Activation of mislocalized opsin kills rod cells: A novel mechanism for rod cell death in retinal disease
Activation of mislocalized opsin kills rod cells: A novel mechanism for rod cell death in retinal disease
复制标题
DOI：
10.1073/pnas.072557799
复制
发表时间：
2002-04-16
影响因子：
11.1
通讯作者：
Townes-Anderson, E
中科院分区：
文献类型：
--
作者：
Alfinito, PD;Townes-Anderson, E
视杆光感受器是高度区室化的感觉神经元，其保持严格的超微结构和分子极性。结构细分包括外节、内节、细胞体和突触末端。视色素视紫红质主要存在于视杆细胞外段的膜中，但变得错误定位，在许多视网膜疾病和损伤中出现在细胞的整个质膜中。目前，视紫红质再分布和视杆细胞死亡之间没有已知的联系。我们认为，激活错误定位的视紫红质杀死视杆细胞刺激正常无法访问的信号通路。在含有光感受器的原代视网膜细胞培养物中测试了这一假设。在视杆细胞中，视蛋白免疫荧光发生在整个视杆细胞质膜上。在异视紫红质形成后通过光刺激或通过与P-紫罗酮（视蛋白激动剂）孵育来激活这种错误定位的视蛋白杀死19-30%的视杆细胞。视杆细胞的死亡是凋亡性的，如显着的染色质凝聚和caspase-3激活的要求所示。毛喉素（腺苷酸环化酶激动剂）可以诱导视杆细胞死亡，相反，P-紫罗兰酮诱导的细胞死亡可以通过与SQ 22536（腺苷酸环化酶抑制剂）共同处理来阻断。百日咳毒素（G蛋白抑制剂）也阻断P-紫罗酮诱导的细胞死亡。这些数据支持了一种机制，即错误定位的视蛋白激活通过G蛋白刺激腺苷酸环化酶启动凋亡性视杆细胞死亡。
Rod photoreceptors are highly compartmentalized sensory neurons that maintain strict ultrastructural and molecular polarity. Structural subdivisions include the outer segment, inner segment, cell body, and synaptic terminal. The visual pigment rhodopsin is found predominantly in membranes of the rod cell outer segment but becomes mislocalized, appearing throughout the plasma membrane of the cell in many retinal diseases and injuries. Currently, there is no known link between rhodopsin redistribution and rod cell death. We propose that activation of mislocalized rhodopsin kills rod cells by stimulating normally inaccessible signaling pathways. This hypothesis was tested in primary retinal cell cultures, which contain photoreceptors. In rod photoreceptors, opsin immunofluorescence occurred throughout the rod cell plasma membrane. Activation of this mislocalized opsin by photostimulation after formation of isorhodopsin or by incubation with P-ionone (opsin agonist) killed 19-30% of rod cells. Rod cell death was apoptotic, as indicated by marked chromatin condensation and the requirement for caspase-3 activation. Rod cell death could be induced by forskolin (adenylate cyclase agonist), and conversely, P-ionone-induced cell death could be blocked by cotreatment with SQ22536 (an adenylate cyclase inhibitor). Pertussis toxin (a G protein inhibitor) also blocked P-ionone-induced cell death. The data support a mechanism by which activation of mislocalized opsin initiates apoptotic rod cell death through G protein stimulation of adenylate cyclase.