MicroRNA 133b (miR-133b)

MicroRNA 133b is a short (about 22 nucleotides) non-coding RNA subclassified as a muscle-specific microRNA (myomiR). It plays a critical role in the regulation of gene expression by binding to target mRNAs, usually resulting in their degradation or translation inhibition. miR-133b is highly enriched in cardiac and skeletal muscle, where it is indispensable for normal tissue development, differentiation, and structure. Abnormal miR-133b expression has been found in diverse cancers, often acting as a tumor suppressor (e.g., suppressing oncogenes like Sox9, c-MET, and WAVE2, and pathways including PI3K/AKT, MAPK, and STAT3). In some cellular contexts, it may have an oncogenic effect due to regulatory network complexity. miR-133b's regulatory impact extends to cell cycle control, apoptosis, energy metabolism (e.g., glycolysis via PKM2), and cell migration. It is under transcriptional control by various factors, including SREBP-1c and androgen receptor, and participates in metabolic and metastatic pathways crucial to cancer and muscle diseases. While not the direct target of any approved drugs, miR-133b is an active area of research for RNA therapeutics and biomarker development.

Other names

hsa-miR-133bMIRN133BmiRNA133Bmir-133bhsa-mir-133bMIR133B

Drugs or biologics targeting miR-133b typically act via: miRNA mimicry (supplementation of miR-133b to restore tumor suppressive function); Anti-miR oligonucleotides (inhibit endogenous miR-133b when overactivity is pathogenic); Modulation of upstream regulators impacting miR-133b expression (e.g., SREBP-1c, androgen receptor, long non-coding RNAs).