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

• Class III β-tubulin is expressed by human melanocytes, in vivo and in vitro.
• Expression was found both in epidermal and hair follicle melanocytes.
• Expression starts upon differentiation of melanoblasts into mature melanocytes.
• TUBB3 expression and melanogenesis are separately regulated.
• This data adds to the debate over similarity between melanocytes and neurons.

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.