• MicroRNAs (miRNAs) are essential regulators of gene expression in metazoans and plants. In plants, most miRNAs are generated from primary miRNA transcripts (pri-miRNAs), which are processed by the Dicer-like 1 (DCL1) complex along with accessory proteins.
• Serrate-Associated Protein 1 (SEAP1), a conserved splicing-related protein, has been studied in human and yeast. However, the functions of SEAP1 in plants remain elusive.
• Lack of SEAP1 results in embryo lethality and knockdown of SEAP1 by an artificial miRNA (amiR^SEAP1) causes pleiotropic developmental defects and reduction in miRNA accumulation. SEAP1 associates with the DCL1 complex, and may promote the interaction of the DCL1 complexes with pri-miRNAs. SEAP1 also enhances pri-miRNA accumulation, but does not affect pri-miRNA transcription, suggesting it may indirectly or directly stabilize pri-miRNAs. In addition, SEAP1 affects the splicing of some pri-miRNAs and intron retention of messenger RNAs at global levels.
• Our findings uncover both conserved and novel functions of SEAP1 in plants. Besides the role as a splicing factor, SEPA1 may promote miRNA biogenesis by positively modulating pri-miRNA splicing, processing and/or stability.

中文翻译：

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锯齿相关蛋白 1，一种剪接相关蛋白，促进拟南芥中 miRNA 的生物发生

• MicroRNA (miRNA) 是后生动物和植物中基因表达的重要调节剂。在植物中，大多数 miRNA 由初级 miRNA 转录本 (pri-miRNA) 生成，初级 miRNA 转录本由 Dicer-like 1 (DCL1) 复合物与辅助蛋白一起加工。
• 锯齿相关蛋白 1 (SEAP1) 是一种保守的剪接相关蛋白，已在人类和酵母中进行了研究。然而，SEAP1 在植物中的功能仍然难以捉摸。
• 缺乏SEAP1会导致胚胎死亡，人工 miRNA ( amiR ^SEAP1 ) 敲低SEAP1会导致多效性发育缺陷和 miRNA 积累减少。SEAP1 与 DCL1 复合体结合，并可能促进 DCL1 复合体与 pri-miRNA 的相互作用。SEAP1 也增强了 pri-miRNA 的积累，但不影响 pri-miRNA 的转录，表明它可能间接或直接稳定 pri-miRNA。此外，SEAP1 在全局水平上影响一些 pri-miRNA 的剪接和信使 RNA 的内含子保留。
• 我们的研究结果揭示了植物中 SEAP1 的保守功能和新功能。除了作为剪接因子的作用外，SEPA1 还可以通过正向调节 pri-miRNA 的剪接、加工和/或稳定性来促进 miRNA 的生物发生。