09-P033 Expression of SOX3 in the urogenital ridge is associated with XX male sex reversal in mice

tem, where distal lung tissue from E18.5 Glucocorticoid Receptor (GR)–null mice have been exposed to at-RA. Whole genome microarrays and quantitative Real-time PCR have been utilized to identify and confirm GR-antagonised RA-responsive genes. Only the common rarb2/4 transcript and tcf15 (paraxis) were found to match this criteria. We propose that the antagonistic effects on alveolarisation by GC and RA are regulated by signaling through the rarb2/4-promoter. Furthermore, the transcriptional activation of some RA-responsive genes was dependent on the presence of GR. These genes include the RA-metabolising enzymes cyp1a1 and cyp7b1, the tight junction proteins cldn5 and cldn4 and the ECM-protein eln. These studies will provide a better understanding of the processes involved in alveolar development and the specific roles of GCand RA-signaling. These findings may impact on the procedures used in the care of premature infants, and hence reduce the effects of respiratory distress syndrome.