Expression of genes involved in sumoylation in the Drosophila germline.

Post-translational modification of proteins by the covalent addition of small ubiquitin-related modifier (SUMO) proteins has been reported to regulate a wide range of cellular processes. However, the spatiotemporal expression pattern of genes encoding the sumoylation machinery during development is largely unknown. Here, we report the expression of five sumoylation genes, Uba2, Aos1, smt3, Ulp1, and lesswright (lwr), in the Drosophila germline. Transcripts from all five genes were detected throughout the early embryo by whole-mount in situ hybridization, while they were predominantly expressed in the germline progenitors, or pole cells, in late stage embryos. These genes were also expressed in the germline during oogenesis and spermatogenesis. Finally, we found that SUMO protein was enriched in the nuclei of pole cells and gametogenic cells. Given that a large fraction of SUMO substrates are nuclear proteins, these data suggest that sumoylation is highly active in the germline. Our data provide a basis for understanding how sumoylation regulates germline development.