Molecular mechanisms underlying replicative stress and genome damage in pluripotent stem cells

早期胚胎中的多能干细胞(PSCs)产生了体内所有的体细胞。保持PSCs的遗传完整性对于防止遗传缺陷传递给多个后代细胞至关重要，因为这将对发育中的胚胎不利。当放置在适当的培养条件下时，PSCs保持了从所有三个胚胎生殖层分化出细胞的能力，同时获得了广泛自我更新的能力，从而提供了一个优秀的、遗传正常的模型系统来研究控制基因组完整性的机制。我们和其他人之前已经证明，PSCs在延长培养时间后获得非随机的遗传变化。然而，它们获得的分子机制仍然知之甚少。为此，我们的项目将确定不同的基因组损伤机制对我们观察到的常见基因变化的贡献。我们还将阐明外部环境(具体地说，培养介质成分)是如何增强或减弱这些损伤机制的。我们之前的数据表明，在不同的培养介质和环境条件下生长的细胞会显著改变它们的突变率。来自其他小组的研究强调，白蛋白是介质中的关键成分，对于稳定小分子和离子以及清除可能对大分子，特别是DNA有害的自由基是必要的。因此，我们将与专门从事重组白蛋白生产的工业合作伙伴Alumedix合作，确定内在机制和利基条件对PSCs基因组损伤的贡献。

Pluripotent stem cells (PSCs) in the early embryo give rise to all ofthe somatic cells in the body. Maintenance of the genetic integrity of PSCs isessential for preventing genetic defects to be passed onto multiple progeny cells,which would be detrimental for a developing embryo. When placed underappropriate culture conditions, PSCs retain the ability to give rise to differentiatedcells from all three embryonic germ layers, whilst acquiring the ability to self-renew extensively and thus provide an excellent, genetically normal modelsystem to investigate mechanisms that control genome integrity. We and othershave previously shown that PSCs acquire non-random genetic changes uponprolonged culture. However, the molecular mechanisms underlying theiracquisition remain poorly understood. To this end, our project will determine thecontribution of different genome damage mechanisms to the common geneticchanges we observe. We will also elucidate how extrinsic environment(specifically, culture medium composition) enhance or diminish these damagemechanisms. Our previous data has shown that growing cells in different culturemedia and environmental conditions significantly alters their mutation rates.Work from other groups highlighted albumin as a key component of the medium,necessary for stabilizing small molecules and ions and scavenging free radicalsthat could be harmful for macromolecules, particularly the DNA. Hence, incollaboration with our industrial partner Albumedix, who specializes inrecombinant albumin production, we will determine the contribution of intrinsicmechanisms and niche conditions on genome damage of PSCs.