Nordic Center for Earth Evolution, University of Southern Denmark, Odense, Denmark.
Translational Cancer Research, Department of Laboratory Medicine, Lund University, Lund, Sweden.
Nat Ecol Evol. 2018 Feb;2(2):220-228. doi: 10.1038/s41559-017-0410-5. Epub 2018 Jan 18.
Animal diversification on Earth has long been presumed to be associated with the increasing extent of oxic niches. Here, we challenge that view. We start with the fact that hypoxia (<1-3% O) maintains cellular immaturity (stemness), whereas adult stem cells continuously-and paradoxically-regenerate animal tissue in oxygenated settings. Novel insights from tumour biology illuminate how cell stemness nevertheless can be achieved through the action of oxygen-sensing transcription factors in oxygenated, regenerating tissue. We suggest that these hypoxia-inducible transcription factors provided animals with unprecedented control over cell stemness that allowed them to cope with fluctuating oxygen concentrations. Thus, a refinement of the cellular hypoxia-response machinery enabled cell stemness at oxic conditions and, then, animals to evolve into the oxic realm. This view on the onset of animal diversification is consistent with geological evidence and provides a new perspective on the challenges and evolution of multicellular life.
地球上动物的多样化长期以来一直被认为与含氧生境的范围不断扩大有关。在这里，我们对这一观点提出质疑。我们首先要认识到，缺氧（<1-3% O）维持着细胞的不成熟状态（干性），而成年干细胞在含氧环境中不断地——矛盾的是——再生动物组织。肿瘤生物学的新见解阐明了氧感应转录因子如何在含氧、再生组织中通过作用来实现细胞干性。我们认为，这些缺氧诱导转录因子为动物提供了对细胞干性的前所未有的控制，使它们能够应对氧浓度的波动。因此，对细胞缺氧反应机制的精细调控使细胞在含氧条件下保持干性，随后动物进化到含氧环境中。这种关于动物多样化起源的观点与地质证据是一致的，并为多细胞生命的挑战和进化提供了一个新的视角。
