Scientists have known that long nucleotide base repeats in the human genome have led to heritable human diseases such as Huntington’s disease. Huntington’s disease is a neurodegenerative disease that affects muscle coordination and leads to a deterioration of cognitive thought. There are many nucleotide base repeats that are stable, but their lengthening over time leads to genome instability and changes in gene expression which can cause these diseases. Up until now, it was thought that the lengthening of these nucleotide base repeats was caused during DNA replication or when DNA repair machinery was active in the cell. However, it was found that the lengthening of these base pair repeats also occurs during transcription, which is the process of forming RNA from a DNA template within a cell.
In a study performed by a research team led by Sergei Mirkin, the White Family Professor of Biology at Tufts' School of Arts and Sciences, the correlation between transcription and the expansion of base pair repeats was observed in yeast. The team used genetic systems to track the lengthening of nucleotide base pair repeats during DNA replication, DNA repair, and transcription. These genetic systems were also used to track the number of expansions in transcribed and non-transcribed parts of reporter genes. It was found that both transcribed and non-transcribed fragments of the reporter genes showed expansion, but the transcribed form of the reporter genes was ten times more likely to undergo the expansion process. This is because in a transcriptionally active state, the transcribed DNA segment has significantly less nucleosome density which leaves more room for repeat expansions of nucleotide base pairs.
I find this article interesting because it relates the expansion of nucleotide base pairs to heritable diseases such as Huntington’s. By learning more about what causes these diseases, more efficient methods of treatment or cures can be discovered and implemented.
Source: Link Between DNA Transcription, Disease-Causing Expansions
No comments:
Post a Comment