Microarray detection of novel nuclear RNA substrates for the exosome

Area of Science:

• Molecular Biology
• Yeast Genetics
• RNA Metabolism

Background:

• The exosome complex is crucial for RNA degradation in eukaryotic cells.
• Nuclear and cytoplasmic exosome functions are distinct but interconnected.
• Understanding exosome-mediated RNA turnover is vital for gene expression regulation.

Purpose of the Study:

• To investigate the role of nuclear exosome components in mRNA regulation using microarray analysis.
• To identify specific mRNAs regulated by nuclear turnover.
• To elucidate the impact of exosome mutations on gene expression heterogeneity.

Main Methods:

• Microarray analysis of yeast strains with mutations in nuclear exosome components (Rrp6p, Rrp47p/Lrp1p, Rrp41p/Ski6p).
• Northern blot and primer extension analyses to validate gene expression changes.
• Comparison of nuclear vs. cytoplasmic exosome mutant phenotypes.

Main Results:

• 339 mRNAs showed altered expression in nuclear exosome mutants, with significant heterogeneity.
• 27 overexpressed mRNAs are candidates for nuclear turnover regulation, including NRD1 mRNA.
• Accumulation of truncated NRD1 mRNA fragments suggests disrupted autoregulation.
• Read-through transcription products from snoRNA genes were stabilized in exosome mutants.

Conclusions:

• The nuclear exosome plays a significant role in regulating mRNA levels and turnover.
• Defects in nuclear exosome function can lead to autoregulation disruption and altered gene expression.
• Exosome-mediated degradation of read-through transcripts is essential for preventing aberrant gene expression.