June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
NMNAT1-Associated Retinal Degeneration: Consequences of Reduced Nuclear NAD+ Production
Author Affiliations & Notes
  • Emily Brown
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Michael Scandura
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Sudeep Mehrotra
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Scott H Greenwald
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Daniela Pignatta
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Jianhai Du
    Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, United States
    Biochemistry, West Virginia University, Morgantown, West Virginia, United States
  • Eric A Pierce
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Footnotes
    Commercial Relationships   Emily Brown, None; Michael Scandura, None; Sudeep Mehrotra, None; Scott Greenwald, None; Daniela Pignatta, None; Jianhai Du, None; Eric Pierce, None
  • Footnotes
    Support  2R01EY012910-21
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 3060. doi:
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      Emily Brown, Michael Scandura, Sudeep Mehrotra, Scott H Greenwald, Daniela Pignatta, Jianhai Du, Eric A Pierce; NMNAT1-Associated Retinal Degeneration: Consequences of Reduced Nuclear NAD+ Production. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3060.

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

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Abstract

Purpose : NMNAT1 is expressed ubiquitously, but mutations in this gene lead to retina-specific disease. The molecular mechanisms underlying disease pathogenesis, and why the retina is uniquely affected by mutations in NMNAT1, are poorly understood. We used a mouse model of NMNAT1-mediated disease to address the hypothesis that reduced NMNAT1 enzymatic function results in nuclear NAD+ depletion and transcriptional alterations specifically in the retina.

Methods : RNAseq and metabolomic analyses were performed on retina and kidney tissue collected from mice with the p.Val9Met mutation in Nmnat1 (a model of NMNAT1-associated disease) and wild type (WT) littermate controls. Samples were collected at 2 and 3 weeks of age, which is prior to the onset of retinal degeneration that begins at about 4 weeks of age. Western blotting, IHC, and qRT-PCR were performed to further assess the alterations in gene and protein expression identified by RNAseq. All experiments were conducted in compliance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.

Results : Nmnat1V9M/V9M mice had a retina-specific reduction in the levels of NAD+ (P < 0.0001, unpaired t-test) that was not observed in other tissues, including the kidney, brain, skin, and heart. The kidney was used as a control tissue for RNAseq, and there were no differences in gene expression between WT and Nmnat1V9M/V9M kidney samples at 2 or 3 weeks of age. Although no differences in gene expression were detected in the neural retinas of 2-week-old mutant and WT mice, by 3 weeks of age there were over 2,600 differentially expressed genes in the retinas of Nmnat1V9M/V9M mice. These genes were enriched for immune pathways, phototransduction, apoptosis, and variety of other processes. Western blotting, qRT-PCR, and IHC were used to confirm the alteration in expression of several of the most highly significant genes, such as Gfap and Lad1.

Conclusions : These findings suggest that reduced NMNAT1 activity results in a retina-specific reduction in NAD+ and retina-specific transcriptional reprogramming prior to retinal degeneration. This includes increased expression of PARPs, the main nuclear consumer of NAD+, and other genes associated with DNA damage. Future work aims to further identify how mutations in NMNAT1 lead to this rapid alteration in gene expression and how these alterations contribute to retinal degeneration.

This is a 2021 ARVO Annual Meeting abstract.

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