lncRNS

Long non-coding RNAs (lncRNAs), sometimes written as lncRNS, are RNA transcripts longer than 200 nucleotides that generally do not encode functional proteins. They are transcribed by RNA polymerase II, often capped, polyadenylated, and spliced, and they can be located in the nucleus or cytoplasm. lncRNAs tend to exhibit more tissue- and condition-specific expression than many protein-coding genes and can function at multiple levels of gene regulation.

lncRNAs are categorized by their genomic context as intergenic (lincRNAs), intronic, or overlapping antisense transcripts, among others. They can act in cis, influencing neighboring genes, or in trans, affecting distant loci. Distinct mechanisms include serving as guides that recruit chromatin-modifying enzymes to specific genomic sites, scaffolds that assemble protein complexes, decoys that sequester transcription factors or microRNAs, and enhancers that modulate enhancer activity or gene transcription. Some lncRNAs participate in the organization of nuclear compartments, such as XIST in X-chromosome inactivation and NEAT1 in paraspeckle formation.

lncRNAs participate in development, differentiation, and responses to stress, and dysregulation of lncRNA expression has been linked to cancers and neurological diseases. Because many lncRNAs are expressed at low levels and are poorly conserved, functional characterization remains challenging. Advances rely on complementary approaches, including RNA sequencing, localization studies, and genome editing to perturb lncRNA function.

Examples commonly cited include XIST, HOTAIR, and MALAT1, among others. While some lncRNAs can encode small peptides, the majority exert regulatory roles at the RNA level.