DIFFERENTIAL ACTIVITY OF ELAV-LIKE RNA-BINDING PROTEINS IN HUMAN NEUROBLASTOMA

Many short-lived mRNAs contain AU-rich instability elements within the ir 3'-untranslated region. Cellular factors that bind to these element s are thought to play a role in the regulation of mRNA degradation. In the accompanying paper (Chagnovich, D., and Cohn, S. L. (1996) J. Bio l. Chem. 271, 33580-33586) we characterized the binding activity of a 40-kDa protein (p40) that interacts with high specificity with at leas t two AU-rich elements located within the 3'-untranslated region of N- myc. p40 activity correlates with N-myc mRNA stability in subclones of the NBL-W neuroblastoma cells line (W-N and W-S). In an effort to det ermine the identity of p40 we performed immunoblotting studies, immuno precipitation experiments, and RNA gel mobility shift assays using ant ibodies that are directed against known RNA-binding proteins. In this paper we demonstrate that in W-N and W-S cells, p40 activity parallels the expression of embryonic letal abnormal vision (ELAV)-like protein s, and that antibodies directed against this family of RNA-binding pro teins recognize p40, We also show that purified ELAV-like proteins (Hu D and Hel-N1) bind with high specificity to the same N-myc 3'-untransl ated region sequences as p40. Our data indicate that p40 is a member o f the ELAV-like family, and suggest that this family of RNA-binding pr oteins may regulate N-myc mRNA turnover.