Class III β-tubulin, a novel biomarker in the human melanocyte lineage.

It is generally thought that class III β-tubulin expression is limited to cells of the neural lineage and is therefore often used to identify neurons amongst other cell types, both in vivo and in vitro. Melanocytes are derived from the neural crest and share both morphological features and functional characteristics with peripheral neurons. Here, we show that these similarities extend to class III β-tubulin (TUBB3) expression, and that human melanocytes express this protein both in vivo and in vitro. In addition, we studied the expression of class III β-tubulin in two murine melanogenic cell lines and show that expression of this protein starts as melanoblasts mature into melanocytes. Melanin bleaching experiments revealed close proximity between melanin and TUBB3 proteins. In vitro stimulation of primary human melanocytes by α-MSH indicated separate regulatory mechanisms for melanogenesis and to TUBB3 expression. Together, these observations imply that human melanocytes express TUBB3 and that this protein should be recognized as a wider marker for multiple neural crest-derived cells.