miRNAVarianten

miRNAVarianten, also known as microRNA variants or miRNA isoforms, refer to variations in the sequence or structure of microRNA (miRNA) molecules. These variations can arise from several sources, including genetic polymorphisms in the miRNA gene itself, post-transcriptional modifications, or processing errors during miRNA biogenesis. The most common type of miRNA variation is due to single nucleotide polymorphisms (SNPs) within the miRNA gene sequence or its precursor (pri-miRNA) or mature (miRNA) forms. These sequence changes can alter miRNA biogenesis, stability, or their ability to bind to target messenger RNA (mRNA) molecules.

Another significant source of variation is the processing of pri-miRNA and pre-miRNA. While canonical processing by the Drosha and Dicer enzymes produces the mature miRNA, alternative cleavage events can lead to isomiRs. IsomiRs can differ from the canonical miRNA by the addition or deletion of nucleotides at their 5' or 3' ends, or by internal sequence variations. These variations can impact the target recognition and binding affinity of the miRNA, potentially leading to different regulatory outcomes compared to the canonical miRNA. Post-transcriptional modifications, such as adenosine-to-inosine (A-to-I) editing, can also create functional variants by altering the nucleotide composition of the miRNA, affecting its base pairing with target mRNAs. Understanding miRNAVarianten is crucial as they can influence gene expression networks and have implications in various biological processes, including development, disease pathogenesis, and drug response.