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Friedreich's ataxia (FRDA) is an incurable neurodegenerative disorder caused by reduced expression of the mitochondrial protein frataxin (FXN). The genetic cause of the disease is an expanded GAA repeat within the FXN gene. Agents that increase expression of FXN protein are a potential approach to therapy. We previously described anti-trinucleotide GAA duplex RNAs (dsRNAs) and antisense oligonucleotides (ASOs) that activate FXN protein expression in multiple patient derived cell lines. Here we test two distinct series of compounds for their ability to increase FXN expression. ASOs with butane linkers showed low potency, which is consistent with the low T m values and suggesting that flexible conformation impairs activity. By contrast, single-stranded siRNAs (ss-siRNAs) that combine the strengths of dsRNA and ASO approaches had nanomolar potencies. ss-siRNAs provide an additional option for developing nucleic acid therapeutics to treat FRDA., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Rett Syndrome is an X-linked progressive neurological disorder caused by inactivation of one allele of the MECP2 gene. There are no curative treatments, and activation of wild-type MECP2 expression is one strategy for stabilizing or reversing the disease. We isolated fibroblast clones that express exclusively either the wild-type or a 32-bp-deletion mutant form of MECP2. We developed a sensitive assay for measuring wild-type MECP2 mRNA levels and tested small molecule epigenetic activators for their ability to activate gene expression. Although our pilot screen did not identify activators of MECP2 expression, it established the value of using clonal cells and defined challenges that must be overcome., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Double-stranded RNA has become a ubiquitous tool for inhibition of gene expression in the laboratory. If similar success could be achieved in vivo, duplex RNA might provide a new class of therapeutics capable of treating a broad spectrum of disease. Chemists and biologists developing duplex RNA as a drug have made progress but continue to face challenges. This review presents the current status of duplex RNA in the clinic and comments on future prospects for the approach., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Peptide nucleic acid (PNA) is a successful DNA/RNA mimic. A major challenge for research is to invent chemically modified PNAs that retain the favorable properties of the parent compound while improving biological recognition. Here, we test modified PNAs containing [bis-o-(aminoethoxy)phenyl]pyrrolocytosine bases designed to engage guanine with an additional hydrogen bond. We observe elevated melting temperatures, localization to cellular compartments, and allele-selective inhibition of mutant huntingtin protein expression.

Synthetic small duplex RNAs that are complementary to gene promoters can activate or inhibit target gene expression. The potency and robustness of gene modulation by these RNAs suggests that natural mechanisms may exist to facilitate recognition of sequences within gene promoters by endogenous small RNAs. Here, we describe computational methods for identifying potential miRNA target sites within gene promoters. These methods will facilitate investigations of whether miRNAs interact with sequences outside of 3'-untranslated regions and suggest new targets for the design of synthetic modulators of gene expression.

Short interfering RNAs (siRNAs) are valuable tools for analyzing protein function in mammalian cell culture. This success has led to high expectations for in vivo and therapeutic applications. However, the pharmacokinetic properties of siRNA are not known. Here we report the biodistribution of a phosphodiester (PO) siRNA duplex and examine the effect of phosphorothioate (PS) linkages. Our findings indicate that biodistribution of siRNA is similar to that for single-stranded antisense oligonucleotides and offer insights for use of siRNA in vivo.

BIBR 1532 has been reported to be a potent, small molecule inhibitor of human telomerase, suggesting it as a lead for the development of anti-telomerase therapy. We confirm the ability of BIBR 1532 to inhibit telomerase and report the discovery of an equally potent analogue. Importantly, IC(50) values in cell extract are considerably higher than those previously reported using assays for purified enzyme, indicating that substantial improvement may be necessary.

Chimeric molecules consisting of peptide nucleic acid (PNA) and lactose have been synthesized to test the hypothesis that lactose moieties can promote cell-specific uptake of PNAs. We find that lactose modified PNAs rapidly enter liver-derived HepG2 cells while unmodified PNAs do not and that lactose modified PNAs can inhibit cellular telomerase.

Resins for solid-phase synthesis can affect coupling efficiencies by interacting with reactants. We have observed that polyethylene glycol-polystyrene (PEG-PS) solid support absorbs added activated fluorophores, preventing efficient labeling of peptide nucleic acids (PNAs). We now report that addition of an inexpensive unactivated fluorophore blocks the resin and allows efficient labeling. This protection strategy may have general benefits for peptide and combinatorial synthesis.