Genome-wide identification of transcript start and end sites by transcript isoform sequencing

Area of Science:

• Molecular Biology
• Genomics
• Transcriptomics

Background:

• Cellular genomes produce numerous transcript isoforms with diverse regulatory signals.
• Understanding transcriptional heterogeneity is crucial for deciphering gene regulation.
• Existing methods struggle to capture the full spectrum of transcript isoform variations.

Purpose of the Study:

• To introduce transcript isoform sequencing (TIF-seq) for genome-wide profiling of full-length transcript isoforms.
• To enable precise determination of 5' and 3' transcript boundaries.
• To characterize complex transcriptional heterogeneity, including short, bicistronic, and overlapping transcripts.

Main Methods:

• Development of TIF-seq, a novel method for full-length transcript isoform profiling.
• Generation of full-length cDNA libraries, followed by circularization.
• Sequencing of junction fragments spanning 5' and 3' transcript ends to determine co-occurrence of start and end sites.

Main Results:

• TIF-seq accurately profiles full-length transcript isoforms by defining exact 5' and 3' boundaries.
• The method distinguishes transcript variations, such as short abortive transcripts, bicistronic messages, and overlapping transcripts, which are often missed by conventional approaches.
• TIF-seq provides a comprehensive view of transcriptional heterogeneity.

Conclusions:

• TIF-seq is a powerful tool for studying transcriptional heterogeneity across eukaryotic organisms.
• The protocol allows for detailed analysis of transcript isoform diversity.
• This method advances the understanding of gene expression regulation at the isoform level.