Retinal degeneration caused by alterations in protein tyrosine O-sulfation

Summary

Principal Investigator: Muayyad R Al-Ubaidi
Abstract: DESCRIPTION (provided by applicant): Research on retinitis pigmentosa (RP) and age related macular degeneration (AMD) has significantly advanced knowledge into their genetic causes. Although such findings triggered exploration of numerous therapeutic paradigms, we still come short in our understanding of the cause of the late onset of visual loss although the mutant protein is present from birth. It is often proposed that these cells survive due to effects f neuroprotective factors that significantly prolong the life of the sick cell. However, it is not clar as to why the patient starts to encounter visual difficulties all of a sudden? Here we propose an additional contributing hypothesis for the delayed onset of visual loss based upon two related findings. The first is the identification of CFH and fibulin 5 as sulfated proteins. Besides being present in drusen, mutations in both proteins associate with AMD. Our second is that we observe modulations in levels and types of tyrosine-sulfated proteins during retinal degeneration in two well-studied animal models of RP, the VPP and the rds+/- mouse models. Since sulfation is a post-translational modification that occurs on secreted and membrane-associated extracellular matrix (ECM) proteins, we hypothesize that the slow death of cells will lead to gradual deterioration of ECM. However, when a critical number of ECM-maintaining cells are lost, a breaking point is reached, suddenly accelerating the degenerative process. We propose two specific aims to address our hypothesis. In Aim 1, we are generating retina/RPE-specific conditional knockout mice for both of the enzymes responsible for protein sulfation, protein tyrosyl sulfotransferases 1 and 2. The double knockout (DKO) mice will be characterized functionally, structurally and biochemically from birth to 2 years of age for effects of lack of sulfation. To determine if the lack of sulfation of ECM proteins exacerbate the AMD phenotype, we plan to backcross these mice into an AMD transgenic model (cfhY402H). To address the effect of lack of sulfation of ECM proteins on the RP phenotype, we plan to backcross the DKO mice to two well-studied RP models representing the P23H mutation in the rhodopsin gene (VPP) and the haploinsufficiency of the retinal degeneration slow (rds+/-) protein. In Aim 2, we will evaluate the role of sulfation in the function of CFH and fibulin 5. The identified sulfated tyrosine(s) will be mutated to phenylalanines and in vitro analyses of 1) ability of unsulfated CFH to bind CRP (C-reactive protein), 2) its ability to self-dimerize and 3) its interactions with polyanions. For fibulin 5, we will test the ability of the unsulfated protein to interact with interins and ECM super oxide dismutase (SOD) 3. Subsequently, we will generate and characterize retina/RPE-specific conditional knock-in mice expressing either sulfation-deficient CFH or fibulin 5. Accomplishment of the proposed studies will open a new window on the role of ECM in degenerative process and direct attention to development of new therapeutic approaches focusing on protection of the ECM to prolong vision in patients and widen the window for interventions. This is of significance to over 10 million US Citizens of all ages and races that suffer from RP and AMD.
Funding Period: 2007-04-01 - 2014-08-31
more information: NIH RePORT

Top Publications

  1. pmc Retinoid processing in cone and Müller cell lines
    Yogita Kanan
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
    Exp Eye Res 86:344-54. 2008
  2. pmc p53 selectively regulates developmental apoptosis of rod photoreceptors
    Linda Vuong
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
    PLoS ONE 8:e67381. 2013
  3. pmc Differential developmental deficits in retinal function in the absence of either protein tyrosine sulfotransferase-1 or -2
    David M Sherry
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
    PLoS ONE 7:e39702. 2012
  4. pmc Pattern of expression of p53, its family members, and regulators during early ocular development and in the post-mitotic retina
    Linda Vuong
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
    Invest Ophthalmol Vis Sci 53:4821-31. 2012
  5. pmc Photoreceptor cells constitutively express functional TLR4
    Zhidan Tu
    Department of Pathology, Case Western Reserve University, Cleveland 44106, USA
    J Neuroimmunol 230:183-7. 2011
  6. pmc Rhodopsin: the functional significance of asn-linked glycosylation and other post-translational modifications
    Anne R Murray
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
    Ophthalmic Genet 30:109-20. 2009
  7. pmc Protein tyrosine-O-sulfation in the retina
    Yogita Kanan
    Department of Cell Biology, University of Oklahoma Health Sciences Center, BMSB 781, 940 Stanton L Young Blvd, Oklahoma City, OK 73104, USA
    Exp Eye Res 89:559-67. 2009
  8. pmc Fibulin 2, a tyrosine O-sulfated protein, is up-regulated following retinal detachment
    Yogita Kanan
    From the Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
    J Biol Chem 289:13419-33. 2014

Research Grants

Detail Information

Publications10

  1. pmc Retinoid processing in cone and Müller cell lines
    Yogita Kanan
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
    Exp Eye Res 86:344-54. 2008
    ..Alternatively, this could be due to the potential that rMC-1, as a transformed cell line, has stopped expressing the proteins needed for the regeneration of 11-cis retinoids...
  2. pmc p53 selectively regulates developmental apoptosis of rod photoreceptors
    Linda Vuong
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
    PLoS ONE 8:e67381. 2013
    ....
  3. pmc Differential developmental deficits in retinal function in the absence of either protein tyrosine sulfotransferase-1 or -2
    David M Sherry
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
    PLoS ONE 7:e39702. 2012
    ....
  4. pmc Pattern of expression of p53, its family members, and regulators during early ocular development and in the post-mitotic retina
    Linda Vuong
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
    Invest Ophthalmol Vis Sci 53:4821-31. 2012
    ..To shed light on the role of p53 in retinal development and maintenance, this study investigated the pattern of expression of p53, its family members, and its regulators during the development of the mouse eye...
  5. pmc Photoreceptor cells constitutively express functional TLR4
    Zhidan Tu
    Department of Pathology, Case Western Reserve University, Cleveland 44106, USA
    J Neuroimmunol 230:183-7. 2011
    ..We conclude that TLR4 on photoreceptor cells could directly contribute to retinal inflammatory diseases and photoreceptor cell survival...
  6. pmc Rhodopsin: the functional significance of asn-linked glycosylation and other post-translational modifications
    Anne R Murray
    Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
    Ophthalmic Genet 30:109-20. 2009
    ..These studies have provided insights into the possible role of rhodopsin glycosylation, but have yielded conflicting results...
  7. pmc Protein tyrosine-O-sulfation in the retina
    Yogita Kanan
    Department of Cell Biology, University of Oklahoma Health Sciences Center, BMSB 781, 940 Stanton L Young Blvd, Oklahoma City, OK 73104, USA
    Exp Eye Res 89:559-67. 2009
    ..These data show that retinal protein tyrosine-O-sulfation is highly conserved which suggest a functional significance of these proteins to retinal function and structure...
  8. pmc Fibulin 2, a tyrosine O-sulfated protein, is up-regulated following retinal detachment
    Yogita Kanan
    From the Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
    J Biol Chem 289:13419-33. 2014
    ..Understanding the role of fibulin 2 in enhancing retinal attachment is likely to help improve the current therapies or allow the development of new strategies for the treatment of this sight-threatening condition. ..

Research Grants30

  1. Models of Retinal Degeneration
    Matthew M Lavail; Fiscal Year: 2013
    ..More than 90 current and pending grant projects are dependent upon this Retinal Degeneration Rat Model Resource established by the National Eye Institute in 1986. ..
  2. A Ribozyme Rescue Strategy for Dry Age-Related Macular Degeneration
    John M Sullivan; Fiscal Year: 2013
    ..This proposed study is a proof-of-concept test of a novel gene therapy strategy for dry AMD. Success in a mouse model is a first essential step toward human clinical trials, which could be conducted in the VA system. ..
  3. Experimental and Clinical Investigations of Retinal Stimulation
    JAMES DAVID WEILAND; Fiscal Year: 2013
    ..Secondly, and more broadly, we will establish in vitro retina as tool to infor the design of future implants that promise higher acuity vision. ..
  4. Jules Stein Eye Institute Core Grant for Vision Research
    Wayne L Hubbell; Fiscal Year: 2013
    ..Support in the form of the Core grant is requested to maintain these Modules through instrument service contracts, and to provide necessary personnel support to assist and train users and provide routine maintenance. ..
  5. Complex Mouse Models of Age-related Macular Degeneration
    Caroline J Zeiss; Fiscal Year: 2013
    ..The award spans three years, and its successful funding will support one trainee per year, and provide protected time for the PI to consolidate her lab and establish solid research support. ..