Cell type-specific negative regulatory element in low-affinity nerve growth factor receptor gene.
Developmental changes in the expression pattern of the low-affinity nerve growth factor receptor (LNGFR) gene suggest a complex mechanism of gene regulation. We demonstrate the presence of a negative regulatory element (NRE) localized to a 40 base pair (bp) segment, -1731 to -1690 bp upstream from the translation start site in the LNGFR gene. The NRE possesses two tandemly arranged sequences with similarity to immunoglobulin gene enhancer E-boxes. The NRE is active in neurons and neuronal cell lines but not in astrocytes. Electrophoretic mobility shift analysis (EMSA) demonstrates changing expression pattern of proteins binding to the NRE in developing nervous system. Since the specific binding of the proteins to the NRE is competed with oligonucleotides containing E-box sequences we suggest that factor(s) responsible for down regulation of LNGFR gene include members of the helix-loop-helix class of transcription factors.