University of Louisville
Mutagenic Proteins Detected in DNA Stalled by UV Radiation
Institution
University of Louisville
Faculty Advisor/ Mentor
William G. McGregor
Abstract
UV causes cancer by inducing damage in the DNA of skin cells. If the damage is not repaired it can induce alterations in the DNA sequence. A protein encoded by the rad18 gene is required for the maintenance of genomic integrity after DNA damage. To examine the role of RAD18 in the response of human cells to UV synchronized repairproficient human skin fibroblasts. Cells were irradiated in mid-G1 phase or in S-phase and fixed. The cells were stained and examined with confocal microscopy for (PCNA), a protein required for repair of the UV damage for DNA replication, for RAD18, and for nuclear DNA. UV damage induced nuclear PCNA in cells in either G1 or S-phase. In contrast, RAD18 was present in the nucleus only in cells irradiated in S-phase, and colocalized with PCNA. The subcellular distribution of DNA polymerase iota was examined. This enzyme was found in nuclear foci of S-phase cells, and co-localized with PCNA and RAD18. These results support the hypothesis that RAD18 is recruited to DNA replication forks stalled by UV damage, and the subsequent recruitment of newly discovered error-prone DNA polymerases that can complete the replication of DNA containing UV damage.
Mutagenic Proteins Detected in DNA Stalled by UV Radiation
UV causes cancer by inducing damage in the DNA of skin cells. If the damage is not repaired it can induce alterations in the DNA sequence. A protein encoded by the rad18 gene is required for the maintenance of genomic integrity after DNA damage. To examine the role of RAD18 in the response of human cells to UV synchronized repairproficient human skin fibroblasts. Cells were irradiated in mid-G1 phase or in S-phase and fixed. The cells were stained and examined with confocal microscopy for (PCNA), a protein required for repair of the UV damage for DNA replication, for RAD18, and for nuclear DNA. UV damage induced nuclear PCNA in cells in either G1 or S-phase. In contrast, RAD18 was present in the nucleus only in cells irradiated in S-phase, and colocalized with PCNA. The subcellular distribution of DNA polymerase iota was examined. This enzyme was found in nuclear foci of S-phase cells, and co-localized with PCNA and RAD18. These results support the hypothesis that RAD18 is recruited to DNA replication forks stalled by UV damage, and the subsequent recruitment of newly discovered error-prone DNA polymerases that can complete the replication of DNA containing UV damage.