Discovery of functionally selective C5aR2 ligands: novel modulators of C5a signalling.
The complement cascade is comprised of a highly sophisticated network of innate immune proteins that are activated in response to invading pathogens or tissue injury. The complement activation peptide, C5a, binds two seven transmembrane receptors, namely the C5a receptor 1 (C5aR1) and C5a receptor 2 (C5aR2, or C5L2). C5aR2 is a non-G-protein-signalling receptor whose biological role remains controversial. Some of this controversy arises owing to the lack of selective ligands for C5aR2. In this study, a library of 61 peptides based on the C-terminus of C5a was assayed for the ability to selectively modulate C5aR2 function. Two ligands (P32 and P59) were identified as functionally selective C5aR2 ligands, exhibiting selective recruitment of β-arrestin 2 via C5aR2, partial inhibition of C5a-induced ERK1/2 activation and lipopolysaccharide-stimulated interleukin-6 release from human monocyte-derived macrophages. Importantly, neither ligand could induce ERK1/2 activation or inhibit C5a-induced ERK1/2 activation via C5aR1 directly. Finally, P32 inhibited C5a-mediated neutrophil mobilisation in wild-type, but not C5aR2(-/-) mice. These functionally selective ligands for C5aR2 are novel tools that can selectively modulate C5a activity in vitro and in vivo, and thus will be valuable tools to interrogate C5aR2 function.
School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia.|Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
Daniel E
DE
Croker
Department of Infection, Immunity and Cardiovascular Disease, Sheffield University Medical School, Sheffield, UK.
Peter N
PN
Monk
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
Reena
R
Halai
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
Geraldine
G
Kaeslin
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
Zoe
Z
Schofield
School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia.
Mike Cl
MC
Wu
School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia.
Richard J
RJ
Clark
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
Mark At
MA
Blaskovich
Department of Bioengineering, University of California, Riverside, CA, USA.
Dimitrios
D
Morikis
Artie McFerrin Department of Chemical Engineering and Texas A&M Energy Institute, Texas A&M University, College Station, TX, USA.
Christodoulos A
CA
Floudas
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
Matthew A
MA
Cooper
School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia.
Trent M
TM
Woodruff
D000818:Animals; D016466:CHO Cells; D015936:Complement C5a / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008024:Ligands; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D009000:Monocytes / Q000166:cytology; D009504:Neutrophils / Q000378:metabolism; D019151:Peptide Library; D011485:Protein Binding; D055503:Protein Multimerization; D044087:Receptor, Anaphylatoxin C5a / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation; D000071560:beta-Arrestin 2
D015850:Interleukin-6; D008024:Ligands; D019151:Peptide Library; D044087:Receptor, Anaphylatoxin C5a; D000071560:beta-Arrestin 2; D015936:Complement C5a; D048049:Extracellular Signal-Regulated MAP Kinases