Mature Microsatellites: Mechanisms Underlying Dinucleotide Microsatellite Mutational Biases in Human Cells
| Autor: | Guruprasad Ananda, Kateryna D. Makova, Kristin A. Eckert, Su Jen Khoo, Maria M. Krasilnikova, Abhinaya Srikanth, Nari Kim, Andrew Lutzkanin, Beverly A. Baptiste, Noelle Strubczewski |
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| Rok vydání: | 2013 |
| Předmět: |
DNA Replication
Genome instability DNA repair DNA Mutational Analysis Genetic Vectors Replication Origin Investigations Biology DNA Mismatch Repair Genomic Instability 03 medical and health sciences 0302 clinical medicine Mutation Rate Genetics Humans Molecular Biology Gene DNA Polymerase beta Genetics (clinical) Cell Line Transformed 030304 developmental biology 0303 health sciences Base Sequence Genome Human DNA replication HCT116 Cells short tandem repeats mismatch repair DNA Repair Enzymes MutL Proteins Mutagenesis 030220 oncology & carcinogenesis Microsatellite microsatellite instability Human genome DNA mismatch repair strand slippage Microsatellite Repeats |
| Zdroj: | G3: Genes|Genomes|Genetics |
| ISSN: | 2160-1836 |
| Popis: | Dinucleotide microsatellites are dynamic DNA sequences that affect genome stability. Here, we focused on mature microsatellites, defined as pure repeats of lengths above the threshold and unlikely to mutate below it in a single mutational event. We investigated the prevalence and mutational behavior of these sequences by using human genome sequence data, human cells in culture, and purified DNA polymerases. Mature dinucleotides (≥10 units) are present within exonic sequences of >350 genes, resulting in vulnerability to cellular genetic integrity. Mature dinucleotide mutagenesis was examined experimentally using ex vivo and in vitro approaches. We observe an expansion bias for dinucleotide microsatellites up to 20 units in length in somatic human cells, in agreement with previous computational analyses of germ-line biases. Using purified DNA polymerases and human cell lines deficient for mismatch repair (MMR), we show that the expansion bias is caused by functional MMR and is not due to DNA polymerase error biases. Specifically, we observe that the MutSα and MutLα complexes protect against expansion mutations. Our data support a model wherein different MMR complexes shift the balance of mutations toward deletion or expansion. Finally, we show that replication fork progression is stalled within long dinucleotides, suggesting that mutational mechanisms within long repeats may be distinct from shorter lengths, depending on the biochemistry of fork resolution. Our work combines computational and experimental approaches to explain the complex mutational behavior of dinucleotide microsatellites in humans. |
| Databáze: | OpenAIRE |
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