Associate Professor, Eppley Institute
M.S. Department of Genetics, Leningrad State University, USSR; Genetics
Ph.D. Department of Genetics, Leningrad State University, USSR; Genetics
Our laboratory is interested in DNA replication, repair and recombination. In particular, we want to understand the mechanisms of global and region-specific control of mutation rates in different cell types and along chromosomes in eukaryotes.
Genetic stability depends on the DNA repair and high fidelity of chromosomal DNA replication, which is achieved by several sequential processes. Mutations in genes affecting any of these systems are global mutators, greatly enhancing mutation rate and drastically decreasing viability due to cancer onset. Examples are defects in 8-oxo-dGTPase or proofreading by polymerase d in mice, defects in mismatch repair in families with hereditary nonpolyposis colorectal cancer, or a defect in DNA lesion bypass in XP-V patients in humans. Being deleterious, global mutators cannot account for evolutionary and developmental processes in eukaryotes in the situations when high level of mutagenesis is desired. Current evidence suggests that mutation rates differ significantly along the genome. The most striking example of such variation comes from the immunology field. In specialized cells responsible for antibody production, the variable regions of immunoglobulin genes have six orders of magnitude higher mutation rates than other genes.
Astonishing recent findings have found that, in addition to faithful repair, human cells are equipped with proteins which act in the opposite way and introduce damage into their own DNA or RNA. This provides an opportunity to create variability "on demand". Most of the important players of the systems of this newly recognized type of diversification are members of AID/APOBEC family of DNA/RNA cytosine deaminases. They introduce site-directed damage to DNA.
Differential mutability of certain regions of the genome in certain tissues could be critical to life and evolution. One example of human disease associated with mutability of selected genes is fragile X and Huntington disease, which depend on expansion of triplet repeats in certain region of chromosome.
We are creating novel systems to study the fidelity of isolated DNA polymerases in vitro on DNA templates representing critical eukaryotic genes, e.g. immunoglobulins or cancer susceptibility genes. Inventory of mutational signatures of individual replication components enables to find these signatures in mutational spectra of selected human or mouse genes critical for a disease. We investigate the mechanisms of differential mutability by identifying genes or chromosome regions affecting the distribution of mutation events along the chromosomes in trans or cis positions. We use several traditional molecular genetics model objects, primarily baker’s yeast Saccharomyces cerevisiae. We use Next Generation Sequencing for the characterization of the distribution of mutations arising when replication is inaccurate. Recently we initiated similar studies with human cell lines.
Selected Publications (see PubMed for Pavlov YI)
Phone: 402-559 -7717
E-mail: Youri Pavlov