An endothelial specific mouse model for the capillary malformation mutation Gnaq p.R183Q

Capillary malformation (CM) is a congenital, non-hereditary lesion composed of enlarged and tortuous blood vessels. CM is associated with a somatic p.R183Q activating mutation in the Guanine nucleotide-binding protein G(q) subunit alpha (GNAQ) gene in endothelial cells (EC). Cutaneous CMs are present in 1/300 infants and in 55-70% of CM cases soft tissue overgrowth is observed. Pharmacotherapy for CM does not exist. Here we report a conditional mouse model allowing the simultaneous tissue specific expression of GNAQ p.R183Q and Green Fluorescent Protein (GFP) from the Rosa26 (R26) locus (R26^{GT - Gnaq-GFP}). We show that expression of GNAQ p.R183Q in ECs results in vascular malformations with features similar to human CM lesions. GNAQ p.R183Q expression during embryonic development (Tg-Cadherin5Cre (Tg-Cdh5Cre)) resulted in a severe vascular phenotype, lethal by embryonic (E) 16.5. Sporadic induction of mutant GNAQ expression in ECs at postnatal (P) day 1 (Tg-Cdh5CreER) led to tortuous and enlarged blood vessels, most noticeable in the intestines. GNAQ p.R183Q/GFP expressing ECs co-localized with lesions and displayed increased proliferation. Mutant ECs had abnormal mural cell coverage and abnormal pericellular extracellular matrix deposition, which was confirmed in human CM samples. Similar to human CM they displayed strong expression of the tip cell marker Endothelial cell-specific molecule 1 (ESM1) and increased Angiopoietin 2 (ANGPT2) expression. In conclusion, GNAQ p.R183Q expression in mouse ECs causes vascular malformations supporting the mutation's causality for CM. The lesions recapitulate multiple features of human CM, making the mouse model suitable for the preclinical testing of future CM pharmacotherapy.