title: Dynamic DNA methylation regulates neuronal intrinsic membrane excitability.
abstract: Epigenetic modifications, such as DNA cytosine methylation, contribute to the mechanisms underlying learning and memory by coordinating adaptive gene expression and neuronal plasticity. Transcription-dependent plasticity regulated by DNA methylation includes synaptic plasticity and homeostatic synaptic scaling. Memory-related plasticity also includes alterations in intrinsic membrane excitability mediated by changes in the abundance or activity of ion channels in the plasma membrane, which sets the threshold for action potential generation. We found that prolonged inhibition of DNA methyltransferase (DNMT) activity increased intrinsic membrane excitability of cultured cortical pyramidal neurons. Knockdown of the cytosine demethylase TET1 or inhibition of RNA polymerase blocked the increased membrane excitability caused by DNMT inhibition, suggesting that this effect was mediated by subsequent cytosine demethylation and de novo transcription. Prolonged DNMT inhibition blunted the medium component of the after-hyperpolarization potential, an effect that would increase neuronal excitability, and was associated with reduced expression of the genes encoding small-conductance Ca(2+)-activated K(+) (SK) channels. Furthermore, the specific SK channel blocker apamin increased neuronal excitability but was ineffective after DNMT inhibition. Our results suggested that DNMT inhibition enables transcriptional changes that culminate in decreased expression of SK channel-encoding genes and decreased activity of SK channels, thus providing a mechanism for the regulation of neuronal intrinsic membrane excitability by dynamic DNA cytosine methylation. This study has implications for human neurological and psychiatric diseases associated with dysregulated intrinsic excitability.
authors.affiliation: Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Jarrod P
authors.initials: JP
authors.lastname: Meadows
authors.affiliation: Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Mikael C
authors.initials: MC
authors.lastname: Guzman-Karlsson
authors.affiliation: Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Phillips
authors.affiliation: Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Jordan A
authors.initials: JA
authors.lastname: Brown
authors.affiliation: Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Strange
authors.affiliation: Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA. Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: J David
authors.initials: JD
authors.lastname: Sweatt
authors.affiliation: Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA. jhablitz@uab.edu.
authors.forename: John J
authors.initials: JJ
authors.lastname: Hablitz
mesh_terms: D000818:Animals; D001030:Apamin / Q000494:pharmacology; D002460:Cell Line; D019175:DNA Methylation / Q000187:drug effects / Q000502:physiology*; D044127:Epigenesis, Genetic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D017966:Pyramidal Cells / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism
chemical_list: D051640:Small-Conductance Calcium-Activated Potassium Channels; D001030:Apamin