Defects in autophagosome-lysosome fusion underlie Vici syndrome, a neurodevelopmental disorder with multisystem involvement

• Published in: Scientific reports Vol. 7; no. 1; pp. 3552 - 11
• Main Authors: Hori, Ikumi, Otomo, Takanobu, Nakashima, Mitsuko, Miya, Fuyuki, Negishi, Yutaka, Shiraishi, Hideaki, Nonoda, Yutaka, Magara, Shinichi, Tohyama, Jun, Okamoto, Nobuhiko, Kumagai, Takeshi, Shimoda, Konomi, Yukitake, Yoshiya, Kajikawa, Daigo, Morio, Tomohiro, Hattori, Ayako, Nakagawa, Motoo, Ando, Naoki, Nishino, Ichizo, Kato, Mitsuhiro, Tsunoda, Tatsuhiko, Saitsu, Hirotomo, Kanemura, Yonehiro, Yamasaki, Mami, Kosaki, Kenjiro, Matsumoto, Naomichi, Yoshimori, Tamotsu, Saitoh, Shinji
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 14.06.2017; Nature Publishing Group UK; Nature Portfolio
• Subjects: Agenesis of Corpus Callosum - genetics; Agenesis of Corpus Callosum - pathology; Asian People; Autophagosomes - metabolism; Autophagy-Related Proteins; Biopsy; Brain - diagnostic imaging; Brain - pathology; Cardiomyopathy; Cataract - genetics; Cataract - pathology; Cataracts; Clonal deletion; Corpus callosum; CRISPR; Epithelial Cells - pathology; Family Health; Fibroblasts; Fibroblasts - pathology; Gene Knockdown Techniques; Gene Knockout Techniques; HeLa Cells; Hereditary diseases; Humans; Immunodeficiency; Lysosomal Membrane Proteins; Lysosomes - metabolism; Magnetic Resonance Imaging; Muscles - pathology; Mutation; Neurodevelopmental disorders; Neurodevelopmental Disorders - genetics; Neurodevelopmental Disorders - pathology; Phagocytosis; Pigmentation; Proteins - genetics; siRNA; Skin; Splicing; Vesicular Transport Proteins
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-02840-8

Vici syndrome (VICIS) is a rare, autosomal recessive neurodevelopmental disorder with multisystem involvement characterized by agenesis of the corpus callosum, cataracts, cardiomyopathy, combined immunodeficiency, developmental delay, and hypopigmentation. Mutations in EPG5, a gene that encodes a key autophagy regulator, have been shown to cause VICIS, however, the precise pathomechanism underlying VICIS is yet to be clarified. Here, we describe detailed clinical (including brain MRI and muscle biopsy) and genetic features of nine Japanese patients with VICIS. Genetic dissection of these nine patients from seven families identified 14 causative mutations in EPG5. These included five nonsense, two frameshift, three splicing, one missense, and one multi-exon deletion mutations, and two initiation codon variants. Furthermore, cultured skin fibroblasts (SFs) from two affected patients demonstrated partial autophagic dysfunction. To investigate the function of EPG5, siRNA based EPG5 knock-down, and CRISPR/Cas9 mediated EPG5 knock-out HeLa cells were generated. EPG5-depleted cells exhibited a complete block of autophagic flux caused by defective autophagosome-lysosome fusion. Unexpectedly, endocytic degradation was normal in both VICIS SFs and EPG5 depleted cells, suggesting that EPG5 function is limited to the regulation of autophagosome-lysosome fusion.