UPMC Univ Paris 06, UMR 7102, Paris, France.
Mol Cell Neurosci. 2013 May;54:9-21. doi: 10.1016/j.mcn.2012.11.010. Epub 2012 Nov 29.
During their phase of developmental programmed cell death (PCD), neurons depend on target-released trophic factors for survival. After this period, however, they critically change as their survival becomes target-independent. The molecular mechanisms underlying this major transition remain poorly understood. Here, we investigated, which transcription factors (TFs) might be responsible for the closure of PCD. We used Purkinje cells as a model since their PCD is restricted to the first postnatal week in the mouse cerebellum. Transcriptome analysis of Purkinje cells during or after PCD allowed the identification of Krüppel like factor 9 (Klf9) as a candidate for PCD closure, given its high increase of expression at the end of the 1st postnatal week. Klf9 function was tested in organotypic cultures, through lentiviral vector-mediated manipulation of Klf9 expression. In absence of trophic factors, the Purkinje cell survival rate is of 40%. Overexpression of Klf9 during PCD dramatically increases the Purkinje cell survival rate from 40% to 88%, whereas its down-regulation decreases it to 14%. Accordingly, in organotypic cultures of Klf9 knockout animals, Purkinje cell survival rate is reduced by half as compared to wild-type mice. Furthermore, the absence of Klf9 could be rescued by Purkinje cell trophic factors, Insulin growth factor-1 and Neurotrophin3. Altogether, our results ascribe a clear role of Klf9 in Purkinje cell survival. Thus, we propose that Klf9 might be a key molecule involved in turning off the phase of Purkinje PCD.
在其程序化细胞死亡（PCD）的发育阶段，神经元依赖靶细胞释放的营养因子来存活。然而，在这个阶段之后，它们的存活变得与靶细胞无关，因此会发生关键性变化。这种主要转变的分子机制仍知之甚少。在这里，我们研究了哪些转录因子（TFs）可能负责关闭 PCD。我们使用浦肯野细胞作为模型，因为它们的 PCD 仅发生在小鼠小脑的第一个出生后周内。在 PCD 期间或之后对浦肯野细胞进行转录组分析，发现 Krüppel 样因子 9（Klf9）是 PCD 关闭的候选者，因为其在第一周后表达量急剧增加。通过慢病毒载体介导的 Klf9 表达操纵，在器官型培养物中测试了 Klf9 的功能。在没有营养因子的情况下，浦肯野细胞的存活率为 40%。在 PCD 期间过表达 Klf9 可将浦肯野细胞的存活率从 40%大幅提高到 88%，而下调 Klf9 则将其降低到 14%。因此，与野生型小鼠相比，Klf9 敲除动物的器官型培养物中的浦肯野细胞存活率降低了一半。此外，缺乏 Klf9 可以通过浦肯野细胞营养因子胰岛素生长因子-1 和神经营养因子 3 来挽救。总之，我们的研究结果明确赋予了 Klf9 在浦肯野细胞存活中的作用。因此，我们提出 Klf9 可能是参与关闭浦肯野细胞 PCD 阶段的关键分子。
