Lipocalin-type prostaglandin D synthase as a melanocyte marker regulated by MITF

Microphthalmia-associated transcription factor (MITF) is responsible for differentiation of melanocytes. A recessive MITF mutant, black-eyed white Mitfmi-bw mouse, is characterized by white coat color and deafness, due to the lack of melanocytes in the skin and inner ears. By cDNA microarray analysis, we have identified lipocalin-type prostaglandin D synthase (L-PGDS), whose mRNA is undetectable in the homozygous Mitfmi-bw skin. Immunohistochemical analysis of wild-type mice identified the specific expression of L-PGDS in follicular melanocytes. L-PGDS mRNA is expressed in B16 mouse melanoma cells, but undetectable in human melanoma cell lines. RNA interference analysis against MITF suggests that L-PGDS expression is dependent on MITF in B16 melanoma cells. Furthermore, we have provided evidence that MITF is involved in the melanocyte lineage-specific transcription of the mouse L-PGDS gene. Thus, L-PGDS represents a newly identified melanocyte marker. MITF may modulate the production of prostaglandin D2 by activating the L-PGDS gene in melanocytes.