Regulation of lens connexins

Summary

Principal Investigator: Charles Louis
Abstract: [unreadable] DESCRIPTION (provided by applicant): The long-term goal of this research is to define the critical physiologic changes in the early stages of lens cataract formation. Regulation of connexin-mediated gap junctional communication, and intracellular cytosolic Ca 2+ concentration ([Ca2+]i) are essential for maintaining transparency of the lens of the eye. It has now been demonstrated that the purinergic agonist ATP effects a delayed, transient inhibition, while elevated [Ca2+]i inhibits cell-to-cell coupling mediated by lens gap junctions. The immediate objectives of this project are to define the mechanisms by which ATP and [Ca2+]i regulate lens gap junctions. This will be achieved using a sheep lens cell culture system, as well as HeLa cell lines stably transfected with different lens connexins. These objectives will be achieved in two specific aims. The first aim will determine the mechanism by which ATP effects the inhibition of lens gap junctions. The hypothesis to be tested in this proposal is that the ATP-dependent, delayed, transient inhibition of lens gap junctions is effected by the protein kinase-catalyzed phosphorylation of the lens connexins. The phosphorylated connexin43 (Cx43) amino acid(s) will be identified, and it will then be demonstrated that the phosphorylation of the amino acid(s) is required for this agonist dependent effect; the delayed, transient nature of this ATP-dependent inhibition will also be defined. Finally, the mechanism by which ATP mediates the delayed, transient inhibition of lens Cx44 will be determined. The second aim will determine the mechanism by which elevated intracellular Ca 2+ concentration inhibits lens gap junctions. The hypothesis to be tested is that calmodulin (CAM) mediates the Ca2+-dependent inhibition of lens gap junctions via its direct interaction with the lens connexins. The peptide sequence that CaM interacts with in Cx43 to effect this inhibition will be identified and confirmed by mutating these identified CaM binding sequences(s). Finally, it will be determined whether Ca2+-CaM regulates cell-to-cell communication mediated by Cx44. Altered regulation of lens gap junctions and [Ca2+]i are recognized as key factors in [unreadable] cataract development. These studies, by defining novel physiologic roles for gap junctions in maintaining lens homeostasis, will allow us to generate new models for cataract formation, and enable the development of new therapies to manage and/or prevent human maturity onset cataract. [unreadable] [unreadable]
Funding Period: 1985-04-01 - 2010-08-31
more information: NIH RePORT

Top Publications

  1. pmc Visual motion processing by neurons in area MT of macaque monkeys with experimental amblyopia
    Yasmine El-Shamayleh
    Center for Neural Science, New York University, New York, New York 10003, USA
    J Neurosci 30:12198-209. 2010
  2. pmc Molecular interaction and functional regulation of connexin50 gap junctions by calmodulin
    Yanyi Chen
    Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
    Biochem J 435:711-22. 2011
  3. pmc Gating of connexin 43 gap junctions by a cytoplasmic loop calmodulin binding domain
    Qin Xu
    Department of Pharmacology, SUNY Upstate Medical University, 750 East Adams St, Syracuse, NY 13210, USA
    Am J Physiol Cell Physiol 302:C1548-56. 2012
  4. ncbi Intracellular calcium regulation of connexin43
    Monica M Lurtz
    Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
    Am J Physiol Cell Physiol 293:C1806-13. 2007
  5. ncbi Identification of the calmodulin binding domain of connexin 43
    Yubin Zhou
    Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, USA
    J Biol Chem 282:35005-17. 2007
  6. pmc Calmodulin mediates the Ca2+-dependent regulation of Cx44 gap junctions
    Yubin Zhou
    Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, USA
    Biophys J 96:2832-48. 2009

Scientific Experts

  • Monica M Lurtz
  • Yanyi Chen
  • Yubin Zhou
  • Jenny J Yang
  • Qin Xu
  • Charles F Louis
  • Richard D Veenstra
  • Yasmine El-Shamayleh
  • Jie Jiang
  • Wei Yang
  • Yun Huang
  • Richard F Kopp
  • Michael W Roe
  • Siming Wang
  • Hing Cheung Wong
  • Xianming Lin
  • Adam Kohn
  • Lynne Kiorpes
  • J Anthony Movshon
  • Yiming Ye
  • Hsiau Wei Lee

Detail Information

Publications6

  1. pmc Visual motion processing by neurons in area MT of macaque monkeys with experimental amblyopia
    Yasmine El-Shamayleh
    Center for Neural Science, New York University, New York, New York 10003, USA
    J Neurosci 30:12198-209. 2010
    ..We conclude that some, but not all, of the motion sensitivity deficits associated with amblyopia can be explained by abnormal development of MT...
  2. pmc Molecular interaction and functional regulation of connexin50 gap junctions by calmodulin
    Yanyi Chen
    Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
    Biochem J 435:711-22. 2011
    ..Overall, these results demonstrate that the binding of Ca2+/CaM to the intracellular loop of Cx50 is critical for mediating the Ca2+-dependent inhibition of Cx50 gap junctions in the lens of the eye...
  3. pmc Gating of connexin 43 gap junctions by a cytoplasmic loop calmodulin binding domain
    Qin Xu
    Department of Pharmacology, SUNY Upstate Medical University, 750 East Adams St, Syracuse, NY 13210, USA
    Am J Physiol Cell Physiol 302:C1548-56. 2012
    ..This study provides the first evidence of intrinsic differences in the Ca(2+) regulatory properties of Cx43 and Cx40...
  4. ncbi Intracellular calcium regulation of connexin43
    Monica M Lurtz
    Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
    Am J Physiol Cell Physiol 293:C1806-13. 2007
    ..These data indicate that physiological concentrations of [Ca(2+)](i) regulate the permeability of Cx43 in a calmodulin-dependent manner that does not require the major portion of the COOH terminus of Cx43...
  5. ncbi Identification of the calmodulin binding domain of connexin 43
    Yubin Zhou
    Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, USA
    J Biol Chem 282:35005-17. 2007
    ....
  6. pmc Calmodulin mediates the Ca2+-dependent regulation of Cx44 gap junctions
    Yubin Zhou
    Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, USA
    Biophys J 96:2832-48. 2009
    ..Our data suggest a common mechanism by which the Ca2+-dependent inhibition of the alpha-class of gap junction proteins is mediated by the direct association of an intracellular loop region of these proteins with Ca2+-CaM...