Mouse HP1γ regulates TRF1 expression and telomere stability.

Area of Science:

• Epigenetics and Molecular Biology
• Telomere Biology
• Non-coding RNA Function

Background:

• Telomeric repeat-containing RNAs (TERRAs) are long non-coding RNAs crucial for telomere heterochromatin formation and HP1 protein binding.
• HP1γ, a member of the heterochromatin protein 1 family, is known to influence chromatin compaction and gene silencing.
• The specific role of HP1γ in telomere maintenance and its transcriptional regulation of telomere factors remained unclear.

Purpose of the Study:

• To investigate the effect of mouse HP1γ on the transcription of telomere factors and molecules involved in telomere maintenance.
• To elucidate the role of HP1γ in telomere cohesion and stability.

Main Methods:

• Utilized HP1γ-deficient mouse embryonic fibroblasts (MEFs) to study telomere function.
• Employed gene expression analysis, telomere Fluorescence In Situ Hybridization (FISH), immunofluorescence, RT-qPCR, and DNA-RNA immunoprecipitation (DRIP) to validate findings.

Main Results:

• Loss of HP1γ resulted in downregulation of telomere-associated transcripts, including the shelterin protein TRF1.
• HP1γ deficiency led to increased telomere replication stress and DNA damage (γH2AX), with more pronounced effects in female mice.
• Impaired telomere maintenance was linked to increased telomeric DNA-RNA hybrids and TERRAs originating from specific mouse chromosomes.

Conclusions:

• Mouse HP1γ plays a significant role in the transcriptional regulation of telomere factors, including TRF1 and TERRAs.
• HP1γ is essential for maintaining telomere stability, and its absence leads to profound consequences.
• The study suggests a potential sexually dimorphic role for HP1γ in telomere regulation.