Total Chemical Synthesis of Glycosylated TREM2 Ectodomain

Mutations in a microglia-associated gene TREM2increase the risk of Alzheimer's disease. Currently, structuraland functional studies of TREM2 mainly rely on recombinant TREM2 proteinsexpressed from mammalian cells. However, using this method, it isdifficult to achieve site-specific labeling. Here, we present thetotal chemical synthesis of the 116 amino acid TREM2 ectodomain. Rigorousstructural analysis ensured correct structural fold after refolding.Treating microglial cells with refolded synthetic TREM2 enhanced microglialphagocytosis, proliferation, and survival. We also prepared TREM2constructs with defined glycosylation patterns and found that glycosylationat N79 is critical to the thermal stability of TREM2. This methodwill provide access to TREM2 constructs with site-specific labeling,such as fluorescent labeling, reactive chemical handles, and enrichmenthandles, to further advance our understanding of TREM2 in Alzheimer'sdisease.