Spiny and soft-rayed fin domains in acanthomorph fish are established through a BMP-gremlin-shh signaling network
Spiny and soft-rayed fin domains in acanthomorph fish are established through a BMP-gremlin-shh signaling network
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DOI：
10.1073/pnas.2101783118
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发表时间：
2021-07-20
影响因子：
11.1
通讯作者：
Woltering, Joost M.
中科院分区：
文献类型：
--
作者：
Hoech, Rebekka;Schneider, Ralf F.;Woltering, Joost M.
有超过18，000种，棘鳍鱼，或刺鳍鱼，形成了最大和最多样化的脊椎动物辐射。促成它们进化成功的关键新奇之一是它们鳍上的刺状射线，这是一种防御机制。我们调查的图案化机制分化成离散的多刺和软射线域的直接发展的慈鲷鱼Astatotilapia burtoni的个体发育过程中的中鳍原基。不同的转录因子标记表征了这两个鳍结构域，由此hoxa 13 a/B与alx 4 a/B和tbx 2 B的互斥表达标记了脊柱到软线的边界。软射线域是通过gremlin 1b抑制BMP而建立的，gremlin 1b在后鳍中与从极化活性区分泌的shh协同作用。通过化学抑制或gremlin 1b CRISPR/Cas9敲除来调节BMP信号传导诱导棘向软射线的同源异型转化，反之亦然。在nonacanthomorph鳍的脊柱和软射线基因的表达表明，结合exaptation和后扩张的祖先的前鳍边缘的发展计划允许的发展，强大的个性化的多刺和软射线域。我们认为，这种模式的重复适应可能是鱼类前刺鳍元件趋同进化的基础。
With over 18,000 species, the Acanthomorpha, or spiny-rayed fishes, form the largest and arguably most diverse radiation of vertebrates. One of the key novelties that contributed to their evolutionary success are the spiny rays in their fins that serve as a defense mechanism. We investigated the patterning mechanisms underlying the differentiation of median fin Anlagen into discrete spiny and soft rayed domains during the ontogeny of the direct-developing cichlid fish Astatotilapia burtoni. Distinct transcription factor signatures characterize these two fin domains, whereby mutually exclusive expression of hoxa13a/b with alx4a/b and tbx2b marks the spine to soft-ray boundary. The soft-ray domain is established by BMP inhibition via gremlin1b, which synergizes in the posterior fin with shh secreted from a zone of polarizing activity. Modulation of BMP signaling by chemical inhibition or gremlin1b CRISPR/Cas9 knockout induces homeotic transformations of spines into soft rays and vice versa. The expression of spine and soft-ray genes in nonacanthomorph fins indicates that a combination of exaptation and posterior expansion of an ancestral developmental program for the anterior fin margin allowed the evolution of robustly individuated spiny and soft-rayed domains. We propose that a repeated exaptation of such pattern might underly the convergent evolution of anterior spiny fin elements across fishes.