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Home » NEI Laboratories » Laboratory of Retinal Cell and Molecular Biology » Mechanisms of Retinal Diseases Section

Mechanisms of Retinal Diseases Section

Current Research

Our laboratory is focused on determining the pathogenesis mechanism(s) of age related macular degeneration (AMD). AMD is a complex disease that involves the aging process but is mediated by multiple genetic and environmental factors. The choriocapillaris and Bruch's membrane are known to gradually accumulate LDL-cholesterol as a process of aging. Since these are the tissues most likely involved in the pathogenesis of AMD, we are studying the possible biochemical implications of this age-related accumulation. Our hypothesis is that these LDL deposits are likely to interfere with the permeability of Bruch's membrane and their oxidation could expose the RPE, with its numerous lipoprotein receptors, to the cytotoxic effect of the oxidized cholesterols. The internalization of the oxidized LDL by the RPE may induce a gradual loss of function and cytotoxicity. Another significant problem associated with the accumulation of LDL is the involvement the immune system. The combination of the RPE cytotoxicity and immune system involvement may initiate the early symptoms of AMD (e.g. drusen deposits, loss of pigmentation). Once these processes begin they may eventually involve other pathways leading to choroidal neovacularization and photoreceptor degeneration. Although the age-related factors may initiate the pathogenesis of AMD, the severity and age of onset are likely due to subtle genetic and/or environmental factors.

Oxysterols are known to induce potent pharmacological effects on different cell types and we are interested in understanding the cytotoxicity mechanism in RPE cells. We have tested several different oxysterols naturally found in oxidized LDL and found them to induce cell death in the cultured RPE cells. We find that cultured RPE cells are also highly susceptible to oxidized LDL. Although apoptosis has been reported as the mode of cell death in oxysterol cytotoxicity, all of our analyses thus far suggest that the death of the cultured RPE cells is unrelated to apoptosis. In order to better understand the mechanism(s) of oxysterol action we are studying proteins that bind oxysterols. We have discovered and characterized a family of 12 different oxysterol binding proteins (OSBPs) that are highly conserved and have different tissue expression and oxysterol binding characteristics. The OSBPs in general have two distinct domains, the oxysterol binding domain towards the C-terminus and a pleckstrin homology domain (PH) towards the N-terminus. The PH domains are known to interact with phosphoinositols and other membrane components and seem to target proteins to different cellular organelles. We are in the process of studying their intracellular targeting using GFP fusion constructs containing whole or portions of several selected OSBPs. We are also constructing several RPE cell lines overexpressing some of the OSBPs to determine if this overexpression leads to protection or sensitivity to oxysterol cytotoxicity. Using commercially available and custom microarrays we are examining changes in gene expression in response to oxysterol and oxidized LDL exposure in the cultured RPE cells. We have also identified by co-immunoprecipitation with specific antibodies several proteins that may be interacting with these OSBPs.

We hope to elucidate the relationship between oxysterol cytotoxicity and OSBP function and to determine if this mechanism is related to the pathogenesis of AMD.

Staff

Name Title E-Mail
Ignacio Rodriguez
PubMed Aurhor Search		 Section Chief Ignacio@helix.nih.gov
Shahaabuddin Alam IRTA Fellow alams@intra.nei.nih.gov
Nataliya Gordiyenko IRTA Fellow gordiyenko@nei.nih.gov
Jung Wha Lee Staff Scientist leej@nei.nih.gov

Selected Publications

  1. Provencio, I., Rodriguez, I.R., Jian, G., Hayes, P.W., Moreira, E.F., and Rollag, M.D. A novel human opsin in the retina. J. Neuroscience 20:600-605, 2000

  2. Acharya, S., Foletta, V.C., Lee, J.W., Rayborn, M.E., Rodriguez, I.R., Young, III W.Y. and Hollyfield, J.G. SPACRCAN, a novel human interphotoreceptor matrix hyaluronan binding proteoglycan synthesized by photoreceptors and pinealocytes. J. Biol. Chem. 275: 6945-6955, 2000

  3. Rodriguez, I.R., Moreira, E.F., Bok, D. and Kantorow. Osteonectin/SPARC is secreted by the RPE and localized to the outer plexiform layer of the monkey retina. Invest. Ophthalmol. & Vis. Sci. 41(9):2438-2444, 2000

  4. Lee, Jung W., Chen, Q., Rayborn, M.E., Shadrach, K.G., Crabb, J.W., Rodriguez, I.R., and Hollyfield, J.G. SPACR in the interphotoreceptor matrix of the mouse retina: molecular, biochemical and immunohistochemical characterization. Exp Eye Res. 71(4):341-52, 2000

  5. Hollyfield, J.G., Rayborn, M.E., Nishiyama, K., Shadrach, K.G., Miyagi, M., Crabb, J.W. and Rodriguez, I.R. Interphotoreceptor matrix in the fovea and peripheral retina of the primate Macaca mulatta: distributiom and glycoforms of SPACR and SPACRCAN. Exp. Eye Res. 72:49-61, 2001

  6. Moreira, E.F., Jaworski, C., Li, A. and Rodriguez, I.R. Molecular and biochemical characterization of a novel oxysterol binding protein (OSBP2) highly expressed in retina. J. Biol. Chem 276: 18570-18578, 2001

  7. Jaworski, C.J. , Moreira, E.F., Li, A., Lee, R., and Rodriguez, I.R. Family of twelve genes containing oxysterol-binding domains in the human genome. Genomics 78(3):185-196, 2001

Recent abstracts

  1. E.F. Moreira, C. Jaworski, J. W. Lee and I.R. Rodriguez. Cloning of a novel retina specific oxysterol binding protein (OSBP2). (2000) IOVS, 4680

  2. The cytotoxic effects of oxysterols on retinal pigmented epithelial cells. E.L. Posey-Marcos and I.R. Rodriguez. (2000) IOVS, 592

  3. Bioinformatics and data mining reveal a multi-gene family of oxysterol binding proteins: cDNA sequence and characterization of two novel members, OSBP-5 and OSBP-8. Jaworski, C.J., Moreira, E.F., and Rodriguez, I.R. (2000) IOVS, 4681

  4. Localization of sparc to the outer plexiform layer of the monkey retina and secretion by the macular RPE. I.R. Rodriguez, E.F. Moreira, E.H. Sage and M. Kantorow. (2000) IOVS, 3258

  5. SPACR in the IPM: a glycoprotein in human and a proteoglycan in mice. J.W. Lee, Q. Chen, M.E. Rayborn, J.W. Crabb, J.G. Hollyfield, and I.R. Rodríguez. (2000) IOVS, 4661

  6. SPACRCAN: a novel hyaluronan binding proteoglycan present in the IPM and pineal gland. J.G. Hollyfield, V.C. Foletta, S. Acharya, M.E. Rayborn, J.W. Lee, I.R. Rodriguez, and W.S. Young. (2000) IOVS, 4662

  7. SPACR and SPACRCAN in the primate, macaca mulatta. K.G. Shadrach, M.E. Rayborn, S. Acharya, I.R. Rodriguez, J.G. Hollyfield. (2000) IOVS, 4663

  8. Intracellular targeting by Pleckstrin Homology Domain in Oxysterol Binding Proteins (OSBP). Aiguo Li, Cynthia Jaworski, Robert N. Fariss, Ignacio R. Rodriguez. Abstsract #510. 15th annual meeting of The Protein Society, July 28- August 1, 2001, Philadelphia, PA.

  9. Establishment of Stably Transfected Cell Lines Over-expressing Oxysterol Binding Proteins. Shahabuddin Alam, Cynthia Jaworski, Natalyia Gordiyenko, Ignacio R. Rodriguez. (2003) IOVS, 2617

  10. Cytotoxic effects of oxidized LDL-cholesterol and oxysterols on cultured human RPE cells. Ignacio R. Rodriguez and Shahabuddin Alam. (2003) IOVS,2553

  11. Identification of oxysterol binding proteins (OSBPs) and associated proteins in cultured human RPE cells. Nataliya V. Gordiyenko, Shahabuddin Alam, Cynthia Jaworski, Ignacio R. Rodriguez.(2003) IOVS, 2487

This page was last modified in November 2007