Pan-vertebrate toll-like receptors during evolution.

Area of Science:

• Immunology
• Evolutionary Biology
• Genomics

Background:

• Human toll-like receptors (TLRs) are crucial for innate immunity, recognizing pathogen-associated molecular patterns (PAMPs).
• The discovery of Drosophila Toll highlighted the evolutionary significance of TLRs.
• Understanding TLR origins in vertebrates provides insights into immune system evolution.

Purpose of the Study:

• To investigate the evolutionary origin of the vertebrate toll-like receptor (TLR) family.
• To analyze functional and phylogenetic aspects of TLRs in non-mammalian vertebrates.
• To explore the potential clinical applications of unique TLRs.

Main Methods:

• Phylogenetic analysis of TLR genes across various vertebrate species.
• Functional studies of non-mammalian TLRs, including teleost TLRs.
• Comparative genomics, referencing genome projects like Takifugu rubripes.

Main Results:

• Teleosts possess nearly all human TLR subsets, suggesting early vertebrate origin for the family.
• Mammals likely lost fish-specific TLR21 and TLR22, which emerged early in vertebrate evolution.
• Teleost TLR22 recognizes double-stranded RNA and induces interferon production, with cell surface localization distinct from TLR3.

Conclusions:

• The vertebrate TLR family largely originated early in evolution, with subsequent gene loss in mammals.
• Unique teleost TLRs, like TLR22, possess distinct functions and localization compared to mammalian counterparts.
• These unique TLRs present potential avenues for clinical applications in treating viral infections and cancer.