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Heterochromatin silencing is like a piano that doesn’t make a sound

Memphis, Tenn. - May 31, 2022

St. Jude researcher Mario Halic, PhD

Mario Halic, Ph.D., Department of Structural Biology

DNA is packaged into chromatin. One type of chromatin is heterochromatin. Abnormal chromatin organization has been linked to cancer. Scientists at St. Jude and the University of Munich LMU are studying heterochromatin.

Genes located in heterochromatin regions are usually not expressed. They are silenced. The scientists wanted to understand how that happens.

The team conducted a systematic, genome-wide approach to study the pathways that contribute to heterochromatin gene silencing. They used fission yeast as the model organism for their research.

Think of a silenced gene as a piano that isn’t making a sound. The piano might be inaccessible, locked away in a room. This scenario was thought to be similar to the main reason behind heterochromatin silencing. The gene was inaccessible to transcription.

But there are also other reasons why the piano might be silent. Wearing noise-canceling headphones can silence a piano for listeners. This is similar to how RNA degradation contributes to silencing of heterochromatin genes.

The scientists have also found that another process called low transcriptional efficiency plays a role in silencing of heterochromatin. This is similar to a piano that has muffled sound.

“Before our study we didn’t know how the different pathways contributed to silencing,” said Mario Halic, PhD, Structural Biology. “Now that we know their contributions, we can learn more about the underlying mechanisms.” 

Nucleic Acids Research published this work.

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