Fig. 1
From: Increased PHGDH expression promotes aberrant melanin accumulation
Introducing a PHGDHtetO allele into mice increases PHGDH expression and results in the aberrant appearance of melanin granules. a Western blot analysis to assess PHGDH expression in liver lysates from mice harboring the indicated alleles that were exposed to a doxycycline containing diet (Dox) or a control diet for 5 days. β-actin expression was also assessed as a loading control. b Western blot analysis to assess PHGDH expression in MEFs derived from mice with the Rosa26-M2rtTA allele and the indicated number of PHGDHtetO (tetO) alleles that were cultured in media with or without doxycycline (Dox) as for 72 h as indicated. Both a light and dark exposure (alt exposure) are shown, as is GAPDH expression as a loading control. c The percent increase in the concentration of intracellular phosphoserine (P-ser) in MEFs derived from mice described in (b) harboring one (tetO/+) or two (tetO/tetO) transgene alleles relative to levels found in MEFs derived from wildtype mice is shown. All MEFs were cultured for 4 days in media with doxycycline prior to measurement of P-Ser levels by LC-MS. Data shown represent the mean (+/− SEM). The increase is statistically significant with p values from two-tailed Student’s T test. d Representative H&E staining of skin sections from 3.5-month-old mice of the indicated genotypes that had been exposed to a doxycycline-containing diet for 9 days. Dotted lines delineate the border between the dermis and the subcutis. Arrow indicates melanin granules in the hair follicles (HFs) of the PHGDHtetO;Rosa26-M2rtTA mouse. All hair follicle shown are early anagen as they are contained completely within the dermis. Images were obtained at 40x magnification. Scale bar = 30 μm. Inset images are magnified 80X. e Quantitation of the percent of early anagen hair follicles (HF) in each genotype that contain any melanin granules. Data shown represent the % observed when analyzing 167 HFs from one PHGDHtetO;Rosa26-M2rtTA mouse and 46 HFs from one wild type mouse. f Quantitation of the percent of early anagen hair follicles (HF) in each genotype with three or more melanin granules. Data shown represent the % observed when analyzing 167 HFs from one PHGDHtetO;Rosa26-M2rtTA mouse and 46 HFs from one wild type mouse. The percent increase in hair follicles with melanin granules shown in (e) and (f) is statistically significant with p values derived from one-tailed Fisher’s exact test.