The Activating Transcription Factor 5 (ATF5) is a basic leucine-zipper (bZIP) transcription factor (TF) with proposed stress-protective, anti-apoptotic and oncogenic roles which were all established in cell systems. In whole animals, Atf5 function seems highly context dependent. Atf5 is strongly expressed in the rodent nose and mice knockout (KO) pups have defective olfactory sensory neurons (OSNs), smaller olfactory bulbs (OB), while adults are smell deficient. It was therefore proposed that Atf5 plays an important role in maturation and maintenance of OSNs. Atf5 expression was also described in murine liver and bones where it appears to promote differentiation of progenitor cells. By contrast in the rodent brain, Atf5 was first described as uniquely expressed in neuroprogenitors and thus, proposed to drive their proliferation and inhibit their differentiation. However, it was later also found in mature neurons stressing the need for additional work in whole animals. ATF5 is well conserved with two paralogs, atf5a and atf5b in zebrafish. Here, we present the expression patterns for both from 6 h (hpf) to 5day post-fertilization (dpf). We found early expression for both genes, and from 1dpf onwards overlapping expression patterns in the inner ear and the developing liver. In the brain, at 24hpf both atf5a and atf5b were expressed in the forebrain, midbrain, and hindbrain. However, from 2dpf and onwards we only detected atf5a expression namely in the olfactory bulbs, the mesencephalon, and the metencephalon. We further evidenced additional differential expression for atf5a in the sensory neurons of the olfactory organs, and for atf5b in the neuromasts, that form the superficial sensory organ called the lateral line (LL). Our results establish the basis for future functional analyses in this lower vertebrate.

激活转录因子 5 (ATF5) 是一种基本的亮氨酸拉链 (bZIP) 转录因子 (TF)，具有在细胞系统中建立的应激保护、抗凋亡和致癌作用。在整个动物中，Atf5 功能似乎高度依赖于上下文。Atf5在啮齿动物鼻子中强烈表达，小鼠基因敲除 (KO) 幼崽的嗅觉感觉神经元 (OSN) 和较小的嗅球 (OB) 有缺陷，而成年小鼠则嗅觉不足。因此有人提出 Atf5 在 OSN 的成熟和维持中起着重要作用。在小鼠肝脏和骨骼中也描述了Atf5表达，它似乎促进了祖细胞的分化。相比之下，在啮齿动物的大脑中，Atf5最初被描述为在神经祖细胞中独特表达，因此被提议驱动它们的增殖并抑制它们的分化。然而，后来也在成熟神经元中发现了它，强调需要在整个动物中进行额外的工作。ATF5与斑马鱼中的两个旁系同源物（tf5a和atf5b）保持良好。在这里，我们展示了从 6 小时 (hpf) 到受精后 5 天 (dpf) 的表达模式。我们发现这两个基因的早期表达，以及从 1dpf 开始在内耳和发育中的肝脏中的重叠表达模式。在大脑中，在 24hpf 时，atf5a和atf5b 在前脑、中脑和后脑中均有表达。然而，从 2dpf 开始，我们只检测到atf5a在嗅球、中脑和后脑中表达。我们进一步证明了嗅觉器官感觉神经元中atf5a和神经瘤中atf5b 的额外差异表达，形成称为侧线 (LL) 的浅表感觉器官。我们的结果为未来对这种低等脊椎动物的功能分析奠定了基础。