L1Base: from functional annotation to prediction of active LINE-1 elements

Area of Science:

• Genomics
• Bioinformatics
• Molecular Biology

Background:

• Long Interspersed Nuclear Element-1 (LINE-1) retrotransposons are mobile genetic elements with significant roles in genome evolution and disease.
• Identifying and characterizing active LINE-1 insertions is crucial for understanding their impact on host genomes.
• Existing databases may not comprehensively capture all relevant LINE-1 elements and their functional features.

Purpose of the Study:

• To establish L1Base, a comprehensive database of putatively active LINE-1 insertions in human and rodent genomes.
• To include various types of LINE-1 elements: full-length intact ORFs (FLI-L1s), intact ORF2 but disrupted ORF1 (ORF2-L1s), and full-length non-intact regulatory elements (FLnI-L1s).
• To enable in-depth annotation of functional sequence features critical for LINE-1 activity.

Main Methods:

• Development and application of a novel annotation methodology, L1Xplorer.
• Identification of functional sequence features, including transcription factor binding sites and critical amino acid residues.
• Database construction to store and provide access to annotated LINE-1 insertion data.

Main Results:

• L1Base successfully compiles diverse categories of LINE-1 insertions from human and rodent genomes.
• L1Xplorer facilitates detailed annotation of functional sequence features relevant to LINE-1 activity.
• The database provides online accessibility and integration with existing bioinformatics resources like the Ensembl web browser via DAS.

Conclusions:

• L1Base serves as a valuable resource for researchers studying LINE-1 elements and their genomic impact.
• The integrated annotation approach enhances the understanding of LINE-1 functional sequences and activity.
• The database facilitates further investigation into the role of LINE-1s in genome dynamics and disease.