Global Changes in Unproductive Splicing and NMD Efficiency in Tumors

Area of Science:

• Molecular Biology
• Gene Regulation
• Post-transcriptional Control

Background:

• The nonsense-mediated mRNA decay (NMD) pathway is crucial for mRNA quality control and gene regulation.
• NMD degrades aberrant transcripts and influences gene expression through unproductive splicing.
• Understanding NMD efficiency is key to deciphering post-transcriptional gene regulation.

Purpose of the Study:

• To develop a quantitative metric for assessing NMD pathway efficiency at a sample level.
• To investigate the variability of NMD efficiency across different tissues and within cancer cohorts.
• To identify novel regulators of NMD efficiency.

Main Methods:

• Developed a metric based on splicing quantification from RNA-seq data to measure NMD efficiency.
• Analyzed NMD efficiency in various tissues and TCGA cancer cohorts.
• Applied the metric to RNA-binding protein knockdown data.

Main Results:

• NMD efficiency exhibits substantial variation between and within tissues, comparable to UPF1 knockdown effects.
• Tumors show coordinated changes in unproductive splicing, suggesting global NMD pathway deregulation.
• Cancer NMD efficiency diverges significantly from tissue-specific baselines, indicating a loss of cellular identity.

Conclusions:

• The study provides a robust framework for quantifying NMD efficiency.
• NMD pathway deregulation is evident in many cancers.
• The findings open new avenues for studying post-transcriptional gene regulation and identifying NMD regulators.