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, approximately 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. Knock down 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：
新生mRNA分子的共转录交替加工可以对细胞类型特异性基因表达程序做出重大贡献，因为增殖的前体细胞启动终末分化。选择性切割和聚腺苷酸化(APA)可以导致从具有更长或更短的3'UTR的相同基因座产生mRNA同种型。在果蝇精子发生中，随着增殖精原细胞分化为精母细胞，大约有500个基因经历APA，产生具有缩短的3个UTR的转录本同工型，并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,我们显示PCF11和CBC，裂解因子II(CFII)的两个组成部分，在果蝇精子发生过程中协调APA转换。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。尽管PCF11被广泛表达，精母细胞中cbc强烈上调。我们的发现揭示了一种发育机制，其中特定裂解因子活性的变化可以将细胞类型特异性APA引导到选定的基因。CFII是精子发生过程中APA的关键发育调节因子。
