RNase H2-RED carpets the path to eukaryotic RNase H2 functions

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Eukaryotic RNase H2 enzymes possess dual functions: initiating ribonucleoside monophosphate (rNMP) removal from DNA and processing RNA/DNA hybrids.
• RNase H1 shares hybrid processing but has distinct substrate specificities.
• The Ribonucleotide Excision Repair (RER) pathway completes rNMP removal after RNase H2 incision.

Purpose of the Study:

• To summarize studies utilizing the RNase H2-RED mutant enzyme.
• To elucidate the distinct roles of RNase H2 activities in cellular metabolism and genome integrity.
• To highlight findings across various model systems.

Main Methods:

• Development and utilization of the RNase H2-RED mutant enzyme.
• Studies in Saccharomyces cerevisiae and mouse models.
• Analysis in mammalian cell cultures.

Main Results:

• RNase H2-RED unlinked RNase H2's dual activities, clarifying their individual contributions.
• Both RNase H2 activities are essential for maintaining genome integrity.
• rNMPs in DNA trigger p53-dependent lethality during mouse embryogenesis.
• RNase H2-RED identified Top1 cleavage lesions at rNMPs and confirmed RNase H2's role in LINE-1 retrotransposition.

Conclusions:

• The RNase H2-RED mutant is a valuable tool for dissecting enzyme functions.
• RNase H2 plays critical roles in DNA repair, genome stability, and retrotransposition.
• Distinct roles of RNase H1 and RNase H2 in hybrid processing are further defined.