DSP1 gene of Drosophila melanogaster encodes an HMG-domain protein that plays multiple roles in development

DSP1 is an HMG-box containing protein of Drosophila melanogaster which was first identified as a co-repressor of the Dorsal protein. Recently, the ana lysis of the structure of the gene has led vs to propose that DSP1 is the D rosophila equivalent of the ubiquitous vertebrate HMG 1/2 proteins. In the present paper, the patterns of expression of DSP1 protein and RNA in adult flies and during development are reported. in the adults DSP1 protein is lo cated in nurse cells of ovaries and in brain. During eggs development unifo rm expression of DSP1 protein persists until the end of germband retraction . At later stages, expression is restricted to the ventral nerve chord and brain. Using P-element mutagenesis, we have isolated a mutant deficient in DSP1 functions. Genetic studies of this mutant show that DSP1 protein is es sential for the growth and the development of Drosophila. In addition to be a co-repressor of the transcriptional activator Dorsal our results provide compelling evidence that DSP1 is a regulator involved in several pathways necessary for the development of the fly. Dev. Genet. 23:324-334, 1998. (C) 1998 Wiley-Liss, Inc.