Rao Anjali, Dallman Rebecca, Henderson Scott, Chen Ching-Kang
Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
J Neurosci. 2007 Dec 19;27(51):14199-204. doi: 10.1523/JNEUROSCI.4934-07.2007.
Gbeta5 exists as two splice variants, Gbeta5-S and Gbeta5-L, which interact with and stabilize the R7 members of the regulators of G-protein signaling (RGSs): RGS6, RGS7, RGS9, and RGS11. Although the role of Gbeta5-L and RGS9-1 is established in photoreceptors, the physiological functions of Gbeta5-S and other R7 RGS proteins remain unclear. We found that the electroretinogram of Gbeta5-/- mice lacks the b-wave component and that Gbeta5-S and RGS11 colocalize with Go alpha at the tips of the ON-bipolar cell dendrites. Unexpectedly, we found a significant reduction in the number of synaptic triads in the outer plexiform layer (OPL) of the Gbeta5-/- mice, which is evident at postnatal day 14. Transgenic expression of Gbeta5-L in rods failed to rescue the b-wave or the OPL defects. These results indicate that Gbeta5-S is indispensable for OPL integrity and normal light responses of the retina.
Gβ5 以两种剪接变体 Gβ5-S 和 Gβ5-L 的形式存在，它们与 G 蛋白信号调节因子（RGSs）的 R7 成员相互作用并使其稳定，这些成员包括 RGS6、RGS7、RGS9 和 RGS11。尽管 Gβ5-L 和 RGS9-1 在光感受器中的作用已得到证实，但 Gβ5-S 和其他 R7 RGS 蛋白的生理功能仍不清楚。我们发现 Gβ5-/- 小鼠的视网膜电图缺乏 b 波成分，并且 Gβ5-S 和 RGS11 在 ON 双极细胞树突末端与 Goα 共定位。出乎意料的是，我们发现 Gβ5-/- 小鼠外网状层（OPL）中突触三联体的数量显著减少，这在出生后第 14 天很明显。在视杆细胞中转基因表达 Gβ5-L 未能挽救 b 波或 OPL 缺陷。这些结果表明，Gβ5-S 对于视网膜的 OPL 完整性和正常光反应是不可或缺的。
