microglial immune receptor · BEGINNER LESSON
TREM2
TREM2 is a transmembrane receptor on microglia, the brain’s immune cells, that helps sense ligands outside the cell and start intracellular signaling. It is measured and studied through its expression, its binding partners, and its effects on microglial functions such as phagocytosis and inflammation.
What it is
TREM2 (triggering receptor expressed in myeloid cells 2) is a transmembrane glycoprotein receptor of the immunoglobulin superfamily. It is described as having an extracellular V-like domain, a single membrane-spanning region, and a short cytoplasmic tail. In the sources, it is mainly discussed as a receptor on microglia, the immune cells of the central nervous system.
[1] TREM2 in neurodegeneration and diseases [2] TREM2 and microglial immunity in Alzheimer's disease - PMC [3] Bibliometric Analysis of TREM2 (2001-2022): Trends, Hotspots and Prospects in Human Disease
Where it is found
The sources describe TREM2 as expressed in microglia, with especially notable expression in brain regions such as white matter, spinal cord, hippocampus, basal ganglia, corpus callosum, and brainstem. This makes it a cell-type- and brain-region-associated molecule rather than a general body-wide marker in these excerpts.
[1] TREM2 in neurodegeneration and diseases [2] TREM2 and microglial immunity in Alzheimer's disease - PMC
How it works
When TREM2 binds ligands such as apolipoproteins, phospholipids, or amyloid-β (Aβ), it signals through adaptor proteins DAP12 and DAP10. These adaptor proteins pass the signal inward so microglia can change survival, movement, metabolism, and phagocytosis. Phagocytosis means cell-mediated engulfing and removal of material.
[1] TREM2 in neurodegeneration and diseases [2] TREM2 and microglial immunity in Alzheimer's disease - PMC [3] Bibliometric Analysis of TREM2 (2001-2022): Trends, Hotspots and Prospects in Human Disease
What it does in disease
The sources connect TREM2 with responses to Alzheimer’s disease, Parkinson’s disease, stroke, hemorrhage, and trauma. In Alzheimer’s disease, TREM2 is described as helping microglia clear Aβ plaques, apoptotic neurons, and damaged myelin, while also reducing neuroinflammation. The excerpts also link TREM2 to a disease-associated microglia phenotype and to TREM2-APOE signaling.
[1] TREM2 in neurodegeneration and diseases [2] TREM2 and microglial immunity in Alzheimer's disease - PMC [3] Bibliometric Analysis of TREM2 (2001-2022): Trends, Hotspots and Prospects in Human Disease
Limits and caveats
The sources also show that TREM2 is not simply protective in every context. One excerpt says the effects can depend on the presence of Aβ pathology, and another notes that TREM2 deletion may reduce plaque load early but worsen pathology later. A bibliometric study also warns that database-based summaries can miss studies and that clustering methods can affect results.
[1] TREM2 in neurodegeneration and diseases [2] TREM2 and microglial immunity in Alzheimer's disease - PMC [3] Bibliometric Analysis of TREM2 (2001-2022): Trends, Hotspots and Prospects in Human Disease
SEE THE IDEA
How TREM2 links an outside signal to a microglial response
Aβ, apolipoproteins, phospholipids, and other anionic molecules can bind TREM2.
A membrane receptor that detects these ligands.
These proteins relay the signal across the membrane into the cell.
Changes in phagocytosis, survival, movement, metabolism, and inflammatory signaling.
Signal flow: ligand binding at TREM2 leads through adaptor proteins to altered microglial behavior.
The excerpts describe TREM2 as a microglial receptor that converts extracellular binding events into internal immune responses.
TRY IT YOURSELF
Test your understanding
Choose an answer, then check the explanation.
PUT IT TOGETHER
Match each concept to its meaning
Drag a label onto its description, or select a label and then select a description. This also works with a keyboard.
4 pairs to match
Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.