Monozygotic twins discordant for intermittent allergic rhinitis differ in mRNA and protein levels

Monozygotic (MZ) twins discordant for complex diseases may help to find disease mechanisms that are not due to genetic variants. Intermittent allergic rhinitis (IAR) is an optimal disease model because it occurs at defined time points each year, owing to known external antigens. We hypothesized that MZ twins discordant for IAR could help to find gene expression differences that are not dependent on genetic variants. We collected blood outside of the season from MZ twins discordant for IAR, challenged their peripheral blood mononuclear cells (PBMC) with pollen allergen in vitro, collected supernatants and isolated CD4+ T cells. We identified disease-relevant mRNAs and proteins that differed between the discordant MZ twins. By contrast, no differences in microRNA expression were found. Our results indicate that MZ twins discordant for IAR is an optimal model to identify disease mechanisms that are not due to genetic variants.

Engineering and optimization of the miR-106b cluster for ectopic expression of multiplexed anti-HIV RNAs

Many microRNAs (miRNAs) are encoded within the introns of RNA Pol II transcripts, often as polycistronic precursors. Here we demonstrate the optimization of an intron encoding three endogenous miRNAs for the ectopic expression of heterologous anti-HIV-1 siRNAs processed from a single RNA polymerase II primary miRNA. Our expression system, designated as MCM7, is engineered from the intron embedded, tri-cistronic mir106b cluster that endogenously expresses miR-106b, miR-93 and miR-25. Manipulation of the mir106b cluster demonstrated a strict requirement for maintenance of the native flanking pri-miRNA sequences and key structural features of the native miRNAs for efficient siRNA processing. As a model for testing the efficacy of this approach, we have replaced the three endogenous miRNAs with siRNAs targeting the tat and rev transcripts of HIV-1. This study has enabled us to establish guidelines for optimal processing of the engineered miRNA mimics into functional siRNAs. In addition, we demonstrate that the incorporation of a small nucleolar RNA TAR chimeric decoy (snoRNA) inserted within the MCM7 intron resulted ina substantial enhancement of HIV suppression in long term acute infectious HIV-1 challenges.