Cloning, chromosome mapping and expression analysis of the HIRA gene from Drosophila melanogaster

The human HIRA gene was identified as a putative transcriptional regulator mapping within the DiGeorge syndrome critical region at 22q11. HIRA-related proteins have been described in a number of species, but functional information concerning family members is only available in Saccharomyces cerevisiae, where the Hir1p and Hir2p proteins are known to be transcriptional corepressors. In order to analyse conservation of HIRA-related genes and to provide resources for functional studies in another model organism we have isolated the HIRA gene from Drosophila melanogaster (dhira). The 3374 nucleotide cDNA encodes a protein of 1047 aa, showing 42% identity with the human protein. Alignment with the predicted HIRA proteins from human, mouse, chick and pufferfish reveals strong conservation within the N-terminal region which contains seven WD domains, with less conservation of C-terminal sequences. In situ hybridisation to salivary gland chromosomes indicates that the gene resides in region 7B2-3 of the X chromosome. Dhira is expressed through embryonic development and at lower levels during larval and pupal development. The expression of dhira is dramatically increased in early embryos and in females, suggesting that the dhira mRNA could be maternally deposited in the embryos.