June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Metabolic alterations caused by dysregulation of mitochondrial dynamics in RPE cells
Author Affiliations & Notes
  • Wei-Hua Lee
    Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States
  • Vijesh Bhute
    Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States
  • Sarah Lewis
    Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States
  • Hitoshi Higuchi
    Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States
  • Sakae Ikeda
    Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States
    McPherson Eye Research Institute, Madison, Wisconsin, United States
  • Sean P. Palecek
    Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States
  • Akihiro Ikeda
    Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States
    McPherson Eye Research Institute, Madison, Wisconsin, United States
  • Footnotes
    Commercial Relationships   Wei-Hua Lee, None; Vijesh Bhute, None; Sarah Lewis, None; Hitoshi Higuchi, None; Sakae Ikeda, None; Sean Palecek, None; Akihiro Ikeda, None
  • Footnotes
    Support  NIH Grant R01 EY022086 (Akihiro Ikeda), Retina Research Foundation Professorship (Akihiro Ikeda), WARF discovery challenge award (Wei-Hua Lee)
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 1604. doi:
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      Wei-Hua Lee, Vijesh Bhute, Sarah Lewis, Hitoshi Higuchi, Sakae Ikeda, Sean P. Palecek, Akihiro Ikeda; Metabolic alterations caused by dysregulation of mitochondrial dynamics in RPE cells. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1604.

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

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Abstract

Purpose : Mitochondria are highly dynamic organelles undergoing fusion, fission, and degradation. Although mitochondria are known to be essential for cellular metabolism, it is still unknown how mitochondrial dynamics affect cellular metabolism. We recently identified a mouse gene, transmembrane 135 (Tmem135), which regulates mitochondrial dynamics. Mice with mutant Tmem135 (Mut) show early-onset aging phenotypes and age-related pathologies in the retina including retinal pigment epithelium (RPE). In this study, we aim to identify novel metabolic changes in primary RPE cell cultures from Mut mice and transgenic (TG) mice overexpressing wild-type Tmem135 using nuclear magnetic resonance (NMR) spectroscopy.

Methods : The retinal phenotypes of mice were characterized using hematoxylin and eosin (H&E) staining, immunofluorescence, immunoelectron microscopy and western blotting. Primary RPE cells were isolated from 2-month-old male Mut mice, TG mice and wild-type (WT) mice and were prepared and used for NMR analysis. Forty-six metabolites were quantified in NMR. The concentration data table was processed for statistical analysis using MetaboAnalyst 3.0. One way analysis of variance was used with Tukey’s honest significant difference test for multiple hypothesis testing to identify significant features when comparing multiple conditions (FDR < 0.05).

Results : Histological analysis revealed RPE degeneration in TG mice at postnatal day 21. The thickness of outer nuclear layer was significantly less in TG compared to WT mice at 6 months of age (WT: N=8; TG: N=4). Bone spicule-like phenotype and invasion of blood vassals into the retina were also observed in 6-month-old TG mice. NMR-based metabolomics in primary RPE cells revealed several metabolic changes upon modulating Tmem135 in Mut and TG RPE cells including osmolytes, glucose metabolism, and phospholipid metabolism. A significant depletion of NAD+ was detected in both Mut and TG RPE cells.

Conclusions : Our findings indicate that dysregulation of mitochondrial fission and fusion affect multiple cellular metabolic pathways. Since NAD+ is required for both nuclear DNA damage repair and mitochondrial signaling, depletion of NAD+ suggests increased usage of NAD+ from the nuclear DNA repair and/or mitochondrial signaling. Alternatively, it may be due to decreased NAD+ synthesis.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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