mRNA Degradation

Definition

MRNA degradation is a process to eliminate mRNA that is either no longer required in the cell or has aberrant features. Three subcategories of enzymes prevail in the cells that mediate mRNA degradation; these enzymes are categorized according to the localization at which they cut RNA endonucleases, which cleave RNA internally, 5′ exonucleases, which degrade RNA from the 5′ end, and 3′ exonucleases, which promote hydrolysis at the 3′ end. Most mRNAs are degraded by a deadenylation-dependent pathway in which the poly(A) tail is degraded by the CCR4-NOT or PARN. Subsequently, the 5' cap of the mRNA is removed by the DCP1-DCP2 decapping complex. Following cap removal, the mRNA is degraded by the XRN1 exoribonuclease in a 5' to 3' direction. The mRNA can also be degraded in a 3' to 5' direction by the exosome followed by cap removal from the DcpS scavenger decapping enzyme. In endonuclease-mediated mRNA decay, mRNA is split into two separate pieces by an endonuclease, each one...