Ying Guoxin, Gerstner Cecilia D, Frederick Jeanne M, Boye Sanford L, Hauswirth William W, Baehr Wolfgang
Department of Ophthalmology and Visual Sciences, University of Utah Health Science Center, Salt Lake City, UT, 84132, United States of America.
Department of Ophthalmology, University of Florida, 1600 SW Archer Road, Gainesville, FL, 32610, United States of America.
PLoS One. 2016 Aug 16;11(8):e0161236. doi: 10.1371/journal.pone.0161236. eCollection 2016.
Rab11a and Rab8a are ubiquitous small GTPases shown as required for rhodopsin transport in Xenopus laevis and zebrafish photoreceptors by dominant negative (dn) disruption of function. Here, we generated retina-specific Rab11a (retRab11a) and Rab8a (retRab8a) single and double knockout mice to explore the consequences in mouse photoreceptors. Rhodopsin and other outer segment (OS) membrane proteins targeted correctly to OS and electroretinogram (ERG) responses in all three mutant mouse lines were indistinguishable from wild-type (WT). Further, AAV (adeno-associated virus)-mediated expression of dnRab11b in retRab11a-/- retina, or expression of dnRab8b in retRab8a-/- retina did not cause OS protein mislocalization. Finally, a retRab8a-/- retina injected at one month of age with AAVs expressing dnRab11a, dnRab11b, dnRab8b, and dnRab10 (four dn viruses on Rab8a-/- background) and harvested three months later exhibited normal OS protein localization. In contrast to results obtained with dnRab GTPases in Xenopus and zebrafish, mouse Rab11a and Rab8a are dispensable for proper rhodopsin and outer segment membrane protein targeting. Absence of phenotype after expression of four dn Rab GTPases in a Rab8a-/- retina suggests that Rab8b and Rab11b paralogs maybe dispensable as well. Our data thus demonstrate significant interspecies variation in photoreceptor membrane protein and rhodopsin trafficking.
Rab11a和Rab8a是普遍存在的小GTP酶，通过显性负性（dn）功能破坏，在非洲爪蟾和斑马鱼光感受器的视紫红质运输中显示为必需。在这里，我们生成了视网膜特异性Rab11a（retRab11a）和Rab8a（retRab8a）单敲除和双敲除小鼠，以探索对小鼠光感受器的影响。在所有三个突变小鼠品系中，视紫红质和其他外段（OS）膜蛋白正确靶向OS，并且视网膜电图（ERG）反应与野生型（WT）没有区别。此外，腺相关病毒（AAV）介导的dnRab11b在retRab11a-/-视网膜中的表达，或dnRab8b在retRab8a-/-视网膜中的表达，均未导致OS蛋白定位错误。最后，在1月龄时用表达dnRab11a、dnRab11b、dnRab8b和dnRab10（Rab8a-/-背景下的四种dn病毒）的AAV注射retRab8a-/-视网膜，并在三个月后收获，其OS蛋白定位正常。与在非洲爪蟾和斑马鱼中使用dnRab GTP酶获得的结果相反，小鼠Rab11a和Rab8a对于视紫红质和外段膜蛋白的正确靶向是可有可无的。在Rab8a-/-视网膜中表达四种dn Rab GTP酶后没有表型，这表明Rab8b和Rab11b旁系同源物可能也是可有可无的。因此，我们的数据证明了光感受器膜蛋白和视紫红质运输中存在显著的种间差异。
