Implication of Pseudo Reference Genes in Normalization of Data from Reverse Transcription-Quantitative PCR

Area of Science:

• Molecular Biology
• Genomics
• Biotechnology

Background:

• Pseudogenes, duplicated DNA sequences, can interfere with gene expression studies.
• Amplification of pseudogenes leads to false positives in Reverse Transcription-quantitative PCR (RT-qPCR).
• Selecting accurate reference genes for normalization in RT-qPCR is challenging due to pseudogene interference.

Purpose of the Study:

• To identify a reliable reference gene for RT-qPCR unaffected by pseudogene amplification.
• To assess the impact of pseudogenes on reference gene stability.
• To evaluate methods for mitigating pseudogene amplification signals.

Main Methods:

• In silico analysis to detect pseudogenes in common reference genes.
• Experimental validation using PCR and RT-qPCR.
• Data mining and phylogenetic analysis of pseudogenes and functional genes.
• Application of the ValidPrime Assay (VPA) to deduce pseudogene amplification.

Main Results:

• The B2M gene was identified as lacking pseudogenes, confirmed by in silico, PCR, and RT-qPCR.
• Pseudogene amplification significantly affects reference gene stability assessments.
• Phylogenetic analysis showed high sequence similarity of pseudogenes across mammals.
• VPA effectively reduced pseudogene amplification signals even with genomic DNA contamination.

Conclusions:

• B2M is a suitable pseudogene-free reference gene for accurate RT-qPCR normalization.
• The ValidPrime Assay (VPA) offers a method to overcome pseudogene amplification issues.
• Consistent gene expression analysis requires careful selection of reference genes or appropriate normalization strategies.