Figure 6. TMEM14C is required for synthesis of PPIX.

HPLC analysis of porphyrin intermediates and heme in wild-type, CRISPR, control, and silenced cell lines and E12.5 fetal liver tissue. Porphyrinogens were oxidized to their corresponding porphyrins during isolation; porphyrin levels are a surrogate for porphyrinogen levels in vivo. (A) Uroporphyrin III (UROIII) levels are normal in differentiating Tmem14c-deficient cells in the absence and presence of exogenous ALA. (B) Coproporphyrin III (CPIII) levels are normal in the absence of exogenous ALA but are mildly elevated in ALA-supplemented CRISPR cells. Coproporphyrin III is significantly increased in Tmem14c^gt/gt fetal liver. (C) PPIX levels are reduced in Tmem14c-deficient cells in the absence and presence of exogenous ALA. PPIX levels are significantly decreased in Tmem14c^gt/gt fetal liver. As a control for our assay, PPIX is significantly elevated in Fech^Tm1Pas Fech^Tm1Pas (Fech) fetal liver. (D) Heme levels are significantly reduced in Tmem14c-deficient cells both in the absence and presence of exogenous ALA as well as in Tmem14c^gt/gt fetal liver tissue. (E) There is an increase in the level of total porphyrin excreted into the cell culture media of CRISPR cells. *P < 0.05.