Proteome Remodeling of the Eye Lens at 50 Years Identified With Data-Independent Acquisition

• Published in: Molecular & cellular proteomics Vol. 22; no. 1; p. 100453
• Main Authors: Cantrell, Lee S., Gletten, Romell B., Schey, Kevin L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-01-2023; American Society for Biochemistry and Molecular Biology
• Subjects: aging; Antioxidants - metabolism; Cataract - metabolism; data-independent acquisition; deamidation; Humans; lens; Lens, Crystalline - chemistry; Lens, Crystalline - metabolism; long-lived proteins; Proteome - metabolism; DDA; PTM; MRP; SLC; lens; deamidation; FDR; OAT3; NaDC3; UPS; AQP0/1/5; DIA; PC1; 4F2; MS; SVCT2; GO; Na/K; data-independent acquisition; EAAT; PCA; TEAB; TMM; long-lived proteins; ARNC; PSEA; aging; MCS; DIA-NN
• ISSN: 1535-9476; 1535-9484; 1535-9484
• DOI: 10.1016/j.mcpro.2022.100453

The eye lens is responsible for focusing and transmitting light to the retina. The lens does this in the absence of organelles, yet maintains transparency for at least 5 decades before onset of age-related nuclear cataract (ARNC). It is hypothesized that oxidative stress contributes significantly to ARNC formation. It is in addition hypothesized that transparency is maintained by a microcirculation system that delivers antioxidants to the lens nucleus and exports small molecule waste. Common data-dependent acquisition methods are hindered by dynamic range of lens protein expression and provide limited context to age-related changes in the lens. In this study, we utilized data-independent acquisition mass spectrometry to analyze the urea-insoluble membrane protein fractions of 16 human lenses subdivided into three spatially distinct lens regions to characterize age-related changes, particularly concerning the lens microcirculation system and oxidative stress response. In this pilot cohort, we measured 4788 distinct protein groups, 46,681 peptides, and 7592 deamidated sequences, more than in any previous human lens data-dependent acquisition approach. Principally, we demonstrate that a significant proteome remodeling event occurs at approximately 50 years of age, resulting in metabolic preference for anaerobic glycolysis established with organelle degradation, decreased abundance of protein networks involved in calcium-dependent cell–cell contacts while retaining networks related to oxidative stress response. Furthermore, we identified multiple antioxidant transporter proteins not previously detected in the human lens and describe their spatiotemporal and age-related abundance changes. Finally, we demonstrate that aquaporin-5, among other proteins, is modified with age by post-translational modifications including deamidation and truncation. We suggest that the continued accumulation of each of these age-related outcomes in proteome remodeling contribute to decreased fiber cell permeability and result in ARNC formation.
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•The human lens proteome undergoes remodeling with age, appearing at 50 years.•Gap junctions and aquaporins are truncated or otherwise modified with age.•SLC24A2 was identified as a calcium transporter significantly modified with age.•Measurement offers insights toward lens microcirculation and oxidative homeostasis.
The lens microcirculation system is essential for maintenance of lens transparency. To evaluate maintenance of the microcirculatory system, we measured three developmentally distinct fiber cell populations within 16 human lenses of increasing age. Using data-independent acquisition, we identified a proteome remodeling event that occurs at approximately 50 years of age. Age-modified proteins included gap junctions, a calcium transporter, aquaporin-5, and oxidative stress response–related proteins. Remodeling may result in calcium-activated protease activity and disruption of the microcirculation system.