Jomary Catherine, Cullen Jason, Jones Stephen E
Retinitis Pigmentosa Research Unit, The Rayne Institute, Wolfson Centre for Age-Related Diseases, School of Biomedical and Health Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom.
Invest Ophthalmol Vis Sci. 2006 Apr;47(4):1620-9. doi: 10.1167/iovs.05-1176.
Previous work has indicated that the serine-threonine protein kinase Akt is a general mediator of cellular survival signals and that loss of Akt-mediated signaling can lead to the activation of apoptosis. This study was conducted to establish whether regulation of the Akt survival pathway mechanisms is implicated in the induction of apoptosis during photoreceptor cell death in the rd mouse model of retinal degeneration.
Quantitative Western blot analysis and immunocytochemistry were used to examine the activation status and localization of key components of the Akt signaling cascade (Akt, BAD, Forkhead [FKHR], HSP27, mitogen-activated protein (MAP) kinase kinase-3 and -6 (MKK3/6), the tumor-suppressor phosphatase PTEN, and the cytoplasmic protein-tyrosine kinase cSrc-p60), in the retina of the rd mouse in comparison with the control. The time points examined spanned the period of photoreceptor degeneration.
In the period up to the peak of photoreceptor apoptosis at postnatal day 15, dysregulation of the survival pathway was identified at several levels, including deactivation of both Akt itself and its downstream transcription factor target Forkhead (FKHR) and activation of the upstream negative regulator PTEN.
Taken in conjunction with previous studies, the data support a model in which photoreceptor cell death in the rd mouse is the result of combined inactivation of the Akt survival pathway and the activation of the two major apoptotic pathways.
先前的研究表明，丝氨酸 - 苏氨酸蛋白激酶Akt是细胞存活信号的一般介质，Akt介导的信号传导缺失可导致细胞凋亡的激活。本研究旨在确定Akt存活途径机制的调节是否与视网膜变性rd小鼠模型中光感受器细胞死亡期间的细胞凋亡诱导有关。
采用定量蛋白质免疫印迹分析和免疫细胞化学方法，检测rd小鼠视网膜中Akt信号级联反应关键成分（Akt、BAD、叉头蛋白[FKHR]、热休克蛋白27、丝裂原活化蛋白[MAP]激酶激酶-3和-6[MKK3/6]、肿瘤抑制磷酸酶PTEN以及细胞质蛋白酪氨酸激酶cSrc-p60）的激活状态和定位，并与对照组进行比较。检测的时间点涵盖了光感受器变性的时期。
在出生后第15天光感受器细胞凋亡达到峰值之前的这段时间内，在几个水平上发现了存活途径的失调，包括Akt自身及其下游转录因子靶点叉头蛋白（FKHR）的失活以及上游负调节因子PTEN的激活。
结合先前的研究，这些数据支持一种模型，即rd小鼠中的光感受器细胞死亡是Akt存活途径的联合失活和两条主要凋亡途径激活的结果。
