Comparison of RNA isolation methods on RNA-Seq: implications for differential expression and meta-analyses

Area of Science:

• Molecular Biology
• Genomics
• Bioinformatics

Background:

• Meta-analyses of transcriptomic data increase statistical power but are susceptible to batch effects.
• Batch effects in RNA-sequencing (RNA-seq) experiments arise from technical variations between batches.
• Understanding sources of batch effects, such as RNA isolation methods, is crucial for accurate analysis.

Purpose of the Study:

• To investigate RNA isolation method as a source of batch effects in RNA-sequencing.
• To determine if different RNA isolation methods lead to spurious differential gene expression signals.

Main Methods:

• Comparison of RNA isolation using hot phenol extraction versus two commercial kits.
• Utilized Saccharomyces cerevisiae heat shock response as a model system.
• Analyzed technical replicates differing only in RNA isolation method.

Main Results:

• Over one thousand transcripts showed apparent differential expression between hot phenol extraction and commercial kits.
• Transcripts with higher abundance in phenol-extracted samples were enriched for membrane proteins.
• RNA isolation method can introduce significant bias in RNA-seq results.

Conclusions:

• RNA isolation method had minimal impact within a single experimental batch (e.g., control vs. treatment).
• Researchers conducting meta-analyses across different experimental batches must carefully consider and document RNA isolation methods used.
• Standardizing RNA isolation methods or accounting for them is vital for robust cross-batch transcriptomic analysis.