A Critical role for Bim in retinal ganglion cell death
A Critical role for Bim in retinal ganglion cell death
复制标题
DOI：
10.1111/j.1471-4159.2007.04573.x
复制
发表时间：
2007-08-01
影响因子：
4.7
通讯作者：
Cotter, T. G.
中科院分区：
文献类型：
--
作者：
McKernan, Declan P.;Cotter, T. G.
视神经横断导致视网膜神经节细胞（RGC）因细胞凋亡而死亡。细胞凋亡受 Bcl-2 蛋白家族的调节，其中 Bcl-2 同源蛋白 (BH3) 构成了其中的一个子集。由于仅 BH3 蛋白已被证明在调节中枢神经系统细胞死亡中发挥重要作用，因此我们希望使用体外视网膜外植体研究 Bcl-2 相互作用细胞死亡介质 (Bim) 的作用，Bim 是该蛋白家族的重要成员，在调节 RGC 层细胞死亡中的作用。在这项研究中，我们使用创新的视网膜剃须程序来分离神经节细胞层的细胞，用于蛋白质印迹。仅 BH3 蛋白家族的成员在视网膜发育过程中下调，并且在成人视网膜中通常不表达。使用此程序，我们证明 Bim 重新表达，并且其表达在轴突切除后随着时间的推移而增加。 Bad 和 Bik 的表达在同一时间过程中减少，而没有迹象表明 Bid 和 Puma 重新表达。我们发现，与野生型小鼠相比，Bim 敲除小鼠的外植体能够抵抗轴切术引起的死亡。 Bim 的基因缺失还可以防止 caspase 3 裂解。 Bim 的活性可通过磷酸化进行负向调节。我们发现，在同一时间过程中，Bim 磷酸化的减少与 pAkt 和 pERK 等生存激酶表达的减少相关。这些结果表明 Bim 重新表达对于轴突切断术诱导的 RGC 死亡至关重要，并且 Bim 的磷酸化负向调节其在 RGC 中的活性。
Optic nerve transection results in the death of retinal ganglion cells (RGCs) by apoptosis. Apoptosis is regulated by the Bcl-2 family of proteins, of which the Bcl-2 homology (BH3) -only proteins forms a subset. As BH3-only proteins have been shown to play a significant role in regulating cell death in the central nervous system, we wished to investigate the role of Bcl-2 interacting mediator of cell death (Bim), a prominent member of this protein family in the regulation of cell death in the RGC layer using in vitro retinal explants. In this study, we use an innovative retinal shaving procedure to isolate the cells of the ganglion cell layer to use for western blotting. Members of the BH3-only protein family are down-regulated during retinal development and are not normally expressed in the adult retina. Using this procedure, we demonstrate that Bim is re-expressed and its expression is increased over time fol-lowing axotomy. Expression of Bad and Bik decreases over the same time course, whereas there is no indication that Bid and Puma are re-expressed. We show that explants from Bim knockout mice are resistant to axotomy-induced death when compared with their wild-type counterparts. Genetic deletion of Bim also prevents caspase 3 cleavage. The activity of Bim can be negatively regulated by phosphorylation. We show that the decrease of Bim phosphorylation correlates with a decrease in expression of survival kinases such as pAkt and pERK over the same time course. These results implicate Bim re-expression as being essential for axotomy-induced death of RGCs and that phosphorylation of Bim negatively regulates its activity in RGCs.