Partial Functional Diversification of Drosophila melanogaster Septin Genes Sep2 and Sep5

摘要

The septin family of hetero-oligomeric complex-forming proteins can be divided into subgroups, and subgroup members are interchangeable at specific positions in the septin complex. Drosophila melanogaster has five septin genes, including the two SEPT6 subgroup members and . We previously found that has a unique function in oogenesis, which is not performed by . Here, we find that is uniquely required for follicle cell encapsulation of female germline cysts, and that and are redundant for follicle cell proliferation. The five D. melanogaster septins localize similarly in oogenesis, including as rings flanking the germline ring canals. Pnut fails to localize in ; double mutant follicle cells, indicating that septin complexes fail to form in the absence of both Sep2 and Sep5. We also find that mutations in septins enhance the mutant phenotype of , a key component in the establishment of cell polarity, suggesting a link between septin function and cell polarity. Overall, this work suggests that has undergone partial loss of ancestral protein function, and demonstrates redundant and unique functions of septins.