Somatic GJA4 mutation in intracranial extra-axial cavernous hemangiomas

Area of Science:

• Neuroscience
• Genetics
• Vascular Biology

Background:

• Extra-axial cavernous hemangiomas (ECHs) are rare intracranial vascular lesions with unknown etiology.
• Cavernous hemangiomas typically occur within the cavernous sinus.

Purpose of the Study:

• To investigate the genetic basis and underlying mechanisms of extra-axial cavernous hemangiomas.
• To identify specific mutations and signaling pathways involved in ECH development.

Main Methods:

• Whole-exome sequencing of ECH lesions from a discovery cohort.
• Droplet digital PCR (ddPCR) for mutation validation in an independent cohort.
• Laser capture microdissection (LCM) to isolate lesional endothelial cells.
• In vitro studies using endothelial cells and in vivo studies in a mouse model.

Main Results:

• A somatic GJA4 mutation (c.121G>T, p.G41C) was detected in a significant proportion of ECH patients.
• The GJA4 mutation was enriched in lesional endothelium and activated the SGK1 signaling pathway.
• In vitro and in vivo models demonstrated that the GJA4 mutation promotes endothelial cell hyperproliferation and vascular abnormalities characteristic of ECHs.
• An SGK1 inhibitor reversed the observed pathological features in the mouse model.

Conclusions:

• Extra-axial cavernous hemangiomas are identified as vascular malformations driven by somatic GJA4 mutations.
• Activation of the SGK1 signaling pathway in brain endothelial cells is a key mechanism in ECH pathogenesis.
• These findings provide a genetic and mechanistic understanding of ECHs, opening avenues for targeted therapies.