| HuR (ELAVL1), the ubiquitously expressed founding member of the ELAV RNA-binding protein family alongside neuron-restricted HuB/C/D, orchestrates post-transcriptional control of mRNA stability and translation through high-affinity binding to AU- and U-rich elements (AREs) predominantly in 3' untranslated regions of proliferation, survival, and inflammatory transcripts. Its three tandem RNA recognition motifs (RRMs) form a compact clamp that engages adenine-rich stems with subnanomolar affinity, while nuclear localization/importin signals enable continuous nucleocytoplasmic shuttling that accelerates upon transcriptional stress when HuR relocates to cytoplasmic stress granules. Upon binding, HuR recruits poly(A)-binding protein to circularize mRNAs and excludes decay factors like TTP/BRF1 while promoting cap-dependent translation via eIF4A/eIF4G interactions; concurrently, HuR antagonizes miR-16 and let-7 repression by sterically occluding RISC loading sites on VEGF, c-Myc, and COX-2 transcripts. Phosphorylation by p38 MAPK, PKC, or Chk2 at S202/S220/S318 shifts HuR from nuclear retention to cytoplasmic export, coupling genotoxic stress or inflammatory cues to rapid proteome reprogramming. Physiologically, HuR sustains intestinal epithelial barrier integrity through sustained Mcl-1 expression, coordinates T cell activation via CD154 stabilization, and buffers oncogenic stress in fibroblasts, positioning it as the master regulator of immediate-early gene expression that researchers target with RRM-competitive quinazolines or antisense morpholinos to dissect translational buffering in tumorspheres. Cytoplasmic sequestration via 14-3-3 binding provides feedback inhibition, while HuR auto-regulates its own decay through intronic ARE binding. Overexpression drives chemoresistance through MDR1 stabilization while deficiency impairs wound healing through VEGF deficits. |
Lane 1: 293T, Lane 2: HCT116, Lane 3: 3T3, Lane 4: RAW264.7
