Division of Neuroscience, IIT Network, Research Unit of Molecular Neuroscience, Vita-Salute San Raffaele University and Scientific Institute San Raffaele, DIBIT, Via Olgettina 58, 20132 Milan, Italy.
Cell Mol Neurobiol. 2010 Nov;30(8):1295-302. doi: 10.1007/s10571-010-9602-0. Epub 2010 Nov 3.
A rapid drop of the transcription repressor REST/NRSF during precursor differentiation into nerve cells is known to release the repression of hundreds of specific genes and thus to orchestrate the acquisition of the specific phenotype. REST, however, is important not only for differentiation, but also for the maintenance of key properties in mature nerve cell. The PC12 line is uniquely favorable for studying REST because, in addition to the wild-type, low REST neurosecretory cells, it includes spontaneously defective clones lacking neurosecretion, where REST is as high as in non-nerve cells. In this article, we summarize our cell biologic studies of two nerve cell-specific processes dependent on REST, neurosecretion and neurite outgrowth. We demonstrate that, in wild-type PC12 transfected with REST constructs, expression of genes encoding proteins of dense-core and synaptic-like vesicles is decreased, though, to different extents, with chromogranins being the most and the SNAREs (except SNAP25) the least affected. Concomitantly, dense core-vesicles decrease markedly in size but can still be discharged by regulated exocytosis. When, in contrast, dominant-negative constructs of REST are transfected in high-REST PC12, and the main effector enzymes of REST, histone deacetylases, are blocked, dense-core vesicles reappear and are discharged upon stimulation. In high-REST PC12, also neurite outgrowth is inhibited by down regulation of the NGF receptor. Concomitantly, however, high REST induces the expression of proteins and of an exocytic organelle, the enlargeosome, which sustain a Rac1-dependent form of neurite outgrowth, unknown until now, operative in PC12, in neuroblastoma SH-SY5Y cells, and also in neurons.
已知在神经前体细胞向神经细胞分化过程中，转录抑制剂 REST/NRSF 的迅速下降会解除数百个特定基因的抑制，从而协调特定表型的获得。然而，REST 不仅对分化很重要，对成熟神经细胞的关键特性的维持也很重要。PC12 细胞系是研究 REST 的独特优势，因为除了野生型低 REST 神经分泌细胞外，它还包括自发缺陷的克隆，缺乏神经分泌，其中 REST 的水平与非神经细胞一样高。在本文中，我们总结了我们对依赖 REST 的两个神经细胞特异性过程（神经分泌和轴突生长）的细胞生物学研究。我们证明，在野生型 PC12 细胞中转染 REST 构建体后，编码致密核心和突触样小泡蛋白的基因表达减少，但程度不同，其中嗜铬粒蛋白受影响最大，SNARE（除 SNAP25 外）受影响最小。同时，致密核心小泡的大小明显减小，但仍可通过调节性胞吐作用排出。相反，在高 REST PC12 中转染 REST 的显性负性构建体，并阻断 REST 的主要效应酶组蛋白去乙酰化酶，致密核心小泡会重新出现并在刺激时排出。在高 REST PC12 中，NGF 受体的下调也抑制了轴突生长。然而，同时，高 REST 诱导蛋白质和一种分泌细胞器—— enlargeosome 的表达，后者维持一种 Rac1 依赖的轴突生长形式，这种形式以前在 PC12、神经母细胞瘤 SH-SY5Y 细胞以及神经元中都不为人知。
