RNF213 variant and autophagic impairment: A pivotal link to endothelial dysfunction in Moyamoya disease

Abstract Background Moyamoya disease (MMD) is closely associated with the Ring Finger Protein 213 (RNF213), a susceptibility gene for this disease. However, its biological function remains unclear. We aimed to elucidate the role of RNF213 in the damage incurred by human endothelial cells under oxygen-glucose deprivation (OGD), a condition that mimics intracranial ischemia in patients with MMD. Methods We analyzed autophagy in peripheral blood mononuclear cells (PBMCs) derived from patients carrying either RNF213 wild-type (WT) or variant (R4810K). Subsequently, human umbilical vein endothelial cells (HUVECs) were transfected with RNF213 WT (HUVEC WT ) or R4810K (HUVEC R4810K ) and exposed to OGD for 2 h to determine the role of the RNF213 variant in such a setting. Immunoblotting was used to analyze autophagy marker proteins, and tube formation assays were performed to examine endothelial function. Autophagic vesicles were observed using transmission electron microscopy. Post-OGD exposure, we administered autophagy modulators such as rapamycin and cilostazol. Results The RNF213 variant group during post-OGD exposure (vs. pre-OGD exposure) showed autophagy inhibition, increased protein expression of SQSTM1/p62 ( p < 0.0001) and LC3-II ( p = 0.0039), and impaired endothelial function ( p = 0.0252). HUVEC R4810K during post-OGD exposure (versus pre-OGD exposure) showed a remarkable increase in autophagic vesicles. Administration of autophagy modulators notably restored the function of HUVEC R4810K and cellular autophagy. Conclusions Our findings support the pivotal role of autophagy impaired by the RNF213 variant in MMD-induced endothelial cell dysfunction and underscore the critical mechanism of autophagy leading to progressive endothelial dysfunction and MMD pathogenesis under relative ischemia within the intracranial portion.