Clarification of the role of N-glycans on the common beta-subunit of the human IL-3, IL-5 and GM-CSF receptors and the murine IL-3 beta-receptor in ligand-binding and receptor activation.
Granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-3 and IL-5 are related cytokines that play key roles in regulating the differentiation, proliferation, survival and activation of myeloid blood cells. The cell surface receptors for these cytokines are composed of cytokine-specific alpha-subunits and a common beta-receptor (betac), a shared subunit that is essential for receptor signaling in response to GM-CSF, IL-3 and IL-5. Previous studies have reached conflicting conclusions as to whether N-glycosylation of the betac-subunit is necessary for functional GM-CSF, IL-3 and IL-5 receptors. We sought to clarify whether betac N-glycosylation plays a role in receptor function, since all structural studies of human betac to date have utilized recombinant protein lacking N-glycosylation at Asn(328). Here, by eliminating individual N-glycans in human betac and the related murine homolog, beta(IL-3), we demonstrate unequivocally that ligand-binding and receptor activation are not critically dependent on individual N-glycosylation sites within the beta-subunit although the data do not preclude the possibility that N-glycans may exert some sort of fine control. These studies support the biological relevance of the X-ray crystal structures of the human betac domain 4 and the complete ectodomain, both of which lack N-glycosylation at Asn(328).
Murphy
James M
JM
Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia. Electronic address: jamesm@wehi.edu.au.
Soboleva
Tatiana A
TA
Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia.
Mirza
Shamaruh
S
Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia.
Ford
Sally C
SC
Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia.
Olsen
Jane E
JE
Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia.
Chen
Jinglong
J
Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia.
Young
Ian G
IG
Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia. Electronic address: Ian.Young@anu.edu.au.
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D053648:Cytokine Receptor Common beta Subunit / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007377:Interleukin-3 / Q000378:metabolism; D015848:Interleukin-5 / Q000378:metabolism; D051379:Mice; D016297:Mutagenesis, Site-Directed; D011134:Polysaccharides / Q000737:chemistry / Q000502:physiology*; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry / Q000502:physiology*; D016185:Receptors, Interleukin-3 / Q000737:chemistry / Q000502:physiology*; D053649:Receptors, Interleukin-5 / Q000737:chemistry / Q000502:physiology*
D053648:Cytokine Receptor Common beta Subunit; C508599:IL5 protein, human; D007377:Interleukin-3; D015848:Interleukin-5; D011134:Polysaccharides; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016185:Receptors, Interleukin-3; D053649:Receptors, Interleukin-5