Compared with mammalian ANP32A, most avian-coded ANP32A contains a 33 amino acids insertion (ch-ANP32A-33) or a 29 amino acids insertion (ch-ANP32A-29), which can rescue the mammalian-restricted avian influenza virus polymerase activity, with ch-ANP32A-33 exhibiting a more potent phenotype. The alternative splicing of 3′ splice sites (SSs) of chicken ANP32A intron 4 generates full-length ch-ANP32A-33 and truncated ch-ANP32A-29. In this study, we found a splicing regulatory cis-element that affected the alternative splicing of 3′ SSs by block-scanning mutagenesis. RNA affinity purification and mass spectrometry showed that the SRSF10 bound to the splicing cis-element and the binding was further identified and confirmed by RIP experiment. Overexpression of SRSF10 changed the ratio of the two chicken ANP32A transcripts with the increased ch-ANP32A-29 and the decreased ch-ANP32A-33. The knockdown of both of the ch-ANP32A-33 and ch-ANP32A-29 was harmful to avian influenza virus polymerase activity in DF-1 cells, but the restoration and increasement of only ch-ANP32A-29 could not completely rescue the activity of avian influenza virus polymerase. Overexpression of SRSF10 negatively affected the polymerase activity and replication of avian influenza virus, and the expression of ch-ANP32A-33 could partially recover the decrease of polymerase activity of avian influenza virus. By contrast, SRSF10 had weak inhibition on the polymerase activity of mammalian adapted influenza virus and had no effect on the replication of mammalian adapted influenza virus. Taken together, we demonstrated that SRSF10 acts as a negative regulator in polymerase activity and replication of avian influenza virus by binding to the splicing cis-element to regulate the alternative splicing of chicken ANP32A intron 4 for the reduced ch-ANP32A-33 and increased ch-ANP32A-29.

与哺乳动物ANP32A相比，大多数禽类编码的ANP32A包含33个氨基酸的插入物（ch-ANP32A-33）或29个氨基酸的插入物（ch-ANP32A-29），可以挽救哺乳动物限制的禽流感病毒聚合酶的活性， ch-ANP32A-33具有更强的表型。鸡ANP32A内含子4的3'剪接位点（SS）的选择性剪接产生全长ch-ANP32A-33和截短的ch-ANP32A-29。在这项研究中，我们发现了一个剪接调控顺式元件，通过块​​扫描诱变影响了3'SS的选择性剪接。RNA亲和纯化和质谱分析表明，SRSF10与剪接的顺式元件结合，并且通过RIP实验进一步鉴定并确认了结合。SRSF10的过表达改变了两个鸡ANP32A转录本的比例，其中ch-ANP32A-29增加，而ch-ANP32A-33减少。ch-ANP32A-33和ch-ANP32A-29的组合均对DF-1细胞中的禽流感病毒聚合酶活性有害，但仅ch-ANP32A-29的恢复和增加不能完全挽救ch-ANP32A-29的活性。禽流感病毒聚合酶。SRSF10的过表达对禽流感病毒的聚合酶活性和复制产生负面影响，而ch-ANP32A-33的表达可以部分恢复禽流感病毒聚合酶活性的降低。相比之下，SRSF10对哺乳动物适应性流感病毒的聚合酶活性抑制作用较弱，对哺乳动物适应性流感病毒的复制没有影响。在一起