Meta-Biol

• Pathways

HuR (ELAVL1) is a ubiquitous protein that binds AU-rich elements in mRNAs and acts to stabilize the mRNAs. HuR activity is controlled by phosphorylation, with PKC alpha and PCK delta enhancing the ability of HuR to bind and stabilize mRNAs. Binding of mRNAs occurs in the nucleus and HuR then interacts with the CRM1 export pathway to transfer the mRNA to the cytoplasm. The mechanism by which HuR shields the mRNA from degradation is unknown.
HuR also regulates translation of some mRNAs, in some cases repressing translation and in some cases enhancing translation of bound mRNAs by recruiting them to polysomes.
HuR binds and regulates mRNAs encoding Cyclooxygenase-2 (COX2, PTGS2), Cyclin A (CCNA, CCNA2), Cyclin D1 (CCND1), Cyclin B1 (CCNB1), CD83 antigen (CD83), and proto-oncogene c-Fos (FOS).
HuR is a member of a family of proteins that also contains HuD (ELAVL4), HuB (ELAVL2), and HuC (ELAVL3). HuB, HuC, and HuD are specifically expressed in neural tissue.
HuR participates in apoptosis. During lethal stress HuR becomes mostly cytoplasmic and is a target of Caspase-3 and Caspase-7. The cleavage products of HuR in turn promote apoptosis.

RNA elements rich in adenine and uracil residues (AU-rich elements) bind specific proteins which either target the RNA for degradation or, more rarely, stabilize the RNA. The activity of the AU-element binding proteins is regulated, usually by phosphorylation but also by subcellular localization.

This superpathway encompasses the processes by which RNA transcription products are further modified covalently and non-covalently to yield their mature forms, and the regulation of these processes. Annotated pathways include ones for capping, splicing, and 3'-cleavage and polyadenylation to yield mature mRNA molecules that are exported from the nucleus (Hocine et al. 2010). mRNA editing and nonsense-mediated decay are also annotated. Processes leading to mRNA breakdown are described: deadenylation-dependent mRNA decay, microRNA-mediated RNA cleavage, and regulation of mRNA stability by proteins that bind AU-rich elements.psnRNP assembly is also annotated here.

The aminoacylation of mature tRNAs is annotated in the "Metabolism of proteins" superpathway, as a part of "Translation".