Laboratory of Molecular Neuro-Oncology, The Rockefeller University, New York, New York 10065, USA.
Genes Dev. 2012 Jul 15;26(14):1626-42. doi: 10.1101/gad.191338.112.
Two polypyrimidine tract RNA-binding proteins (PTBs), one near-ubiquitously expressed (Ptbp1) and another highly tissue-restricted (Ptbp2), regulate RNA in interrelated but incompletely understood ways. Ptbp1, a splicing regulator, is replaced in the brain and differentiated neuronal cell lines by Ptbp2. To define the roles of Ptbp2 in the nervous system, we generated two independent Ptbp2-null strains, unexpectedly revealing that Ptbp2 is expressed in neuronal progenitors and is essential for postnatal survival. A HITS-CLIP (high-throughput sequencing cross-linking immunoprecipitation)-generated map of reproducible Ptbp2-RNA interactions in the developing mouse neocortex, combined with results from splicing-sensitive microarrays, demonstrated that the major action of Ptbp2 is to inhibit adult-specific alternative exons by binding pyrimidine-rich sequences upstream of and/or within them. These regulated exons are present in mRNAs encoding proteins associated with control of cell fate, proliferation, and the actin cytoskeleton, suggesting a role for Ptbp2 in neurogenesis. Indeed, neuronal progenitors in the Ptbp2-null brain exhibited an aberrant polarity and were associated with regions of premature neurogenesis and reduced progenitor pools. Thus, Ptbp2 inhibition of a discrete set of adult neuronal exons underlies early brain development prior to neuronal differentiation and is essential for postnatal survival.
两种多嘧啶 tract RNA 结合蛋白（PTBs），一种广泛表达（Ptbp1），另一种高度组织受限（Ptbp2），以相互关联但不完全理解的方式调节 RNA。Ptbp1 是一种剪接调节因子，在大脑和分化神经元细胞系中被 Ptbp2 取代。为了确定 Ptbp2 在神经系统中的作用，我们生成了两种独立的 Ptbp2 缺失株，出人意料地发现 Ptbp2 在神经元祖细胞中表达，并且对出生后存活至关重要。在发育中的小鼠新皮层中，通过 HITS-CLIP（高通量测序交联免疫沉淀）生成的可重复 Ptbp2-RNA 相互作用图谱，结合剪接敏感微阵列的结果，表明 Ptbp2 的主要作用是通过结合嘧啶丰富的序列来抑制成年特异性替代外显子上游和/或其中的序列。这些受调控的外显子存在于编码与细胞命运、增殖和肌动蛋白细胞骨架控制相关的蛋白质的 mRNA 中，表明 Ptbp2 在神经发生中发挥作用。事实上，Ptbp2 缺失大脑中的神经元祖细胞表现出异常的极性，并与早期神经发生和祖细胞池减少的区域相关。因此，Ptbp2 对一组离散的成年神经元外显子的抑制是神经元分化前早期大脑发育的基础，并且对出生后存活至关重要。
