Figure 2.

TLR1/2 and TLR2 induce melanin formation and melanosome exocytosis. Stimuli for the TLR1/2 heterodimer and the TLR2 homodimer promote melanin synthesis by inducing the transcription of melanin synthesis-related genes such as MITF, TYR, and DCT. In addition, TLR2 induces extracellular release of melanosomes by increasing the expression of Rab11. Rab11 initiates exocytosis through the remodeling of mature melanosome membranes. Rab11 also constitutes a subunit with tethering factors such as Sec8, Sec15, and Exo70, and anchors melanosomes to the cell membrane. Abbreviations: TLR: toll-like receptor; MITF: microphthalmia-associated transcription factor; TYR: tyrosinase; DCT: dopachrome tautomerase.