Rna Interference: Imgenex Launched the Psuppressoradeno Construction Kit for Adenovirus Mediated Gene Knockdown

RNA interference (RNAi) is the process of mRNAmiRNAs were discovered through their critical roles in
degradation that is induced by double-stranded RNAdevelopment and cellular regulation, and represent a
in a sequence-specific manner. RNAi has beenlarge class of evolutionarily conserved RNAs. miRNAs
observed in all eukaryotes, from yeast to mammals.have always been recognized as being of
The RNAi pathway is thought to be an ancientendogenous origin. RNA interference has emerged as
mechanism for protecting the host and its genomea natural mechanism for silencing gene expression
against viruses and rogue genetic elements that useover the past decade. This ancient cellular antiviral
double-stranded RNA (dsRNA) in their life cycles.response can be harnessed to allow specific inhibition
They have also been shown to play a role not only inof the function of any chosen target genes, including
mRNA and dsRNA stability/degradation, but also inthose involved in causing diseases such as cancer,
regulation of translation, transcription, chromatinAIDS, and hepatitis. It is already proving to be an
structure, and genome integrity. In plants and animals,invaluable research tool, allowing much more rapid
RNA silencing has been adapted to play a critical rolecharacterization of the function of known genes.
in regulation of cell growth and differentiation using aMore importantly, the technology considerably
class of small RNAs. In the RNA interference process,bolsters functional genomics to aid in the identification
the dsRNAs get processed into 20-25 nucleotide (nt)of novel genes involved in disease processes. Last
small RNAs by an RNase III-like enzyme called Dicer.but not the least the technology can be harnessed
Then, the small RNAs assemble intoas a novel therapeutic agent and is suitable for
endoribonuclease-containing complexes known ascombating viral diseases, cancers and inflammatory
RNA-induced silencing complexes (RISCs), unwindingdiseases.
in the process. The small RNA strands subsequentlyImgenex (San Diego) recently launched the
guide the RISCs to complementary RNA molecules,pSuppressorAdeno construction kit for adenovirus
where they cleave and destroy the cognate RNAmediated gene knockdown. The kit provides the
(effecter step). Cleavage of cognate RNA takesability to infect a broad range of cell types, including
place near the middle of the region bound by themany primary cell lines as well as dividing and
siRNA strand. The small RNAs that provide targetnondividing cells, according to a company official. The
specificity to the silencing machinery includes shortkit also offers the flexibility to validate sequences
interfering RNAs (siRNAs), repeat-associated siRNAsusing the nonviral expression plasmid prior to
(rasiRNAs), and microRNAs (miRNAs) and isconstruction of adenoviruses, notes Sujay K. Singh,
distinguished by their origin. siRNAs are processedPh.D., president and CEO of Imgenex, which markets
from dsRNA precursors made up of two distinctplasmid-based RNA interference (RNAi) products.
strands of perfectly base-paired RNA, while miRNAs“One of the greatest advantages is the ability of
originate from a single, long transcript that formsrecombinant adenovirus vectors to reduce gene
imperfectly base-paired hairpin structures. siRNAsexpression both in vitro and in vivo,” he adds.
were originally identified as intermediates in the RNAiRNAi, initially considered a bizarre attribute of petunias
pathway after induction by exogenous dsRNA;and later a gene-silencing mechanism in worms, is
however, endogenous sources of siRNAs have nowcreating a stir as one of the hottest new
been recognized. The endogenous siRNAs are derivedtechnologies in molecular biology. It is revolutionizing
from repetitive sequences within the genome, andthe field of functional genomics.
are termed repeat-associated siRNAs, or rasiRNAs.