<table class="infobox infobox-gene">
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<th class="infobox-header" colspan="2">TREML2 — Triggering Receptor Expressed on Myeloid Cells-Like 2</th>
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<td class="label">Symbol</td>
<td><strong>TREML2</strong></td>
</tr>
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<td class="label">Full Name</td>
<td>TREML2 — Triggering Receptor Expressed on Myeloid Cells-Like 2</td>
</tr>
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<td class="label">Type</td>
<td>Gene</td>
</tr>
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<td class="label">NCBI</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/?term=TREML2" target="_blank">Search NCBI</a></td>
</tr>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
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</table>
Treml2 — Triggering Receptor Expressed On Myeloid Cells Like 2 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes. PMID: 41351686
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">TREML2 — Triggering Receptor Expressed on Myeloid Cells-Like 2</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>TREML2</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>TREML2 — Triggering Receptor Expressed on Myeloid Cells-Like 2</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Gene</td>
</tr>
<tr>
<td class="label">NCBI</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/?term=TREML2" target="_blank">Search NCBI</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
Treml2 — Triggering Receptor Expressed On Myeloid Cells Like 2 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes. PMID: 41351686
TREML2 (Triggering Receptor Expressed on Myeloid Cells-Like 2), also known as TREM2B, is a gene located on chromosome 6p21.1. It encodes a protein that is structurally similar to [TREM2](/proteins/trem2) (Triggering Receptor Expressed on Myeloid Cells 2) and is involved in immune signaling in myeloid cells [1][2]. The gene belongs to the TREM family of immune receptors, which play critical roles in inflammation, phagocytosis, and immune homeostasis. TREML2 has emerged as a significant player in neuroinflammatory processes that contribute to neurodegenerative conditions, particularly Alzheimer's disease [3][4].
The TREML2 gene is situated on chromosome 6p21.1, a region that contains numerous immune-related genes within the major histocompatibility complex (MHC) cluster. This chromosomal location is evolutionarily significant, as it places TREML2 in close proximity to other immune regulatory genes that coordinate innate immune responses [5]. The genomic architecture of TREML2 encompasses multiple exons that encode distinct protein domains, including an extracellular immunoglobulin-like domain, a transmembrane region, and a short cytoplasmic tail that lacks canonical signaling motifs [2]. PMID: 33090700
The NCBI Gene database lists TREML2 with the identifier 340205, while Ensembl provides the stable gene identifier ENSG00000162009. The UniProt entry Q9GZL5 characterizes the protein product, detailing its molecular weight, post-translational modifications, and subcellular localization patterns [6]. These database references provide foundational information for researchers investigating TREML2 function and regulation. PMID: 27143430
TREML2 encodes a transmembrane receptor protein that shares significant structural homology with TREM2. The protein possesses an extracellular Ig-like domain that facilitates ligand binding, a hydrophobic transmembrane domain that anchors the protein in cellular membranes, and a cytoplasmic tail that interacts with adaptor proteins [7]. Unlike TREM2, TREML2 contains a shorter cytoplasmic domain and exhibits distinct signaling properties that differentiate its functional repertoire from its better-characterized homolog.
The protein functions as an immune receptor primarily expressed on myeloid cell lineages, including [microglia](/cell-types/microglia-neuroinflammation) in the central nervous system, monocytes, macrophages, and dendritic cells [8]. Upon ligand engagement, TREML2 triggers intracellular signaling cascades that modulate inflammatory responses, phagocytic activity, and cell survival pathways. These functions position TREML2 as a critical regulator of neuroinflammation, a process increasingly recognized as a key contributor to neurodegenerative disease pathogenesis [3][9].
TREML2 belongs to a family of TREM-like receptors that includes TREM1, TREM2, TREML1 (also known as TREM-like transcript 1), and TREML2 [1][7]. Among these, TREML2 shares the highest structural similarity with TREM2, a receptor well-established for its role in microglial phagocytosis and Alzheimer's disease risk [10]. The TREM2 gene harbors rare variants that significantly increase Alzheimer's disease risk, with the R47H variant identified as a powerful risk factor for late-onset disease [11][12].
Research has demonstrated that TREML2 can compensate for TREM2 deficiency in certain functional contexts, suggesting overlapping and potentially redundant roles within the TREM family [2][13]. Studies have shown that TREML2 can bind similar ligands as TREM2, including apolipoproteins and lipid-containing molecules, though with differing affinities and signaling outcomes [14]. This functional relationship has generated substantial interest in understanding how TREML2 might modulate neurodegenerative processes either independently or in concert with TREM2.
TREML2 demonstrates tissue-specific expression patterns with highest levels detected in immune organs and the central nervous system. In peripheral tissues, robust expression occurs in the spleen, bone marrow, and lymph nodes, reflecting its role in myeloid cell function [8]. Within the brain, TREML2 is predominantly expressed by microglia, the resident immune cells of the central nervous system, where it participates in surveillance and response to pathological stimuli [3][15].
Microglial expression of TREML2 increases in response to neuroinflammatory signals and during neurodegenerative disease progression. RNA sequencing studies have identified TREML2 expression in disease-associated microglia (DAM) or neurodegenerative microglia, a specialized microglial phenotype that emerges in Alzheimer's disease and other neurodegenerative conditions [16][17]. This upregulation suggests that TREML2 may participate in the microglial response to [amyloid-beta](/proteins/amyloid-beta) plaques and [tau](/proteins/tau) pathology.
TREML2 has garnered considerable attention for its involvement in Alzheimer's disease pathogenesis. Multiple genetic association studies have identified TREML2 variants that influence Alzheimer's disease risk, though the effect sizes are generally smaller than those observed for TREM2 variants [3][18][19]. The rs3747742 polymorphism in TREML2 has been associated with altered Alzheimer's disease risk in various population studies, with conflicting results suggesting complex gene-environment interactions [20][21].
Functional studies have revealed that TREML2 modulates microglial responses to amyloid-beta, the hallmark protein aggregate in Alzheimer's disease. TREML2 signaling can influence amyloid clearance mechanisms, inflammatory cytokine production, and microglial survival under stress conditions [4][22]. These findings position TREML2 as a potential modifier of Alzheimer's disease progression that operates through neuroinflammatory pathways.
Beyond Alzheimer's disease, TREML2 may contribute to other neurodegenerative disorders characterized by neuroinflammation. Parkinson's disease, frontotemporal dementia, and amyotrophic lateral sclerosis all involve microglial activation and chronic neuroinflammation that could be influenced by TREML2 function [23][24]. Preliminary studies have detected TREML2 expression changes in these conditions, though definitive mechanistic links remain to be established.
The clinical relevance of TREML2 extends to potential diagnostic and therapeutic applications. Biomarker studies have investigated TREML2 protein levels in cerebrospinal fluid as a marker of microglial activation in neurodegenerative diseases [25][26]. These approaches may eventually aid in disease diagnosis or progression monitoring.
From a therapeutic perspective, TREML2 represents a potential target for modulating neuroinflammatory processes. Strategies aimed at enhancing TREML2 signaling could promote beneficial microglial functions while mitigating harmful inflammation [27]. However, the complex nature of TREML2 function, including potential dual roles in both promoting and suppressing inflammation, requires careful consideration of therapeutic approaches.
Ongoing research continues to elucidate TREML2 biology and its implications for human health. Single-cell RNA sequencing studies are characterizing TREML2-expressing microglia subsets in various brain regions and disease states [28]. Comparative analyses of TREML2 and TREM2 function are clarifying the distinct and overlapping roles of these receptors in neuroimmunity [13][29].
Future investigations will likely focus on understanding how TREML2 variants influence disease risk, identifying TREML2 ligands and signaling pathways, and developing therapeutic interventions that target TREML2 function. The integration of genetic, molecular, and clinical approaches promises to advance our understanding of TREML2 as a key regulator of neuroinflammation in neurodegenerative diseases.
The study of Treml2 — Triggering Receptor Expressed On Myeloid Cells Like 2 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.