ジャーナル: Proc Natl Acad Sci U S A / 年: 2024 タイトル: Temporal control of acute protein aggregate turnover by UBE3C and NRF1-dependent proteasomal pathways. 著者: Kelsey L Hickey / Alexandra Panov / Enya Miguel Whelan / Tillman Schäfer / Arda Mizrak / Ron R Kopito / Wolfgang Baumeister / Rubén Fernández-Busnadiego / J Wade Harper / 要旨: A hallmark of neurodegenerative diseases (NDs) is the progressive loss of proteostasis, leading to the accumulation of misfolded proteins or protein aggregates, with subsequent cytotoxicity. To ...A hallmark of neurodegenerative diseases (NDs) is the progressive loss of proteostasis, leading to the accumulation of misfolded proteins or protein aggregates, with subsequent cytotoxicity. To combat this toxicity, cells have evolved degradation pathways (ubiquitin-proteasome system and autophagy) that detect and degrade misfolded proteins. However, studying the underlying cellular pathways and mechanisms has remained a challenge, as formation of many types of protein aggregates is asynchronous, with individual cells displaying distinct kinetics, thereby hindering rigorous time-course studies. Here, we merge a kinetically tractable and synchronous agDD-GFP system for aggregate formation with targeted gene knockdowns, to uncover degradation mechanisms used in response to acute aggregate formation. We find that agDD-GFP forms amorphous aggregates by cryo-electron tomography at both early and late stages of aggregate formation. Aggregate turnover occurs in a proteasome-dependent mechanism in a manner that is dictated by cellular aggregate burden, with no evidence of the involvement of autophagy. Lower levels of misfolded agDD-GFP, enriched in oligomers, utilizes UBE3C-dependent proteasomal degradation in a pathway that is independent of RPN13 ubiquitylation by UBE3C. Higher aggregate burden activates the NRF1 transcription factor to increase proteasome subunit transcription and subsequent degradation capacity of cells. Loss or gain of NRF1 function alters the turnover of agDD-GFP under conditions of high aggregate burden. Together, these results define the role of UBE3C in degradation of this class of misfolded aggregation-prone proteins and reveals a role for NRF1 in proteostasis control in response to widespread protein aggregation.
A: 15627.5205 Å / B: 15627.5205 Å / C: 4210.0 Å α=β=γ: 90.0 °
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添付データ
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試料の構成要素
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全体 : Aggregate in AgDD-sfGFP-expressing HEK293 cell 10 min post aggreg...
全体
名称: Aggregate in AgDD-sfGFP-expressing HEK293 cell 10 min post aggregation induction
要素
細胞: Aggregate in AgDD-sfGFP-expressing HEK293 cell 10 min post aggregation induction
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超分子 #1: Aggregate in AgDD-sfGFP-expressing HEK293 cell 10 min post aggreg...
超分子
名称: Aggregate in AgDD-sfGFP-expressing HEK293 cell 10 min post aggregation induction タイプ: cell / ID: 1 / 親要素: 0
由来(天然)
生物種: Homo sapiens (ヒト)
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実験情報
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構造解析
手法
クライオ電子顕微鏡法
解析
電子線トモグラフィー法
試料の集合状態
cell
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試料調製
緩衝液
pH: 7
凍結
凍結剤: ETHANE-PROPANE
Cryo protectant
10 % glycerol
切片作成
集束イオンビーム - 装置: OTHER / 集束イオンビーム - イオン: OTHER / 集束イオンビーム - 電圧: 30 / 集束イオンビーム - 電流: 0.1 / 集束イオンビーム - 時間: 300 / 集束イオンビーム - 温度: 77 K / 集束イオンビーム - Initial thickness: 250 / 集束イオンビーム - 最終 厚さ: 200 集束イオンビーム - 詳細: The value given for _em_focused_ion_beam.instrument is FEI Quanta FIB. This is not in a list of allowed values {'OTHER', 'DB235'} so OTHER is written into the XML file.
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
特殊光学系
位相板: VOLTA PHASE PLATE
撮影
フィルム・検出器のモデル: GATAN K2 SUMMIT (4k x 4k) 平均電子線量: 1.1 e/Å2