title: Marked Differences in C9orf72 Methylation Status and Isoform Expression between C9/ALS Human Embryonic and Induced Pluripotent Stem Cells.
abstract: We established two human embryonic stem cell (hESC) lines with a GGGGCC expansion in the C9orf72 gene (C9), and compared them with haploidentical and unrelated C9 induced pluripotent stem cells (iPSCs). We found a marked difference in C9 methylation between the cells. hESCs and parental fibroblasts are entirely unmethylated while the iPSCs are hypermethylated. In addition, we show that the expansion alters promoter usage and interferes with the proper splicing of intron 1, eventually leading to the accumulation of repeat-containing mRNA following neural differentiation. These changes are attenuated in C9 iPSCs, presumably owing to hypermethylation. Altogether, this study highlights the importance of neural differentiation in the pathogenesis of disease and points to the potential role of hypermethylation as a neuroprotective mechanism against pathogenic mRNAs, envisaging a milder phenotype in C9 iPSCs.
authors: Stem Cell Research Laboratory, Shaare Zedek Medical Center, Hebrew University School of Medicine, Jerusalem 91031, Israel.
authors: Yaara
authors: Y
authors: Cohen-Hadad
authors: Zohar PGD Laboratory, Medical Genetics Institute, Shaare Zedek Medical Center, Hebrew University School of Medicine, Jerusalem 91031, Israel.
authors: Gheona
authors: G
authors: Altarescu
authors: IVF Unit, Shaare Zedek Medical Center, Hebrew University School of Medicine, Jerusalem 91031, Israel.
authors: Talia
authors: T
authors: Eldar-Geva
authors: Zohar PGD Laboratory, Medical Genetics Institute, Shaare Zedek Medical Center, Hebrew University School of Medicine, Jerusalem 91031, Israel.
authors: Ephrat
authors: E
authors: Levi-Lahad
authors: Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON MSS 3H2, Canada.
authors: Ming
authors: M
authors: Zhang
authors: Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON MSS 3H2, Canada.
authors: Ekaterina
authors: E
authors: Rogaeva
authors: Department of Neurology, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel.
authors: Marc
authors: M
authors: Gotkine
authors: Biological Chemistry Department, Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors: Osnat
authors: O
authors: Bartok
authors: Biological Chemistry Department, Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors: Reut
authors: R
authors: Ashwal-Fluss
authors: Biological Chemistry Department, Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors: Sebastian
authors: S
authors: Kadener
authors: Stem Cell Research Laboratory, Shaare Zedek Medical Center, Hebrew University School of Medicine, Jerusalem 91031, Israel.
authors: Silvina
authors: S
authors: Epsztejn-Litman
authors: Stem Cell Research Laboratory, Shaare Zedek Medical Center, Hebrew University School of Medicine, Jerusalem 91031, Israel. Electronic address: rachela@szmc.org.il.
authors: Rachel
authors: R
authors: Eiges
mesh_terms: D017398:Alternative Splicing; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics; D000073885:C9orf72 Protein / Q000235:genetics*; D002454:Cell Differentiation; D002460:Cell Line; D018899:CpG Islands; D019175:DNA Methylation; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006239:Haplotypes; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D000073885:C9orf72 Protein
keywords: C9/ALS; CpG islands; DNA methylation; disease modelling; neurodegeneration; pluripotent stem cells; unstable repeat expansions