Paralogs of Common Carp Granulocyte Colony-Stimulating Factor (G-CSF) Have Different Functions Regarding Development, Trafficking and Activation of Neutrophils

Abstract

Mammalian granulocyte colony-stimulating factor (G-CSF; CSF3) is a primary cytokine that promotes the development, mobilization, and activation of neutrophils and their precursors. Teleosts have been reported to possess two paralogs as a likely result of the teleost-wide whole genome duplication (WGD) event, but functional divergence of G-CSF paralogs remains poorly understood. Common carp are an allotetraploid species owing to an additional WGD event in the carp lineage and here, we report on genomic synteny, sequence similarity, and phylogeny of four common carp G-CSF paralogs ( g-csfa1 and g-csfa2 ; g-csfb1 and g-csfb2 ). G-csfa1 and g-csfa2 show differential and relatively high gene expression levels, while g-csfb1 and g-csfb2 show low basal gene expression levels in most tissues. All paralogs are expressed higher in macrophages than in other leukocyte sub-types and are highly up-regulated by treatment of macrophages with mitogens. Recombinant G-CSFa1 and G-CSFb1 both promoted the proliferation of kidney hematopoietic cells, while only G-CSFb1 induced the differentiation of kidney cells along the neutrophil-lineage. Colony-forming unit assays revealed that G-CSFb1 alone stimulates the formation of CFU-G colonies from head- and trunk-kidney whereas the combination of G-CSFa1 and G-CSFb1 stimulates the formation of both CFU-G and CFU-GM colonies. Recombinant G-CSFa1 and G-CSFb1 also exhibit chemotactic activity against kidney neutrophils and up-regulation of cxcr1 mRNA expression was highest in neutrophils after G-CSFb1 stimulation. Furthermore, G-CSFb1 more than G-CSFa1 induced priming of kidney neutrophils through up-regulation of a NADPH-oxidase component p47 phox . In vivo administration of G-CSF paralogs increased the number of circulating blood neutrophils of carp. Our findings demonstrate that gene duplications in teleosts can lead to functional divergence between paralogs and shed light on the sub-functionalization of G-CSF paralogs in cyprinid fish.

Blood Will Tell: What Hematological Analyses Can Reveal About Fish Welfare

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Exposure to extracellular vesicles from Pseudomonas aeruginosa result in loss of DNA methylation at enhancer and DNase hypersensitive site regions in lung macrophages

“…observed DNA hypomethylation in a human macrophage cell line upon exposure to Burkholderia pseudomallei consistent with our results, the work of Marr et al . demonstrates DNA hypermethylation events associated with Leishmania donovani infection of THP-1 macrophages [ 21 , 34 , 35–39 ]. Additional infection models and testing of alternate disease-related pathogens or pathogen-derived secreted products are required to better understand DNA alterations in host-pathogen interactions.…”

Targeting Macrophage Dysregulation for Viral Infections: Novel Targets for Immunomodulators

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