title: Mislocalization of syntaxin-1 and impaired neurite growth observed in a human iPSC model for STXBP1-related epileptic encephalopathy.
abstract: Syntaxin-binding protein 1 (STXBP1) is essential for synaptic vesicle exocytosis. Mutations of its encoding gene, STXBP1, are among the most frequent genetic causes of epileptic encephalopathies. However, the precise pathophysiology of STXBP1 haploinsufficiency has not been elucidated. Using patient-derived induced pluripotent stem cells (iPSCs), we aimed to establish a neuronal model for STXBP1 haploinsufficiency and determine the pathophysiologic basis for STXBP1 encephalopathy. We generated iPSC lines from a patient with Ohtahara syndrome (OS) harboring a heterozygous nonsense mutation of STXBP1 (c.1099C>T; p.R367X) and performed neuronal differentiation. Both STXBP1 messenger RNA (mRNA) and STXBP1 protein expression levels of OS-derived neurons were approximately 50% lower than that of control-derived neurons, suggesting that OS-derived neurons are a suitable model for elucidating the pathophysiology of STXBP1 haploinsufficiency. Through Western blot and immunocytochemistry assays, we found that OS-derived neurons show reduced levels and mislocalization of syntaxin-1, a component of soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins. In addition, OS-derived neurons have impaired neurite outgrowth. In conclusion, this model enables us to investigate the neurobiology of STXBP1 encephalopathy throughout the stages of neurodevelopment. Reduced expression of STXBP1 leads to changes in the expression and localization of syntaxin-1 that may contribute to the devastating phenotype of STXBP1 encephalopathy.
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamashita
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Chiyonobu
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.|Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Maeda
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Zuiki
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kidowaki
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.|Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Isoda
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Morimoto
authors.affiliation: Department of Pediatrics, Yamagata University Faculty of Medicine, Yamagata, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kato
authors.affiliation: Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
authors.forename: Hirotomo
authors.initials: H
authors.lastname: Saitsu
authors.affiliation: Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
authors.forename: Naomichi
authors.initials: N
authors.lastname: Matsumoto
authors.affiliation: Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan.
authors.forename: Tatsutoshi
authors.initials: T
authors.lastname: Nakahata
authors.affiliation: Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan.
authors.forename: Megumu K
authors.initials: MK
authors.lastname: Saito
authors.affiliation: Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Hosoi
mesh_terms: D002478:Cells, Cultured; D002675:Child, Preschool; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism*; D007223:Infant; D008297:Male; D051938:Munc18 Proteins / Q000378:metabolism*; D016501:Neurites / Q000502:physiology*; D013036:Spasms, Infantile / Q000175:diagnosis* / Q000378:metabolism*; D050827:Syntaxin 1 / Q000378:metabolism*
chemical_list: D051938:Munc18 Proteins; C497937:STXBP1 protein, human; D050827:Syntaxin 1
keywords: Induced pluripotent stem cell; Ohtahara syndrome; SNARE complex