Long-lived metabolic enzymes in the crystalline lens identified by pulse-labeling of mice and mass spectrometry

Pan Liu, Seby Louis Edassery, Laith Ali, Benjamin R. Thomson, Jeffrey N. Savas*, Jing Jin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The lenticular fiber cells are comprised of extremely long-lived proteins while still maintaining an active biochemical state. Dysregulation of these activities has been implicated in diseases such as age-related cataracts. However, the lenticular protein dynamics underlying health and disease is unclear. We sought to measure the global protein turnover rates in the eye using nitrogen-15 labeling of mice and mass spectrometry. We measured the14N/15N-peptide ratios of 248 lens proteins, including Crystallin, Aquaporin, Collagen and enzymes that catalyze glycolysis and oxidation/reduction reactions. Direct comparison of lens cortex versus nucleus revealed little or no15N-protein contents in most nuclear proteins, while there were a broad range of14N/15N ratios in cortex proteins. Unexpectedly, like Crystallins, many enzymes with relatively high abundance in nucleus were also exceedingly long-lived. The slow replacement of these enzymes in spite of young age of mice suggests their potential roles in age-related metabolic changes in the lens.

Original languageEnglish (US)
Article numbere50170
JournaleLife
Volume8
DOIs
StatePublished - Dec 2019

Funding

We are grateful to Dr. Amani Fawzi for her suggestions to the study, and Dr. Hongwen Zhou for assisting data analysis. This study was supported by National Institutes of Health (R01AG061787, to JNS, and R01EY025799 and R21AI131087, to JJ).

ASJC Scopus subject areas

  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology
  • General Neuroscience

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