The novel human HUEL (C4orf1) gene maps to chromosome 4p12-p13 and encodesa nuclear protein containing the nuclear receptor interaction motif

A 3250-bp novel human cDNA sequence was isolated from the MRC-5 human embry onic lung cell line by the rapid amplification of cDNA ends technique. This gene was designated HUEL and given the symbol C4orf1 by the HUGO Nomenclat ure Committee. Within HUEL was identified a continuous ORF of 1704 bp encod ing a predicted hydrophilic protein of 568 amino acids with a calculated mo lecular mass of 63,410 Ha. The putative protein contains the LXXLL signatur e motif considered necessary and sufficient for binding of certain coactiva tors to Liganded nuclear receptors, as well as nuclear localization signals , a nuclear export-like signal, a zinc finger-like motif, an acidic region, and two leucine zipper-like domains. Northern blot analysis of human fetal tissues revealed 3.4-kb transcripts, while RT-PCR demonstrated HUEL expres sion in a wide range of human adult tissues and cancer cell lines, in the S iHa, HT-1080, and G-401 cancer lines was detected an alternative transcript in which a 166-bp segment was excluded by exon skipping, which is predicte d to culminate in a protein with a modified and truncated C-terminus. HUEL was localized to chromosome region 4p12-p13 by fluorescence in situ hybridi zation. In Western blots, affinity-purified antibodies raised against a HUE L-specific synthetic peptide could recognize a distinct protein band of sim ilar to 70 kDa. Immunoblotting of subcellular fractions and indirect immuno fluorescence of human embryonic lung cells demonstrated the distribution of HUEL predominantly in the cytoplasm, with an apparently cytoskeletal assoc iation. However, in smaller or dividing PLC/PRF/5 and TONG: liver carcinoma cells, there was a translocation of HUEL from the cytoplasm to the nucleus . Taken together, these data suggest that HUEL plays a role in transcriptio nal regulation. (C) 1999 Academic Press.