Nousch Marco, Eckmann Christian R
Division of Genetics; Institute of Biology; Martin Luther University, Halle-Wittenberg ; Halle, Saales, Germany.
Division of Genetics; Institute of Biology; Martin Luther University, Halle-Wittenberg ; Halle, Saales, Germany ; Max Planck Institute of Molecular Cell Biology and Genetics ; Dresden, Germany.
Worm. 2015 Jun 2;4(3):e1042644. doi: 10.1080/21624054.2015.1042644. eCollection 2015 Jul-Sep.
Adult tissue maintenance is achieved through a tightly controlled equilibrium of 2 opposing cell fates: stem cell proliferation and differentiation. In recent years, the germ line emerged as a powerful in vivo model tissue to investigate the underlying gene expression mechanisms regulating this balance. Studies in numerous organisms highlighted the prevalence of post-transcriptional mRNA regulation, which relies on RNA-targeting factors that influence mRNA fates (e.g. decay or translational efficiency). Conserved translational repressors were identified that build negative feedback loops to ensure one or the other cell fate. However, to facilitate a fast and efficient transition between 2 opposing cell fates, translational repression per se appears not to be sufficient, suggesting the involvement of additional modes of gene expression regulation. Cytoplasmic poly(A) polymerases (cytoPAPs) represent a unique class of post-transcriptional mRNA regulators that modify mRNA 3' ends and positively influence cytoplasmic mRNA fates. We recently discovered that the 2 main cytoPAPs, GLD-2 and GLD-4, use distinct mechanisms to promote gene expression and that cytoPAP-mediated mRNA activation is important for regulating the size of the proliferative germ cell pool in the adult Caenorhabditis elegans gonad. Here, we comment on the different mechanisms of the 2 cytoPAPs as translational activators in germ cell development and focus on their biological roles in maintaining the balance between germline stem cell proliferation and differentiation in the Caenorhabditis elegans gonad.
成体组织的维持是通过两种相反细胞命运（干细胞增殖和分化）之间严格控制的平衡来实现的。近年来，生殖系成为一种强大的体内模型组织，用于研究调节这种平衡的潜在基因表达机制。对众多生物体的研究突出了转录后mRNA调控的普遍性，这种调控依赖于影响mRNA命运（如降解或翻译效率）的RNA靶向因子。已鉴定出保守的翻译抑制因子，它们构建负反馈环以确保其中一种或另一种细胞命运。然而，为了促进两种相反细胞命运之间快速而有效的转变，仅翻译抑制似乎并不足够，这表明还涉及其他基因表达调控模式。细胞质聚腺苷酸聚合酶（cytoPAPs）代表一类独特的转录后mRNA调节因子，它们修饰mRNA的3'末端并对细胞质mRNA命运产生积极影响。我们最近发现，两种主要的cytoPAPs，即GLD-2和GLD-4，使用不同的机制来促进基因表达，并且cytoPAP介导的mRNA激活对于调节成年秀丽隐杆线虫性腺中增殖性生殖细胞池的大小很重要。在这里，我们评论了这两种cytoPAPs作为生殖细胞发育中翻译激活剂的不同机制，并重点关注它们在维持秀丽隐杆线虫性腺中生殖系干细胞增殖和分化之间平衡的生物学作用。
