Which TLR can signal through both MyD88 dependent and independent pathways?

The Toll-like receptor 4 (TLR4) is notable for its ability to signal through both the MyD88-dependent pathway and the MyD88-independent pathway. This dual signaling capability is significant in the immune response, particularly in the recognition of various pathogens and the initiation of appropriate inflammatory responses.

TLR4 primarily recognizes lipopolysaccharides (LPS) from gram-negative bacteria, which can lead to two different signaling cascades. The MyD88-dependent pathway is often associated with rapid pro-inflammatory cytokine production, while the MyD88-independent pathway (also referred to as the TRIF pathway) typically influences the production of type I interferons and may play a role in innate immunity against viral infections.

This multifaceted signaling capability enhances the immune system's ability to respond to a diverse array of pathogens effectively. In contrast, other Toll-like receptors, such as TLR1, TLR2, and TLR5, primarily rely on the MyD88-dependent pathway for their signaling, which limits their functional versatility in comparison to TLR4.