Human-specific microglial receptor Siglec-11 in neuroinflammatory diseases
Siglecs are members of the immunoglobulin superfamily that bind to sialic acid. Siglec-11 is a recently identified human-specific CD33-related siglec expressed on microglia. Siglec-11 activates src homology 2 domain-containing protein tyrosine phosphatase (SHP) 1 and SHP2, which are known to be involved in anti-inflammatory signalling of microglia. In this project, the function of siglec-11 in microglia cells will be analyzed to determine its role in neuroinflammatory diseases. In an in vitro model, isolated and cultured microglial cells will be genetically modified to overexpress human siglec-11. Gene transcripts and protein expression of cytokines and chemokines produced by microglia will be studied after stimulation of siglec-11. Furthermore, microglial cell lines (BV-2 and N9) will be co-transduced with lentiviral vectors expressing human siglec-11 tagged with citrine at the c-terminus and SHP1 tagged with cerulean at the c-terminus. Fluorescence lifetime (FLIM)-based fluorescence resonance energy transfer (FRET) analysis will be performed to study the interaction between siglec-11 and SHP1. Possible ligands stimulating siglec-11 on the microglia will be analyzed. To establish an in vivo model, transgenic mice will be generated expressing human siglec-11 under the microglial-specific promoter Iba1. Transgenic mice will be challenged to experimental autoimmune encephalomyelitis (EAE). Data obtained from this project will elucidate the role of siglec-11 in brain microglial cells and its impact on the development or novel therapies for neuroinflammatory and neurodegenerative diseases.