Zhang Li, Malkemper E Pascal
Max Planck Research Group Neurobiology of Magnetoreception, Max Planck Institute for Neurobiology of Behavior-caesar, Bonn, Germany.
Front Physiol. 2023 Aug 21;14:1250798. doi: 10.3389/fphys.2023.1250798. eCollection 2023.
Cryptochromes are flavoproteins related to photolyases that are widespread throughout the plant and animal kingdom. They govern blue light-dependent growth in plants, control circadian rhythms in a light-dependent manner in invertebrates, and play a central part in the circadian clock in vertebrates. In addition, cryptochromes might function as receptors that allow animals to sense the Earth's magnetic field. As cryptochromes are also present in mammals including humans, the possibility of a magnetosensitive protein is exciting. Here we attempt to provide a concise overview of cryptochromes in mammals. We briefly review their canonical role in the circadian rhythm from the molecular level to physiology, behaviour and diseases. We then discuss their disputed light sensitivity and proposed role in the magnetic sense in mammals, providing three mechanistic hypotheses. Specifically, mammalian cryptochromes could form light-induced radical pairs in particular cellular milieus, act as magnetoreceptors in darkness, or as secondary players in a magnetoreception signalling cascade. Future research can test these hypotheses to investigate if the role of mammalian cryptochromes extends beyond the circadian clock.
隐花色素是与光解酶相关的黄素蛋白，广泛存在于植物和动物界。它们调控植物依赖蓝光的生长，以依赖光的方式控制无脊椎动物的昼夜节律，并在脊椎动物的生物钟中起核心作用。此外，隐花色素可能作为受体，使动物能够感知地球磁场。由于包括人类在内的哺乳动物中也存在隐花色素，因此存在磁敏蛋白这一可能性令人兴奋。在此，我们试图对哺乳动物中的隐花色素进行简要概述。我们从分子水平到生理学、行为和疾病等方面简要回顾它们在昼夜节律中的典型作用。然后，我们讨论它们存在争议的光敏感性以及在哺乳动物磁感中的假定作用，提出三种机制假说。具体而言，哺乳动物隐花色素可能在特定细胞环境中形成光诱导自由基对，在黑暗中充当磁受体，或作为磁感受信号级联反应中的次要参与者。未来的研究可以检验这些假说，以探究哺乳动物隐花色素的作用是否超出生物钟范畴。
