Purchase this article with an account.
Nazarul Hasan, Bart G Borghuis, Ronald G Gregg; Restoration of cone ON bipolar cells siglanplex expression and function in a mouse model of cCSNB. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2006.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Adeno-associated virus (AAV) mediated gene delivery is showing great potential for treating genetic diseases that disrupt retinal structure and function. The human disease, complete congenital stationary night blindness (cCSNB) is a genetically heterogeneous disorder of the retina characterized by impairment of low light vision and loss of the b-wave of the electroretinogram (ERG). In mouse models of cCSNB the normal ON retinal ganglion cell responses are absent. Synaptic function requires proper alignment of pre- and postsynaptic elements, including alignment of signaling molecules that govern neurotransmitter release and reception. LRIT3 is a presynaptic, leucine rich repeat protein that when absent causes loss of the postsynaptic TRPM1 and Nyctalopin expression from the dendritic tips of rod bipolar cells, and in addition mGluR6, GPR179 and the RGS complex of proteins from dendritic tips of cone ON bipolar cells. Here we investigate whether LRIT3 expression in cone photoreceptors regulates the cone ON bipolar cells signalplex expression and localization.
To express LRIT3 in cone photoreceptors we used a human GNAT2 promoter to selectively express LRIT3 in cones. The construct GNAT2::Lrit3, was packaged in rAAVs, which were injected subretinally into adult mice. We characterized overall retinal function of GNAT2::Lrit3 rAAVs in Lrit3-/- mice using ERG, and retinal ganglion cell (RGC) responses by patch-clamp recording. Expression and localization of synaptic proteins were examined by immunohistochemistry.
We show that expression of LRIT3 in cones restores cone mediated retinal function. Light adapted ERGs from 12 GNAT2::Lrit3 mice showed restoration of the b-wave to between 32% and 72% of WT values. Recordings from ON alpha RGCs showed recovery of light responses and synaptic current oscillations characteristic of Lrit3-/- retina were absent or negligible. Immunohistochemistry showed that LRIT3 expression was restored to cone terminals, as were the post-synaptic signalplex proteins, TRPM1, Nyctalopin, mGluR6, and GPR179.
Our data show that LRIT3 functions in a trans-synaptic manner and controls the expression and localization of the cone ON bipolar cell signalplex proteins. These data also show the potential for gene therapy of cCSNB patients with mutations in LRIT3 by AAV mediated gene delivery.
This is a 2021 ARVO Annual Meeting abstract.
This PDF is available to Subscribers Only