Global amplification of sense RNA: a novel method to replicate and archive mRNA for gene expression analysis.

We have developed a procedure to amplify mRNA into sense RNA (sRNA) so as to create a regenerating biorepository representing the complex mRNA profile in the original sample. The procedure exploits the template-switching activity of reverse transcriptase to incorporate RNA polymerase binding sites upstream of single-stranded cDNA (ss cDNA). Limited PCR was used for double-stranded DNA (dsDNA) synthesis. sRNA was synthesized from PCR products by in vitro transcription (IVT). sRNA was evaluated by real-time reverse transcription (RT)-PCR. sRNA synthesis was successful with RNA from human cell lines and tissues, yielding 2000- to 2500-fold amplification of glyceraldeyde-3 phosphate dehydrogenase (G3PDH). The size of sRNA ranged from 3.0 to 0.1 kb. sRNA synthesis preserved the relative differences in plant mRNAs spiked at abundance ranging over 5 orders of magnitude (0.00001-0.1%). This reflects the high fidelity of sRNA synthesis for mRNA as low as 0.3 copies/cell. sRNA is amplified synthetic mRNA in the 5'-->3' direction; the appropriate template for any gene expression analysis.

Utility of the blood for gene expression profiling and biomarker discovery in chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a debilitating illness lacking consistent anatomic lesions and eluding conventional laboratory diagnosis. Demonstration of the utility of the blood for gene expression profiling and biomarker discovery would have implications into the pathophysiology of CFS. The objective of this study was to determine if gene expression profiles of peripheral blood mononuclear cells (PMBCs) could distinguish between subjects with CFS and healthy controls. Total RNA from PBMCs of five CFS cases and seventeen controls was labeled and hybridized to 1764 genes on filter arrays. Gene intensity values were analyzed by various classification algorithms and nonparametric statistical methods. The classification algorithms grouped the majority of the CFS cases together, and distinguished them from the healthy controls. Eight genes were differentially expressed in both an age-matched case-control analysis and when comparing all CFS cases to all controls. Several of the differentially expressed genes are associated with immunologic functions (e.g., CMRF35 antigen, IL-8, HD protein) and implicate immune dysfunction in the pathophysiology of CFS. These results successfully demonstrate the utility of the blood for gene expression profiling to distinguish subjects with CFS from healthy controls and for identifying genes that could serve as CFS biomarkers.