School of Optometry Vision Sciences, Maindy Road, Cardiff University, Cardiff, UK.
Brain. 2010 Oct;133(10):2942-51. doi: 10.1093/brain/awq218. Epub 2010 Sep 3.
The heterozygous mutation B6;C3-Opa1(Q285STOP), which models autosomal dominant optic atrophy, leads to a 50% reduction in Opa1 transcript and protein in the mouse retina and neural tissues and is associated with visual dysfunction and structural changes in the murine retina and optic nerve. In this article we use this model to quantify and evaluate the dendritic morphology of retinal ganglion cells. Retinal ganglion cells in Opa1(+/-) mutant mice (n=16) and accompanying age- and sex-matched controls (n=11) (age ranges of <10, 10-15 and >20 months) were labelled DiOlistically with carbocyanine dyes to quantify changes in dendritic tree architecture as a function of age. We observed localized dendritic reduction to sublamina b of the inner plexiform layer without retinal ganglion cell loss, showing dendritic pruning of on- but not off-centre retinal ganglion cells, and this effect was exacerbated with age. The mean dendritic field area was reduced in on-centre retinal ganglion cells of 10- to 15-month-old mice (-24.24%; C(V) =0.68; P<0.05) and >20-month-old mice (-43.22%; C(V) =0.75; P<0.05) compared with age-matched wild-type controls. Similar changes were seen in average total dendritic length in on-centre retinal ganglion cells of 10- to 15-month-old mice (-31.66%; C(V) =0.67; P<0.05) and >20-month-old mice (-49.55%; C(V) =0.63; P<0.05). Sholl analysis showed a marked difference in the dendritic arborization of on-centre retinal ganglion cells in the 10- to 15-month-old group (area under the curve -21.67%; P>0.05) and of the >20-month-old group (area under the curve -42.12%; P<0.05) compared with the control group. There was no detectable change in dendritic morphology in <10-month-old Opa1(+/-) mutant mice compared with wild-type (P>0.05). No significant changes (P>0.05) were seen in off-centre retinal ganglion cells. Finally, there was also no significant change (P>0.05) in the retinal ganglion cell count across all age groups. In conclusion, we show dendritic pruning in on-centre retinal ganglion cells of the Opa1(+/-) mouse model of autosomal dominant optic atrophy from as early as 10 months of age. These results highlight the importance of normal mitochondrial fusion balance, as influenced by the OPA1 protein in maintaining the dendritic morphology of retinal ganglion cells. Dendritic pruning precedes the onset of clinical visual loss and structural changes in the optic nerve in the absence of significant cell loss.
杂合突变 B6;C3-Opa1(Q285STOP)，模拟常染色体显性视神经萎缩，导致小鼠视网膜和神经组织中的 Opa1 转录本和蛋白减少 50%，与视觉功能障碍和小鼠视网膜及视神经的结构变化有关。在本文中，我们使用该模型来定量和评估视网膜神经节细胞的树突形态。用 DiI 对 Opa1(+/-)突变小鼠 (n=16) 和伴随的年龄和性别匹配的对照 (n=11)（年龄范围<10、10-15 和>20 个月）进行视网膜神经节细胞的标记，以量化树突结构随年龄的变化。我们观察到局部树突向内丛状层亚层的减少而没有视网膜神经节细胞丢失，表明仅对中心视网膜神经节细胞进行树突修剪，而不是对偏心视网膜神经节细胞进行修剪，并且这种效应随着年龄的增长而加剧。10-15 月龄和>20 月龄小鼠的中心视网膜神经节细胞的平均树突场面积分别减少 (-24.24%；C(V)=0.68；P<0.05) 和 (-43.22%；C(V)=0.75；P<0.05)，与年龄匹配的野生型对照相比。10-15 月龄和>20 月龄的中心视网膜神经节细胞的平均总树突长度也有类似的变化 (-31.66%；C(V)=0.67；P<0.05) 和 (-49.55%；C(V)=0.63；P<0.05)。Sholl 分析显示，10-15 月龄组 (曲线下面积 -21.67%；P>0.05) 和>20 月龄组 (曲线下面积 -42.12%；P<0.05) 的中心视网膜神经节细胞树突分支明显不同与对照组相比。与野生型相比，<10 月龄的 Opa1(+/-)突变小鼠的树突形态没有明显变化 (P>0.05)。偏心视网膜神经节细胞没有明显变化 (P>0.05)。最后，所有年龄组的视网膜神经节细胞计数均无明显变化 (P>0.05)。总之，我们在 10 个月大的常染色体显性视神经萎缩 Opa1(+/-)小鼠模型中观察到中心视网膜神经节细胞的树突修剪，早于临床视觉丧失和视神经结构变化的发生。这些结果强调了正常线粒体融合平衡的重要性，这种平衡受 OPA1 蛋白的影响，可维持视网膜神经节细胞的树突形态。在没有明显细胞丢失的情况下，树突修剪先于临床视觉丧失和视神经结构变化的发生。
