Telomeric RNAs are essential to maintain telomeres

Area of Science:

• Genetics
• Molecular Biology
• Epigenetics

Background:

• Telomeres are crucial for chromosomal stability, and their maintenance involves complex regulatory mechanisms.
• Long non-coding RNAs transcribed from telomeres, known as TERRA, are implicated in telomere biology, but their specific functions and origins remain largely unknown.
• Identifying TERRA loci is essential for understanding their roles and conducting functional genetic studies.

Purpose of the Study:

• To identify the specific human subtelomeric loci responsible for TERRA transcription.
• To investigate the functional consequence of ablating identified TERRA loci on telomere maintenance.
• To elucidate the role of TERRA in cellular responses to telomere dysfunction.

Main Methods:

• Utilized CRISPR-Cas9 gene editing technology to delete specific subtelomeric loci (20q and Xp).
• Quantified TERRA levels following targeted locus deletion.
• Assessed telomere sequence integrity and DNA damage response markers post-ablation.

Main Results:

• Identified human 20q and Xp subtelomeres as sources of TERRA.
• Demonstrated that deletion of the 20q locus significantly reduces TERRA levels.
• Showed that ablation of 20q-TERRA leads to substantial telomere sequence loss and induces a DNA damage response.

Conclusions:

• Chromosome 20q is a major TERRA locus in human cells.
• TERRA is essential for maintaining telomere sequence integrity.
• This study provides the first evidence for an essential role of TERRA in telomere maintenance across any organism.