The common gamma chain cytokine interleukin-21 is expressed by activated lymphocytes from two macropod marsupials, Macropus eugenii and Onychogalea fraenata.
In mammals, interleukin-21 is a member of the common gamma chain cytokine family that also includes IL-2, IL-4, IL-7, IL-9 and IL-15. IL-21 has pleiotropic effects on both myeloid and lymphoid immune cells and as a consequence, the biological actions of IL-21 are broad: regulating both innate and adaptive immune responses and playing a pivotal role in antiviral, inflammatory and antitumour cellular responses. While IL-21 genes have been characterized in mammals, birds, fish and amphibians, there are no reports for any marsupial species to date. We characterized the expressed IL-21 gene from immune tissues of two macropod species, the tammar wallaby (Macropus eugenii), a model macropod, and the closely related endangered bridled nailtail wallaby (Onychogalea fraenata). The open reading frame of macropod IL-21 is 462 nucleotides in length and encodes a 153-mer putative protein that has 46% identity with human IL-21. Despite the somewhat low amino acid conservation with other mammals, structural elements and residues essential for IL-21 conformation and receptor association were conserved in the macropod IL-21 predicted peptides. The detection of IL-21 gene expression in T-cell-enriched tissues, combined with analysis of the promotor region of the tammar wallaby gene, suggests that macropod IL-21 is expressed in stimulated T cells but is not readily detected in other cells and tissues. The similarity of gene expression profile and functionally important amino acid residues to eutherian IL-21 makes it unlikely that the differences in B- and T-cell responses that are reported for some marsupial species are due to a lack of important functional residues or IL-21 gene expression in this group of mammals.
School of Medical and Applied Sciences, Central Queensland University, Rockhampton, Qld, Australia.
A N
AN
Suthers
School of Science and Health, University of Western Sydney, Penrith, NSW, Australia.
J M
JM
Old
School of Science and Health, University of Western Sydney, Penrith, NSW, Australia.
L J
LJ
Young
D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D007378:Interleukins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology*; D007614:Macropodidae / Q000235:genetics / Q000276:immunology*; D016366:Open Reading Frames; D011401:Promoter Regions, Genetic; D013601:T-Lymphocytes / Q000276:immunology; D000098546:Interleukin-21
D007378:Interleukins; D000098546:Interleukin-21