Mariner Transposons Contain a Silencer: Possible Role of the Polycomb Repressive Complex 2

Area of Science:

• Genetics
• Molecular Biology
• Evolutionary Biology

Background:

• Transposable elements (TEs) are crucial for genetic innovation in eukaryotes.
• Mariner elements, a type of TE, possess regulatory sequences with significant implications for genome function.

Purpose of the Study:

• To identify and characterize silencer elements within mariner transposons.
• To elucidate the molecular mechanisms and host factors involved in mariner-mediated gene silencing.

Main Methods:

• Functional analysis of silencer elements in vertebrate and arthropod cells.
• Identification of transcription factors (TFs) and host pathways (e.g., Polycomb Repressive Complex 2) involved in silencing.
• Sequence analysis to identify conserved motifs and TF binding sites.

Main Results:

• A silencer located in the Mos1 transposase open reading frame (ORF) functions across species.
• Silencers are present in other animal mariner elements and affect various eukaryotic promoters.
• Silencing involves conserved TFs (NFAT-5, Alx1, YY1) and the host Polycomb Repressive Complex 2 pathway.
• NRSF binding sites overlap conserved peptide motifs in mariner transposases.

Conclusions:

• Mariner silencers employ conserved animal TFs and host machinery for self-repression.
• These silencers may act as Polycomb Response Elements, regulating TE transcription and mobility.
• Exaptation of mariner silencers could have contributed to chromatin organization in eukaryotic genomes.