Isolation and characterization of several members of the murine Hsd3b gene family

The enzyme 3 beta-hydroxysteroid dehydrogenazse (3 beta HSD) is essential for all steroid hormone biosynthesis, Six distinct 3 beta HSD cDNAs in the mouse (3 beta HSD I-VI) have been isolated previously, This study reports the isolation of genes or partial genes encoding the 3 beta HSD I, II, III, and IV isoforms, Characterization of the genes revealed that they consist of four exons, the same structure that has been observed for characterized human 3(b)eta HSD genes, Primer extension and nuclease S1 analysis identified the start sites of transcription of Hsd3b-1 and -4, The proximal promoter regions of Hsd3b-1 and -4 were sequenced and putative cis-acting sequences were determined, Previously, we reported that the then known 3 beta HSD genes (3 beta HSD I-IV) were located in a small region of mouse chromosome 3, To analyze this locus further, six yeast artificial chromosome clones containing the 3 beta HSD sequence were identified. One clone appears to contain the complete 3 beta HSD locus within its 1,400-kbp insert, Further analysis of this YAC, along with analysis of mouse genomic DNA by pulsed-field gel electrophoresis, suggests all members of the 3 beta HSD gene family may be contained on a 400-kbp fragment.