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Small hairpin RNA

About: Small hairpin RNA is a research topic. Over the lifetime, 9279 publications have been published within this topic receiving 285471 citations.


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01 Feb 2012
TL;DR: The synthesis of a delivery vehicle that combines carrier and cargo: RNA interference polymers that self-assemble into nanoscale pleated sheets of hairpin RNA, which in turn form sponge-like microspheres that provide protection for siRNA during delivery and transport to the cytoplasm is reported.
Abstract: The encapsulation and delivery of short interfering RNA (siRNA) has been realized using lipid nanoparticles, cationic complexes, inorganic nanoparticles, RNA nanoparticles and dendrimers. Still, the instability of RNA and the relatively ineffectual encapsulation process of siRNA remain critical issues towards the clinical translation of RNA as a therapeutic. Here we report the synthesis of a delivery vehicle that combines carrier and cargo: RNA interference (RNAi) polymers that self-assemble into nanoscale pleated sheets of hairpin RNA, which in turn form sponge-like microspheres. The RNAi-microsponges consist entirely of cleavable RNA strands, and are processed by the cell's RNA machinery to convert the stable hairpin RNA to siRNA only after cellular uptake, thus inherently providing protection for siRNA during delivery and transport to the cytoplasm. More than half a million copies of siRNA can be delivered to a cell with the uptake of a single RNAi-microsponge. The approach could lead to novel therapeutic routes for siRNA delivery.

355 citations

Journal ArticleDOI
TL;DR: In this paper, a weekly i.v. injection of non-viral gene therapy causing RNA interference (RNAi) of EGFR gene expression was designed to prolong survival in mice with intracranial human brain cancer.
Abstract: Purpose: The human epidermal growth factor receptor (EGFR) plays an oncogenic role in solid cancer, including brain cancer. The present study was designed to prolong survival in mice with intracranial human brain cancer with the weekly i.v. injection of nonviral gene therapy causing RNA interference (RNAi) of EGFR gene expression. Experimental Design: Human U87 gliomas were implanted in the brain of adult scid mice, and weekly i.v. gene therapy was started at day 5 after implantation of 500,000 cells. An expression plasmid encoding a short hairpin RNA directed at nucleotides 2529 –2557 within the human EGFR mRNA was encapsulated in pegylated immunoliposomes. The pegylated immunoliposome was targeted to brain cancer with 2 receptor-specific monoclonal antibodies (MAb), the murine 83–14 MAb to the human insulin receptor and the rat 8D3 MAb to the mouse transferrin receptor. Results: In cultured glioma cells, the delivery of the RNAi expression plasmid resulted in a 95% suppression of EGFR function, based on measurement of thymidine incorporation or intracellular calcium signaling. Weekly i.v. RNAi gene therapy caused reduced tumor expression of immunoreactive EGFR and an 88% increase in survival time of mice with advanced intracranial brain cancer. Conclusions: Weekly i.v. nonviral RNAi gene therapy directed against the human EGFR is a new therapeutic approach to silencing oncogenic genes in solid cancers. This is enabled with a nonviral gene transfer technology that delivers liposome-encapsulated plasmid DNA across cellular barriers with receptor-specific targeting ligands.

354 citations

Journal ArticleDOI
22 Aug 2003-Science
TL;DR: These analyses directly implicate interspersed LTRs in regulating gene expression during cellular differentiation in plants through nearby retrotransposon long terminal repeats.
Abstract: The expression of short hairpin RNAs in several organisms silences gene expression by targeted mRNA degradation. This RNA interference (RNAi) pathway can also affect the genome, as DNA methylation arises at loci homologous to the target RNA in plants. We demonstrate in fission yeast that expression of a synthetic hairpin RNA is sufficient to silence the homologous locus in trans and causes the assembly of a patch of silent Swi6 chromatin with cohesin. This requires components of the RNAi machinery and Clr4 histone methyltransferase for small interfering RNA generation. A similar process represses several meiotic genes through nearby retrotransposon long terminal repeats (LTRs). These analyses directly implicate interspersed LTRs in regulating gene expression during cellular differentiation.

344 citations

Journal ArticleDOI
TL;DR: Targeting the Nrf2 pathway in prostate cancer cells may provide a novel strategy to enhance chemotherapy and radiotherapy responsiveness and ameliorate the growth and tumorigenicity, leading to improved clinical outcomes.
Abstract: Loss-of-function mutations in the nuclear factor erythroid-2-related factor 2 (Nrf2) inhibitor Kelch-like ECH-associated protein 1 (Keap1) result in increased Nrf2 activity in non-small cell lung cancer and confer therapeutic resistance. We detected point mutations in Keap1 gene, leading to nonconservative amino acid substitutions in prostate cancer cells. We found novel transcriptional and posttranscriptional mechanisms of Keap1 inactivation, such as promoter CpG island hypermethylation and aberrant splicing of Keap1, in DU-145 cells. Very low levels of Keap1 mRNA were detected in DU-145 cells, which significantly increased by treatment with DNA methyltransferase inhibitor 5-aza-deoxycytidine. The loss of Keap1 function led to an enhanced activity of Nrf2 and its downstream electrophile/drug detoxification pathway. Inhibition of Nrf2 expression in DU-145 cells by RNA interference attenuated the expression of glutathione, thioredoxin, and the drug efflux pathways involved in counteracting electrophiles, oxidative stress, and detoxification of a broad spectrum of drugs. DU-145 cells constitutively expressing Nrf2 short hairpin RNA had lower levels of total glutathione and higher levels of intracellular reactive oxygen species. Attenuation of Nrf2 function in DU-145 cells enhanced sensitivity to chemotherapeutic drugs and radiation-induced cell death. In addition, inhibition of Nrf2 greatly suppressed in vitro and in vivo tumor growth of DU-145 prostate cancer cells. Thus, targeting the Nrf2 pathway in prostate cancer cells may provide a novel strategy to enhance chemotherapy and radiotherapy responsiveness and ameliorate the growth and tumorigenicity, leading to improved clinical outcomes.

342 citations

Journal ArticleDOI
TL;DR: It is demonstrated that expression of virus-specific artificial miRNAs is an effective and predictable new approach to engineering resistance to CMV and, possibly, to other plant viruses as well.
Abstract: RNA silencing in plants is a natural defense system against foreign genetic elements including viruses. This natural antiviral mechanism has been adopted to develop virus-resistant plants through expression of virus-derived double-stranded RNAs or hairpin RNAs, which in turn are processed into small interfering RNAs (siRNAs) by the host's RNA silencing machinery. While these virus-specific siRNAs were shown to be a hallmark of the acquired virus resistance, the functionality of another set of the RNA silencing-related small RNAs, microRNAs (miRNAs), in engineering plant virus resistance has not been extensively explored. Here we show that expression of an artificial miRNA, targeting sequences encoding the silencing suppressor 2b of Cucumber mosaic virus (CMV), can efficiently inhibit 2b gene expression and protein suppressor function in transient expression assays and confer on transgenic tobacco plants effective resistance to CMV infection. Moreover, the resistance level conferred by the transgenic miRNA is well correlated to the miRNA expression level. Comparison of the anti-CMV effect of the artificial miRNA to that of a short hairpin RNA-derived small RNA targeting the same site revealed that the miRNA approach is superior to the approach using short hairpin RNA both in transient assays and in transgenic plants. Together, our data demonstrate that expression of virus-specific artificial miRNAs is an effective and predictable new approach to engineering resistance to CMV and, possibly, to other plant viruses as well.

340 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023804
2022477
2021384
2020454
2019541
2018518