许多基因的mRNA有多个poly(A)位点，选择不同位点可使mRNA有不同3'UTR，该现象被称为alternative polyadenylation（APA）。APA广泛存在于真核生物，且不同组织具有不同3'UTR profile。同时发现较短的3'UTR与细胞增殖相关，较长的3'UTR与细胞分化相关。然而前人的研究主要集中于高通量测序和生物信息学分析poly(A)位点，缺乏APA与体内细胞增殖分化的直接数据。我们发现果蝇精原细胞和精母细胞具有不同的3'UTR profile，并筛选到两个APA相关因子，其RNAi导致精原细胞过度增殖。这提示APA可能参与调控生殖细胞的分化。我们计划测定不同分化阶段生殖细胞的3'UTR profile，分析不同3'UTR profile是如何实现的，及研究具有不同3'UTR的基因在细胞分化过程中的作用。总之，我们将解析APA如何参与生殖细胞发育。

Recent research reveals that a large portion of mRNAs contain more than one poly(A) site, generating mRNAs with alternative 3'UTRs，a phenomenon that is defined as alternative polyadenylation (APA). APA is well conserved from all model eukaryotes to human. APA exhibits a strong trend of tissue specificity, in a way that different tissues contain different 3'UTR profiles. In general, shorter 3'UTR is correlated with cell proliferation, while longer 3'UTR with cell differentiation. However, most APA studies were based on high-throughput sequencing of poly(A) sites and bioinformatical analysis, missing the direct link between APA and differentiation in vivo. We have found that 3'UTR profile is different between spermatogonia and spermatocytes in Drosophila. We also identified two APA related factors whose RNAi led to spermatogonial over-proliferation. These results indicate that APA is likely involved in the regulation of germ cell differentiation. We will examine the 3'UTR profile of germ cells at different differentiating stages, analyze how the changes of 3'UTR profile during germ cell differentiation is achieved, and unravel the functions of the genes with alternative 3'UTRs during germ cell differentiation. Collectively, we will dissect how APA regulates germ cell differentiation in vivo.