Conserved overlapping gene arrangement, restricted expression, and biochemical activities of DNA polymerase ν (POLN).
DNA polymerase ν (POLN) is one of 16 DNA polymerases encoded in vertebrate genomes. It is important to determine its gene expression patterns, biological roles, and biochemical activities. By quantitative analysis of mRNA expression, we found that POLN from the zebrafish Danio rerio is expressed predominantly in testis. POLN is not detectably expressed in zebrafish embryos or in mouse embryonic stem cells. Consistent with this, injection of POLN-specific morpholino antisense oligonucleotides did not interfere with zebrafish embryonic development. Analysis of transcripts revealed that vertebrate POLN has an unusual gene expression arrangement, sharing a first exon with HAUS3, the gene encoding augmin-like complex subunit 3. HAUS3 is broadly expressed in embryonic and adult tissues, in contrast to POLN. Differential expression of POLN and HAUS3 appears to arise by alternate splicing of transcripts in mammalian cells and zebrafish. When POLN was ectopically overexpressed in human cells, it specifically coimmunoprecipitated with the homologous recombination factors BRCA1 and FANCJ, but not with previously suggested interaction partners (HELQ and members of the Fanconi anemia core complex). Purified zebrafish POLN protein is capable of thymine glycol bypass and strand displacement, with activity dependent on a basic amino acid residue known to stabilize the primer-template. These properties are conserved with the human enzyme. Although the physiological function of pol ν remains to be clarified, this study uncovers distinctive aspects of its expression control and evolutionarily conserved properties of this DNA polymerase.
From the Department of Epigenetics and Molecular Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville, Texas 78957, the University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030, ktakata@mdanderson.org.
Kei-Ichi
K
Takata
From the Department of Epigenetics and Molecular Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville, Texas 78957, the University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030.
Junya
J
Tomida
From the Department of Epigenetics and Molecular Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville, Texas 78957, the University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030.
Shelley
S
Reh
the Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, and.
Lisa M
LM
Swanhart
the Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto 606-8501, Japan.
Minoru
M
Takata
the Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, and.
Neil A
NA
Hukriede
From the Department of Epigenetics and Molecular Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville, Texas 78957, the University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030.
Richard D
RD
Wood
D017398:Alternative Splicing; D000818:Animals; D019313:BRCA1 Protein / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D005091:Exons; D051856:Fanconi Anemia Complementation Group Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D023061:Gene Order; D005807:Genes, Overlapping; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008297:Male; D051379:Mice; D011995:Recombination, Genetic; D013737:Testis / Q000378:metabolism*; D019076:Transgenes; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000378:metabolism*
C102108:BACH1 protein, human; D019313:BRCA1 Protein; D050976:Basic-Leucine Zipper Transcription Factors; D051856:Fanconi Anemia Complementation Group Proteins; C556200:Haus3 protein, zebrafish; D029961:Zebrafish Proteins; D004247:DNA; D004259:DNA-Directed DNA Polymerase; C546205:POLN protein, human; C000603999:POLN protein, zebrafish
BRCA1; DNA damage; DNA polymerase; alternative splicing; zebrafish