Axolotl pronephric duct cell migration is sensitive to phosphatidylinositol-specific phospholipase C

On the basis of its distribution pattern in embryos of the axolotl (Ambystoma mexicanum), we recently identified alkaline phosphatase as a molecule potentially involved in guiding the migration of the pronephric duct. Alkaline phosphatase is a cell surface protein anchored to cell membranes via a covalent linkage to a phosphatidylinositol glycan (PI-G). The enzyme phosphatidylinositol-specific phospholipase C (PIPLC) specifically releases from cell surfaces molecules anchored by the PI-G linkage. In order to test the possibility that a PI-G anchored protein is involved in directing pronephric duct cell migration, PIPLC was applied to axolotl embryos. The enzyme was introduced into embryos through the use of a novel slow-release bead material, hydrolysed polyacrylamide. PIPLC blocked pronephric duct cell migration without interfering with somite fissure formation, a concurrent, neighbouring morphogenetic cell rearrangement which occurs with little if any alkaline phosphatase present. In addition, alkaline phosphatase activity was markedly diminished in the vicinity of the implanted beads. These observations suggest that at least one protein anchored to the cell membrane by a PI-G linkage, possibly alkaline phosphatase, is involved in guiding or promoting pronephric duct cell migration.