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Sci Rep. 2017 Sep 6;7(1):10651. doi: 10.1038/s41598-017-11034-1.

Abnormal Electroretinogram after Kir7.1 Channel Suppression Suggests Role in Retinal Electrophysiology.

Author information

1
Department of Pediatrics, University of Wisconsin-Madison, Madison, USA.
2
McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, USA.
3
Department of Pharmacology, Vanderbilt University, Madison, USA.
4
Department of Medical Genetics, University of Wisconsin-Madison, Madison, USA.
5
Department of Pediatrics, University of Wisconsin-Madison, Madison, USA. pattnaik@wisc.edu.
6
Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, USA. pattnaik@wisc.edu.
7
McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, USA. pattnaik@wisc.edu.

Abstract

The KCNJ13 gene encodes the inwardly rectifying potassium channel, Kir7.1. Mutations in this gene cause childhood blindness, in which the a- and b-wave responses of electroretinogram (ERG) are abolished. The ERG a-wave is the light-induced hyperpolarization of retinal photoreceptors, and the b-wave is the depolarization of ON-bipolar cells. The Kir7.1 channel is localized to the apical aspects of retinal pigment epithelium (RPE) cells and contributes to a delayed c-wave response. We sought to understand why a defect in an RPE ion-channel result in abnormal electrophysiology at the level of the retinal neurons. We have established the expression of Kir7.1 channels in the mouse RPE. ERGs recorded after mice Kir7.1 suppression by shRNA, or by blocking with VU590, showed reduced a-, b- and c-wave amplitudes. In contrast, the Kir7.1 blocker had no effect on the ex-vivo isolated mouse retina ERG where the RPE is not attached to the isolated retina preparation. Finally, we confirmed the specificity of VU590 action by inhibition of native mouse RPE Kir7.1 current in patch-clamp experiment. We propose that mutant RPE Kir7.1 channels contribute directly to the abnormal ERG associated with blindness via alterations in sub-retinal space K+ homeostasis in the vicinity of the photoreceptor outer segment.

PMID:
28878288
PMCID:
PMC5587531
DOI:
10.1038/s41598-017-11034-1
[Indexed for MEDLINE]
Free PMC Article

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