Embryonic Stem Cells Exhibit mRNA Isoform Specific Translational Regulation

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Alternative mRNA splicing generates multiple variants, contributing significantly to protein diversity.
• Cell-type specific processing of mRNA variants critically impacts gene expression control.

Purpose of the Study:

• To investigate differential translation rates of mRNA variants in embryonic stem cells (ESCs) and Neural Precursor Cells (NPCs).
• To explore the role of Untranslated Regions (UTRs) in regulating variant-specific translation.
• To assess the presence and translational activity of non-coding RNAs.

Main Methods:

• Polysome profiling coupled with RNA sequencing (RNA-seq) was employed.
• Analysis focused on distinguishing translation rates of individual mRNA variants.
• ESC and NPC samples were utilized to examine cell-type specific differences.

Main Results:

• A substantial number of detectable mRNA variants were identified in both ESCs and NPCs.
• Many mRNA variants displayed variant-specific translation rates.
• Differences in UTRs, particularly the 5'UTR, were correlated with translation rate variations.
• Annotated non-coding mRNAs were found to be present in polysome fractions.

Conclusions:

• mRNA variants with alternative UTRs are subject to distinct post-transcriptional controls, likely involving miRNA and protein binding sites.
• Translation rate is a crucial factor to consider when inferring protein abundance from mRNA levels.
• Polysome profiling coupled with RNA-seq is a valuable method for analyzing the translational state of diverse RNAs.