Isolation, characterization, and mapping of the mouse and human WDR8 genes, members of a novel WD-repeat gene family

The Trp-Asp (WD) motif has been shown to exist in a number of proteins. Gen es containing repeats of the WD motif compose a large gene family associate d with a variety of cellular functions and can be divided into a number of functional subfamilies. By means of the differential display method using t tw, a mouse model for the early stage of ectopic ossification, we have iden tified a novel mouse gene, Wdr8 (WD repeat domain 8), which contains two WD repeats, together with its human orthologue. The human and mouse WDR8 gene s encode 460 and 462 amino acids, respectively, with 89% identity, and are expressed in almost all tissues, including bone and cartilage, and in bone- forming cells, including osteoblasts and chondrocytes. Wdr8 expression in c artilage was differentially displayed by stimuli for ectopic ossification i n ttw and was observed strongly only at a transition period from hypertroph ic to mineralizing stages in ATDC5, a chondrogenic cell line that exhibits endochondral ossification, suggesting a potential role for Wdr8 in the proc ess of ossification. The WDR8 protein is highly conserved among a variety o f species, but is distinctly different from other WD-repeat proteins, indic ating that it represents a novel subfamily of the WD-repeat gene family. (C ) 2001 Academic Press.