MIDB

MIDB catalogs U12-type (minor) introns—characterized by divergent terminal dinucleotide sequences—and minor intron-containing genes (MIGs) in human and mouse to support analysis of minor intron distribution, splicing, alternative splicing, and tissue-specific regulation.

Key Features:

• Comprehensive Minor Intron List: Contains an updated set of 722 mouse and 770 human minor introns identified using position-weight matrices, including ~150 newly identified MIGs and an expansion relative to U12DB.
• Tissue-Specific Expression and Splicing Analysis: Incorporates RNAseq data analysis from eleven mouse tissues to reveal tissue-specific MIG expression and patterns of minor intron retention linked to minor spliceosome regulation.
• Alternative Splicing Events: Identifies novel, tissue-dependent alternative splicing events across minor introns that can produce novel tissue-specific protein isoforms and implicate coordinated activity of major and minor spliceosomes.
• Regulatory Insights: Reports organized regulation of MIG expression and minor intron splicing, including the observation that longer minor introns are more frequently spliced efficiently while shorter minor introns are more prone to retention.

Scientific Applications:

• Study of minor spliceosome-related disease: Enables investigation of tissue-specific phenotypes associated with minor spliceosome dysfunction, including disorders such as cerebellar ataxia and microcephalic osteodysplastic primordial dwarfism type 1 (MOPD1).
• Characterization of tissue-specific isoforms: Supports identification and analysis of novel tissue-specific protein isoforms generated by alternative splicing of minor introns.
• Gene regulation and splicing research: Provides a framework to study how the minor spliceosome impacts gene regulation and tissue-dependent splicing patterns.

Methodology:

Minor introns were identified using position-weight matrices, classifications were updated using the latest reference genomes, and RNAseq data analysis from eleven mouse tissues was used to assess expression, intron retention, and alternative splicing.