Altered phosphorylation of connexin 43 contributes to increased gap-junction coup

Summary

Principal Investigator: HEIDI GRABENSTATTER
Abstract: DESCRIPTION (provided by applicant): Pilocarpine-induced status epileptics (SE) induce reactive gliosis and activate calcium signaling in astrocytes of the hippocampus in a time-dependent manner (1, 2). Primary studies demonstrate significant decreases in connexin phosphorylation 48 h after SE and in chronically epileptic rats 30 d after SE. This data combined with previous studies showing that paroxysmal depolarization shifts can be initiated by release of glutamate from astrocytes3 suggests that increased open probability of gap- junction hemi channels via dephosphorylating of connexin 43 in hippocampal astrocytes may contribute to the progression of epileptogenesis. The major goal of this proposal is to characterize the role of serine/threonine kinases and phosphatases in seizure-induced dephosphorylating of connexin 43 and specifically, to evaluate the hypothesis that status epileptics acutely activates phosphatases (and may decrease kinases at specific time points) in glyptic astrocytes which dephosphorylates connexin 43 to subsequently increase connexin 43-containing hemi channel open probability and astrocytes gap- junction coupling during epileptogenesis in the hippocampus. Molecular methods will be used to characterize the time course of phosphatase and kinase activation. Alterations in gap-junction coupling will be quantitatively measured in response to equilibrium shifts between kinase and phosphatase activity in hippocampal slices at multiple time points following SE. Kinase and phosphatase activity will be pharmacologically and genetically modulated to determine the primary mechanism responsible for the seizure-induced dephosphorylating of connexin 43 and downstream effects on gap-junction coupling, potassium currents, and glutamate transporter currents prior to and after the onset of spontaneous seizures. Chronic video-EEG monitoring and freeze-fracture replica immunogold labeling (FRIL) will be used to determine whether seizure-induced alterations in phosphorylated connexin 43 membrane expression and potential increases in seizure frequency associated with phosphorylation-mediated hemi channel opening can be prevented with pharmacological or transgenic methods. The proposal will provide valuable translational information about how phosphatase inhibitors or kinase agonists may be exploited to prevent the progression of epileptogenesis and achieve and disease-modification.
Funding Period: 2013-09-01 - 2018-07-31
more information: NIH RePORT

Research Grants

  1. Epilepsy and dendritic excitability
    Nicholas P Poolos; Fiscal Year: 2013
  2. Stem Cell Transplantation for Epilepsy
    JANICE RAE NAEGELE; Fiscal Year: 2013
  3. CELLULAR MECHANISMS IN EPILEPTOGENESIS
    John R Huguenard; Fiscal Year: 2013
  4. ENHANCEMENT OF THE CPRC-SPF RHESUS MONKEY PROGRAM
    Carlos A Sariol; Fiscal Year: 2013
  5. Perisomatic Inhibitory Network Dysfunction in Neurological Disease
    Vijayalakshmi Santhakumar; Fiscal Year: 2013
  6. Amino Acid Transport and the Biology of Human Gliomas
    Harald W Sontheimer; Fiscal Year: 2013
  7. Proneurotrophin signaling in epilepsy
    AJAY THOMAS; Fiscal Year: 2013
  8. mTOR dysregulation in Epilepsy
    Angela N Carter; Fiscal Year: 2013
  9. The Role of Connexin32 in the Pathogensis of CMTX
    STEVEN SIMON SCHERER; Fiscal Year: 2013
  10. Enduring Effects of Early-Life Serotonin Signaling
    Randy D Blakely; Fiscal Year: 2013

Detail Information

Research Grants30

  1. Epilepsy and dendritic excitability
    Nicholas P Poolos; Fiscal Year: 2013
    ..The outcome of this study may identify specific biochemical pathways that could be targeted for development of novel antiepileptic drugs, improving the likelihood that currently poorly-controlled patients may one day be seizure-free. ..
  2. Stem Cell Transplantation for Epilepsy
    JANICE RAE NAEGELE; Fiscal Year: 2013
    ..4: Measure inhibitory post-synaptic currents in retrovirally-labeled populations of GCs by patch-clamp electrophysiological recordings in hippocampal slices from mice with transplants of mPSC-derived MGE-like basal forebrain cells. ..
  3. CELLULAR MECHANISMS IN EPILEPTOGENESIS
    John R Huguenard; Fiscal Year: 2013
    ....
  4. ENHANCEMENT OF THE CPRC-SPF RHESUS MONKEY PROGRAM
    Carlos A Sariol; Fiscal Year: 2013
    ..Our Center will continue to make significant contributions to AIDS and to other research programs by providing high quality, healthy, and genetically-characterized SPF rhesus monkeys to NIH-sponsored research initiatives. ..
  5. Perisomatic Inhibitory Network Dysfunction in Neurological Disease
    Vijayalakshmi Santhakumar; Fiscal Year: 2013
    ..It is anticipated that the study will identify fundamental mechanisms underlying dynamical instability of dentate network activity in acquired epilepsy. ..
  6. Amino Acid Transport and the Biology of Human Gliomas
    Harald W Sontheimer; Fiscal Year: 2013
    ....
  7. Proneurotrophin signaling in epilepsy
    AJAY THOMAS; Fiscal Year: 2013
    ....
  8. mTOR dysregulation in Epilepsy
    Angela N Carter; Fiscal Year: 2013
    ..We will employ a series of biochemical, pharmacological, neurophysiological and behavioral assays for these studies. ..
  9. The Role of Connexin32 in the Pathogensis of CMTX
    STEVEN SIMON SCHERER; Fiscal Year: 2013
    ..We will determine whether (a) activity increases the extent of 2-NDBG diffusion, and (b) whether glucose infused into a single oligodendrocyte can "rescue" axonal conduction in glucose-deprived conditions. ..
  10. Enduring Effects of Early-Life Serotonin Signaling
    Randy D Blakely; Fiscal Year: 2013
    ..abstract_text> ..
  11. Calcium Signaling in a Model of Temporal Lobe Epilepsy
    Karen S Wilcox; Fiscal Year: 2013
    ..Finally it is anticipated that the proposed experiments will lead to the identification of novel molecular targets for innovative therapeutic approaches for the treatment, prevention, and/or cure of this devastating seizure disorder. ..
  12. Cre, Dre Dual Lineage Model for Calcium Imaging and Optogenetic Manipulations
    Petr Tvrdik; Fiscal Year: 2013
    ..We will be able to determine if Hoxb8 mutant microglia respond to neural stimuli correctly. Taken together, the proposed work will advance the set of tools available to address the underlying causes of glial and other disorders. ..
  13. Subunit dependent properties of kainate receptors
    David D Mott; Fiscal Year: 2013
    ..A better understanding of kainate receptor properties is essential in the rational development of novel therapeutic agents targeted at these receptors. ..
  14. Group I Metabotropic Glutamate Receptors and Epileptogenesis
    Paul A Rutecki; Fiscal Year: 2013
    ....
  15. GABAergic regulation of entorhino-hippocampal excitability in epilepsy.
    Ivan Soltesz; Fiscal Year: 2013
    ..The project will determine whether aberrant inhibitory regulation of the entorhino-hippocampal circuits contributes to the generation of seizures. ..
  16. Modulating ProNGF-induced cell death in Epilepsy: strategies for neuroprotection
    Helen E Scharfman; Fiscal Year: 2013
    ..abstract_text> ..
  17. GAP JUNCTION INTERCELLULAR COMMUNICATION AND POLYAMINES
    YURIY KUCHERYAVYKH; Fiscal Year: 2013
    ..By regulation of Cxs, we can modulate gap junctional intercellular communication between glioma cells and potentially communication between glioma cells and the normal astrocytes in the tumor microenvironment. ..
  18. Glutamate release and uptake at central synapses
    Craig E Jahr; Fiscal Year: 2013
    ..Rational design of therapies for neurological deficits is not possible without a fundamental understanding of synaptic function. ..
  19. MODULATION OF NEOCORTICAL INTERNEURONAL FUNCTION
    DAVID ALLAN PRINCE; Fiscal Year: 2013
    ..The long term goals are to identify critical abnormalities that might eventually be targets for selective agents that would used to prevent or treat human posttraumatic epilepsy. ..
  20. GABA(A) RECEPTOR TRAFFICKING AND EPILEPTOGENESIS
    Marco I Gonzalez; Fiscal Year: 2013
    ..The proposed studies aim to develop a better understanding of the molecular mechanisms that trigger epilepsy development to provide new therapeutic targets and generate novel strategies to ameliorate epilepsy progression. ..
  21. GABA(A) Receptor Subunit Regulation in Epileptogenesis
    Shelley J Russek; Fiscal Year: 2013
    ..The proposed studies seek to find new ways of treating and preventing epilepsy by identifying and then reversing the changes in brain cells that lead to this condition. ..
  22. Emory Alzheimer's Disease Center
    Allan I Levey; Fiscal Year: 2013
    ..abstract_text> ..
  23. Glutamine Synthetase and the Mechanism of Seizures in Mesial Temporal Lobe Epilep
    Tore Eid; Fiscal Year: 2013
    ..The hypothesis is that restoration of glutamine synthetase in the hippocampus leads to cessation of seizures even in the presence of extensive brain pathology. ..
  24. A Novel Mouse Model of Temporal Lobe Epilepsy
    Karen S Wilcox; Fiscal Year: 2013
    ....
  25. Dentate Gyrus Circuitry In Temporal Lobe Epilepsy
    Paul S Buckmaster; Fiscal Year: 2013
    ..If mossy cells do play an epileptogenic role, then they may offer new therapeutic targets to dampen excitability and provide better seizure control for patients. ..
  26. Differential modes of cholinergic transmission onto cellular hippocampal targets
    JOHN JOSHUA LAWRENCE; Fiscal Year: 2013
    ....
  27. INTERNEURON BASED MECHANISMS OF TEMPORAL LOBE EPILEPSY
    Paul S Buckmaster; Fiscal Year: 2013
    ..Seizures might be caused by inadequate inhibition. This project will investigate in detail how and why inhibition is abnormal in dentate gyrus of a rat model of epilepsy. ..