Elucidation of the molecular mechanism how deficiency of deglycosylation in the cytosol causes abnormalities in organism.

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02926
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 38060:Applied molecular and cellular biology-related
• Research Institution: Tokyo Metropolitan Institute of Medical Science
• Principal Investigator: YOSHIDA Yukiko 公益財団法人東京都医学総合研究所, 基礎医科学研究分野, 主席研究員 (90271543)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: NGLY1 / F-boxタンパク質 / ユビキチンリガーゼ / 糖鎖 / タンパク質品質管理 / プロテアソーム

Outline of Final Research Achievements

Peptide:N-glycanase (NGLY1) is responsible for removing N-glycans from glycoprotein in the cytosol. Mutations in the human NGLY1 gene cause multisystemic symptoms, but the molecular mechanism underlying pathogenesis remains unknown. In mice, Ngly1 knockout (KO) is embryonic lethal. We found that deletion of Fbs2, which encodes a SCF-type ubiquitin ligase subunit that recognizes N-glycans, rescued the lethality and progressive defects in Ngly1-KO mice. In NGLY1-KO cells, Fbs2 expression caused cytotoxicity. Nrf1, an endoplasmic reticulum-associated transcriptional factor for the proteasome, was ubiquitinated by SCFFbs2 in NGLY1-KO cells, resulting in its retention in the cytosol. The cytotoxicity caused by Fbs2 expression was restored by overexpression of glycan-less Nrf1 mutations, or by the deletion of Nrf1 in NGLY1-KO cells. Thus, the proteasome dysfunction caused by accumulation of NRF1 ubiquitinated by SCFFbs2 causes cytotoxicity in NGLY1 deficiency.

Free Research Field

分子生物学

Academic Significance and Societal Importance of the Research Achievements

多くの多細胞生物において、細胞質でN型糖鎖を除去する酵素NGLY1遺伝子の不活化変異は様々な不具合を生じるが、その機序は不明であった。今回の研究成果は、細胞質における２つのN型糖鎖関連タンパク質NGLY1とFbs2の遺伝的相互作用に着目し、細胞質でNGLY1により糖鎖が除去されない場合にどのように個体に異常を引き起こすのか、その分子機構を明確に示した。
また、Fbs2がこれまで治療法のなかったヒト希少疾患NGLY1欠損症の有望な治療ターゲットとなり得ることを示した。