The transcription factor TBX2 regulates melanogenesis in melanocytes by repressing Oca2

The T-box transcription factor TBX2 is known for its role as a critical regulator of melanoma cell proliferation, but its role in regulating melanogenesis has not been widely studied. Here we use a series of experiments to show in primary and immortalized mouse melanocytes that TBX2 acts as regulator of melanogenesis by repressing the expression of the gene encoding the melanosomal protein OCA2. We find that α-MSH or forskolin, both of which stimulate melanogenesis, also reduce TBX2 expression, and that specific knockdown of TBX2 increases melanogenesis. This effect primarily involves an increase in Oca2 expression as the combined knockdown of both Tbx2 and Oca2 interferes with the Tbx2 knockdown-mediated increase in melanogenesis. Standard chromatin immunoprecipitation and reporter assays suggest that TBX2 represses Oca2 at least in part directly. Hence, the results suggest that TBX2 may act as a nexus linking cell proliferation and melanogenesis.