microRNA（miRNA）途径参与许多生物学过程。本文中，研究人员在线虫中对于miRNA途径中两个特异蛋白进行了研究，试图发现miRNA在调节生物学事件中更多的功能。
ALG-1和ALG2是Argonaute蛋白家族的成员，研究人员发现，突变的ALG-1和ALG-2会导致线虫的子代数量减少。进一步分析显示，在ALG-1和ALG-2突变的个体中，有丝分裂的生殖细胞减少，并且有一部分细胞会提前进入减数分裂阶段。在野生型线虫中，ALG-1特异表达在顶端细胞（distal tip cell，DTC)。在顶端细胞内表达有功能的ALG-1可以一定程度上修复突变体中生殖细胞的缺陷。有趣的是，阻碍5个miRNA的表达也会导致类似的表型。
研究人员表示，这一结果说明，microRNA途径调节线虫生殖细胞的增殖和分化中起着重要的作用，同时该研究也揭示了miRNA的一项新功能。（生物谷 Bioon.com ）
doi:10.1038/cr.2012.31
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The microRNA pathway controls germ cell proliferation and differentiation in C. elegans
Syed Irfan Ahmad Bukhari, Alejandro Vasquez-Rifo, Dominic Gagné, Eric R Paquet, Monique Zetka, Claude Robert, Jean-Yves Masson and Martin J Simard
The discovery of the miRNA pathway revealed a new layer of molecular control of biological processes. To uncover new functions of this gene regulatory pathway, we undertook the characterization of the two miRNA-specific Argonaute proteins in Caenorhabditis elegans, ALG-1 and ALG-2. We first observed that the loss-of-function of alg-1 and alg-2 genes resulted in reduced progeny number. An extensive analysis of the germline of these mutants revealed a reduced mitotic region, indicating fewer proliferating germ cells. We also observed an early entry into meiosis in alg-1 and alg-2 mutant animals. We detected ALG-1 and ALG-2 protein expressions in the distal tip cell (DTC), a specialized cell located at the tip of both C. elegans gonadal arms that regulates mitosis-meiosis transition. Re-establishing the expression of alg-1 specifically in the DTC of mutant animals partially rescued the observed germline defects. Further analyses also support the implication of the miRNA pathway in gametogenesis. Interestingly, we observed that disruption of five miRNAs expressed in the DTC led to similar phenotypes. Finally, gene expression analysis of alg-1 mutant gonads suggests that the miRNA pathway is involved in the regulation of different pathways important for germline proliferation and differentiation. Collectively, our data indicate that the miRNA pathway plays a crucial role in the control of germ cell biogenesis in C. elegans.
