Investigating the therapeutic potential of soluble TREM2 interactions with Transgelin-2 in Alzheimer's disease

Abstract

Triggering receptor expressed on myeloid cells 2 (TREM2) is a regulator of microglial function in Alzheimer's disease (AD), and its soluble ectodomain (sTREM2) has emerged as a potential neuroprotective factor. Recent work shows that sTREM2 exerts protective effects through direct interaction with neuronal transgelin-2 (TG2) and modulates downstream tau pathology, yet the molecular basis of this interaction remains unknown. Here, we use all-atom molecular dynamics simulations to define the structural mechanisms of sTREM2-TG2 binding. We identify an electrostatically driven interface centered on the TG2 calponin homology domain. This surface is engaged by a binding motif on sTREM2 in which charged anchoring residues are flanked by hydrophobic contacts. We further show that the AD-risk TREM2R47H variant maintains a more open, solvent-exposed CDR2 loop that redistributes interfacial contacts while preserving overall binding affinity, offering a structural explanation for reports that R47H does not exacerbate tau pathology in tauopathy models. Leveraging these insights, we design optimized sTREM2-derived peptides that outperform a previously reported therapeutic peptide in binding persistence, energetics, and recapitulation of native TG2 contacts, supporting engagement at the epitope through which sTREM2 suppresses tau phosphorylation. Taken together, our results define a mechanistic framework for the sTREM2-TG2 axis in AD and establish a structure-guided strategy for developing peptide modulators of this interaction.