Faculty Bibliography

RNA interference (RNAi), through expression of small, double-stranded RNAs or short hairpin RNAs, produces sequence-specific mRNA degradation and decreased gene expression. Since its discovery in 1998 (Fire et al., 1998, Nature 391, 806-811), RNAi has rapidly become one of the most widely used technologies for exploring gene function in eukaryotic cells. Although the topic of RNAi has been the subject of a large number of excellent reviews, the focus of this article is on its application to the study of ion channel physiology in animal cells. In this regard, RNAi has provided definitive identification of ion channel subtypes responsible for both basal and stimulated ion conduction across the plasma membrane of several cell types. The approach has been particularly effective in identifying and establishing the contribution of auxiliary subunits and regulatory proteins to the overall function of ion channel complexes. Moreover, selective knockdown of ion channel expression has been a valuable means of demonstrating roles in the development of specific cell domains and in the normal growth of certain cell types. In this review, a brief description of the general mechanism of RNAi is presented, followed by a discussion of some important considerations for the in vitro application of this technology and in producing transgenic animals as models for human disease. We then describe several examples of where RNAi has been used to investigate the physiological role of ion channels in cells from model organisms (Caenorhabditis elegans and Drosophila melanogaster) and in mammalian cells

BACKGROUND/AIMS: Treatment regimens with pegylated interferons have yielded improved response rates, compared with conventional interferon-based regimens, for chronic hepatitis C. However, little is known about the utility of such regimens for individuals who failed to respond to prior conventional interferon-based treatment. METHODS: 182 patients who had previously failed to eliminate circulating hepatitis C virus 24 weeks after completion of a multi-week course of either interferon monotherapy or interferon in combination with ribavirin were treated with peginterferon alfa-2b weekly and ribavirin daily for 48 weeks. RESULTS: The sustained viral response, was 20% (23/116) in previous non-responders and 55% (36/66) in previous relapsers (P<0.001). In previous non-responders, the sustained viral response in those with viral genotype 1 was 17% (19/109) compared to 57% (4/7) in those with genotypes 2 and 3 (P=0.03). In previous relapsers, the sustained viral response in those with viral genotype 1 was 53% (26/49) compared to 59% (10/17) with genotypes 2 and 3 (P=0.78). CONCLUSIONS: The response to pegylated interferon and ribavirin in previous non-responders with genotypes 2 and 3 and in prior relapsers with chronic hepatitis C is comparable to overall sustained viral response rates seen in previously untreated patients