Aberrant axon branching via Fos-B dysregulation in FUS-ALS motor neurons.

Abstract

BACKGROUND:

The characteristic structure of motor neurons (MNs), particularly of the long axons, becomes damaged in the early stages of amyotrophic lateral sclerosis (ALS). However, the molecular pathophysiology of axonal degeneration remains to be fully elucidated.

METHOD:

Two sets of isogenic human-induced pluripotent stem cell (hiPSCs)-derived MNs possessing the single amino acid difference (p.H517D) in the fused in sarcoma (FUS) were constructed. By combining MN reporter lentivirus, MN specific phenotype was analyzed. Moreover, RNA profiling of isolated axons were conducted by applying the microfluidic devices that enable axon bundles to be produced for omics analysis. The relationship between the target gene, which was identified as a pathological candidate in ALS with RNA-sequencing, and the MN phenotype was confirmed by intervention with si-RNA or overexpression to hiPSCs-derived MNs and even in vivo. The commonality was further confirmed with other ALS-causative mutant hiPSCs-derived MNs and human pathology.

FINDINGS:

We identified aberrant increasing of axon branchings in FUS-mutant hiPSCs-derived MN axons compared with isogenic controls as a novel phenotype. We identified increased level of Fos-B mRNA, the binding target of FUS, in FUS-mutant MNs. While Fos-B reduction using si-RNA or an inhibitor ameliorated the observed aberrant axon branching, Fos-B overexpression resulted in aberrant axon branching even in vivo. The commonality of those phenotypes was further confirmed with other ALS causative mutation than FUS.

INTERPRETATION:

Analyzing the axonal fraction of hiPSC-derived MNs using microfluidic devices revealed that Fos-B is a key regulator of FUS-mutant axon branching. FUND: Japan Agency for Medical Research and development; Japanese Ministry of Education, Culture, Sports, Science and Technology Clinical Research, Innovation and Education Center, Tohoku University Hospital; Japan Intractable Diseases (Nanbyo) Research Foundation; the Kanae Foundation for the Promotion of Medical Science; and "Inochi-no-Iro" ALS research grant.

• Authors: Tetsuya Akiyama, Naoki Suzuki, Mitsuru Ishikawa, Koki Fujimori, Takefumi Sone, Jiro Kawada, Ryo Funayama, Fumiyoshi Fujishima, Shio Mitsuzawa, Kensuke Ikeda, Hiroya Ono, Tomomi Shijo, Shion Osana, Matsuyuki Shirota, Tadashi Nakagawa, Yasuo Kitajima, Ayumi Nishiyama, Rumiko Izumi, Satoru Morimoto, Yohei Okada, Takayuki Kamei, Mayumi Nishida, Masahiro Nogami, Shohei Kaneda, Yoshiho Ikeuchi, Hiroaki Mitsuhashi, Keiko Nakayama, Teruo Fujii, Hitoshi Warita, Hideyuki Okano, Masashi Aoki
• Journal: EBioMedicine (EBioMedicine) Vol. 45 Pg. 362-378 (Jul 2019) ISSN: 2352-3964 [Electronic] Netherlands
• PMID: 31262712 (Publication Type: Journal Article)
• Copyright: Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.

Chemical References

• FOSB protein, human
• FUS protein, human
• Proto-Oncogene Proteins c-fos
• RNA, Small Interfering
• RNA-Binding Protein FUS

Topics

• Amyotrophic Lateral Sclerosis (genetics, pathology)
• Animals
• Axons (metabolism, pathology)
• Cell Differentiation (genetics)
• Cell Line
• Gene Editing (methods)
• High-Throughput Nucleotide Sequencing
• Humans
• Induced Pluripotent Stem Cells (metabolism)
• Lentivirus (genetics)
• Motor Neurons (metabolism)
• Mutation
• Neurogenesis (genetics)
• Phenotype
• Proto-Oncogene Proteins c-fos (genetics)
• RNA, Small Interfering (genetics)
• RNA-Binding Protein FUS (genetics)