Transfer of Metabolites through Lens Gap Junctions

Summary

Principal Investigator: Gary Goldberg
Abstract: Lens cells require gap junction proteins to communicate with each other and develop properly. In particular, connexin43 (Cx43), Cx46, and Cx5O are needed for normal lens development and function. Knockout or mutations of genes encoding these connexins cause cataracts in mice and humans, respectively. Cx43, Cx46, and Cx5O form channels with different permeability characteristics. We hypothesize that transjunctional molecules needed for lens development pass through lens gap junctions, and that cataracts can result from an inability of cells to share these signals. We propose to identify and compare the transfer of endogenous metabolites that pass through these channels. This new research program will introduce a particularly innovative technological approach to investigate the role of gap junctions in the lens. In Specific Aim 1 we will determine the single channel size, total conductance, and number of functional gap junction channels expressed by mammalian cells transfected with connexins that are expressed in the lens. This will be done by standard dual voltage-clamp whole-cell recording methods. In Specific Aim 2 we will identify, quantitate, and compare the transfer of endogenous metabolites that pass through channels formed by connexins expressed in the lens. This will be accomplished with a novel strategy to identify and quantitate the transfer of endogenous molecules that pass through gap junctions between cells within a given time frame. Measurement will be taken at several time points to measure and compare the rates of transfer of specific metabolites through gap junction channels formed by Cx43, Cx46, and Cx5O. These results will be combined with data obtained from Aim 1 to calculate the permselectivity of these gap junctions to metabolites on a per channel basis. We hypothesize that lens connexins form channels that display selective permeabilities to specific metabolites, and that this connexin permselectivity can not be predicted solely on the basis of size and charge of the permeant. We will begin to identify the permeability characteristics and actual transjunctional molecules that are responsible for lens development, transparency, and disease. This work should lead to a greater understanding, and, ultimately, treatments, of eye diseases that result from aberrant gap junctional communication.
Funding Period: 2003-08-01 - 2007-07-31
more information: NIH RePORT

Top Publications

  1. pmc Individual Cas phosphorylation sites are dispensable for processive phosphorylation by Src and anchorage-independent cell growth
    Parag Patwardhan
    Department of Physiology and Biophysics, School of Medicine, State University of New York, Stony Brook, 11794, USA
    J Biol Chem 281:20689-97. 2006
  2. ncbi Nontransformed cells can normalize gap junctional communication with transformed cells
    Virginijus Valiunas
    Department of Physiology and Biophysics, School of Medicine, Basic Science Tower L6, Health Science Complex, State University of New York at Stony Brook, 11794 8661, USA
    Biochem Biophys Res Commun 333:174-9. 2005
  3. ncbi SRC uses Cas to suppress Fhl1 in order to promote nonanchored growth and migration of tumor cells
    Yongquan Shen
    Department of Molecular Biology, University of Medicine and Dentistry of New Jersey, Science Center, 2 Medical Center Drive, Stratford, NJ 08084, USA
    Cancer Res 66:1543-52. 2006
  4. ncbi SRC utilizes Cas to block gap junctional communication mediated by connexin43
    Yongquan Shen
    Department of Molecular Biology, Science Center, University of Medicine and Dentistry, Stratford, New Jersey 08084, USA
    J Biol Chem 282:18914-21. 2007
  5. ncbi Phosphorylation of connexin43 induced by Src: regulation of gap junctional communication between transformed cells
    Madhuri Pahujaa
    Department of Cell Biology, University of Medicine and Dentistry of New Jersey, Science Center, 2 Medical Center Dr, Stratford, NJ 08084, USA
    Exp Cell Res 313:4083-90. 2007

Scientific Experts

  • Virginijus Valiunas
  • Yongquan Shen
  • Gary S Goldberg
  • Madhuri Pahujaa
  • Hitoshi Ichikawa
  • Parag Patwardhan
  • P Raaj Khusial
  • Alonso P Moreno
  • Xun Li
  • Michael Anikin
  • Robert G Nagele
  • Zhenyu Jia
  • W Todd Miller

Detail Information

Publications5

  1. pmc Individual Cas phosphorylation sites are dispensable for processive phosphorylation by Src and anchorage-independent cell growth
    Parag Patwardhan
    Department of Physiology and Biophysics, School of Medicine, State University of New York, Stony Brook, 11794, USA
    J Biol Chem 281:20689-97. 2006
    ..Mutants lacking some or all YXXP sites augment the ability of Src to promote anchorage-independent growth. On the other hand, deletion of YXXP sites compromises the ability of Cas to promote tumor cell migration...
  2. ncbi Nontransformed cells can normalize gap junctional communication with transformed cells
    Virginijus Valiunas
    Department of Physiology and Biophysics, School of Medicine, Basic Science Tower L6, Health Science Complex, State University of New York at Stony Brook, 11794 8661, USA
    Biochem Biophys Res Commun 333:174-9. 2005
    ..Thus, nontransformed cells can effectively "normalize" the conductance of gap junction channels expressed by adjacent tumor cells...
  3. ncbi SRC uses Cas to suppress Fhl1 in order to promote nonanchored growth and migration of tumor cells
    Yongquan Shen
    Department of Molecular Biology, University of Medicine and Dentistry of New Jersey, Science Center, 2 Medical Center Drive, Stratford, NJ 08084, USA
    Cancer Res 66:1543-52. 2006
    ....
  4. ncbi SRC utilizes Cas to block gap junctional communication mediated by connexin43
    Yongquan Shen
    Department of Molecular Biology, Science Center, University of Medicine and Dentistry, Stratford, New Jersey 08084, USA
    J Biol Chem 282:18914-21. 2007
    ..This finding introduces a novel role of the Cas focal adhesion linker protein in the gap junction complex. This observation may help explain how gap junctional communication can be suppressed between malignant and metastatic tumor cells...
  5. ncbi Phosphorylation of connexin43 induced by Src: regulation of gap junctional communication between transformed cells
    Madhuri Pahujaa
    Department of Cell Biology, University of Medicine and Dentistry of New Jersey, Science Center, 2 Medical Center Dr, Stratford, NJ 08084, USA
    Exp Cell Res 313:4083-90. 2007
    ..It has become clear that Src can affect Cx43 activity by multiple mechanisms. Here, we review how Src may orchestrate events that regulate intercellular communication mediated by Cx43...