The screening of somatic mutations using whole exome sequencing in brain malformations

• Project/Area Number: 15K10367
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Neurosurgery
• Research Institution: Hamamatsu University School of Medicine (2017); Yokohama City University (2015-2016)
• Principal Investigator: Nakashima Mitsuko 浜松医科大学, 医学部, 准教授 (20541965)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2016: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2015: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
• Keywords: 体細胞変異 / 全エクソーム解析 / TAS変異 / droplet digital PCR / GNAQ / MTOR / ラパマイシン / TAS解析

Outline of Final Research Achievements

We performed whole exome sequencing using paired samples from Sturge Weber syndrome and FCD Type IIb subjects and further investigated using deep sequencing. We identified lesion-specific somatic GNAQ mutation in individuals with Sturge Weber syndrome and MTOR mutations in individuals with FCD Type IIb. Functional analyses showed that phosphorylation of ribosomal protein S6 in FCD Type IIb brain tissues with MTOR mutations was clearly elevated compared with control samples. Transfection of any of the four MTOR mutants into HEK293T cells led to elevated phosphorylation of 4EBP, the direct target of mTOR kinase. These findings suggest that mutations in MTOR are likely to cause hyperactivation of the mTOR signaling pathway and induce dysregulation of growth of neurons and glia, or presumably of their progenitors during brain development. MTOR mutations are sensitive to rapamycin, therefore, mTOR inhibitors would be able to alleviate intractable epilepsy caused by MTOR mutations.

Research Products

• [Journal Article] High prevalence of genetic alterations in early-onset epileptic encephalopathies associated with infantile movement disorders. (2016)
  • Author(s): Kobayashi Y, Tohyama J, Kato M, Akasaka N, Magara S, Kawashima H, Ohashi T, Shiraishi H, Nakashima M, Saitsu H, Matsumoto N.
  • Journal Title: Brain Dev. Volume: 38 Issue: 7 Pages: 285-92
  • DOI: 10.1038/jhg.2016.27
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Somatic Mutations in the MTOR gene cause focal cortical dysplasia type IIb (2015)
  • Author(s): Nakashima M, Saitsu H, Takei N, Tohyama J, Kato M, Kitaura H, Shiina M, Shirozu H, Masuda H, Watanabe K, Ohba C, Tsurusaki Y, Miyake N, Zheng Y, Sato T, Takebayashi H, Ogata K, Kameyama S, Kakita A, Matsumoto N
  • Journal Title: Ann. Neurol. Volume: 78 Issue: 3 Pages: 375-386
  • DOI: 10.1002/ana.24444
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] De novo DNM1 mutations in two cases of epileptic encephalopathy. (2015)
  • Author(s): Nakashima M, Kouga T, Lourenço CM, Shiina M, Goto T, Tsurusaki Y, Miyatake S, Miyake N, Saitsu H, Ogata K, Osaka H, Matsumoto N.
  • Journal Title: Epilepsia Volume: Epub 2015 Nov 27. Issue: 1
  • DOI: 10.1111/epi.13257
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Presentation] 全エクソーム解析を用いた希少難治性てんかん1230例の包括的遺伝子解析 (2017)
  • Author(s): 中島光子
  • Organizer: 日本人類遺伝学会
• [Presentation] WDR45 mutations in three male patients with West syndrome. (2016)
  • Author(s): Nakashima M, Takano K, Tsuyusaki Y, Yoshitomi S, Shimono M, Aoki Y, Kato M, Aida N, Mizuguchi T, Miyatake S, Miyake N, Osaka H, Saitsu H, Matsumoto
  • Organizer: American Society of Human Genetics Annual Meeting 2016
  • Place of Presentation: Vancouver, Canada
  • Year and Date: 2016-10-18
  • Int'l Joint Research
• [Presentation] De novo DNM1 mutations in two cases of epileptic encephalopathy. (2016)
  • Author(s): Nakashima M, Kouga T, Lourenço CM, Shiina M, Goto T, Tsurusaki Y, Miyatake S, Miyake N, Saitsu H, Ogata K, Osaka H, Matsumoto N.
  • Organizer: The 13th International Congress of Human Genetics
  • Place of Presentation: 国立京都国際会館（京都府京都市）
  • Year and Date: 2016-04-03
  • Int'l Joint Research
• [Presentation] 限局性皮質異形成(FCD)IIb型におけるMTOR体細胞変異の同定． (2015)
  • Author(s): 中島光子
  • Organizer: 日本人類遺伝学会第60回大会
  • Place of Presentation: 京王プラザホテル、新宿、東京
  • Year and Date: 2015-10-14
• [Presentation] Somatic mutations in the MTOR gene cause focal cortical dysplasia Type IIb (2015)
  • Author(s): Mitsuko Nakashima
  • Organizer: merican Society of Human Genetics Annual Meeting 2015
  • Place of Presentation: Baltimore, MD, USA
  • Year and Date: 2015-10-06
  • Int'l Joint Research