The C-type Lectin Receptor CLECSF8 (CLEC4D) Is Expressed by Myeloid Cells and Triggers Cellular Activation through Syk Kinase

Lisa M. Graham; Vandana Gupta; Georgia Schafer; Delyth M. Reid; Matti Kimberg; Kevin M. Dennehy; William G. Hornsell; Reto Guler; Maria A. Campanero-Rhodes; Angelina S. Palma; Ten Feizi; Stella K. Kim; Peter Sobieszczuk; Janet A. Willment; Gordon D. Brown

doi:10.1074/jbc.M112.384164

The C-type Lectin Receptor CLECSF8 (CLEC4D) Is Expressed by Myeloid Cells and Triggers Cellular Activation through Syk Kinase*

From the ^‡Institute of Infectious Disease and Molecular Medicine, Central Laboratory Services, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town 7925, South Africa,
the ^§Section of Immunology and Infection, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom,
the ^¶Glycosciences Laboratory, Imperial College London, Burlington Danes Building, Du Cane Road, London W12 0NN, United Kingdom,
the ^‖School of Dentistry, University of California at San Francisco, San Francisco, CA 94143, and
the ^**Auckland Cancer Society Research Center, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

↵5 To whom correspondence may be addressed: Section of Immunology and Infection, Division of Applied Medicine, Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom. E-mail: janet.willment{at}abdn.ac.uk.
↵6 To whom correspondence may be addressed: Section of Immunology and Infection, Division of Applied Medicine, Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom. E-mail: gordon.brown{at}abdn.ac.uk.

↵4 Both authors contributed equally to this work.

↵1 Present address: Institut für Medizinische Virologie, Universitätsklinikum Tübingen, 72076 Tübingen, Germany.
↵2 Present address: Instituto de Química-Física “Rocasolano,” Consejo Superior de Investigaciones Cientificas, and Ciber of Respiratory Diseases (CIBERES) Serrano 119, 28006 Madrid, Spain.
↵3 Present address: Rede de Química e Tecnologia/Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.

Background: C-type lectins play important roles in immunity and homeostasis.

Results: CLECSF8 is expressed on neutrophils and monocytes and can mediate phagocytosis, the respiratory burst and inflammatory cytokine production, in part through association with a novel adaptor.

Conclusion: CLECSF8 can trigger cellular activation.

Significance: This study identifies a novel C-type lectin that can control immune cell function.

Abstract

CLECSF8 is a poorly characterized member of the “Dectin-2 cluster” of C-type lectin receptors and was originally thought to be expressed exclusively by macrophages. We show here that CLECSF8 is primarily expressed by peripheral blood neutrophils and monocytes and weakly by several subsets of peripheral blood dendritic cells. However, expression of this receptor is lost upon in vitro differentiation of monocytes into dendritic cells or macrophages. Like the other members of the Dectin-2 family, which require association of their transmembrane domains with signaling adaptors for surface expression, CLECSF8 is retained intracellularly when expressed in non-myeloid cells. However, we demonstrate that CLECSF8 does not associate with any known signaling adaptor molecule, including DAP10, DAP12, or the FcRγ chain, and we found that the C-type lectin domain of CLECSF8 was responsible for its intracellular retention. Although CLECSF8 does not contain a signaling motif in its cytoplasmic domain, we show that this receptor is capable of inducing signaling via Syk kinase in myeloid cells and that it can induce phagocytosis, proinflammatory cytokine production, and the respiratory burst. These data therefore indicate that CLECSF8 functions as an activation receptor on myeloid cells and associates with a novel adaptor molecule. Characterization of the CLECSF8-deficient mice and screening for ligands using oligosaccharide microarrays did not provide further insights into the physiological function of this receptor.

Footnotes

↵* This work was funded by the Wellcome Trust, the National Research Foundation, the Deutscher Akademischer Austauschdienst, the University of Cape Town, the UK Research Council Basic Technology Initiative “Glycoarrays” (GRS/79268), and the UK Medical Research Council. A. S. P is a fellow of the Fundação para a Ciência e Tecnologia (SFRH/BPD/26515/2006, Portugal) and M. A. C. of the Consejo Superior de Investigaciones Cientificas, Programe “Junta para la Ampliación de Estudios” (JaeDoc/098/2011) cofinanced by the Fondo Social Europeo.
↵ This article contains supplemental Figs. 1–8 and Methods.