January 10, 2018 | David F. Coppedge

Cell Repair Majors on Majors

When hit by damaging mutations, cells repair genes before non-coding areas. How do they know?

Cells have an uncanny sense of priority. Researchers at the University of Oxford have found that they send their repairmen to the most critical areas first. They found this by cutting down on the repair staff, and watching what happened. MMR (DNA mismatch repair) is a repair service that fixes mutations.

The paper finds that MMR preferentially repairs genes, rather than other regions of the genome. This finding significantly enhances our understanding of how organisms use MMR to reduce spontaneous mutation rates.

Although the study was conducted on plants, the finding also has implications for medicine:

The study has important implications for human health, and is particularly useful for understanding the changes that occur in cells during the development of the tumors that underlie cancers. MMR-deficiency predisposes cells to become tumorous, presumably because MMR-deficient cells lack the gene protection that reduces the risk of mutation in the genes that normally suppress tumor formation.

In other words, the cell needs to protect its genes to fight cancer. This doesn’t mean that non-genic regions are unimportant, but perhaps they rank lower on the priority list for the cell’s repair crew. The researchers, however, do not know how the cell targets the genes:

‘Whilst genes are essential for the biology of organisms, the functions, if any, of the non-genic regions of the genome are less clear’, said Prof. Harberd. ‘It is therefore understandable that natural selection may have favoured the relative targeting of MMR to genes rather than non-genic regions. The challenge now is to understand how that targeting works.’

Once again, we see scientists attributing design to ‘natural selection’ by default, instead of honoring the Creator of life. This should have received an ‘Amazing’ award, but the writers stuck a Darwin fly in the ointment. The opening sentence gets Stupid Evolution Quote of the Week:

Whilst DNA sequence mutation is the fundamental fuel of species evolution, mutations in genes are often harmful. As a form of defence, organisms have evolved repair mechanisms to correct the DNA sequence following mutation.


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