Antisense mRNA is an mRNA transcript that is complementary to endogenous mRNA. It is the noncoding strand complementary to the coding sequence of mRNA. Introducing a transgene coding for antisense mRNA is a strategy used to block expression of a gene of interest. A strand of antisense mRNA can also be introduced into the cytosol by microinjection. Radioactively-labelled antisense mRNA can be used to hybridise to endogenous sense mRNA, which can show the level of transcription of genes in various cell types.

Analogous molecules with modified backbones have been designed which change various characteristics of RNA, such as its instability to degradative enzymes. Some alternative antisense structural types are phosphorothioate, Morpholino, PNA (peptide nucleic acid), LNA (locked nucleic acid), and 2'-O alkyl oligos. Some antisense structural types are being experimentally applied as antisense therapy, with at least one antisense therapy approved for use in humans.

RNA | Antisense-RNA