High throughput sequencing analysis of RNA libraries reveals the influences of initial library and PCR methods on SELEX efficiency.

The systemic evolution of ligands by exponential enrichment (SELEX) technique is a powerful and effective aptamer-selection procedure. However, modifications to the process can dramatically improve selection efficiency and aptamer performance. For example, droplet digital PCR (ddPCR) has been recently incorporated into SELEX selection protocols to putatively reduce the propagation of byproducts and avoid selection bias that result from differences in PCR efficiency of sequences within the random library. However, a detailed, parallel comparison of the efficacy of conventional solution PCR versus the ddPCR modification in the RNA aptamer-selection process is needed to understand effects on overall SELEX performance. In the present study, we took advantage of powerful high throughput sequencing technology and bioinformatics analysis coupled with SELEX (HT-SELEX) to thoroughly investigate the effects of initial library and PCR methods in the RNA aptamer identification. Our analysis revealed that distinct "biased sequences" and nucleotide composition existed in the initial, unselected libraries purchased from two different manufacturers and that the fate of the "biased sequences" was target-dependent during selection. Our comparison of solution PCR- and ddPCR-driven HT-SELEX demonstrated that PCR method affected not only the nucleotide composition of the enriched sequences, but also the overall SELEX efficiency and aptamer efficacy

A role for the Dicer helicase domain in the processing of thermodynamically unstable hairpin RNAs

In humans a single species of the RNAseIII enzyme Dicer processes both microRNA precursors into miRNAs and long double-stranded RNAs into small interfering RNAs (siRNAs). An interesting but poorly understood domain of the mammalian Dicer protein is the N-terminal helicase-like domain that possesses a signature DExH motif. Cummins et al. created a human Dicer mutant cell line by inserting an AAV targeting cassette into the helicase domain of both Dicer alleles in HCT116 cells generating an in-frame 43-amino-acid insertion immediately adjacent to the DExH box. This insertion creates a Dicer mutant protein with defects in the processing of most, but not all, endogenous pre-miRNAs into mature miRNA. Using both biochemical and computational approaches, we provide evidence that the Dicer helicase mutant is sensitive to the thermodynamic properties of the stems in microRNAs and short-hairpin RNAs, with thermodynamically unstable stems resulting in poor processing and a reduction in the levels of functional mi/siRNAs. Paradoxically, this mutant exhibits enhanced processing efficiency and concomitant RNA interference when thermodynamically stable, long-hairpin RNAs are used. These results suggest an important function for the Dicer helicase domain in the processing of thermodynamically unstable hairpin structures

Interplay between HIV-1 infection and host microRNAs

Using microRNA array analyses of in vitro HIV-1-infected CD4+ cells, we find that several host microRNAs are significantly up- or downregulated around the time HIV-1 infection peaks in vitro. While microRNA-223 levels were significantly enriched in HIV-1-infected CD4+CD8− PBMCs, microRNA-29a/b, microRNA-155 and microRNA-21 levels were significantly reduced. Based on the potential for microRNA binding sites in a conserved sequence of the Nef-3′-LTR, several host microRNAs potentially could affect HIV-1 gene expression. Among those microRNAs, the microRNA-29 family has seed complementarity in the HIV-1 3′-UTR, but the potential suppressive effect of microRNA-29 on HIV-1 is severely blocked by the secondary structure of the target region. Our data support a possible regulatory circuit at the peak of HIV-1 replication which involves downregulation of microRNA-29, expression of Nef, the apoptosis of host CD4 cells and upregulation of microRNA-223

Rice Grassy Stunt Tenuivirus Nonstructural Protein p5 Interacts with Itself To Form Oligomeric Complexes In Vitro and In Vivo

We investigated the interaction of Rice grassy stunt tenuivirus (RGSV) nonstructural protein p5, a protein of 22 kDa encoded on vRNA 5, with all 12 RGSV proteins by using a GAL4 transcription activator-based yeast two-hybrid system. The p5 protein interacted only with itself and not with any other viral protein; the interacting domains were localized within the N-terminal 96 amino acids of p5. The p5-p5 interaction was reproduced in an Sos recruitment-mediated yeast two-hybrid system as well in by far-Western blots. Native p5 protein extracted from RGSV-infected rice tissue was detected in a large complex with a molecular mass of approximately 260 kDa composed of 12 molecules of p5 or a p5 oligomer with an unidentified host factor(s)

hairpin RNAs

role for the Dicer helicase domain in the processing of thermodynamically unstabl

Multi-center phase II trial of bortezomib and rituximab maintenance combination therapy in patients with mantle cell lymphoma after consolidative autologous stem cell transplantation

Abstract Background Mantle cell lymphoma (MCL) is an aggressive and incurable lymphoma. Standard of care for younger patients with MCL is induction chemotherapy followed by autologous stem cell transplantation (auto-HCT). Rituximab maintenance after auto-HCT has been shown to improve progression-free survival (PFS) and overall survival (OS) in MCL. Bortezomib maintenance therapy has also been shown to be tolerable and feasible in this setting. However, the combination of bortezomib and rituximab as maintenance therapy post-auto-HCT has not been studied. Methods We conducted a multicenter, phase II trial of bortezomib given in combination with rituximab as maintenance in MCL patients after consolidative auto-HCT. Enrolled patients (n = 23) received bortezomib 1.3 mg/m2 subcutaneously weekly for 4 weeks every 3 months (up to 24 months) and rituximab 375 mg/m2 intravenously weekly for 4 weeks every 6 months (up to 24 months) for a total duration of 2 years. The primary study endpoint was disease-free survival (DFS). Results With a median follow-up of 35.9 months, the 2-year DFS probability was 90.2% (95% CI 66–97), and 2-year OS was 94.7% (95% CI 68–99). The most frequent grade 3/4 toxic events were neutropenia (in 74% of patients) and lymphopenia (in 35%). The incidence of peripheral neuropathy was 48% for grade 1, 9% for grade 2, and 0% for grade 3/4. We also examined the role of quantitative cyclin D1 (CCND1) mRNA in monitoring minimal residual disease. Conclusion Combined bortezomib and rituximab as maintenance therapy in MCL patients following auto-HCT is an active and well-tolerated regimen. Trial registration ClinicalTrials.gov NCT01267812, registered Dec 29, 2010