Characterization of connexin36 gap junctions in the human outer retina

Brain Struct Funct. 2016 Jul;221(6):2963-84. doi: 10.1007/s00429-015-1082-z. Epub 2015 Jul 15.

Abstract

Retinal connexins (Cx) form gap junctions (GJ) in key circuits that transmit average or synchronize signals. Expression of Cx36, -45, -50 and -57 have been described in many species but there is still a disconcerting paucity of information regarding the Cx makeup of human retinal GJs. We used well-preserved human postmortem samples to characterize Cx36 GJ constituent circuits of the outer plexiform layer (OPL). Based on their location, morphometric characteristics and co-localizations with outer retinal neuronal markers, we distinguished four populations of Cx36 plaques in the human OPL. Three of these were comprised of loosely scattered Cx36 plaques; the distalmost population 1 formed cone-to-rod GJs, population 2 in the mid-OPL formed cone-to-cone GJs, whereas the proximalmost population 4 likely connected bipolar cell dendrites. The fourth population (population 3) of Cx36 plaques conglomerated beneath cone pedicles and connected dendritic tips of bipolar cells that shared a common presynaptic cone. Overall, we show that the human outer retina displays a diverse cohort of Cx36 GJ that follows the general mammalian scheme and display a great functional diversity.

Keywords: Bipolar cell; Cone; Electrical synapse; Gap junction; Photoreceptor; Rod.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Calbindin 1 / metabolism
  • Connexins / metabolism*
  • Dendrites / metabolism
  • Female
  • Gap Junctions / metabolism*
  • Humans
  • Male
  • Middle Aged
  • Presynaptic Terminals / metabolism
  • Protein Kinase C-alpha / metabolism
  • Receptors, Glutamate / metabolism
  • Recoverin / metabolism
  • Retina / metabolism*
  • Retinal Bipolar Cells / metabolism
  • Retinal Cone Photoreceptor Cells / metabolism
  • Retinal Rod Photoreceptor Cells / metabolism
  • Synapses / metabolism

Substances

  • Calbindin 1
  • Connexins
  • RCVRN protein, human
  • Receptors, Glutamate
  • connexin 36
  • Recoverin
  • Protein Kinase C-alpha