CORE-SINEs: eukaryotic short interspersed retroposing elements with common sequence motifs.

Area of Science:

• Genomics
• Evolutionary Biology
• Molecular Biology

Background:

• A 65-bp "core" sequence is abundant in the human genome.
• This sequence is a central part of mammalian-wide interspersed repeats (MIRs), a type of short interspersed element (SINE).
• MIRs proliferated before the diversification of placental mammals.

Purpose of the Study:

• To propose that the core sequence represents an ancient tRNA-like SINE element.
• To investigate the evolutionary history and survival of this ancient SINE across different vertebrate and invertebrate lineages.
• To understand the mechanisms contributing to the evolutionary success and proliferation of CORE-SINE families.

Main Methods:

• Bioinformatic analysis of genomic sequences.
• Comparative genomics across various species (mammals, reptiles, birds, fish, mollusks).
• Phylogenetic analysis to trace the evolutionary history of SINE elements.

Main Results:

• The core sequence is identified as an ancient tRNA-like SINE element.
• This element has survived for over 550 million years, persisting in mammals, reptiles, birds, fish, and mollusks.
• CORE-SINE families, including MIRs, evolved with distinct 3' ends associated with different long interspersed element (LINE) families.

Conclusions:

• The CORE-SINE element's survival is attributed to its ability to recruit promoters from host RNA and adapt through sequence exchange with LINEs.
• The evolutionary success of SINEs is dependent on their cohabitation with LINEs and the host genome.
• This study highlights the ancient origins and enduring evolutionary strategies of SINEs.