miRNAProzessierung

miRNA Prozessierung refers to the cellular mechanism by which precursor microRNA (miRNA) molecules are processed into mature, functional miRNAs. This process is crucial for the regulation of gene expression in eukaryotes. The journey begins in the nucleus with the transcription of a primary miRNA (pri-miRNA) from a miRNA gene. This pri-miRNA is then cleaved by a complex called Drosha-DGCR8, shortening it to a hairpin-shaped precursor miRNA (pre-miRNA). This pre-miRNA is then exported from the nucleus to the cytoplasm. In the cytoplasm, the pre-miRNA undergoes further processing by the enzyme Dicer, which cleaves the hairpin structure to produce a short, double-stranded RNA molecule approximately 20-25 nucleotides in length. One strand of this duplex, the mature miRNA, is then loaded into the RNA-induced silencing complex (RISC). The RISC, now guided by the miRNA, can bind to complementary sequences in messenger RNA (mRNA) molecules. This binding typically leads to the repression of protein translation or the degradation of the target mRNA, thereby fine-tuning gene expression. The efficiency and specificity of miRNA Prozessierung are tightly regulated, ensuring appropriate cellular function.