Retinal ganglion cell loss and mild vasculopathy in methylene tetrahydrofolate reductase (Mthfr)-deficient mice: A model of mild hyperhomocysteinemia

Shanu Markand, Alan B Saul, Penny Roon, Puttur D Prasad, Pamela Moore Martin, Rima Rozen, Vadivel Ganapathy, Sylvia B Smith

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

PURPOSE. Methylenetetrahydrofolate reductase (Mthfr) is a key enzyme in homocysteinemethionine metabolism. We investigated Mthfr expression in retina and asked whether mild hyperhomocysteinemia, due to Mthfr deficiency, alters retinal neurovascular structure and function. METHODS. Expression of Mthfr was investigated at the gene and protein level using quantitative (q) RT-PCR, in situ hybridization, immunoblotting, and immunohistochemistry (IHC). The Mthfr+/- and Mthfr+/- mice were subjected to comprehensive evaluation using ERG, funduscopy, fluorescein angiography (FA), spectral-domain optical coherence tomography (SD-OCT), HPLC, and morphometric and IHC analysis of glial fibrillary acidic protein (GFAP) at 8 to 24 weeks. RESULTS. Gene and protein analyses disclosed widespread retinal expression of Mthfr. Electroretinography (ERG) revealed a significant decrease in positive scotopic threshold response in retinas of Mthfr+/- mice at 24 weeks. Fundus examination in mice from both groups was normal; FA revealed areas of focal vascular leakage in 20% of Mthfr+/- mice at 12 to 16 weeks and 60% by 24 weeks. The SD-OCT revealed a significant decrease in nerve fiber layer (NFL) thickness at 24 weeks in Mthfr+/- compared to Mthfr +/- mice. There was a 2-fold elevation in retinal hcy at 24 weeks in Mthfr+/- mice by HPLC and IHC. Morphometric analysis revealed an approximately 20% reduction in cells in the ganglion cell layer of Mthfr+/-mice at 24 weeks. The IHC indicated significantly increased GFAP labeling suggestive of Müller cell activation. CONCLUSIONS. Mildly hyperhomocysteinemic Mthfr+/- mice demonstrate reduced ganglion cell function, thinner NFL, and mild vasculopathy by 24 weeks. The retinal phenotype is similar to that of hyperhomocysteinemic mice with deficiency of cystathionine-b-synthase (Cbs) reported earlier. The data support the hypothesis that hyperhomocysteinemia may be causative in certain retinal neurovasculopathies.

Original languageEnglish (US)
Pages (from-to)2684-2695
Number of pages12
JournalInvestigative Ophthalmology and Visual Science
Volume56
Issue number4
DOIs
StatePublished - Jan 1 2015

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Methylenetetrahydrofolate Reductase (NADPH2)
Hyperhomocysteinemia
Retinal Ganglion Cells
Immunohistochemistry
Electroretinography
Fluorescein Angiography
Glial Fibrillary Acidic Protein
Optical Coherence Tomography
Nerve Fibers
Ganglia
Retina
High Pressure Liquid Chromatography
Cystathionine
Immunoblotting

Keywords

  • ERG
  • Homocysteine
  • Methylation pathway
  • Mouse
  • Retina
  • Retinal degeneration

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

@article{cc8788c16a5c416684cc0bcf5031429c,
title = "Retinal ganglion cell loss and mild vasculopathy in methylene tetrahydrofolate reductase (Mthfr)-deficient mice: A model of mild hyperhomocysteinemia",
abstract = "PURPOSE. Methylenetetrahydrofolate reductase (Mthfr) is a key enzyme in homocysteinemethionine metabolism. We investigated Mthfr expression in retina and asked whether mild hyperhomocysteinemia, due to Mthfr deficiency, alters retinal neurovascular structure and function. METHODS. Expression of Mthfr was investigated at the gene and protein level using quantitative (q) RT-PCR, in situ hybridization, immunoblotting, and immunohistochemistry (IHC). The Mthfr+/- and Mthfr+/- mice were subjected to comprehensive evaluation using ERG, funduscopy, fluorescein angiography (FA), spectral-domain optical coherence tomography (SD-OCT), HPLC, and morphometric and IHC analysis of glial fibrillary acidic protein (GFAP) at 8 to 24 weeks. RESULTS. Gene and protein analyses disclosed widespread retinal expression of Mthfr. Electroretinography (ERG) revealed a significant decrease in positive scotopic threshold response in retinas of Mthfr+/- mice at 24 weeks. Fundus examination in mice from both groups was normal; FA revealed areas of focal vascular leakage in 20{\%} of Mthfr+/- mice at 12 to 16 weeks and 60{\%} by 24 weeks. The SD-OCT revealed a significant decrease in nerve fiber layer (NFL) thickness at 24 weeks in Mthfr+/- compared to Mthfr +/- mice. There was a 2-fold elevation in retinal hcy at 24 weeks in Mthfr+/- mice by HPLC and IHC. Morphometric analysis revealed an approximately 20{\%} reduction in cells in the ganglion cell layer of Mthfr+/-mice at 24 weeks. The IHC indicated significantly increased GFAP labeling suggestive of M{\"u}ller cell activation. CONCLUSIONS. Mildly hyperhomocysteinemic Mthfr+/- mice demonstrate reduced ganglion cell function, thinner NFL, and mild vasculopathy by 24 weeks. The retinal phenotype is similar to that of hyperhomocysteinemic mice with deficiency of cystathionine-b-synthase (Cbs) reported earlier. The data support the hypothesis that hyperhomocysteinemia may be causative in certain retinal neurovasculopathies.",
keywords = "ERG, Homocysteine, Methylation pathway, Mouse, Retina, Retinal degeneration",
author = "Shanu Markand and Saul, {Alan B} and Penny Roon and Prasad, {Puttur D} and Martin, {Pamela Moore} and Rima Rozen and Vadivel Ganapathy and Smith, {Sylvia B}",
year = "2015",
month = "1",
day = "1",
doi = "10.1167/iovs.14-16190",
language = "English (US)",
volume = "56",
pages = "2684--2695",
journal = "Investigative Ophthalmology and Visual Science",
issn = "0146-0404",
publisher = "Association for Research in Vision and Ophthalmology Inc.",
number = "4",

}

TY - JOUR

T1 - Retinal ganglion cell loss and mild vasculopathy in methylene tetrahydrofolate reductase (Mthfr)-deficient mice

T2 - A model of mild hyperhomocysteinemia

AU - Markand, Shanu

AU - Saul, Alan B

AU - Roon, Penny

AU - Prasad, Puttur D

AU - Martin, Pamela Moore

AU - Rozen, Rima

AU - Ganapathy, Vadivel

AU - Smith, Sylvia B

PY - 2015/1/1

Y1 - 2015/1/1

N2 - PURPOSE. Methylenetetrahydrofolate reductase (Mthfr) is a key enzyme in homocysteinemethionine metabolism. We investigated Mthfr expression in retina and asked whether mild hyperhomocysteinemia, due to Mthfr deficiency, alters retinal neurovascular structure and function. METHODS. Expression of Mthfr was investigated at the gene and protein level using quantitative (q) RT-PCR, in situ hybridization, immunoblotting, and immunohistochemistry (IHC). The Mthfr+/- and Mthfr+/- mice were subjected to comprehensive evaluation using ERG, funduscopy, fluorescein angiography (FA), spectral-domain optical coherence tomography (SD-OCT), HPLC, and morphometric and IHC analysis of glial fibrillary acidic protein (GFAP) at 8 to 24 weeks. RESULTS. Gene and protein analyses disclosed widespread retinal expression of Mthfr. Electroretinography (ERG) revealed a significant decrease in positive scotopic threshold response in retinas of Mthfr+/- mice at 24 weeks. Fundus examination in mice from both groups was normal; FA revealed areas of focal vascular leakage in 20% of Mthfr+/- mice at 12 to 16 weeks and 60% by 24 weeks. The SD-OCT revealed a significant decrease in nerve fiber layer (NFL) thickness at 24 weeks in Mthfr+/- compared to Mthfr +/- mice. There was a 2-fold elevation in retinal hcy at 24 weeks in Mthfr+/- mice by HPLC and IHC. Morphometric analysis revealed an approximately 20% reduction in cells in the ganglion cell layer of Mthfr+/-mice at 24 weeks. The IHC indicated significantly increased GFAP labeling suggestive of Müller cell activation. CONCLUSIONS. Mildly hyperhomocysteinemic Mthfr+/- mice demonstrate reduced ganglion cell function, thinner NFL, and mild vasculopathy by 24 weeks. The retinal phenotype is similar to that of hyperhomocysteinemic mice with deficiency of cystathionine-b-synthase (Cbs) reported earlier. The data support the hypothesis that hyperhomocysteinemia may be causative in certain retinal neurovasculopathies.

AB - PURPOSE. Methylenetetrahydrofolate reductase (Mthfr) is a key enzyme in homocysteinemethionine metabolism. We investigated Mthfr expression in retina and asked whether mild hyperhomocysteinemia, due to Mthfr deficiency, alters retinal neurovascular structure and function. METHODS. Expression of Mthfr was investigated at the gene and protein level using quantitative (q) RT-PCR, in situ hybridization, immunoblotting, and immunohistochemistry (IHC). The Mthfr+/- and Mthfr+/- mice were subjected to comprehensive evaluation using ERG, funduscopy, fluorescein angiography (FA), spectral-domain optical coherence tomography (SD-OCT), HPLC, and morphometric and IHC analysis of glial fibrillary acidic protein (GFAP) at 8 to 24 weeks. RESULTS. Gene and protein analyses disclosed widespread retinal expression of Mthfr. Electroretinography (ERG) revealed a significant decrease in positive scotopic threshold response in retinas of Mthfr+/- mice at 24 weeks. Fundus examination in mice from both groups was normal; FA revealed areas of focal vascular leakage in 20% of Mthfr+/- mice at 12 to 16 weeks and 60% by 24 weeks. The SD-OCT revealed a significant decrease in nerve fiber layer (NFL) thickness at 24 weeks in Mthfr+/- compared to Mthfr +/- mice. There was a 2-fold elevation in retinal hcy at 24 weeks in Mthfr+/- mice by HPLC and IHC. Morphometric analysis revealed an approximately 20% reduction in cells in the ganglion cell layer of Mthfr+/-mice at 24 weeks. The IHC indicated significantly increased GFAP labeling suggestive of Müller cell activation. CONCLUSIONS. Mildly hyperhomocysteinemic Mthfr+/- mice demonstrate reduced ganglion cell function, thinner NFL, and mild vasculopathy by 24 weeks. The retinal phenotype is similar to that of hyperhomocysteinemic mice with deficiency of cystathionine-b-synthase (Cbs) reported earlier. The data support the hypothesis that hyperhomocysteinemia may be causative in certain retinal neurovasculopathies.

KW - ERG

KW - Homocysteine

KW - Methylation pathway

KW - Mouse

KW - Retina

KW - Retinal degeneration

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U2 - 10.1167/iovs.14-16190

DO - 10.1167/iovs.14-16190

M3 - Article

C2 - 25766590

AN - SCOPUS:84939485655

VL - 56

SP - 2684

EP - 2695

JO - Investigative Ophthalmology and Visual Science

JF - Investigative Ophthalmology and Visual Science

SN - 0146-0404

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ER -