Proteins without transmembrane domains could be anchored to the cell surface for regulating various biological processes when covalently linked to glycosylphosphatidylinositol (GPI) molecules by the GPI transamidase (GPIT) complex. However, it remains poorly understood whether and how the GPIT complex affects primordial germ cell (PGC) development. In this study, we report the important roles of the GPIT complex in PGC migration and development in zebrafish embryos. Mutation of pigu or pigk, both encoding essential GPIT complex subunits, resulted in defective PGC migration with ectopically located PGCs and reduction of PGC counts. Notably, a detailed analysis of filopodia in PGCs revealed the attenuated polarity of filopodia distribution along the migration direction in mutant embryos. PGC transplantation and PGC-specific rescue experiments demonstrated that both PGC and somatic cell-expressed Pigu are required for PGC migration. Furthermore, expression levels of PGC-specific genes decreased in pigu mutant PGCs with the derepression of somatic cell genes. Hence, we propose that the GPIT complex plays a critical role during PGC migration and development.
