Siglec functions of microglia.
Microglia are the resident immune cells of the central nervous system. They can sense intact or lesioned cells and then respond in an appropriate way. Therefore, microglia need recognition receptors that lead to either the activation or the inhibition of the immune response pathways. Most Siglecs contain an immunoreceptor tyrosine based inhibition motif and its signaling leads to the termination of signals emerging from immunoreceptor tyrosine-based activation motif-signaling receptors. Pro-inflammatory immune responses and phagocytosis are turned down in microglia by inhibitory Siglec signaling. Recently, it was demonstrated that inhibitory Siglecs have neuroprotective effects on cultured neurons by preventing the phagocytosis-associated oxidative burst. Furthermore, microglial mouse Siglec-E and human Siglec-11 have been shown to prevent neurotoxicity via interaction with sialic acid exposed on the neuronal glycocalyx. Thus, Siglecs sensing the intact glycocalyx of neighboring cells keep microglia in a silent homeostatic status.
Neural Regeneration Group, Institute of Reconstructive Neurobiology, University Hospital Bonn, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany.
Bettina
B
Linnartz-Gerlach
Neural Regeneration Group, Institute of Reconstructive Neurobiology, University Hospital Bonn, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany.
Jens
J
Kopatz
Neural Regeneration Group, Institute of Reconstructive Neurobiology, University Hospital Bonn, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany hneuman1@uni-bonn.de.
Harald
H
Neumann
D000818:Animals; D006801:Humans; D017628:Microglia / Q000276:immunology / Q000378:metabolism*; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000378:metabolism; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism; D063265:Sialic Acid Binding Immunoglobulin-like Lectins / Q000378:metabolism*; D015398:Signal Transduction
D011971:Receptors, Immunologic; D063265:Sialic Acid Binding Immunoglobulin-like Lectins; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6
Siglecs; central nervous system; microglia