The Orphan Cytokine Receptor CRLF3 Emerged With the Origin of the Nervous System and Is a Neuroprotective Erythropoietin Receptor in Locusts
The Orphan Cytokine Receptor CRLF3 Emerged With the Origin of the Nervous System and Is a Neuroprotective Erythropoietin Receptor in Locusts
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DOI：
10.3389/fnmol.2019.00251
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发表时间：
2019-10-11
影响因子：
4.8
通讯作者：
Heinrich, Ralf
中科院分区：
文献类型：
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作者：
Hahn, Nina;Bueschgens, Luca;Heinrich, Ralf
孤儿细胞因子受体样因子3（CRLF 3）被鉴定为蝗虫神经元中的神经保护性促红细胞生成素受体，并随着真后生动物神经系统的进化而出现。人CRLF 3属于I类螺旋细胞因子受体，其介导对损伤和多种生理挑战的多效性细胞反应。它在包括中枢神经系统在内的各种组织中表达，但其配体仍未鉴定。一个CRLF 3直向同源物在全变态甲虫赤拟谷盗最近被证明诱导抗凋亡机制后，刺激与人类重组促红细胞生成素。为了验证CRLF 3代表促红细胞生成素样细胞因子的古老细胞保护受体的假设，我们研究了其在后生动物物种中的存在。此外，我们研究了CRLF 3在半代谢昆虫飞蝗中的表达和功能。系统发育分析表明，CRLF 3基因在孔动物门、浮游动物门和栉水母门中缺失，它们都缺乏传统的神经系统。然而，它存在于所有主要的真后生动物群中，从刺胞动物到原口动物到哺乳动物。CRLF 3序列在脊椎动物中高度保守和丰富。相比之下，相对较少的无脊椎动物表达CRLF 3，这些序列显示出更大的变异性，这表明由于功能重要性低而频繁丢失。在洛本研究利用RACE-PCR技术鉴定了Lm-crlf 3基因的转录本，并检测了其在蝗虫脑、骨骼肌和血细胞中的表达。这些发现与crlf 3在哺乳动物组织中的普遍表达相一致。我们证明，唯一添加的双链RNA的培养基（称为浸泡RNA干扰）特异性干扰蝗虫原代脑细胞培养物中的蛋白质表达。该技术用于敲低Lm-crlf 3表达并消除其生理功能。我们证实，重组人促红细胞生成素拯救蝗虫脑神经元缺氧诱导的细胞凋亡，并表明这种神经保护作用是敲低Lm-crlf 3后不存在。我们的研究结果证实了CRLF 3在来自不同分类群的第二种昆虫物种中的促红细胞生成素诱导的神经保护功能。他们认为，CRLF 3受体在遗传学上保守，可能在其他动物（包括脊椎动物和哺乳动物）中也作为促红细胞生成素或结构相关细胞因子的细胞保护受体发挥作用。
The orphan cytokine receptor-like factor 3 (CRLF3) was identified as a neuroprotective erythropoietin receptor in locust neurons and emerged with the evolution of the eumetazoan nervous system. Human CRLF3 belongs to class I helical cytokine receptors that mediate pleiotropic cellular reactions to injury and diverse physiological challenges. It is expressed in various tissues including the central nervous system but its ligand remains unidentified. A CRLF3 ortholog in the holometabolous beetle Tribolium castaneum was recently shown to induce anti-apoptotic mechanisms upon stimulation with human recombinant erythropoietin. To test the hypothesis that CRLF3 represents an ancient cell-protective receptor for erythropoietin-like cytokines, we investigated its presence across metazoan species. Furthermore, we examined CRLF3 expression and function in the hemimetabolous insect Locusta migratoria. Phylogenetic analysis of CRLF3 sequences indicated that CRLF3 is absent in Porifera, Placozoa and Ctenophora, all lacking the traditional nervous system. However, it is present in all major eumetazoan groups ranging from cnidarians over protostomians to mammals. The CRLF3 sequence is highly conserved and abundant amongst vertebrates. In contrast, relatively few invertebrates express CRLF3 and these sequences show greater variability, suggesting frequent loss due to low functional importance. In L. migratoria, we identified the transcript Lm-crlf3 by RACE-PCR and detected its expression in locust brain, skeletal muscle and hemocytes. These findings correspond to the ubiquitous expression of crlf3 in mammalian tissues. We demonstrate that the sole addition of double-stranded RNA to the culture medium (called soaking RNA interference) specifically interferes with protein expression in locust primary brain cell cultures. This technique was used to knock down Lm-crlf3 expression and to abolish its physiological function. We confirmed that recombinant human erythropoietin rescues locust brain neurons from hypoxia-induced apoptosis and showed that this neuroprotective effect is absent after knocking down Lm-crlf3. Our results affirm the erythropoietin-induced neuroprotective function of CRLF3 in a second insect species from a different taxonomic group. They suggest that the phylogenetically conserved CRLF3 receptor may function as a cell protective receptor for erythropoietin or a structurally related cytokine also in other animals including vertebrate and mammalian species.