Multiple recent publications on RNA-Seq have demonstrated the power of next generation sequencing technologies in whole transcriptome analysis. The vendor specific protocols used for RNA library construction typically require at least 100ng of total RNA. However, under certain conditions such as single cells, stem cells, difficult to isolate cell types, or fractionated cancer cells, only a small amount of material is available. In these cases, effective transcriptome profiling requires amplification of subnanogram amounts of RNA. Several RNA amplification kits are available for amplification prior to library construction and next generation sequencing but these kits have not been comprehensively field evaluated for accuracy and performance of RNA-Seq for picogram amounts of RNA.
This study conducted by the DNA Sequencing Research Group (DSRG) focuses on the evaluation of amplification kits for RNA-Seq. Four commercial amplification kits were chosen: Ovation v2 (NuGEN Technologies), SMARTer (Clontech), Seqplex (Sigma Aldrich), and Super-AMP (Miltenyi Biotech). Starting material was 5ng, 500pg and 50pg of human total reference RNA (Clontech) spiked with Ambion ERCC control mix (Life Technologies) following the manufacturer’s protocol. Each kit was tested at 3 different sites to assess reproducibility. Total RNA and ERCC RNA spike-in control mixes from the same lots were sent to 12 ABRF lab sites for amplification and cDNA generation. Ideally, this would have resulted in 36 different amplified samples, 3 from each input RNA. Libraries were constructed at one site from the amplified cDNAs using the TruSeq RNA library preparation kit on the Tecan Freedom EVO Liquid Handling Robot. As an unamplified control, ribosomal depletion and PolyA selection were performed separately using 5ng, 100ng and 1ug of total RNA prior to library construction. All libraries were pooled and sequenced using the Illumina HiSeq platform. An overview of the study and the results will be presented.