期刊
VISUAL NEUROSCIENCE
卷 27, 期 1-2, 页码 9-17出版社
CAMBRIDGE UNIV PRESS
DOI: 10.1017/S0952523809990319
关键词
Electroretinogram; ERG b-wave; RGS proteins; Retina
资金
- National Institutes of Health [EY09534, EY014700, EY018625, MH067094, RR000163]
- National Health and Medical Research Council
- American Australian Association
- NATIONAL CENTER FOR RESEARCH RESOURCES [K01RR000163, P51RR000163] Funding Source: NIH RePORTER
- NATIONAL EYE INSTITUTE [R01EY018625, R01EY014700, R01EY009534] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [R01GM066099] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF MENTAL HEALTH [R01MH067094] Funding Source: NIH RePORTER
The rate-limiting step in the recovery of the photoreceptor light response is the hydrolysis of GTP by transducin, a reaction that is accelerated by the RGS9-G beta 5 complex, and its membrane anchor, R9AP. Similar complexes, including RGS7, RGS11, and G beta 5, are found in retinal ON-bipolar cell dendrites. Here, we present evidence that R9AP is also expressed in the dendritic tips of ON-bipolar cells. Immunofluorescent staining for R9AP revealed a punctilio pattern of labeling in the outer plexiform layer, where it colocalized with mGluR6. In photoreceptors, MAP is required for proteolytic stability of the entire regulator of G protein signaling complex, and we found that genetic deletion of R9AP also results in a marked reduction in the levels of RGS11 and G beta 5 in the bipolar cell dendrites; the level of RGS7 was unaffected, suggesting the presence of another interaction partner to stabilize RGS7. To determine the effect of R9AP deletion on the response kinetics of ON-bipolar cells, we compared the electroretinogram (ERG) between wild-type and R9AP-deficient mice. The ERG b-wave, reflecting ON-bipolar cell activity, was delayed and larger in the R9AP-deficient mice. Our data indicate that R9AP is required for stable expression of RGS11-G beta 5 in ON-bipolar cell dendrites. Furthermore, they suggest that the RGS11-G beta 5-R9AP complex accelerates the initial ON-bipolar cell response to light.
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