Yang Liu, Bula Deisy, Arroyo Jorge G, Chen Dong F
Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA.
Invest Ophthalmol Vis Sci. 2004 Feb;45(2):648-54. doi: 10.1167/iovs.03-0827.
To characterize photoreceptor cell apoptosis and cell loss in a mouse model of experimental retinal detachment (RD), and to use the technology of mouse genetics to study the molecular mechanisms underlying RD-associated photoreceptor degeneration.
Retinal detachments were created in adult wild-type and Bax-deficient mice by subretinal injection of 1.4% sodium hyaluronate. At 1, 3, 7, and 28 days after injection, animals were killed, eyes enucleated, and retinal sections studied by histochemistry, immunofluorescence labeling, and confocal microscopy. Rods and cones were labeled, and apoptotic cells were identified with terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Photoreceptor cell apoptosis and cell loss were assessed quantitatively by counting both surviving and TUNEL-positive rods and cones.
TUNEL-positive cells were found within the outer nuclear layer (ONL) of the detached portions of the retina. They were detected in the detached retina on day 1, peaked on day 3, and dropped precipitously after day 7 after RD. Photoreceptor cell loss of both rods and cones followed a similar time course after RD. Moreover, deletion of the proapoptotic gene Bax in a knockout mouse model abolished the RD-associated photoreceptor cell degeneration.
Apoptosis is a major mechanism leading to photoreceptor cell death after RD. Blockage of the activity of the proapoptotic molecule Bax in a knockout mouse model prevents photoreceptor cell apoptosis and cell loss. These data suggest that the Bax-mediated apoptotic signaling pathway plays a critical role in RD-associated photoreceptor cell death.
在实验性视网膜脱离（RD）小鼠模型中表征光感受器细胞凋亡和细胞丢失，并利用小鼠遗传学技术研究RD相关光感受器变性的分子机制。
通过视网膜下注射1.4%透明质酸钠，在成年野生型和Bax基因缺陷小鼠中造成视网膜脱离。在注射后1、3、7和28天，处死动物，摘除眼球，通过组织化学、免疫荧光标记和共聚焦显微镜研究视网膜切片。标记视杆细胞和视锥细胞，并用末端脱氧核苷酸转移酶dUTP缺口末端标记法（TUNEL）鉴定凋亡细胞。通过计数存活的和TUNEL阳性的视杆细胞和视锥细胞，定量评估光感受器细胞凋亡和细胞丢失。
在视网膜脱离部分的外核层（ONL）中发现了TUNEL阳性细胞。在RD后第1天在脱离的视网膜中检测到这些细胞，在第3天达到峰值，并在第7天后急剧下降。RD后视杆细胞和视锥细胞的光感受器细胞丢失遵循相似的时间进程。此外，在基因敲除小鼠模型中删除促凋亡基因Bax可消除RD相关的光感受器细胞变性。
凋亡是RD后导致光感受器细胞死亡的主要机制。在基因敲除小鼠模型中阻断促凋亡分子Bax的活性可防止光感受器细胞凋亡和细胞丢失。这些数据表明，Bax介导的凋亡信号通路在RD相关的光感受器细胞死亡中起关键作用。
