Dysfunction of heterotrimeric kinesin-2 in rod photoreceptor cells and the role of opsin mislocalization in rapid cell death.
Dysfunction of heterotrimeric kinesin-2 in rod photoreceptor cells and the role of opsin mislocalization in rapid cell death.
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DOI：
10.1091/mbc.e10-08-0715
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发表时间：
2010-12
影响因子：
3.3
通讯作者：
Williams DS
中科院分区：
文献类型：
--
作者：
Lopes VS;Jimeno D;Khanobdee K;Song X;Chen B;Nusinowitz S;Williams DS
驱动蛋白-2功能的丧失导致视杆细胞光感受器的快速死亡。细胞死亡依赖于视蛋白的表达，视蛋白首先沿着沿着积累到外节，但不依赖于视蛋白-抑制蛋白复合物或光激活的信号传导;关键因素似乎是过量蛋白质在错误的地方积累。由于光感受器纤毛的广泛加工以形成外节，光感受器中的轴丝运输（IFT）非常忙碌繁忙，并且视网膜变性是许多纤毛病的组成部分。异源三聚体驱动蛋白-2（一种主要的顺行IFT马达）的功能丧失导致视蛋白定位错误，随后细胞快速死亡。在这里，我们已经分析了蛋白质的错误定位的性质和死亡的驱动蛋白-2-突变杆光感受器的要求。定量免疫电镜显示，视蛋白最初积聚在内节内，然后积聚在质膜中。光激活运动的arrestin的外节也受损，但这种缺陷可能是次要的结果，从结合到错误定位的视蛋白。与其他一些视网膜变性不同，视蛋白-抑制蛋白复合物和光活化都不是细胞丢失所必需的。相比之下，视杆视蛋白表达减少提供增强的视杆和视锥光感受器存活和功能，如通过光感受器细胞计数、凋亡测定和ERG分析所测量的。Rho−/−几乎完全消除了驱动蛋白-2功能丧失导致的细胞死亡。我们的研究结果表明，错误定位的视蛋白是感光细胞死亡的驱动蛋白-2功能障碍的主要原因，并证明积累错误定位的蛋白本身的重要性，而不是特定的信号转导特性的视蛋白，源于光活化或抑制蛋白结合。
Loss of kinesin-2 function causes rapid death of rod photoreceptors. The cell death is dependent on the expression of opsin, which first accumulates along the route to the outer segment, but not on signaling by opsin-arrestin complexes or by light activation; the key element appears to be the accumulation of excessive protein in the wrong place. Due to extensive elaboration of the photoreceptor cilium to form the outer segment, axonemal transport (IFT) in photoreceptors is extraordinarily busy, and retinal degeneration is a component of many ciliopathies. Functional loss of heterotrimeric kinesin-2, a major anterograde IFT motor, causes mislocalized opsin, followed by rapid cell death. Here, we have analyzed the nature of protein mislocalization and the requirements for the death of kinesin-2-mutant rod photoreceptors. Quantitative immuno EM showed that opsin accumulates initially within the inner segment, and then in the plasma membrane. The light-activated movement of arrestin to the outer segment is also impaired, but this defect likely results secondarily from binding to mislocalized opsin. Unlike some other retinal degenerations, neither opsin–arrestin complexes nor photoactivation were necessary for cell loss. In contrast, reduced rod opsin expression provided enhanced rod and cone photoreceptor survival and function, as measured by photoreceptor cell counts, apoptosis assays, and ERG analysis. The cell death incurred by loss of kinesin-2 function was almost completely negated by Rho−/−. Our results indicate that mislocalization of opsin is a major cause of photoreceptor cell death from kinesin-2 dysfunction and demonstrate the importance of accumulating mislocalized protein per se, rather than specific signaling properties of opsin, stemming from photoactivation or arrestin binding.