Hsal 1 is Related to Kidney and Gonad Development and is Expressed in Wilms Tumor

Townes-Brocks syndrome (TBS) is a human genetic disorder with features including urogenital, limb, anal and cardiac malformations associated with mutations of the TBS gene, Hsal 1. To begin to understand the role of the Hsal 1 protein (p140) in both normal development and disease pathogenesis, both message and protein expression were evaluated in specific tissues associated with TBS. DNA sequence information for Hsal 1 predicts that this homeotic, Drosophila homologue (Sal) encodes a zinc-finger protein consistent with a transcription factor. mRNA for Hsal 1 was highly expressed in fetal kidney and brain, with detectable production in thymus and heart. p140 was found in fetal ureteric bud, fetal and postnatal renal tubular epithelium, and renal blastema. In the 14-week fetal testis, the Hsal 1 protein was specifically expressed in the testosterone producing Leydig cells while in adult gonads Hsal 1 was also found in both Leydig and Sertoli cells, spermatogonia of the testis, and granulosa cells of the ovary. Evaluation of Wilms tumor revealed consistently high expression of the gene product in the epithelial and blastemal components. These spatial and temporal patterns of expression for Hsal 1, and the phenotypic effects associated with TBS, suggest that Hsal 1 plays an important role in the development and functional maintenance of the kidney and gonads. Furthermore, the Hsal 1 gene product may play a part in the pathogenesis of specific neoplasms occurring in these organs in addition to its specific role in Townes-Brocks syndrome.