Insulin-like growth factor 2 mRNA binding protein-2 (IGF2BP2 or IMP2) is a member of a conserved family of RNA binding proteins. These proteins bind to and regulate target mRNA localization, stability, and translation. Their structure, expression and functions in bony fish are not well understood. Here, we characterized the zebrafish igf2bp2 gene and investigated its functional role in early development. Zebrafish igf2bp2 gives rise to 4 alternatively spliced transcripts. When expressed in cultured cells, all 4 proteins were detected in the cytoplasm. Igf2bp2-A, the longest isoform, has a domain structure similar to its mammalian counterpart. Igf2bp2-B lacks one of the C-terminal KH domains, while Igf2bp2-C lacks the two N-terminal RRM domains. Igf2bp2-D lacks both regions. In adult fish, these igf2bp2 isoforms were detected exclusively in the oocyte. After fertilization, they disappeared within 6 h post fertilization (hpf). At 20 ~ 24 hpf, igf2bp2-A mRNA, but not other mRNAs, was re-expressed in the embryos including in primordial germ cells. Targeted knockdown of Igf2bp2s reduced the numbers of primordial germ cells but did not affect global patterning or growth. The effect was rescued by overexpression of Igf2bp2-A. Likewise, dominant-negative inhibition of Igf2bp2 resulted in a similar reduction in primordial germ cell number. These results not only provide new information about the structure and expression of zebrafish Igf2bp2, but also reveal a critical role of this conserved RNA binding protein in primordial germ cell development.

胰岛素样生长因子 2 mRNA 结合蛋白 2（IGF2BP2 或 IMP2）是 RNA 结合蛋白保守家族的成员。这些蛋白质结合并调节靶mRNA定位、稳定性和翻译。它们在硬骨鱼中的结构、表达和功能尚不清楚。在这里，我们对斑马鱼igf2bp2基因进行了表征，并研究了它在早期发育中的功能作用。斑马鱼igf2bp2产生 4 个交替剪接的转录本。当在培养细胞中表达时，在细胞质中检测到所有 4 种蛋白质。Igf2bp2-A 是最长的同种型，具有与其哺乳动物对应物相似的结构域结构。Igf2bp2-B 缺少一个 C 端 KH 域，而 Igf2bp2-C 缺少两个 N 端 RRM 域。Igf2bp2-D 缺乏这两个区域。在成年鱼中，这些igf2bp2亚型仅在卵母细胞中检测到。受精后，它们在受精后 6 小时 (hpf) 内消失。在 20 ~ 24 hpf，igf2bp2-AmRNA，但不是其他 mRNA，在胚胎中重新表达，包括在原始生殖细胞中。Igf2bp2s 的靶向敲低减少了原始生殖细胞的数量，但不影响全局模式或生长。通过 Igf2bp2-A 的过表达挽救了这种效果。同样，Igf2bp2 的显性负抑制导致原始生殖细胞数量的类似减少。这些结果不仅提供了关于斑马鱼 Igf2bp2 结构和表达的新信息，而且揭示了这种保守的 RNA 结合蛋白在原始生殖细胞发育中的关键作用。