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Updated: Apr 20, 2026
Two Peeling Methods for the Isolation of Photoreceptor Cell Compartments in the Mouse Retina for Protein Analysis
Published on: December 7, 2021
Spata7 is a retinal ciliopathy gene critical for correct RPGRIP1 localization and protein trafficking in the retina
Aiden Eblimit1, Thanh-Minh T Nguyen2, Yiyun Chen1
1HGSC, Department of Molecular and Human Genetics.
Insights
SPATA7 protein is crucial for vision, localizing to the eye
Area of Science:
- Ophthalmology
- Genetics
- Cell Biology
Background:
- Leber congenital amaurosis (LCA) and juvenile retinitis pigmentosa (RP) are severe inherited retinal diseases causing childhood vision loss.
- SPATA7 is a recently identified gene associated with LCA type 3 and juvenile RP, but its retinal function is unknown.
Purpose of the Study:
- To elucidate the function of SPATA7 in the retina and its role in LCA and juvenile RP.
Main Methods:
- Immunofluorescence to determine SPATA7 localization in photoreceptor cells.
- Co-immunoprecipitation to identify SPATA7 interacting proteins.
- Analysis of Spata7 null mutant mice retinas to assess RPGRIP1 localization and protein trafficking.
- Assessment of photoreceptor degeneration and visual function in Spata7 mutant mice.
Main Results:
- SPATA7 localizes to the primary and connecting cilia (CC) of photoreceptor cells, identifying it as a ciliary protein.
- SPATA7 directly interacts with RPGRIP1, a known LCA-associated protein.
- Spata7 deficiency leads to reduced RPGRIP1 at the CC and mislocalization of rhodopsin, causing photoreceptor apoptosis.
- Spata7 null mutant mice exhibit a juvenile RP-like phenotype with progressive photoreceptor degeneration.
Conclusions:
- SPATA7 is essential for the proper localization and function of the RPGRIP1 complex at the connecting cilium.
- The SPATA7-RPGRIP1 complex is critical for protein transport to the outer segments of photoreceptors.
- Protein mislocalization and subsequent rod photoreceptor apoptosis are key mechanisms driving disease progression in SPATA7-related retinal ciliopathies like LCA3 and juvenile RP.
Abstract:
Leber congenital amaurosis (LCA) and juvenile retinitis pigmentosa (RP) are severe hereditary diseases that causes visual impairment in infants and children. SPATA7 has recently been identified as the LCA3 and juvenile RP gene in humans, whose function in the retina remains elusive. Here, we show that SPATA7 localizes at the primary cilium of cells and at the connecting cilium (CC) of photoreceptor cells, indicating that SPATA7 is a ciliary protein. In addition, SPATA7 directly interacts with the retinitis pigmentosa GTPase regulator interacting protein 1 (RPGRIP1), a key connecting cilium protein that has also been linked to LCA. In the retina of Spata7 null mutant mice, a substantial reduction of RPGRIP1 levels at the CC of photoreceptor cells is observed, suggesting that SPATA7 is required for the stable assembly and localization of the ciliary RPGRIP1 protein complex. Furthermore, our results pinpoint a role of this complex in protein trafficking across the CC to the outer segments, as we identified that rhodopsin accumulates in the inner segments and around the nucleus of photoreceptors. This accumulation then likely triggers the apoptosis of rod photoreceptors that was observed. Loss of Spata7 function in mice indeed results in a juvenile RP-like phenotype, characterized by progressive degeneration of photoreceptor cells and a strongly decreased light response. Together, these results indicate that SPATA7 functions as a key member of a retinal ciliopathy-associated protein complex, and that apoptosis of rod photoreceptor cells triggered by protein mislocalization is likely the mechanism of disease progression in LCA3/ juvenile RP patients.
