Characterization of an RNA-binding protein PpCSP that promotes reprogramming of the moss Physcomitrella patens

PpCSP是一种RNA结合蛋白，可促进藓类小立碗藓分化叶细胞向干细胞的重编程。为了揭示PpCSP促进重编程的分子机制，我们试图鉴定PpCSP的靶RNA分子和相互作用蛋白。我们进行了RNA免疫沉淀测序，发现PpCSP结合几乎所有的mRNA。我们先前分离出多个基因，其在PpCSP过表达系中表现出比野生型更高的转录物积累。我们建立了这些基因的过表达株系，并发现几个过表达株系表现出异常的形态。此外，我们分离出多个相互作用的合作伙伴的PpCSP进行免疫沉淀，然后通过液相色谱-质谱。我们证实，细胞定位在很大程度上与PpCSP重叠。

PpCSP, an RNA-binding protein, facilitates the reprogramming from differentiated leaf cells to stem cells in the moss Physcomitrella patens. To reveal the molecular mechanisms underlying the promotion of reprogramming by PpCSP, we have tried to identify the target RNA molecules and the interacting proteins of PpCSP. We performed RNA immunoprecipitation-sequencing and found that PpCSP binds to almost all mRNAs. We previously isolated multiple genes, which exhibited higher transcripts accumulation in the over-expression line of PpCSP than in wild type. We produced over-expression lines of those genes, and found that several over-expression lines exhibited abnormal morphologies. In addition, we isolated multiple interacting partners of PpCSP by performing immunoprecipitation followed by liquid chromatography-mass spectrometry. We confirmed that the cellular localization largely overlapped with that of PpCSP.