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Invest Ophthalmol Vis Sci. 2006 May;47(5):2185-94.

Effects of low AIPL1 expression on phototransduction in rods.

Author information

  • 1Howe Laboratory, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston 02114, USA. cmakino@meei.harvard.edu

Erratum in

  • Invest Ophthalmol Vis Sci. 2006 Jun;47(6):2279.

Abstract

PURPOSE:

To investigate the impact of aryl hydrocarbon receptor-interacting protein-like (AIPL)-1 on photoreception in rods.

METHODS:

Photoresponses of mouse rods expressing lowered amounts of AIPL1 were studied by single-cell and electroretinogram (ERG) recordings. Phototransduction protein levels and enzymatic activities were determined in biochemical assays. Ca2+ dynamics were probed with a fluorescent dye. Comparisons were made to rods expressing mutant Y99C guanylate cyclase activating protein (GCAP)-1, to understand which effects arose from elevated dark levels of cGMP and Ca2+.

RESULTS:

Except for PDE, transduction protein levels were normal in low-AIPL1 retinas, as were guanylate cyclase (GC), rhodopsin kinase (RK), and normalized phosphodiesterase (PDE) activities. Y99C and low-AIPL1 rods were more sensitive to flashes than normal, but flash responses of low-AIPL1 rods showed an abnormal delay, reduced rate of increase, and longer recovery not present in Y99C rod responses. In addition, low-AIPL1 rods but not Y99C rods failed to reach the normal light-induced minimum in Ca2+ concentration.

CONCLUSIONS:

Reduced AIPL1 delayed the photoresponse, decreased its amplification constant, slowed a rate-limiting step in its recovery, and limited the light-induced decrease in Ca2+. Not all changes were attributable to decreased PDE or to elevated cGMP and Ca2+ in darkness. Therefore, AIPL1 directly or indirectly affects more than one component of phototransduction.

PMID:
16639031
[PubMed - indexed for MEDLINE]
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