REGULATION OF AQUAPORIN-2 GENE-TRANSCRIPTION BY GATA-3

To evaluate the functional role of GATA motifs in the 5'-flanking regi on of a kidney-specific AQP-2 water channel gene, we sought to isolate a GATA factor(s) expressed in collecting ducts and determined the rol e on the AQP-2 promoter, Two cDNAs encoding GATA factors were isolated from rat kidney, whose sequences were highly homologous with human GA TA-2 and -3, Reverse-transcription PCR using dissected nephron segment s revealed that rat GATA-3 but not GATA-2 was expressed in collecting ducts, thus indicating that GATA-3 could interact with GATA motifs in the AQP-2 promoter, Transactivation experiments utilizing the rat GATA -3 expression vector indicated that rat GATA-3 increased the AQP-2 pro moter activity about fourfold, These results indicated that GATA motif s in the 5'-flanking region of the hAQP-2 gene were functional cis-ele ments and that GATA-3 in collecting ducts may be one of the important regulators of AQP-2 expression in vivo. (C) 1997 Academic Press.