Gnat1-KO Mouse

GNAT1, encoding the rod-specific transducin α -subunit, is a key element in the rod phototransduction cascade, playing a crucial role in vision [2,3]. It is involved in the process of converting light stimuli into neural signals in the retina, thus being of great biological importance for normal visual function. Genetic models, such as gene knockout mice, are valuable tools for studying its function.

In a consanguineous Pakistani family, a missense mutation in GNAT1 (p.D129G) was associated with autosomal recessive stationary night blindness, suggesting that loss-of-function of GNAT1 can lead to non-progressive retinal disorders affecting night vision [2]. In a Japanese family, a GNAT1 variant (p.G38D) was found in patients with Nougaret-type congenital stationary night blindness (CSNB), and co-existence of GNAT1 and biallelic ABCA4 variants was associated with an overlapping phenotype of CSNB and childhood-onset cone-rod dystrophy [1]. A novel homozygous truncating mutation in GNAT1 was reported in a patient with retinitis pigmentosa, indicating that some GNAT1 variants can cause a recessive, mild, late-onset retinal degeneration in addition to night-blindness [3]. In Gnat1-/-mice, constitutively depolarized rods release excessive glutamate, accelerating deep plexus angiogenesis and paracellular blood-retinal barrier maturation, demonstrating the role of GNAT1 in regulating glutamatergic neuronal activity-related angiogenesis and blood-retinal barrier maturation [4]. In Gnat1-/-; Gnat2cpfl3/cpfl3 mice, which lack rod and cone α-transducin proteins, robust light responses were still observed, suggesting that melanopsin-mediated phototransduction can contribute to the primary pattern-forming visual pathway even without functional rods and cones [5].

In conclusion, GNAT1 is essential for normal rod phototransduction and visual function. Gene knockout mouse models have revealed its role in various retinal diseases, including congenital stationary night blindness, cone-rod dystrophy, and retinitis pigmentosa. These studies help in understanding the mechanisms of retinal diseases related to GNAT1 and may provide potential directions for treatment.