The research in our laboratory is aimed at helping to realize the tremendous therapeutic potential of RNA interference (RNAi). This new technology allows the specific knockdown of expression of targeted genes and is well-suited for anti-viral applications. Our efforts originally focused on developing RNAi-based therapies for hepatitis B virus (HBV). Approximately 400 million people are chronically infected with HBV and therefore are at high risk for end stage liver disease, such as cirrhosis and hepatocellular carcinoma. Current therapies are inadequate in that they are often ineffective, can lead to the emergence of resistant virus, or can be difficult for the patient to tolerate.
Our laboratory has developed vectors that allow the simultaneous expression of multiple interfering RNAs that target viral transcripts. This is a strategy that should maximize efficacy against a broad range of viral genotypes while minimizing the potential for the emergence of escape mutants. We have developed a series of vectors to express interfering RNAs that target HBV transcripts, including both viral RNA replicative intermediates and mRNAs encoding viral proteins. Our vector design incorporates many features of endogenous microRNA (miRNA) gene organization that are proving useful for the development of reagents for RNAi. In some of our vectors, we use an RNA pol II promoter where expression of multiple miRNAs can be directed to particular cell types. We have also shown that it is possible to express multiple functional interfering RNAs from a single RNA pol III promoter. Our vectors have shown potent silencing of HBV targets in cell culture and animal models of HBV infection. We are now applying similar principles of design in the development of silencing vectors that target HIV-1 and are inducible in HIV-1 infected cells.
In a second project, our laboratory is investigating the interplay between HIV-1 and the cellular RNAi pathway. In plants, RNAi is a significant component of the cellular anti-viral defense system, and it is increasingly apparent that it can have a similar function in mammalian cells. Interactions between HIV-1 and the RNAi pathway are evident in that proteins involved in HIV-1 replication can also have a role in the processing of miRNAs. For instance, the cellular protein TRBP significantly enhances expression from TAR-containing viral transcripts, and it is also a necessary co-factor for Dicer activity in the RNAi pathway. In addition, the HIV-1 transcriptional transactivator protein Tat has been claimed to be a suppressor of RNAi. We are exploring this interplay between HIV-1 and the endogenous RNAi pathway in order to know how it might differ in different cell lineages and how it might affect disease progression.
Patent Application
(PCT/US07/81103) MicroRNA-formatted multitarget interfering RNA vector constructs and methods of using the same.
Selected Publications (See all Laura Steel's publications in PubMed.)
"Regulation of HIV-1 replication by TRBP occurs primarily through inhibition of PKR activation"
Sanghvi VR and Steel LF
In preparation, 2011
"A re-examination of global suppression of RNA interference by HIV-1"
Sanghvi VR and Steel LF
PLoS One, 6(2): e17246, 2011
"Expression of interfering RNAs from an HIV-1 Tat-inducible chimeric promoter"
Sanghvi VR and Steel LF
Virus Research, 155: 106-111, 2010
"Multiple functional miRNAs can be produced from a single RNA polymerase III promoter"
Snyder LL, Ahmed I, and Steel LF
Nucleic Acids Research, 37: e127, 2009
"Vector design for liver-specific expression of multiple interfering RNAs that target hepatitis B virus transcripts"
Snyder LL, Esser JM, Pachuk CJ, and Steel LF
Antiviral Research, 80(1): 36-44, 2008
"GP73, a resident Golgi glycoprotein, is a novel serum marker for hepatocellular carcinoma"
Marrero JA, Romano PR, Nikolaeva O, Steel L, Mehta A, Fimmel CJ, Comunale MA, D’Amelio A, Lok AS and Block TM
Journal of Hepatology, 43:1007-1012, 2005
"SELDI-TOF-MS profiling of serum for detection of the progression of cirrhotic hepatitis C disease to hepatocellular carcinoma"
Schwegler EE, Cazares L, Steel LF, Adam BA, Johnson DA, Semmes OJ, Block T, Marrero JA, and Drake RR
Journal of Hepatology, 41:634-642, 2005
"Use of targeted glycoproteomics to identify serum glycoproteins that correlate with liver cancer in woodchucks and people"
Block TM, Comunale MA, Lowman M, Steel LF, Romano PR, Fimmel C, Tennant BC, London WT, Evans AA, Blumberg BS, Dwek RA, Mattu TS, and Mehta AS
Proceedings from the National Academy of Sciences, 102:779-784, 2004
"Methods of comparative proteomic profiling for disease diagnosis"
Steel LF, Haab BB, and Hanash SM
Journal of Chromatography B, 815:275-284, 2004
"Comparative proteomic analysis of de-N-glycosylated serum from hepatitis B carriers reveals polypeptides that correlate with disease status"
Comunale MA, Mattu TS, Lowman M, Evans AA, London WT, Semmes, OJ, Ward M, Drake R, Romano PR, Steel LF, Block TM, and Mehta A
Proteomics, 4:826-838, 2004
"Efficient and specific removal of albumin from human serum samples"
Steel LF, Trotter MG, Nakajima, PB, Mattu, TS, Gonye G, and Block TM
Molecular & Cellular Proteomics, 2.4: 262-270, 2003
"A strategy for the comparative analysis of serum proteomes for the discovery of biomarkers for hepatocellular carcinoma"
Steel LF, Shumpert D, Trotter M, Seeholzer SH, Evans AA, London WT, Dwek R, and Block TM
Proteomics, 3:601-609, 2003
"A proteomic approach for the discovery of early detection markers of hepatocellular carcinoma"
Steel LF, Mattu TS, Mehta A, Hebestreit H, Dwek R, Evans A, London WT, and Block T
Disease Markers, 17:179-189, 2001
"Transformation of bacteria and purification of plasmid DNA"
Steel LF
in Gene Transfer Methods: Introducing DNA into Living Cells and Organisms, eds. P. Norton and L. Steel, Eaton Publishing, 2000
"Elements in the murine c-mos messenger RNA 5'-untranslated region repress translation of downstream coding sequences"
Steel LF, Telly DL, Leonard J, Rice BA, and Sawicki JA
Cell Growth & Differentiation, 7:1415-1424, 1996
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