Glycosylphosphatidylinositol biosynthesis and remodeling are required for neural tube closure, heart development, and cranial neural crest cell survival.

Abstract

Glycosylphosphatidylinositol (GPI) anchors attach nearly 150 proteins to the cell membrane. Patients with pathogenic variants in GPI biosynthesis genes develop diverse phenotypes including seizures, dysmorphic facial features and cleft palate through an unknown mechanism. We identified a novel mouse mutant (<i>cleft lip/palate, edema and exencephaly; Clpex)</i> with a hypo-morphic mutation in <i>Post-Glycophosphatidylinositol Attachment to Proteins-2 (Pgap2)</i>, a component of the GPI biosynthesis pathway. The <i>Clpex</i> mutation decreases surface GPI expression. Surprisingly, <i>Pgap2</i> showed tissue-specific expression with enrichment in the brain and face. We found the <i>Clpex</i> phenotype is due to apoptosis of neural crest cells (NCCs) and the cranial neuroepithelium. We showed folinic acid supplementation <i>in utero</i> can partially rescue the cleft lip phenotype. Finally, we generated a novel mouse model of NCC-specific total GPI deficiency. These mutants developed median cleft lip and palate demonstrating a previously undocumented cell autonomous role for GPI biosynthesis in NCC development.