RNA Processing

RNA Processing is a crucial mechanism that occurs in eukaryotic cells to modify and refine RNA transcripts, ensuring their functionality and stability. This intricate process involves several key steps, beginning with pre-mRNA synthesis in the nucleus by RNA polymerase II. Following transcription, the pre-mRNA undergoes capping, where a 7-methylguanosine cap is added to the 5' end, protecting it from degradation and facilitating mRNA export. Concurrently, the pre-mRNA is spliced, where introns are excised and exons are ligated together by the spliceosome complex, generating a mature mRNA molecule. Additionally, polyadenylation occurs, where a poly(A) tail is added to the 3' end of the mRNA, aiding in translation and stability. RNA editing can also take place, altering nucleotide sequences to diversify gene expression. This processed mRNA is then exported from the nucleus into the cytoplasm, where it serves as a template for protein synthesis by ribosomes. However, not all RNA molecules undergo translation; some function as non-coding RNAs (ncRNAs), playing regulatory roles in gene expression, splicing, and chromatin structure. These include microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), which modulate mRNA stability and translation through complementary base pairing or chromatin remodeling. RNA processing is tightly regulated, with various factors, including RNA-binding proteins and small nuclear RNAs (snRNAs), controlling splicing accuracy and efficiency. Dysregulation of RNA processing can lead to diseases such as cancer, where aberrant splicing patterns contribute to tumor development and progression.