Multiple Forms of Human DNA Polymerase Delta Sub-Assembling in Cellular DNA Transactions

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• DNA Polymerase delta (Pol δ) is crucial for eukaryotic DNA replication and repair.
• Human Pol δ is typically a heterotetramer, but accessory subunits regulate its function.
• The p12 subunit of Pol δ is critical for its regulatory mechanisms.

Purpose of the Study:

• To review recent advances in understanding human Pol δ.
• To explore the generation and properties of multiple Pol δ forms, particularly Pol δ3.
• To discuss pathways of Pol δ3 formation and the evolutionary history of the POLD4 gene.

Main Methods:

• Review of existing research and recent studies from the authors' group.
• Analysis of Pol δ reconstitution and enzymatic properties.
• Investigation of ubiquitin-proteasome and calpain-mediated pathways for Pol δ3 formation.
• Phylogenetic analysis of the POLD4 gene.

Main Results:

• Pol δ3, a heterotrimer lacking the p12 subunit, forms via ubiquitin-proteasome degradation or calpain-mediated proteolysis.
• Pol δ3 exhibits altered enzymatic properties compared to the heterotetrameric form.
• These alterations significantly impact cellular genomic surveillance, DNA replication, and repair processes.
• The POLD4 gene, encoding the p12 subunit, has undergone evolutionary changes.

Conclusions:

• Human Pol δ exists in multiple functional forms, with Pol δ3 being a key player in cellular responses to DNA damage and stress.
• Distinct pathways regulate Pol δ3 formation, highlighting complex cellular mechanisms for maintaining genomic integrity.
• Understanding these multiple forms and formation pathways is essential for comprehending DNA replication, repair, and disease.