Coleoid cephalopods (octopus, squid and cuttlefish) have unusually complex nervous systems. The coleoid nervous system is also the only one currently known to recode the majority of expressed proteins through A-to-I RNA editing. The deamination of adenosine by adenosine deaminase acting on RNA (ADAR) enzymes produces inosine, which is interpreted as guanosine during translation. If this occurs in an open reading frame, which is the case for tens of thousands of editing sites in coleoids, it can recode the encoded protein. Here, we describe recent findings aimed at deciphering the mechanisms underlying high-level recoding and its adaptive potential. We describe the complement of ADAR enzymes in cephalopods, including a recently discovered novel domain in sqADAR1. We further summarize current evidence supporting an adaptive role of high-level RNA recoding in coleoids, and review recent studies showing that a large proportion of recoding sites is temperature-sensitive. Despite these new findings, the mechanisms governing the high level of RNA recoding in coleoid cephalopods remain poorly understood. Recent advances using genome editing in squid may provide useful tools to further study A-to-I RNA editing in these animals.

中文翻译：

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高水平RNA编辑使鞘状头足类大脑蛋白质组多样化

鞘形头足类动物（章鱼、鱿鱼和墨鱼）具有异常复杂的神经系统。胶状神经系统也是目前已知的唯一一个通过 A 到 I RNA 编辑重新编码大多数表达蛋白质的系统。腺苷脱氨酶作用于 RNA (ADAR) 酶，使腺苷脱氨，产生肌苷，在翻译过程中被解释为鸟苷。如果这种情况发生在开放阅读框中，即胶体中数以万计的编辑位点的情况，它可以重新编码编码的蛋白质。在这里，我们描述了旨在破译高级重新编码背后的机制及其自适应潜力的最新发现。我们描述了头足类动物 ADAR 酶的补充，包括最近在 sqADAR1 中发现的新结构域。我们进一步总结了当前支持高水平RNA重新编码在胶体中发挥适应性作用的证据，并回顾了最近的研究表明大部分重新编码位点对温度敏感。尽管有这些新发现，但控制鞘状头足类动物高水平 RNA 重新编码的机制仍然知之甚少。在鱿鱼中使用基因组编辑的最新进展可能为进一步研究这些动物的 A-to-I RNA 编辑提供有用的工具。