July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Altered ubiquitin signaling in mammalian lens development causes metabolic and mitochondrial dysfunction leading to cataractogenesis
Author Affiliations & Notes
  • Sheldon Rowan
    Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts, United States
    Dept. Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts, United States
  • Elizabeth Whitcomb
    Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts, United States
  • Eloy Bejarano
    Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts, United States
  • Fu Shang
    Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts, United States
    Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
  • Ke Liu
    Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts, United States
    College of Life Science, Sichuan University, Chengdu, China
  • Rebecca L Pfeiffer
    Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
  • Roberto Calitri
    Dept. Developmental, Molecular & Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States
  • James D Baleja
    Dept. Developmental, Molecular & Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States
  • Bryan W Jones
    Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
  • Paul G FitzGerald
    Dept. Cell Biology and Human Anatomy, University of California - Davis, Davis, California, United States
  • Allen Taylor
    Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts, United States
    Dept. Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts, United States
  • Footnotes
    Commercial Relationships   Sheldon Rowan, None; Elizabeth Whitcomb, None; Eloy Bejarano, None; Fu Shang, None; Ke Liu, None; Rebecca Pfeiffer, None; Roberto Calitri, None; James Baleja, None; Bryan Jones, None; Paul FitzGerald, None; Allen Taylor, None
  • Footnotes
    Support  NIH Grant R01 EY026979, NIH Grant RO1 EY015128, USDA AFRI grant 2015-05470, USDA contract 1950-510000-060-03A from ARS, and BrightFocus Foundation
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 1383. doi:https://doi.org/
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    • Get Citation

      Sheldon Rowan, Elizabeth Whitcomb, Eloy Bejarano, Fu Shang, Ke Liu, Rebecca L Pfeiffer, Roberto Calitri, James D Baleja, Bryan W Jones, Paul G FitzGerald, Allen Taylor; Altered ubiquitin signaling in mammalian lens development causes metabolic and mitochondrial dysfunction leading to cataractogenesis. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1383. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Ubiquitin signaling participates in multiple critical functions in lens development and maintenance of lens transparency. Impaired ubiquitin signaling, via transgenic misexpression of a mutant ubiquitin protein (K6W-Ub) in the mouse, causes a severe congenital cataract, characterized by inappropriate calpain activation leading to altered calcium signaling, abrogation of lens fiber cell denucleation, and protein aggregation. We have undertaken a multiomics approach to evaluate the proteome and metabolome of K6W-Ub transgenic lenses to uncover the molecular mechanisms underlying cataractogenesis.

Methods : Lenses from E15.5, P1, or P30 K6W-Ub transgenic or WT littermates were analyzed via mass spectrometry to characterize the proteome. Computational molecular phenotyping (CMP) and 1H-NMR were utilized to characterize the metabolome. Mitochondrial function was ascertained ultrastructurally via electron microscopy and using inhibitor studies.

Results : Proteomic analysis revealed that K6W-Ub expression led to an increase in enzymes involved in glycolysis, citric acid cycle, and amino acid metabolism, including the rate-limiting enzyme PGK1. Spatial analysis of the P1 K6W-Ub metabolome via CMP revealed an increase in levels of alanine and decreases in levels of taurine, glutathione, and glutamine. Aspartate and cysteine had abnormal variegated levels. P1 K6W-Ub mitochondria were increased in number and had unusual swollen cristae. Inhibitor studies using the depolarizing drug FCCP indicated that K6W-Ub expressing human lens epithelial cells were more sensitive to FCCP than WT-Ub expressing cells.

Conclusions : Altered ubiquitin signaling appears to alter glycolytic and oxidative metabolism in the lens, which leads to abnormal build-up or depletion of key glycolytic amino acid precursors. Mitochondrial function is impaired. Altered function of K6 on Ub also appears to alter mitophagic removal of damaged mitochondria. These metabolic alterations may contribute to cataract development. Analysis of the metabolome of the K6W-Ub cataractous lens shows significant overlap with human cataract samples, as well as with the aging mouse lens. Together, our findings illuminate multiple roles of ubiquitin signaling in the lens that extend beyond proteolysis and that may be common signatures of cataractogenesis.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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