclease H2 C subunit-knockout NIH3T3 cells.

Mammalian ribonuclease (RNase) H2 is a trimer consisting of catalytic A and accessory B and C subunits. RNase H2 is involved in the removal of misincorporated ribonucleotides from genomic DNA. In humans, mutations in RNase H2 gene cause a severe neuroinflammatory disorder, Aicardi-Goutières syndrome (AGS). Here, we constructed RNase H2 C subunit (RH2C)-knockout mouse fibroblast NIH3T3 cells. Compared with the wild-type NIH3T3 cells, the knockout cells exhibited a decreased single ribonucleotide-hydrolyzing activity and an increased accumulation of ribonucleotides in genomic DNA. Transient expression of wild-type RH2C in the knockout cells increased this activity and decreased this ribonucleotide accumulation. Same events were observed when RH2C variants with an AGS-causing mutation, R69W or K145I, were expressed. These results corresponded with our previous results on the RNase H2 A subunit (RH2A)-knockout NIH3T3 cells and the expression of wild-type RH2A or RH2A variants with an AGS-causing mutation, N213I and R293H, in the RH2A-knockout cells.