Fragmented RNA Polyadenylation for Gene Expression Profiling
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Solution Overview
Problem
Gene expression profiling in clinical oncology and research is hindered by the degradation of RNA in fixed paraffin-embedded tissue samples, which are fragmented and lack polyadenylation, making it difficult to perform effective reverse transcription and PCR amplification.
Innovation Solution
A method involving polyadenylation of fragmented RNA, followed by deblocking of 3' termini using enzymes like calf alkaline phosphatase or polynucleotide kinase, and subsequent conversion to cDNA using reverse transcriptase and oligo-dT primers, with optional enrichment and immobilization on solid phase beads for enhanced PCR amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If RNA is obtained from fixed paraffin-embedded tissue samples, then archived tissue samples can be used for gene expression profiling, but the RNA becomes degraded and fragmented making reverse transcription ineffective
Solution Approach 1:
The patent applies preliminary action by performing polyadenylation on fragmented RNA before reverse transcription. The method adds poly(A) tails to the 3' ends of RNA fragments using poly(A) polymerase, creating suitable substrates for oligo(dT) priming. This preliminary modification enables effective reverse transcription of otherwise unusable fragmented RNA from archived tissue samples.
Solution Approach 2:
The patent changes the chemical parameter of the RNA by adding poly(A) sequences to fragmented molecules. This parameter change transforms the RNA from a state incompatible with oligo(dT) priming to a state that can be efficiently reverse transcribed, thereby resolving the contradiction between having archived tissue samples and maintaining reverse transcription effectiveness.
2Ease of operation
If conventional RT-PCR is used on fragmented RNA, then the process is simple, but the sensitivity and detection accuracy are insufficient
Solution Approach 1:
The patent introduces a preliminary polyadenylation step before RT-PCR to enhance detection sensitivity. By adding poly(A) tails to fragmented RNA, the method enables more efficient oligo(dT) priming and reverse transcription, thereby improving the sensitivity and accuracy of mRNA level detection while maintaining relative operational simplicity.
3Reliability
If polyadenylation is performed on fragmented RNA, then reverse transcription efficiency is improved, but additional enzymatic steps are required
Solution Approach 1:
The patent employs poly(A) polymerase that can process various fragmented RNA molecules universally, regardless of their specific fragmentation patterns or lengths. This multi-functional enzyme approach improves reverse transcription efficiency across diverse fragmented RNA samples while keeping the additional enzymatic steps manageable through a single polyadenylation reaction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the sensitive analysis and amplification of mRNA levels from degraded RNA samples, including non-polyadenylated species, allowing for accurate gene expression profiling in archived tissue samples, improving the detection of mRNA levels and increasing the throughput of gene expression analysis.
Implementation Method 1
treating the fragmented RNA with poly(A) polymerase and adenosine triphosphate to add polyadenylate sequences to a 3' end of the fragmented RNA
Implementation Method 2
converting the polyadenylated RNA into complementary DNA
Implementation Method 3
deblocking of 3' termini using enzymes like calf alkaline phosphatase or polynucleotide kinase
Data Source
AI summary
The invention relates to methods of using fragmented RNA, such as RNA obtained from archived fixed paraffin-embedded tissue material (FPET RNA) or other clinically biopsied tissue specimens for universal gene expression profiling.