Overexpression of NUDT7, a candidate quantitative trait locus for pork color, downregulates heme biosynthesis in L6 myoblasts

While testing a quantitative trait locus (QTL) for pork color in a cross population of pigs from the mating of Large White dams to a Japanese wild boar, our laboratory discovered a candidate gene (NUDT7) that might affect heme biosynthesis in porcine muscle. Therefore, this experiment was designed to test the effect of NUDT7 on heme biosynthesis in cultured myoblasts. Rat L6 myoblasts were transfected with a mammalian expression vector for pig NUDT7 immediately after the induction of cell differentiation, and samples were harvested at 2, 4, 6, and 8 days. Expression of exogenous NUDT7 mRNA was highest on day 4, when the heme content was substantially lower (P < 0.01) than that of the control (14.2 vs. 63.9 pmol/105 cells). These results suggest that overexpression of pig NUDT7 may be associated with heme biosynthesis downregulation in skeletal muscle, which may partially explain differences in meat color among breeds of livestock.