Coyle Maxwell C, King Nicole
Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, CA, USA.
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
Nat Rev Genet. 2025 Jul 9. doi: 10.1038/s41576-025-00864-9.
The development of a single-celled zygote into a complex, multicellular animal is directed by transcription factors and regulatory RNAs that coordinate spatio-temporal gene expression patterns. Given the morphological complexity of animals, some prior work has hypothesized that the origin of animals required the evolution of unique and markedly complex transcriptional regulatory mechanisms. Such postulated animal innovations include the evolution of greater numbers of transcription factors, new transcription factor families, distal enhancers and the emergence of long non-coding RNAs. Here, we revisit these explanations in light of new genomic and functional data from diverse early-branching animals and close relatives of animals, which provide essential phylogenetic context for reconstructing the origin of animals. These experimental models also offer examples of how some animal developmental pathways were built from core mechanisms inherited from their protistan ancestors. These new data provide fresh perspectives on whether animal origins entailed fundamental innovations in transcriptional regulation or whether, alternatively, a gradual accumulation of smaller changes sufficed to generate the complex developmental and cell differentiation mechanisms of early animals.
单细胞受精卵发育成复杂的多细胞动物是由转录因子和调控RNA指导的，它们协调时空基因表达模式。鉴于动物形态的复杂性，一些先前的研究假设动物的起源需要独特且明显复杂的转录调控机制的进化。这种假定的动物创新包括更多转录因子的进化、新的转录因子家族、远端增强子以及长链非编码RNA的出现。在这里，我们根据来自不同早期分支动物及其近亲的新基因组和功能数据重新审视这些解释，这些数据为重建动物起源提供了重要的系统发育背景。这些实验模型还展示了一些动物发育途径是如何从其原生生物祖先遗传的核心机制构建而来的。这些新数据为动物起源是否需要转录调控方面的根本性创新，或者相反，较小变化的逐渐积累是否足以产生早期动物复杂的发育和细胞分化机制提供了新的视角。
