Regulation of Cx26 and Cx32 Channels by Cytosolic Interdomain Interactions

Summary

Principal Investigator: Andrew L Harris
Abstract: DESCRIPTION (provided by applicant): Connexin proteins form the gap junction channels that mediate direct intercellular molecular communication crucial in development, physiology and response to trauma/inflammation/disease. Mutations in connexins cause human pathologies. Elucidation of the molecular mechanisms that regulate connexin channel function is essential for understanding their roles in human physiology and pathophysiology, and to identify targets for translational and basic science studies. The long-term goal of this project is to understand the cytosolic inter-domain interactions of connexin proteins that control channel gating. In connexin43 (Cx43), interactions between the cytoplasmic loop (CL) and the C-terminal domain (CT) is crucially involved physiological function of the channel and is a target for cardiovascular therapies. However, the roles and mechanisms of CL-CT interactions in modulation of other connexin channels, just as likely to be biomedically important, have not been explored. We have found that Cx26 channels are modulated by CL-CT interactions. Cx26 and Cx43 are representative members of the two largest families of connexins. Though structurally analogous, the effects of CL-CT interaction on Cx26 channel function seem to be fundamentally different from those in Cx43, suggesting that CL-CT interaction is a common modulatory mechanism in connexins, yet operates in connexin-specific ways. We propose to elucidate the molecular mechanisms of CL-CT control of channel function using Cx26 and its closely related isoform Cx32. Cx26 is the only connexin channel for which there is a high-resolution structure, making it the cornerstone for structure-based studies of all connexin channels. The proposed studies explore the basis and mechanisms of CL-CT interactions and channel properties they modulate, using strategies successfully applied to other channels, including macroscopic and single channel recordings, use of competing peptides, engineered Cys linkages and mutational analysis. The experiments utilize intact channels, complemented by peptide NMR. We propose to (a) determine the involvement of CL-CT interactions in channel gating, (b) identify the sites of CL-CT interactions, and (c) determine how CL-CT interaction and its effects are altered by mutations that cause human disease. Cx26 and Cx32 are widely distributed in the body. Cx26 mutations cause over half the inherited non-syndromic sensorineural deafness worldwide, and serious disfiguring skin disorders. Cx32 mutations cause a peripheral demyelination. Significantly, in both connexins many disease-causing mutations are in the CL and CT domains. Both connexins are involved in a wide range of pathological and physiological processes, so understanding the basis for their dysregulation has broad biomedical implications, for these connexins and others. The large number of disease causing mutations and the extensive experience of both PIs in studying gating and permeability of Cx26 and Cx32 channels provide a basis for productive, informative investigation of CL-CT interactions, how they are altered by pathological mutations and the effects on channel function.
Funding Period: 2013-02-01 - 2013-06-30
more information: NIH RePORT

Research Grants

  1. Cyclic nucleotide permeability of connexin mutants related to genetic disease
    Virginijus Valiunas; Fiscal Year: 2013
  2. STRUCTURE AND DYNAMICS OF CONNEXIN26 GAP JUNCTIONS
    Gina E Sosinsky; Fiscal Year: 2013
  3. DEGENERATIVE AND DEMENTING DISEASES OF AGING
    Stanley B Prusiner; Fiscal Year: 2013
  4. DRUGS OF ABUSE - ROLE OF PROTEIN PHOSPHORYLATION
    Paul Greengard; Fiscal Year: 2013
  5. STRUCTURAL BASIS OF ORGANELLE TETHERING
    Adam D Linstedt; Fiscal Year: 2013
  6. Molecular and Cellular Therapies for Muscular Dystrophy
    Stanley C Froehner; Fiscal Year: 2013
  7. HORMONAL REGULATION OF BLOOD PRESSURE
    Michal Laniado Schwartzman; Fiscal Year: 2013
  8. Structure and Dynamics of Gap Junction Channels
    MARK JAY YEAGER; Fiscal Year: 2013
  9. Signaling of Endothelial Permeability and Lung Vascular Injury
    Asrar B Malik; Fiscal Year: 2013
  10. Pulmonary Surface Liquid Homeostasis
    RICHARD CHARLES BOUCHER; Fiscal Year: 2013

Detail Information

Research Grants30

  1. Cyclic nucleotide permeability of connexin mutants related to genetic disease
    Virginijus Valiunas; Fiscal Year: 2013
    ..The results of the proposed research will establish a baseline for understanding the role of perm-selectivity as a potential determinant of disease states such as oculodentodigital dysplasia and atrial fibrillation. ..
  2. STRUCTURE AND DYNAMICS OF CONNEXIN26 GAP JUNCTIONS
    Gina E Sosinsky; Fiscal Year: 2013
    ..The proposed research is significant because results will be useful in defining better drugs and other therapeutics that potentially ameliorate connexin-related diseases. ..
  3. DEGENERATIVE AND DEMENTING DISEASES OF AGING
    Stanley B Prusiner; Fiscal Year: 2013
    ..The ultimate goal of all the proposed studies is to define the molecular events that feature in the formation of human prions in order to develop therapeutics that cure the human prion diseases. ..
  4. DRUGS OF ABUSE - ROLE OF PROTEIN PHOSPHORYLATION
    Paul Greengard; Fiscal Year: 2013
    ..Results from the three Projects will complement each other. In addition, there will be a significant level of collaboration between the three Projects, as well as close interaction of the three Projects with the Scientific Core. ..
  5. STRUCTURAL BASIS OF ORGANELLE TETHERING
    Adam D Linstedt; Fiscal Year: 2013
    ....
  6. Molecular and Cellular Therapies for Muscular Dystrophy
    Stanley C Froehner; Fiscal Year: 2013
    ..The mechanism of NPC1 phenotype amelioration and its applicability to LGMDs will be studied. Two core facilities will serve the participating laboratories. ..
  7. HORMONAL REGULATION OF BLOOD PRESSURE
    Michal Laniado Schwartzman; Fiscal Year: 2013
    ..ular tone, in the pathophysiology of hypertension and cardiovascular disease. ..
  8. Structure and Dynamics of Gap Junction Channels
    MARK JAY YEAGER; Fiscal Year: 2013
    ..Such a detailed molecular picture will provide insight into how these channels are involved in such diverse processes as regulating the heartbeat and hereditary deafness. ..
  9. Signaling of Endothelial Permeability and Lung Vascular Injury
    Asrar B Malik; Fiscal Year: 2013
    ..Moreover the depth of understanding to be gained of the signaling pathways mediating the increase in lung vascular permeability will provide novel insights into the mechanisms of protein-rich pulmonary edema and ARDS. ..
  10. Pulmonary Surface Liquid Homeostasis
    RICHARD CHARLES BOUCHER; Fiscal Year: 2013
    ..abstract_text> ..
  11. Immune-Based Interventions Against Infectious Diseases
    Alan L Rothman; Fiscal Year: 2013
    ..3. Recruit promising junior investigators and provide mentoring by established NIH-funded researchers. 4. Support a multidisciplinary research program led by junior investigators in translational infectious diseases immunology. ..
  12. STRUCTURAL ANALYSIS OF GAP JUNCTION TRAFFICKING
    Gina E Sosinsky; Fiscal Year: 2013
    ..We investigate the connexin43 trafficking process using an imaging based approach examining the hierarchy of connexin43 phosphorylation events and where within the cell cycle, connexin43-kinase(s) interactions occurs. ..
  13. Mechanisms of Gap Junction Regulation
    Paul L Sorgen; Fiscal Year: 2013
    ....