Functional insights from biophysical study of TREM2 interactions with apoE and Aβ1‐42

Daniel L. Kober, Melissa D. Stuchell‐Brereton, Colin E. Kluender, Hunter B. Dean, Michael R. Strickland, Deborah F. Steinberg, Samantha S. Nelson, Berevan Baban, David M. Holtzman, Carl Frieden, Jennifer Alexander‐Brett, Erik D. Roberson, Yuhua Song, Tom J. Brett. Alzheimers Dementia. 2020 Oct 8 Read More

Abstract

Introduction
Triggering receptor expressed on myeloid cells‐2 (TREM2) is an immune receptor expressed on microglia that also can become soluble (sTREM2). How TREM2 engages different ligands remains poorly understood.

Methods
We used comprehensive biolayer interferometry (BLI) analysis to investigate TREM2 and sTREM2 interactions with apolipoprotein E (apoE) and monomeric amyloid beta (Aβ) (mAβ42).

Results
TREM2 engagement of apoE was protein mediated with little effect of lipidation, showing slight affinity differences between isoforms (E4 > E3 > E2). Another family member, TREML2, did not bind apoE. Disease‐linked TREM2 variants within a “basic patch” minimally impact apoE binding. Instead, TREM2 uses a unique hydrophobic surface to bind apoE, which requires the apoE hinge region. TREM2 and sTREM2 directly bind mAβ42 and potently inhibit Aβ42 polymerization, suggesting a potential role for soluble sTREM2 in preventing AD pathogenesis.

Discussion
These findings demonstrate that TREM2 has at least two ligand‐binding surfaces that might be therapeutic targets and uncovers a potential function for sTREM2 in directly inhibiting Aβ polymerization.

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Posted on November 4, 2020
Posted in: HPAN, Neurodegeneration, Publications Authors: , ,