miRNA stands for microRNA, which is a type of small non-coding RNA molecule, typically 20 to 25 nucleotides in length, that plays a role in regulating gene expression within cells. miRNA works by binding to specific sequences on target mRNA molecules, which can then result in the inhibition or degradation of those mRNA molecules, ultimately affecting protein translation. miRNA plays important roles in many biological processes, including cell differentiation, proliferation, and apoptosis. miRNA has also been implicated in the development and progression of many diseases, including cancer, cardiovascular disease, and neurological disorders. Due to the important roles that miRNA plays in many biological processes, researchers have conducted extensive studies into the functions and regulatory mechanisms of miRNA.

miRNA is a type of small RNA molecule that regulates gene expression within cells. It plays an important role in post-transcriptional regulation of gene expression by binding to the 3'-untranslated regions (3'-UTRs) of target mRNAs, leading to their degradation or translational repression.

miRNA is transcribed from the genome as a long primary transcript, which is processed by the RNAse III enzyme Drosha in the nucleus to generate a pre-miRNA hairpin structure. The pre-miRNA is then transported to the cytoplasm by exportin-5 and further processed by the RNAse III enzyme Dicer to generate the mature miRNA. The mature miRNA is then incorporated into the RNA-induced silencing complex (RISC), where it guides the complex to target mRNAs.

miRNA has been shown to play important roles in many biological processes, including cell differentiation, proliferation, and apoptosis. Dysregulation of miRNA expression has been implicated in the development and progression of many diseases, including cancer, cardiovascular disease, and neurological disorders.

In cancer, miRNA can function as either tumor suppressors or oncogenes, depending on the specific miRNA and the context in which it is expressed. Some miRNAs can promote cancer cell proliferation, invasion, and metastasis, while others can inhibit these processes.

miRNA has also been studied as a potential diagnostic and therapeutic target. miRNA expression profiling can be used to classify different types of cancer and predict patient prognosis. miRNA-based therapeutics, such as miRNA mimics or antagomiRs, are being developed as a new class of drugs for the treatment of cancer and other diseases.