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Updated: Jan 24, 2026

Measurement of Protein Turnover Rates in Senescent and Non-Dividing Cultured Cells with Metabolic Labeling and Mass Spectrometry
Published on: April 6, 2022
Changes in MCM2-7 proteins at senescence
Yuka Suzuki1, Yukako Yamaguchi1, Hiroko Hanada1
1College of Science, Ibaraki University.
Abstract:
Cellular aging is characterized by the loss of DNA replication capability and is mainly brought about by various changes in chromatin structure. Here, we examined changes in MCM2-7 proteins, which act as a replicative DNA helicase, during aging of human WI38 fibroblasts at the single-cell level. We used nuclear accumulation of p21 as a marker of senescent cells, and examined changes in MCM2-7 by western blot analysis. First, we found that senescent cells are enriched for cells with a DNA content higher than 4N. Second, the levels of MCM2, MCM3, MCM4 and MCM6 proteins decreased in senescent cells. Third, cytoplasmic localization of MCM2 and MCM7 was observed in senescent cells, from an analysis of MCM2-7 except for MCM5. Consistent with this finding, fragmented MCM2 was predominant in these cells. These age-dependent changes in MCM2-7, a protein complex that directly affects cellular DNA replication, may play a critical role in cellular senescence.
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