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Eugenia Gurevich Lab

Neuroscience

AUTHORS

Song XX , Vishnivetskiy SA S A , Seo J J , Chen J J , Gurevich EV E V , Gurevich VV V V . Neuroscience. 2011 2 3; 174(). 37-49

ABSTRACT

In rod photoreceptors, signaling persists as long as rhodopsin remains catalytically active. Phosphorylation by rhodopsin kinase followed by arrestin-1 binding completely deactivates rhodopsin. Timely termination prevents excessive signaling and ensures rapid recovery. Mouse rods express arrestin-1 and rhodopsin at ∼0.8:1 ratio, making arrestin-1 the second most abundant protein in the rod. The biological significance of wild type arrestin-1 expression level remains unclear. Here we investigated the effects of varying arrestin-1 expression on its intracellular distribution in dark-adapted photoreceptors, rod functional performance, recovery kinetics, and morphology. We found that rod outer segments isolated from dark-adapted animals expressing arrestin-1 at wild type or higher level contain much greater fraction of arrestin-1 than previously estimated, 15-25% of the total. The fraction of arrestin-1 residing in the outer segments (OS) in animals with low expression (4-12% of wild type) is much lower, 5-7% of the total. Only 4% of wild type arrestin-1 level in the outer segments was sufficient to maintain near-normal retinal morphology, whereas rapid recovery required at least ∼12%. Supra-physiological arrestin-1 expression improved light sensitivity and facilitated photoresponse recovery, but was detrimental for photoreceptor health, particularly in the peripheral retina. Thus, physiological level of arrestin-1 expression in rods reflects the balance between short-term functional performance of photoreceptors and their long-term health.

In rod photoreceptors, signaling persists as long as rhodopsin remains catalytically active. Phosphorylation by rhodopsin kinase followed by arrestin-1 binding completely deactivates rhodopsin. Timely termination prevents excessive signaling and ensures rapid recovery. Mouse rods express arrestin-1 and rhodopsin at ∼0.8:1 ratio, making arrestin-1 the second most abundant protein in the rod. The biological significance of wild type arrestin-1 expression level remains unclear. Here we investigated the effects of varying arrestin-1 expression on its intracellular distribution in dark-adapted photoreceptors, rod functional performance, recovery kinetics, and morphology. We found that rod outer segments isolated from dark-adapted animals expressing arrestin-1 at wild type or higher level contain much greater fraction of arrestin-1 than previously estimated, 15-25% of the total. The fraction of arrestin-1 residing in the outer segments (OS) in animals with low expression (4-12% of wild type) is much lower, 5-7% of the total. Only 4% of wild type arrestin-1 level in the outer segments was sufficient to maintain near-normal retinal morphology, whereas rapid recovery required at least ∼12%. Supra-physiological arrestin-1 expression improved light sensitivity and facilitated photoresponse recovery, but was detrimental for photoreceptor health, particularly in the peripheral retina. Thus, physiological level of arrestin-1 expression in rods reflects the balance between short-term functional performance of photoreceptors and their long-term health.