The conserved Pelado/ZSWIM8 protein regulates actin dynamics by promoting linear actin filament polymerization

Actin filaments form either branched or linear structures, depending on the regulatory proteins involved. These structures are essential for cell specialization and morphogenesis. In Drosophila, cuticular hairs are formed by linear actin filaments, requiring precise regulation. Prior research has shown that the balance between linear and branched actin polymerization is critical for cellular function. However, the specific proteins that control this balance remain partially understood. No prior work had resolved the role of conserved SWIM domain proteins in actin dynamics. This gap motivated the investigation of Pelado/ZSWIM8. The gene is conserved across species, suggesting a fundamental role in actin regulation. Understanding its function could clarify how actin structures are controlled in different cell types.

This study aimed to determine the role of Pelado/ZSWIM8 in actin filament dynamics. The researchers focused on its function in epithelial and hemocyte cells of Drosophila. They hypothesized that Pelado influences actin polymerization by favoring linear over branched structures. To test this, they analyzed Pelado mutant cells for actin-related defects. They also examined whether manipulating actin monomer levels could reverse these defects. The study extended to human cells to assess conservation of function. The goal was to identify how Pelado affects actin dynamics in both invertebrate and mammalian systems. By linking Pelado to filopodia formation and cell migration, the researchers sought to clarify its role in cytoskeletal regulation.

The researchers used Drosophila epithelial and hemocyte cells to study Pelado function. They generated Pelado mutants and observed actin hair elongation defects. To test for reversibility, they manipulated actin monomer levels and altered polymerization pathways. They used genetic tools to increase linear actin polymerization or reduce branched filament formation. In hemocytes, they assessed filopodia formation as a readout of Pelado activity. The study also included human cell models to evaluate conservation. They tested Pelado’s effect on branched actin polymerization during cell migration. Imaging and biochemical assays were used to quantify actin structures and dynamics. The approach combined genetic, cellular, and biochemical techniques to assess Pelado’s role in actin regulation.

Pelado mutant cells showed defects in actin hair elongation in Drosophila epithelial cells. Increasing actin monomer levels reversed this defect. Promoting linear actin polymerization also restored normal hair formation. Reducing branched actin polymerization had a similar effect. In hemocytes, Pelado was essential for filopodia formation, which relies on linear actin. The function of Pelado was conserved in human cells. In a cell migration context, Pelado inhibited branched actin polymerization. These findings suggest that Pelado favors linear over branched actin structures. The data indicate that Pelado/ZSWIM8 regulates actin dynamics by promoting linear polymerization. The results support a conserved role for Pelado in cytoskeletal regulation.

The study concludes that Pelado/ZSWIM8 regulates actin dynamics by promoting linear polymerization. This function is conserved in both Drosophila and human cells. The protein appears to favor linear actin structures over branched ones. The findings suggest that Pelado influences the balance between different actin polymerization modes. In epithelial cells, Pelado is necessary for proper hair elongation. In hemocytes, it supports filopodia formation. In human cells, Pelado inhibits branched actin polymerization during migration. The authors propose that Pelado’s role is to regulate actin filament type in a cell-specific manner. The results highlight the importance of actin regulation in cell specialization and function.