Gandolfi Fulvio, Arcuri Sharon, Pennarossa Georgia, Brevini Tiziana A L
Department of Agricultural and Environmental Sciences - Production, Landscape, Agroenergy, University of Milan, Italy.
Department of Health, Animal Science and Food Safety, University of Milan, Italy.
Anim Reprod. 2019 Oct 23;16(3):475-484. doi: 10.21451/1984-3143-AR2019-0043.
Somatic cell nuclear transfer and iPS are both forms of radical cell reprogramming able to transform a fully differentiated cell type into a totipotent or pluripotent cell. Both processes, however, are hampered by low efficiency and, in the case of iPS, the application to livestock species is uncertain. Epigenetic manipulation has recently emerged as an efficient and robust alternative method for cell reprogramming. It is based upon the use of small molecules that are able to modify the levels of DNA methylation with 5-azacitidyne as one of the most widely used. Among a number of advantages, it includes the fact that it can be applied to domestic species including pig, dog and cat. Treated cells undergo a widespread demethylation which is followed by a renewed methylation pattern induced by specific chemical stimuli that lead to the desired phenotype. A detailed study of the mechanisms of epigenetic manipulation revealed that cell plasticity is achieved through the combined action of a reduced DNA methyl transferase activity with an active demethylation driven by the TET protein family. Surprisingly the same combination of molecular processes leads to the transformation of fibroblasts into iPS and regulate the epigenetic changes that take place during early development and, hence, during reprogramming following SCNT. Finally, it has recently emerged that mechanic stimuli in the form of a 3D cell rearrangement can significantly enhance the efficiency of epigenetic reprogramming as well as of maintenance of pluripotency. Interestingly these mechanic stimuli act on the same mechanisms both in epigenetic cell conversion with 5-Aza-CR and in iPS. We suggest that the balanced combination of epigenetic erasing, 3D cell rearrangement and chemical induction can go a long way to obtain ad hoc cell types that can fully exploit the current exiting development brought by gene editing and animal cloning in livestock production.
体细胞核移植和诱导多能干细胞都是激进的细胞重编程形式，能够将完全分化的细胞类型转化为全能或多能细胞。然而，这两个过程都受到效率低下的阻碍，就诱导多能干细胞而言，其在牲畜物种中的应用尚不确定。表观遗传操作最近已成为一种高效且强大的细胞重编程替代方法。它基于使用能够改变DNA甲基化水平的小分子，5-氮杂胞苷是使用最广泛的小分子之一。在众多优势中，它包括可以应用于猪、狗和猫等家畜物种这一事实。经处理的细胞会经历广泛的去甲基化，随后由特定化学刺激诱导产生新的甲基化模式，从而导致所需的表型。对表观遗传操作机制的详细研究表明，细胞可塑性是通过DNA甲基转移酶活性降低与由TET蛋白家族驱动的主动去甲基化的联合作用实现的。令人惊讶的是，相同的分子过程组合会导致成纤维细胞转化为诱导多能干细胞，并调节早期发育过程中以及因此在体细胞核移植后的重编程过程中发生的表观遗传变化。最后，最近发现以3D细胞重排形式的机械刺激可以显著提高表观遗传重编程以及多能性维持的效率。有趣的是，这些机械刺激在使用5-氮杂胞苷进行表观遗传细胞转化和诱导多能干细胞过程中作用于相同的机制。我们认为，表观遗传消除、3D细胞重排和化学诱导的平衡组合对于获得能够充分利用基因编辑和动物克隆在畜牧生产中带来的当前现有进展的特定细胞类型大有帮助。
