PLATFORM SESSION 14. GENE REGULATION AND FUNCTION I
Monday, August 2, 2004
2:00 PM–4:00 PM
Chair: Colin Clay
Co-Chair: Ted Chauvin
(324) RHOX: A NEW HOMEOBOX GENE CLUSTER.
MacLean, James1, Chen, Mingang1, Wayne, Chad1, Bruce, Shirley1, Meistrich, Marvin2, MacLeod, Carol3, Wilkinson, Miles1, 1 The University of Texas M. D. Anderson Cancer Center, Houston, TX2 The University of Texas M. D. Anderson Cancer Center, Houston, TX3 University of California, San Diego, CA
ABSTRACT- Homeobox genes encode transcription factors that regulate developmental events. Here we report the discovery of a cluster of 11 related homeobox genes on the mouse X chromosome expressed selectively in male and female reproductive tissues. These reproductive homeobox (Rhox)genes are good candidates for regulating reproductive tract developmental events because they display cell-type specific expression, several are hormonally regulated, and most exhibit developmentally regulated expression. Remarkably, the timing of their expression during testis development corresponds with their relative position on the X chromosome, suggesting that like Hox homeobox genes, Rhox genes are regulated by a global transcriptional enhancer. Most of the Rhox genes are expressed in Sertoli cells, the nurse cells in direct contact with developing male germ cells, suggesting that Rhox genes regulate the expression of somatic cell gene products critical for germ cell development. In support of this, targeting disruption of Rhox-5, which is exclusively expressed in Sertoli cells within the testis, increased germ cell apoptosis in the testis, reduced sperm production and sperm motility, and caused subfertility. This new family of homeobox genes on the X chromosome provides a model system with which to study temporal colinear gene expression and the transcriptional control of reproduction.
KEY WORDS: Testis, Androgen Regulation, Homeobox, Placenta