TLR3 (Toll-Like Receptor 3) is a member of the Toll-like receptor family of pattern recognition receptors that plays a critical role in innate immune responses. TLR3 recognizes double-stranded RNA (dsRNA), a viral replication intermediate, and initiates signaling cascades that lead to the production of type I interferons and pro-inflammatory cytokines[@akira2006].
TLR3 (Toll-Like Receptor 3) is a member of the Toll-like receptor family of pattern recognition receptors that plays a critical role in innate immune responses. TLR3 recognizes double-stranded RNA (dsRNA), a viral replication intermediate, and initiates signaling cascades that lead to the production of type I interferons and pro-inflammatory cytokines[@akira2006].
Within the central nervous system, TLR3 is expressed primarily in neurons, astrocytes, and microglia, where it participates in antiviral defense and modulates neuroinflammatory responses. Dysregulation of TLR3 signaling has been implicated in the pathogenesis of various neurodegenerative diseases, making it an important target for understanding neuroinflammation mechanisms.
Structure
Receptor Architecture
TLR3 is a type I transmembrane protein with distinct structural domains:
Extracellular domain: Leucine-rich repeat (LRR) motifs responsible for ligand recognition
Cytoplasmic domain: TIR (Toll/IL-1 receptor) domain for signal transduction
Structural Features
The extracellular LRR domain forms a solenoid structure that recognizes dsRNA with specificity for helical geometry rather than sequence. The TIR domain dimerizes upon ligand binding to initiate downstream signaling through adaptor protein recruitment.
Molecular Function
Ligand Recognition
TLR3 specifically recognizes:
Viral dsRNA: Replication intermediates of positive-strand RNA viruses
Synthetic dsRNA: Poly(I:C) used experimentally to mimic viral infection
Self-RNA: Under certain pathological conditions, may recognize endogenous dsRNA