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BackgroundCopy number gain of the D-3-phosphoglycerate dehydrogenase (PHGDH) gene, which encodes the first enzyme in serine biosynthesis, is found in some human cancers including a subset of melanomas.MethodsIn order to study the effect of increased PHGDH expression in tissues in vivo, we generated mice harboring a PHGDH(tetO) allele that allows tissue-specific, doxycycline-inducible PHGDH expression, and we analyzed the phenotype of mice with a ubiquitous increase in PHGDH expression.ResultsTissues and cells derived from PHGDH(tetO) mice exhibit increased serine biosynthesis. Histological examination of skin tissue from PHGDH(tetO) mice reveals the presence of melanin granules in early anagen hair follicles, despite the fact that melanin synthesis is closely coupled to the hair follicle cycle and does not normally begin until later in the cycle. This phenotype occurs in the absence of any global change in hair follicle cycle timing. The aberrant presence of melanin early in the hair follicle cycle following PHGDH expression is also accompanied by increased melanocyte abundance in early anagen skin.ConclusionsThese data suggest increased PHGDH expression impacts normal melanocyte biology, but PHGDH expression alone is not sufficient to cause cancer.