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RNAi, PTGS and quelling - three variations on one subject?

100%

Szweykowska-Kulinska Z., Jarmolowski A., Figlerowicz M.

In 1990, it was already discovered that plant transformation with a transgene containing its homologue in the plant nuclear genome is able to promote silencing of both the transgene and the homologous, endogenous gene. The phenomenon was named posttranscriptional gene silencing (PTGS) or co-suppression. The same results were obtained when a transgene was introduced into the nuclear genome of fungus Neurospora crassa. This process was termed quelling. In 1998, RNAi (RNA interference) was discovered in the Caenorhabditis elegans worm. Specific gene silencing occurred after the introduction into the worm of cells of double stranded RNA with sequence complementarity to the endogenous gene. It was shown that RNAi operates at the stage of the mature mRNA in the cytoplasm. dsRNAs are converted into siRNAs (small interfering RNAs) due to the Dicer enzyme activity. siRNAs are incorporated into the RISC (RNA ? induced silencing complex). Active RISC promotes specific mRNA degradation. RNAi/PTGS/quelling processes show many mechanistic similarities, but they also differ in some details. All of them represent an ancient mechanism that probably evolved to protect eukaryotic cells against invasive forms of nucleic acids like viruses, transposons, and others.

RNA interference and its role in the regulation of eucaryotic gene expression.

88%

Szweykowska-Kulińska Z., Jarmołowski A., Figlerowicz M.

2003

vol. 50

issue 1

217-229

Several years ago it was discovered that plant transformation with a transcribed sense transgene could shut down the expression of a homologous endogenous gene. Moreover, it was shown that the introduction into the cell of dsRNA (double-stranded RNA) containing nucleotide sequence complementary to an mRNA sequence causes selective degradation of the latter and thus silencing of a specific gene. This phenomenon, called RNA interference (RNAi) was demonstrated to be present in almost all eukaryotic organisms. RNAi is also capable of silencing transposons in germ line cells and fighting RNA virus infection. Enzymes involved in this process exhibit high homology across species. Some of these enzymes are involved in other cellular processes, for instance developmental timing, suggesting strong interconnections between RNAi and other metabolic pathways. RNAi is probably an ancient mechanism that evolved to protect eukaryotic cells against invasive forms of nucleic acids.

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1 Acta Biochimica Polonica

1 Biotechnologia

2 2003

2 Figlerowicz M.

1 Jarmolowski A.

1 Jarmołowski A.

1 Szweykowska-Kulinska Z.

1 Szweykowska-Kulińska Z.

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RNAi, PTGS and quelling - three variations on one subject?

RNA interference and its role in the regulation of eucaryotic gene expression.