Having roots in the earliest Mendelian experiments, the scientific examination of pigmentation offers the unique opportunity to better understand the contributions of genetics, signaling pathways, hormones, and the external environment on the phenotype of our body’s largest organ system: the skin. Epidermal pigmentation is a product of the genetically determined melanin content, the cellular response to external stimuli, and the individual capacity for tanning. These processes are dependent upon a functional pigmentation pathway, which requires proper melanocyte migration, adequate melanogenic enzyme activity, and correct packaging and transfer of melanin to neighboring cells. Disruption of any of these processes leads to alterations in pigmentation. Although cutaneous pigmentation is most heavily focused upon, information about pigment patterning can also be gleaned from other pigmented tissues, including the hair and eyes. Numerous molecular signaling pathways and hormone systems converge to modulate pigment at the cellular level, which further contribute to the overall phenotype. These systems acquire greater importance when considered in the context of melanoma development, as these pathways are frequently found to be dysregulated.
KeywordsPigmentation Melanocyte MC1R MITF Melanocyte stem cells Tanning Melanin Ultraviolet
The authors acknowledge the numerous outstanding researchers who have contributed to our understanding of melanocyte biology and whose work has not been fully cited due to space constraints. The authors also acknowledge grant support from NIH (5P01 CA163222-04; 5R01 AR043369-19; 5R01CA178315-02), the Melanoma Research Alliance, and the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation.
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