Rupture of intracranial aneurysms (IAs) leads to subarachnoid hemorrhage (SAH), a sudden-onset disease often causing severe disability or death. Using whole exome sequencing, we identified significant enrichment of rare, deleterious mutations in PPIL4 in both index and familial IA cases. Ppil4 depletion causes intracerebral hemorrhage, defects in cerebrovascular morphology, and impaired Wnt signaling in vivo. Wild type, but not IA-mutant PPIL4, potentiates Wnt signaling by binding JMJD6, a known angiogenesis regulator and Wnt activator. These findings identify a novel PPIL4-dependent Wnt signaling mechanism involved in brain-specific angiogenesis and maintenance of cerebrovascular integrity, and implicate PPIL4 gene variation in the pathogenesis of human IA.

Rupture of intracranial aneurysms (IAs) leads to subarachnoid hemorrhage (SAH), a sudden-onset disease often causing severe disability or death. Using whole exome sequencing, we identified significant enrichment of rare, deleterious mutations in PPIL4 in both index and familial IA cases. Ppil4 depletion causes intracerebral hemorrhage, defects in cerebrovascular morphology, and impaired Wnt signaling in vivo. Wild type, but not IA-mutant PPIL4, potentiates Wnt signaling by binding JMJD6, a known angiogenesis regulator and Wnt activator. These findings identify a novel PPIL4-dependent Wnt signaling mechanism involved in brain-specific angiogenesis and maintenance of cerebrovascular integrity, and implicate PPIL4 gene variation in the pathogenesis of human IA.

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