A Gene Upregulated in the Acoustically Damaged Chick Basilar Papilla Encodes a Novel WD40 Repeat Protein

The chickWDR1gene is expressed at higher levels in the chick basilar papilla after acoustic overstimulation. The 3.3-kbWDR1cDNA encodes a novel 67-kDa protein containing nine WD40 repeats, motifs that mediate protein–protein interactions. The predicted WDR1 protein has high sequence identity to WD40-repeat proteins in budding yeast (Saccharomyces cerevisiae), two slime molds (Dictyostelium discoideumandPhysarum polycephalum), and the roundworm (Caenorhabditis elegans). The yeast andP. polycephalumproteins bind actin, suggesting that the novel chick protein may be an actin-binding protein. Sequence database comparisons identified mouse and human cDNAs with high sequence identity to the chickWDR1cDNA. The mouse Wdr1 and human WDR1 proteins showed 95% sequence identity to each other and 86% identity to the chick WDR1 protein. Northern blot analysis of total RNA from the chick basilar papilla after noise trauma revealed increased levels of a 3.1-kb transcript in the lesioned area. TheWDR1gene was mapped to human chromosome 4, between 22 and 24 cM from the telomere of 4p.