Division of labor between human DNA polymerases in DNA replication

Group Leader:

Juhani Syväoja, PhD, Professor of Biochemistry

Replication of chromosomal DNA and its coordination with repair of DNA damage, and cell cycle progression are key processes in the maintenance of genetic integrity.Failure of these processes lead to increased mutation rates that are likely to disturb normal cellular functions. Accumulation of mutations can transform normally regulated cells into cancer cells.The principle of DNA replication in bacterial cells has long been relatively well known. However, it has turned out that this basic process is quite different in eukaryotic cells.The complex structure of eukaryotic chromosomes is obviously the most important reason for this difference. In vitro approaches and genetic methods with yeast cells that have been heavily applied in studies on eukaryotic DNA replication are not able to model the replication of human cells in a satisfactory manner. Therefore, we have introduced in vivo methods for studying human cell DNA replication.

Our research is focused on molecular and cellular biology of human cell DNA replication and its association with processes regulating the cell cycle.In particular, we aim to understand the division of labor between the eukaryotic replicative DNA polymerases, alpha, delta and epsilon and their interactions with other replication factors and cell cycle regulating proteins throughout the S phase. Also, we aim to understand how roles ofreplicative DNA polymerases and associated components vary in distinct regions of the human genome. For these studies replication-related nucleoprotein complexes are purified by chromatin immunoprecipitation (Chip) methods from S phase cells for analysis of their DNA and protein components. The DNAs of the nucleoprotein complexes fromearly S phase cells represent replication initiation sites, and can be identified by genome scale sequencing methods. The protein components at different stages of the S phase are identified by mass spectrometric and immunological methods, providing a tool set for screening the composition of these complexes throughout the S phase. We believe that these in vivo approaches lead to deeper understanding of the complex chromatin replication in human cells.  

RESEARCH GROUP

  • Group Leader: Juhani Syväoja, PhD, Professor
  • Postdoctorals: Thomas Dunlop, PhD
  • PhD students: Markku Vaara, MSc, Miiko Sokka, MSc, Tarmo Nuutinen, MSc

COLLABORATORS

  • Dr. Helmut Pospiech, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
  • Dr. Giuseppe Villani, Institute de Pharmacologie et de Biologie Structurale, CNRS-Université Paul Sabatier Toulouse III, France
  • Dr. Minna Nyström, Department of Biosciences, University of Helsinki, Finland
  • Dr. Rolf Knippers, University of Konstanz, Germany

Selected Publications