regulatory ncRNA-mediated gene silencing

Definition

Target type: biologicalprocess

A process in which an regulatory non-coding RNA molecule reduces expression of target genes. This can occur pre-transcriptionally by assembly of heterochromatin and prevention of transcription or co- or post-transcriptionally by targeting RNAs for degradation or by interfering with splicing or translation. This process starts once the inhibitory RNA molecule has been transcribed, and includes processing of the RNA such as cleavage, modifications, transport from the nucleus to the cytoplasm, loading onto the RISC complex, and the effect on transcription or translation. [PMID:15020054]

Regulatory ncRNAs, a diverse class of non-coding RNAs, play a crucial role in gene silencing through various mechanisms. They can directly bind to target mRNAs, preventing their translation or promoting their degradation. Some common mechanisms of regulatory ncRNA-mediated gene silencing include:

**1. RNA Interference (RNAi):** Small interfering RNAs (siRNAs) and microRNAs (miRNAs) are key players in RNAi. These short, double-stranded RNAs are processed from larger precursors. The guide strand of the siRNA/miRNA complex associates with the RNA-induced silencing complex (RISC). RISC then recognizes and binds to complementary sequences within target mRNAs, leading to either:

* **Translation repression:** The RISC complex blocks the ribosome from initiating translation, inhibiting protein synthesis.
* **mRNA degradation:** RISC recruits enzymes that cleave and degrade the target mRNA, preventing its translation.

**2. Long Non-coding RNAs (lncRNAs):** These are longer ncRNAs that can act as scaffolds or guide proteins to target genes. They can:

* **Recruit chromatin-modifying complexes:** lncRNAs can interact with proteins that modify chromatin structure, leading to silencing of target genes by altering their accessibility to transcription machinery.
* **Block transcription initiation:** lncRNAs can bind to promoter regions of target genes, physically preventing transcription factors from binding and initiating transcription.
* **Act as decoys:** lncRNAs can sequester proteins that are involved in gene activation, preventing them from interacting with their target genes.

**3. Circular RNAs (circRNAs):** These are single-stranded RNA molecules that are covalently closed into a loop. They can:

* **Sponge miRNAs:** circRNAs can act as "miRNA sponges" by binding to and sequestering specific miRNAs, preventing them from targeting their mRNA targets and leading to increased expression of these targets.
* **Regulate transcription:** Some circRNAs have been shown to directly interact with transcription factors and influence gene expression.

The specific mechanisms of action and targets of regulatory ncRNAs are highly diverse and context-dependent. They play crucial roles in various biological processes, including development, cell differentiation, and immune response. Dysregulation of regulatory ncRNAs is often associated with various diseases, highlighting their importance in maintaining cellular homeostasis.'
"

Proteins (1)

Compounds (4)