QIAGEN offers a true Sample to Insight workflow, from sample isolation to data analysis and interpretation. Total RNA is first extracted from biofluids (such as serum, plasma, CSF and urine), cells, fresh/frozen tissues or FFPE tissues using a miRNeasy kit. From there, miRNA sequencing libraries are prepared using the QIAseq miRNA Library Kit (see figure Under a day prep).
In an unbiased reaction, adapters are ligated sequentially to the 3’ and 5’ ends of miRNAs. Subsequently, universal cDNA synthesis with UMI assignment, cDNA cleanup, library amplification and library cleanup are performed. Proprietary methodology, using modified oligonucleotides, virtually eliminates the presence of adapter dimers in the sequencing library and effectively removes a major contaminant often observed during sequencing. Bead-based cleanups eliminate the majority of unwanted background noise that steals sequencing reads from a budget. The UMIs ensure that during data analysis, the sample is analyzed specifically, not amplification or sequencing artifacts. To go from sample to sequencer, the process takes only eight hours, with minimal hands-on time. Up to a maximum of 48 samples can be multiplexed.
After sequencing, “.fastq” or “.fastq.gz” file formats can be uploaded directly to the GeneGlobe Data Analysis Center
for primary mapping and molecular tag counting. For well-characterized species, such as human, mouse and rat, reads are mapped to species-specific miRBase and genome databases. For poorly-characterized or novel species, read are mapped to the entire miRBase database. Secondary differential expression analysis is then performed with multiple methods for molecular tag count normalization and visualization of the resulting data.