May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
Expression and Localization of Cytochrome 46A1 in Monkey Retina
J. W. Lee; N. Mast; I. Pascual; N. Tserentsoodol; N. B. Javitt; I. A. Pikuleva; N. Gordiyenko; I. R. Rodriguez
Author Affiliations & Notes
  • J. W. Lee
    Mechanism of Retinal Diseases Section/LRCMB, NEI - NIH, Bethesda, Maryland
  • N. Mast
    Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas
  • I. Pascual
    Mechanism of Retinal Diseases Section/LRCMB, NEI - NIH, Bethesda, Maryland
  • N. Tserentsoodol
    Mechanism of Retinal Diseases Section/LRCMB, NEI - NIH, Bethesda, Maryland
  • N. B. Javitt
    Divisions of Gastroenterology, New York University Medical Center, New York, New York
  • I. A. Pikuleva
    Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas
  • N. Gordiyenko
    Mechanism of Retinal Diseases Section/LRCMB, NEI - NIH, Bethesda, Maryland
  • I. R. Rodriguez
    Mechanism of Retinal Diseases Section/LRCMB, NEI - NIH, Bethesda, Maryland
  • Footnotes
    Commercial Relationships J.W. Lee, None; N. Mast, None; I. Pascual, None; N. Tserentsoodol, None; N.B. Javitt, None; I.A. Pikuleva, None; N. Gordiyenko, None; I.R. Rodriguez, None.
  • Footnotes
    Support NEI intramural research program
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 58. doi:
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      J. W. Lee, N. Mast, I. Pascual, N. Tserentsoodol, N. B. Javitt, I. A. Pikuleva, N. Gordiyenko, I. R. Rodriguez; Expression and Localization of Cytochrome 46A1 in Monkey Retina. Invest. Ophthalmol. Vis. Sci. 2007;48(13):58.

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Abstract

Purpose:: Cytochrome P450 46A1 (CYP46A1) is known to be a brain-selective sterol hydroxylase that converts cholesterol to 24-hydroxycholesterol for the purpose of maintaining cholesterol homeostasis. The purpose of this study is to demonstrate the expression and localization of CYP46A1 in the monkey retina and to learn about its potential function in the retina.

Methods:: CYP46A1 protein and mRNA expression were measured in monkey retina and cultured RPE cells by immunoblot analyses and real time RT-PCR. CYP46A1 localization was performed by immunohistochemistry and imaged by confocal microscopy. Subcellular localization was performed by co-transfection of ARPE19 cells with a CYP46A1-GFP construct and pDsRed2 cellular organelle markers. Monkey retina lipids were extracted and analyzed by GC-MS.

Results:: Immunoblot analyses detected a significant presence of CYP46A1 enzyme in the monkey retina. Semi-quantitative RT-PCR detected mRNA levels in the retina that were approximately one fifth of those found in the brain. CYP46A1 localized mainly to the photoreceptors outer segments, especially the cones outer segments and synaptic pedicles. Immunoreactivity was also observed in the ganglion cell layer (GCL), RPE and choriocapillaris. CYP46A1-GFP expression in transiently transfected cells localized mainly to the ER but also to the mitochondria. Small amounts of 24-hydroxycholesterol were identified as a TMS derivative by GC-MS in the monkey retina extracts.

Conclusions:: CYP46A1 is highly expressed in the photoreceptors, especially the cones outer segments and synaptic pedicles. The localization to cone synaptic pedicles supports the partial mitochondrial localization observed in the transfected ARPE19 cells. The detection of 24-hydroxycholesterol supports its potential function in maintaining cholesterol homeostasis. However, its localization in the photoreceptor outer segments and synaptic pedicles hints at alternative functions.

Keywords: retina • lipids • mitochondria 
© 2007, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2024 Association for Research in Vision and Ophthalmology.
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