<p>Many physicochemical properties in the cellular milieu are important for cell function and survival. However, the polarity of different subcellular compartments and its role in protein condensate and aggregate formation within cells are less characterized. Here, we develop a method to compare the polarity in different subcellular compartments using the same polarity-sensitive solvatochromic fluorescent probe. Unexpectedly, the endoplasmic reticulum (ER) lumen displays a higher polarity and a more crowded environment than the cytosol in human cells. Polarity-decreasing and crowding-increasing hypertonic conditions induce condensate or aggregate formation of two intrinsically disordered proteins, with-no-lysine kinase 1 and Huntingtin gene (Htt) exon1 with an expanded polyQ stretch (Htt-polyQ), in the cytosol. However, targeting Htt-polyQ to the ER prevents its aggregation, suggesting that polarity but not crowding is more relevant to protein aggregation. Our results reveal the heterogeneity in subcellular polarity and crowding, and uncover previously unrecognized high-polarity in the ER lumen, which provides a unique environment for maintaining robust proteostasis.</p><p></p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

The endoplasmic reticulum displays high polarity with low protein aggregation in human cells

  • Xinwei Hu,
  • Junlin Chen,
  • Ping Liu,
  • Huaiyue Zhang,
  • Yu Liu,
  • Xin Zhang,
  • Lei Wang

摘要

Many physicochemical properties in the cellular milieu are important for cell function and survival. However, the polarity of different subcellular compartments and its role in protein condensate and aggregate formation within cells are less characterized. Here, we develop a method to compare the polarity in different subcellular compartments using the same polarity-sensitive solvatochromic fluorescent probe. Unexpectedly, the endoplasmic reticulum (ER) lumen displays a higher polarity and a more crowded environment than the cytosol in human cells. Polarity-decreasing and crowding-increasing hypertonic conditions induce condensate or aggregate formation of two intrinsically disordered proteins, with-no-lysine kinase 1 and Huntingtin gene (Htt) exon1 with an expanded polyQ stretch (Htt-polyQ), in the cytosol. However, targeting Htt-polyQ to the ER prevents its aggregation, suggesting that polarity but not crowding is more relevant to protein aggregation. Our results reveal the heterogeneity in subcellular polarity and crowding, and uncover previously unrecognized high-polarity in the ER lumen, which provides a unique environment for maintaining robust proteostasis.