Full-length mRNA sequencing resolves novel variation in 5' UTR length for genes expressed during human CD4 T-cell...

Area of Science:

• Molecular Biology
• Immunology
• Genomics

Background:

• Isoform sequencing (Iso-Seq) provides highly accurate, full-length mRNA transcript reads.
• Untranslated regions (UTRs) of mRNA can contain regulatory elements influencing gene expression.
• Understanding transcript variation is crucial for comprehending cellular processes like T-cell activation.

Purpose of the Study:

• To generate the first Iso-Seq reference transcriptome of activated human CD4 T cells.
• To investigate transcript isoform variation, particularly in 5' UTRs, during T-cell activation.
• To identify novel transcript isoforms and assess their functional impact.

Main Methods:

• Isoform sequencing (Iso-Seq) applied to activated human CD4 T cells.
• Bioinformatic analysis to identify novel splice variants and end variants.
• Functional investigation of novel isoforms in a model cell system.

Main Results:

• Discovery of numerous novel splice and end-variant transcripts.
• Identification of significantly lengthened 5' UTRs in approximately 12.5% of expressed genes.
• Characterization of two novel CXCR5 isoforms with altered transcript stability and translation kinetics due to 5' UTR modifications.

Conclusions:

• Current reference databases may be incomplete for capturing full transcript diversity.
• Iso-Seq is a powerful tool for revealing complex transcriptomic landscapes.
• Transcriptional and post-transcriptional regulation, including 5' UTR variations, significantly impacts protein expression during immune cell activation.