ASPM ノックアウトフレットは,脳皮質の大きさを制御する進化的メカニズムを明らかにします
Matthew B Johnson1,2, Xingshen Sun3,4,5, Andrew Kodani1,2
1Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
Nature
|April 13, 2018
まとめ
フレットにおける異常なスパインドル型小頭症関連 (ASPM) 遺伝子喪失は小頭症を引き起こし,神経原始細胞の行動を制御することによって人間の脳サイズと折り畳みを調節する役割を明らかにします.
科学分野:
- 進化生物学
- 神経科学
- 遺伝学
背景:
- 人間の脳皮質は大きさと複雑な折りたたみ (ガイリフィケーション) が特徴です.
- 皮質の膨張を促す進化的メカニズムは ほとんど不明です
- ネズミの研究は,脳構造と遺伝子機能の種別差異により,人間の皮質の発達に関する限られた洞察をもたらしました.
研究 の 目的:
- 脳皮質の大きさと構造を調節する異常なスパインドル型小頭症関連遺伝子 (ASPM) の進化的役割を調査する.
- 脳の発達におけるASPMの機能の基礎となる細胞メカニズムを理解する.
- 渦巻状の皮質を持つモデル生物を用いてASPMの機能を探求し,人間のASPMに近い同質性を持つ.
主な方法:
- ゲノム編集は,フレット (Mustela putorius furo) のアスプム遺伝子の生殖系ノックアウトを作成するために使用されました.
- 脳の重量,皮質の表面積,および厚さに焦点を当てたASPMノックアウトフレットの表型分析.
- 胎児フェレット皮質の発達,特に神経原細胞の行動と分布の顕微鏡検査.
主要な成果:
- ASPMノックアウトフェレットは重度の小頭症を示し,脳の重量と皮質表面積が著しく減少し,人間の小頭症を反映した.
- 腹腔内半球細胞の早急な移転が腹腔外半球領域に顕著に増加した.
- これらの移転した細胞は外側の放射性状腺に似ており,霊長類の皮質の膨張に絡み合っているが,マウスでは存在しない.
結論:
- ASPMは,大脳皮質の膨張を調節する上で重要な役割を果たし,おそらくは,心室表面と放射性膠質細胞の相互作用を制御する.
- この調節は,異なる神経原細胞集団間のバランスを調節し",皮質単位"の生成に影響を与えます.
- この発見は,原始細胞のダイナミクスに対するASPMの制御を含む人間の脳サイズ増加の進化的メカニズムを示唆しています.
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