LRIT1 Modulates Adaptive Changes in Synaptic Communication of Cone Photoreceptors

Cell Rep. 2018 Mar 27;22(13):3562-3573. doi: 10.1016/j.celrep.2018.03.008.


Cone photoreceptors scale dynamically the sensitivity of responses to maintain responsiveness across wide range of changes in luminance. Synaptic changes contribute to this adaptation, but how this process is coordinated at the molecular level is poorly understood. Here, we report that a cell adhesion-like molecule, LRIT1, is enriched selectively at cone photoreceptor synapses where it engages in a trans-synaptic interaction with mGluR6, the principal receptor in postsynaptic ON-bipolar cells. The levels of LRIT1 are regulated by the neurotransmitter release apparatus that controls photoreceptor output. Knockout of LRIT1 in mice increases the sensitivity of cone synaptic signaling while impairing its ability to adapt to background light without overtly influencing the morphology or molecular composition of photoreceptor synapses. Accordingly, mice lacking LRIT1 show visual deficits under conditions requiring temporally challenging discrimination of visual signals in steady background light. These observations reveal molecular mechanisms involved in scaling synaptic communication in the retina.

Keywords: G protein coupled receptors; ON-bipolar neurons; cone photoreceptors; leucine-rich repeat proteins; synaptic transmission.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • HEK293 Cells
  • Humans
  • Membrane Glycoproteins / metabolism*
  • Mice
  • Mouse Embryonic Stem Cells / metabolism
  • Receptors, Metabotropic Glutamate / metabolism
  • Retinal Cone Photoreceptor Cells / metabolism*
  • Synapses / metabolism*


  • LRIT1 protein, human
  • Membrane Glycoproteins
  • Receptors, Metabotropic Glutamate
  • metabotropic glutamate receptor 6