cytes. In this case, the small size of
siRNAs may have led to greater hepatic
RNA interference gene therapy
……………………………………………………………… transfection efficiency resulting in rela-
tively successful in vivo RNAi.
A story of mice and men The promising new data from Lewis et
al appear as a number of other exciting
Anton P. McCaffrey and Mark A. Kay
RNAi studies are being published. For
example, recent reports that describe
gene therapy (2002) 9, 1563. doi:10.1038/sj.gt.3301890
inhibition of viral replication in cultured
cells seem likely to lead to an entirely
new class of therapeutic agents. How-
dependent protein kinase response (PKR)
RNA interference (RNAi) has emerged as
ever, the work of Gitlin et al9 sounds a
causes global, non-specific repression of
one of the hottest topics in molecular and
note of caution for the field. They found
translation in response to dsRNAs longer
organismal biology. A flurry of recent
that polio escape mutants, with silent
than 30 nucleotides, thus masking any
papers suggest that RNAi may be useful
point mutations in the middle of the tar-
RNAi-based silencing. However with
as a human therapeutic. Significantly, in
get sequence, emerged after treatment
... selective TLR agonists that mimic host-defence-induced responses might have therapeutic benefit in a topic diseases. There is ... as a potential therapeutic strategy is obvious when bacteria and bacterial products, through over expressed TLR responses, activate a ... how TLR agonists or antagonists might offer possibilities for therapeutic intervention. It is proposed that the relatively sterile ...
shorter dsRNAs (short interfering RNAs
a paper in September’s Nature Genetics,
with RNAi.9 Thus, it may be necessary to
or siRNAs) Elbashir et al, in their ground-
David Lewis and his colleagues have
attack viruses with multiple RNAi
breaking study, were able to silence
shown that RNAi is functional in numer-
sequences simultaneously to prevent the
ous tissues of therapeutic interest.1 genes in mammalian cells without trig-
emergence of resistant strains.
gering the PKR response.2 More recently
RNAi is an evolutionarily conserved
This is clearly an exciting time for
surveillance mechanism that silences small hairpins RNAs (shRNAs) have
RNAi therapeutics. However, intracellu-
RNAs having homology to a double- been used to silence genes in mammalian
Write the correct Lewis structure for CS2. Write the formal charges on each atom in [F-S=F]2+ (lone pairs are not shown). How many ions are formed when Ca3(PO4)2 dissolves? How many protons, neutrons, and electrons are there in 19F- ion? Discuss the properties of molecules used as liquid crystals. (ignore this question) What is the molarity of the solution made when 1. 25 grams of sodium chloride ...
lar RNAi delivery in humans is a major
cells,5 raising the prospect of therapeutic
stranded RNA (dsRNA) trigger. It is an
obstacle that must be overcome. At least
RNAi through the expression of hairpin
indispensable tool for targeted gene inhi-
now we have evidence that any viral or
RNAs from gene therapy vectors.
bition in plants, worms and flies.
non-viral vector system can deliver
Recently, Elbashir et al2 electrified the Recently, we described a method for
RNAi6 and that it should be useful in
inducing RNAi in adult mice.6 We used
field by showing that RNAi functions in
many tissues.1 As with current gene
hydrodynamic transfection7,8 to co-
mammalian cells too. The new Lewis et al
transfer technologies, the limitations of
... show any significant to the outcome of the study. Nature also contributes with health. You can never ... source of play. Humans have evolved with nature. Nature fosters the imagination because there is no limits ... structures. It is all based on nature and using nature as materials for the playground. These ... children about the cycle of plants, respecting nature, and all about gardening. These are important ...
deliver target genes with siRNAs or
study provides additional evidence that
the available vectors may represent the
shRNAs. This strategy effectively sil-
RNAi is functional in adult mammals.
rate-limiting step towards developing
enced (up to 98%) luciferase RNAs, as
The excitement surrounding RNAi
RNAi into a bona fide therapeutic. None-
well as RNAs derived from hepatitis C
stems from the possibility that it could
theless, the study of RNAi efficacy in pre-
virus. It is clear, that all the tools neces-
potentially be used to inactivate any
clinical models of disease will become a
sary for RNAi gene therapy are now
pathogenic RNA. RNA from infectious
robust area of research. Over time, the
... the CFTR (cystic fibrosis transmembrane conductance regulator) gene is working as a result of mutation and therefore inheritance. Sickle cell ... baby that was born with Foetal alcohol syndrome is nature as the baby had no say in how its ... I believe that the baby with Down syndrome is nature as the baby was born with these defects and ... The nature nurture debate is where philosophers and theorist argue ...
agents, like viruses, as well as disease-
true value of this new class of thera-
The new study also uses hydrodyn-
causing host genes could be targeted for
peutics will likely be realized.
amic transfection to deliver siRNA to
inactivation. The new Nature Genetics
Anton McCaffrey and Mark Kay are in the Pro-
tissues in mice (this time without the use
study extends our knowledge of the
gram in Human Gene Therapy, Departments of
of RNase inhibitor) with similarly
parameters that affect the gene silencing
Pediatrics and Genetics, Stanford University
impressive results. Importantly, Lewis
process in vivo.
School of Medicine, Stanford, California 94305,
and his co-workers observed RNAi in
... Scientists Can Use RNA Interference to Turn Off Genes The discovery of miRNAs, siRNAs, and the mechanism of RNAi has been greeted ... is then assembled with specialized proteins to form an RNA-induced silencing complex (RISC). The RISC patrols the cytoplasm, searching ... reintroduced into the genome of a Drosophila embryo, the resulting embryo expresses -galactosidase precisely in the position of the ...
From work in Drosophila extracts, USA.
liver, spleen, kidney and pancreas.1
plants, and C. elegans, a plausible model
These results suggest a RNAi gene ther-
for RNAi gene silencing has emerged. e-mail: email@example.com
apy strategy could be applied to a
The ‘Dicer’ enzyme cuts long double- 1 Lewis DL et al. Nat Genet 2002; 32: 107–108.
diverse array of tissues.
stranded RNAs that the cell recognizes as 2 Elbashir SM et al. Nature 2001; 411: 494–498.
The new study also showed, for the
pathogenic into much shorter sections 3 Bernstein E, Caudy AA, Hammond SM, Han-
non GJ. Nature 2001; 409: 363–366.
nucleotides).3 These short first time in mice, that RNAi can sup-
4 Hammond SM, Bernstein E, Beach D, Hannon
dsRNAs, known as guide RNAs, are then press an endogenous chromosomal
GJ. Nature 2000; 404: 293–296.
gene.1 Lewis and his co-workers signifi-
incorporated into a large multi-subunit 5 Tuschl T. Nat Biotechnol 2002; 20: 446–448.
cantly reduced expression of the trans-
complex, the RNA induced silencing 6 McCaffrey AP et al. Nature 2002; 418: 38–39.
complex (RISC).4 This complex sub- gene in a large percentage of hepatocytes 7 Zhang G, Budker V, Wolff JA. Hum Gene Ther
1999; 10: 1735–1737.
sequently identifies and cleaves RNAs in an EGFP transgenic mouse. This is an
8 Liu F, Song Y, Lui D. Gene Therapy 1999; 6:
homologous to the guide RNAs. impressive result, given hydrodynamic 1258–1266.
RNAi silencing was always going to be transfection of plasmids usually results 9 Gitlin L, Karelsky S, Andino R. Nature 2002; 418:
hard to detect in mammals. The RNA- in transfection of only 5–40% of hepato- 430–434.