PDF(Pubmed)
Abstract：
Alternative cleavage and polyadenylation (APA) often results in production of mRNA isoforms with either longer or shorter 3\' UTRs from the same genetic locus, potentially impacting mRNA translation, localization, and stability. Developmentally regulated APA can thus make major contributions to cell type-specific gene expression programs as cells differentiate. During Drosophila spermatogenesis, ∼500 genes undergo APA when proliferating spermatogonia differentiate into spermatocytes, producing transcripts with shortened 3\' UTRs, leading to profound stage-specific changes in the proteins expressed. The molecular mechanisms that specify usage of upstream polyadenylation sites in spermatocytes are thus key to understanding the changes in cell state. Here, we show that upregulation of PCF11 and Cbc, the two components of cleavage factor II (CFII), orchestrates APA during Drosophila spermatogenesis. Knockdown of PCF11 or cbc in spermatocytes caused dysregulation of APA, with many transcripts normally cleaved at a proximal site in spermatocytes now cleaved at their distal site, as in spermatogonia. Forced overexpression of CFII components in spermatogonia switched cleavage of some transcripts to the proximal site normally used in spermatocytes. Our findings reveal a developmental mechanism where changes in expression of specific cleavage factors can direct cell type-specific APA at selected genes.
摘要：
选择性切割和聚腺苷酸化（APA）通常会导致从同一遗传基因座产生具有更长或更短的3UTR的mRNA同工型。可能影响mRNA翻译，本地化,和稳定性。因此，随着细胞分化，发育调节的APA可以对细胞类型特异性基因表达程序做出重大贡献。在果蝇精子发生期间，当增殖精原细胞分化成精母细胞时，500个基因经历APA，用缩短的3个UTR产生转录本，导致表达的蛋白质发生深刻的阶段特异性变化。因此，指定精母细胞上游聚腺苷酸化位点使用的分子机制是理解细胞状态变化的关键。这里,我们表明PCF11和Cbc的上调，裂解因子II（CFII）的两个成分，在果蝇精子发生过程中协调APA。精母细胞中PCF11或cbc的敲除导致APA失调，精母细胞中许多转录物通常在近端位点被切割，现在在其远端位点被切割，如精原细胞。精原细胞中CFII成分的强制过表达将某些转录物的裂解转换为精母细胞中通常使用的近端位点。我们的发现揭示了一种发育机制，其中特定裂解因子表达的变化可以将细胞类型特异性APA引导到选定的基因。
