DELETION OF PLPP3 IN WNT1-EXPRESSING DOMAINS DISRUPTS TELENCEPHALIC DEVELOPMENT

Phospholipid phosphatase 3 (Plpp3) is an integral membrane enzyme that dephosphorylates bioactive lipids such as lysophosphatidic acid and sphingosine-1-phosphate. Complete loss of Plpp3 causes embryonic lethality around E9.5 in mice, indicating a critical developmental role. Previous work from our group showed that global Plpp3 deletion alters neural crest cell (NCC) behavior. NCCs are a multipotent population contributing to numerous craniofacial and forebrain-associated structures. To further investigate this role, earlier studies examined Plpp3 function at the midbrain–hindbrain boundary, where in situ hybridization revealed expanded Wnt1 signal at neuroepithelial edges in mutant embryos. Scanning electron microscopy demonstrated disorganized cellular architecture, while immunofluorescence against active caspase-3 revealed increased apoptosis along NCC migratory routes. In vitro neural tube explant assays further showed reduced NCC migration in global mutants. Conditional deletion of Plpp3 in Wnt1-expression domains was achieved by crossing Wnt1::Cre2 transgenic mice with a Plpp3^F/F line. Mutants displayed craniofacial and cardiac defects and neonatal lethality, accompanied by reduced telencephalic vesicles and a hypoplastic frontonasal process at E10.5–E11.5. To explore underlying mechanisms, we examined neurogenesis and NCC-derived structures, including meninges and pericytes. Immunofluorescence for phospho-histone H3 revealed no major neurogenesis defects at E13.5–E14.5. However, altered development of pia-associated perivascular fibroblasts, disorganization of the subarachnoid trabecular layer, and reduced telencephalic pericyte coverage were observed in embryos and neonates. These results highlight a critical role for Plpp3 in NCC-derived telencephalic structures required for proper telencephalic expansion.