HuD, a neuronal-specific RNA-binding protein, is a potential regulator of MYCN expression in human neuroblastoma cells

• Published in: European journal of cancer (1990) 1997-10, Vol.33 (12), p.2071-2074
• Main Authors: Ross, R.A, Lazarova, D.L, Manley, G.T, Smitt, P.S, Spengler, B.A, Posner, J.B, Biedler, J.L
• Format: Article
• Language: English
• Subjects: Binding Sites; Blotting, Northern; ELAV Proteins; ELAV-Like Protein 4; HuD; human neuroblastoma; Humans; MYCN regulation; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Neoplasm Proteins - physiology; Nerve Tissue Proteins; Neuroblastoma - metabolism; Neuroblastoma - pathology; Protein Binding; Proto-Oncogene Proteins c-myc - genetics; Proto-Oncogene Proteins c-myc - metabolism; Proto-Oncogene Proteins c-myc - physiology; RNA, Messenger - metabolism; RNA-binding proteins; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; RNA-Binding Proteins - physiology; Sequence Deletion; Tumor Cells, Cultured
• ISSN: 0959-8049; 1879-0852
• DOI: 10.1016/S0959-8049(97)00331-6

HuD is one of a family of neural antigens recognised by the sera of patients with antibody-associated paraneoplastic encephalomyelitis. Localised exclusively to neurons, these proteins are among the earliest markers of the developing nervous system. Sequence analysis suggests that HuD is an RNA-binding protein. Hu protein levels were determined for the three cell types characterising human neuroblastoma cell lines: sympathoadrenal neuroblasts (N), substrate-adherent Schwann/glial/melanoblastic precursors (S) and stem cells (I) which can give rise to both N and S cells. Western blot analysis showed similar levels of protein in three N-type cell lines; S cells have no detectable Hu protein. Northern blot analysis indicated that N cells express all three Hu genes, HuD, HuC and Hel-N1. N cells, mostly from MYCN-amplified cell lines, have consistently higher steady-state levels of MYCN mRNA than S cell counterparts. Nuclear run-on and mRNA half-life experiments revealed no differences in transcription rate or mRNA stability between N and S cells from the LA-N-1 cell line, implicating differences in post-transcriptional regulation. HuD is postulated to be instrumental in splicing/processing and/or stabilisation of mRNAs involved in cell growth and neuronal differentiation. As determined by gel-mobility shift assays, HuD fusion protein binds to the 3′UTR of human MYCN mRNA. Analysis of HuD deletion mutants has demonstrated that the first and second RNA-recognition motifs (RRMs) are required for binding. Whether HuD regulates MYCN expression and thereby influences tumour aggressiveness is of major interest.