The Orphan Cytokine Receptor CRLF3 Emerged With the Origin of the Nervous System and Is a Neuroprotective Erythropoietin Receptor in Locusts

Abstract

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.

High-quality chromosome-level genome assembly and full-length transcriptome analysis of the pharaoh ant Monomorium pharaonis

“…On the basis of GO term analysis, we revealed that these genes were significantly enriched in phosphotransferase activity (GO:0016773), carbohydrate derivative binding (GO:0097367), and neurotransmitters (GO:0005328) ( Supplementary Table S19 ). For example, cytokine receptor-like factor 3 ( crlf3 ), which is a neuroprotective erythropoietin receptor in beetle ( Tribolium castaneum ) and locust ( Locusta migratoria ) neurons and emerged with the evolution of the eumetazoan nervous system [ 50 , 51 ], had several caste-specific isoforms and different dominant expressed isoforms in each pharaoh ant caste ( Supplementary Fig. S4 ).…”

Gene expression changes associated with trajectories of psychopathology in a longitudinal cohort of children and adolescents

“…CRLF3 (Cytokine Receptor Like Factor 3, adjusted p = 0.034, logFC = −0.187) encodes a largely uncharacterized orphan cytokine receptor that is expressed in various human tissues, including brain. Its function is not well known; however, it has been associated with cell cycle regulation, neuronal morphology, and amyotrophic lateral sclerosis 44 .…”

Locust Hemolymph Conveys Erythropoietin-Like Cytoprotection via Activation of the Cytokine Receptor CRLF3

“…We have recently reported the expression of the cytokine receptor, cytokine receptor-like factor 3 (CRLF3), in hemocytes of Locusta migratoria (Hahn et al, 2019). CRLF3 is an orphan class I cytokine receptor that shares similarities with vertebrate receptors for prolactin, growth hormone, thrombopoietin, and Epo (Boulay et al, 2003;Liongue and Ward, 2007).…”

“…CRLF3 is an orphan class I cytokine receptor that shares similarities with vertebrate receptors for prolactin, growth hormone, thrombopoietin, and Epo (Boulay et al, 2003;Liongue and Ward, 2007). While most class 1 cytokine receptors are exclusively present in vertebrates, CRLF3 is highly conserved throughout eumetazoan species ranging from cnidarians to humans (Hahn et al, 2019). Despite the absence of Epo or recognized Epo receptors in insects, recombinant human Epo (rhEpo) protects cultured insect neurons from apoptotic cell death (Miljus et al, 2014;Hahn et al, 2017;Heinrich et al, 2017) and promotes regeneration of neurites in vitro and in vivo (Ostrowski et al, 2011).…”