miR15a

miR-15a is a human microRNA encoded by the MIR15A gene. It is part of the miR-15a/miR-16-1 cluster located on chromosome 13q14. The cluster is transcribed as a primary transcript and processed through the canonical microRNA biogenesis pathway to produce the mature miR-15a-5p, typically co-expressed with miR-16-1 due to their shared origin.

Functionally, miR-15a acts as a post-transcriptional regulator of gene expression. It binds complementary sequences in the 3' untranslated regions of target mRNAs, leading to mRNA degradation or translation inhibition. Well-established targets include the anti-apoptotic gene BCL2 and the cell cycle regulator CCND1, among others. Through these interactions, miR-15a influences apoptosis, cell proliferation, differentiation, and responses to cellular stress.

Expression of the miR-15a/miR-16-1 cluster is often reduced in disease. Deletions in the 13q14 region, which remove both miR-15a and miR-16-1, are a common and prognostically relevant alteration in chronic lymphocytic leukemia (CLL). Altered miR-15a levels have also been observed in other cancers and in cardiovascular conditions, highlighting its role in multiple physiological and pathological processes. Regulation of miR-15a involves transcriptional controls, epigenetic modifications, and feedback with its targets and broader signaling networks.

In research and therapy, restoring miR-15a expression using mimics or inhibiting competing pathways is being explored to modulate apoptosis and cell cycle in cancer models. While promising, these approaches face challenges in delivery, specificity, and safety for clinical use.