Trem1 — Triggering Receptor Expressed On Myeloid Cells 1 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Official Symbol: TREM1
Official Full Name: Triggering Receptor Expressed on Myeloid Cells 1
Gene ID: 54206
Chromosomal Location: 6p21.1
Protein: Triggering Receptor Expressed on Myeloid Cells 1 (TREM-1)
The TREM1 gene encodes Triggering Receptor Expressed on Myeloid Cells 1 (TREM-1), a cell surface receptor primarily expressed on neutrophils, monocytes, and macrophages. TREM-1 amplifies inflammatory responses to microbial infections and plays a significant role in inflammatory diseases, including neuroinflammation in neurodegenerative disorders.
The TREM1 gene spans approximately 3.5 kb on chromosome 6p21.1 and consists of 5 exons. The gene encodes a 234 amino acid type I transmembrane protein. TREM1 is part of a gene family including TREM2 and TREM3 (a pseudogene in humans).
TREM-1 is a member of the immunoglobulin superfamily:
- Extracellular domain: V-type immunoglobulin-like domain
- Transmembrane domain: Single pass helix
- Cytoplasmic tail: Short (5 aa) - signals through adaptor protein DAP12
The receptor forms a complex with DAP12 (TYROBP), which contains an ITAM motif for signal transduction.
TREM-1 functions as an amplifier of innate immune responses:
- Binds to various ligands including:
- Bacterial cell wall components (peptidoglycan, LPS)
- Heat shock proteins
- HMGB1 (High Mobility Group Box 1)
- TREM-1 transmodulation (crosstalk with other receptors)
- DAP12 phosphorylation → Syk activation
- NF-κB activation → Pro-inflammatory cytokine production
- MAPK pathways (ERK, p38, JNK)
- Increased expression of chemokines and adhesion molecules
- Rapid and robust inflammatory response
- Cytokine storm induction (TNF-α, IL-1β, IL-6, IL-8, MCP-1)
- Neutrophil degranulation
- Phagocytosis modulation
TREM-1 is expressed primarily on:
- Neutrophils: Highest expression
- Monocytes and macrophages: Including microglia in CNS
- Dendritic cells: Some subsets
- Osteoclasts: Bone resorption function
In the CNS, TREM-1 is expressed primarily on activated microglia and infiltrating macrophages.
- TREM-1 is upregulated in AD brain, especially around plaques
- TREM-1 amplifies Aβ-induced neuroinflammation
- May contribute to chronic microglial activation
- TREM-1/TREM2 imbalance affects microglial phenotype
- TREM-1 elevated in substantia nigra and CSF
- Contributes to neuroinflammation in PD models
- TREM-1 blockade reduces dopaminergic neuron loss
- Synergistic effects with α-synuclein pathology
- TREM-1 is increased in ALS spinal cord
- Contributes to motor neuron inflammation
- TREM-1 inhibition shows protective effects in models
- TREM-1 expression correlates with disease activity
- TREM-1 blockade reduces EAE severity
- Role in blood-brain barrier disruption
¶ Stroke and TBI
- TREM-1 is rapidly upregulated after injury
- Contributes to post-ischemic inflammation
- TREM-1 inhibition may be neuroprotective
TREM-1 is a promising therapeutic target:
- TREM1 inhibitors: Anti-TREM1 antibodies, TREM1-Fc decoy
- Small molecule inhibitors: In development
- Gene therapy approaches: Targeting microglial expression
- Combination therapy: TREM1 + TREM2 targeting
Clinical trials are underway for TREM1 inhibitors in inflammatory diseases.
- TREM1 knockout mice: Reduced inflammation in infection models
- TREM1 transgenic mice: Exaggerated inflammatory responses
- TREM1/DAP12 models: Studying signal transduction
The study of Trem1 — Triggering Receptor Expressed On Myeloid Cells 1 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- TREM-1 in neuroinflammation and AD - Nature Reviews Neuroscience, 2022
- TREM-1 in Parkinson's disease - Brain, 2021
- TREM-1 and ALS pathogenesis - JCI, 2021
- TREM-1 in multiple sclerosis - Annals of Neurology, 2020
- TREM1 as therapeutic target - Drug Discovery Today, 2021