Present an overview of RNA-induced gene silencing achieved through RNA interfere
ID: 181610 • Letter: P
Question
Present an overview of RNA-induced gene silencing achieved through RNA interference (RNAi). How do the silencing processes begin, and what major components participate? Select all that apply. The RISC complex, guided by single-stranded RNA, can silence gene expression by affecting either mRNA stability or translation. The RITS complex, guided by single-stranded RNA, recruits chromatin remodeling proteins that can repress transcription. The Dicer complex can cleave both siRNA and miRNA precursors into siRNAs and miRNAs. siRNA molecules are derived from single-stranded RNAs that are transcribed from the cell's own genome. Short, double-stranded RNA molecules are recognized by either the RISC or RITS complex and the sense strand is degraded.Explanation / Answer
RNA interferance (RNAi) is a regulatory mechanism ( inhibits or activates gene expression) generally at post transcriptional (translation) or hindering transcription of specific genes. Small RNA fragments binds to complimentary fragment of mRNA making a double stranded streatch and a enzyme called dycer then cleaves the double stranded RNA (dsRNA) into approximately 20 nucleotide RNA which subsequently unwinds to 2 single stranded RNA (ssRNA) and binds other sites ( passenger strand and the guide strand) and interfere gene regulatiopn i.e. small interering RNAs (siRNAs). Besides siRNAs micro RNA (miRNAs) also the player of RNAi pathway. The dicer complex can cleave both siRNA and miRNA precursors into siRNAs and miRNAs.The passenger strand is degraded and the guide strand get into RNA-induced silencing complex (RISC)(by RISC-Loading Complex (RLC) which includes Dicer-2 and R2D2, and is crucial to unite Ago2 and RISC) and induces cleavage by Argonaute 2 (Ago2).
RNA-induced transcriptional silencing (RITS) is done by histone regulated unwinding of genes (heterocromatinization/remodeling) followed by argonaute and RdRP proteins association RITS protein complex formation with siRNA and processing.
The RISC complex, guided by siRNA, can silence gene expression by affecting either mRNA stability or translation.
The RITS complex, guided by siRNA, recruits remodeling proteins that can repress transcription.
The dicer complex can cleave both siRNA and miRNA precursors into siRNAs and miRNAs.
siRNA molecules natively derived from ssRNAs and transcribed from cell's own genome.
Small, dsRNAs are recognised by either RISC or RITS complexes and the anti-sence strand guide RISC complex to complementary mRNA (sence strand) for subsequent endonucleolytic cleavage.
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