RNAi-mediated knock down of mammalian selenocysteine lyase

Abstract

Selenocysteine lyase (SCL), which specifically catalyzes the decomposition of L-selenocysteine into Se and L-alanine, is proposed to function as a Se delivery protein to selenophosphate synthetase in selenoprotein biosynthesis. However, the physiological role of SCL has not been established. To address the role of SCL in mammalian cells, we have used RNA-interference (RNAi) to deplete SCL in a HeLa cell line. RNAi-mediated depletion of SCL resulted in growth inhibition in cells cultivated with a serum-containing medium. The similar growth inhibition was observed in SCL-depleted cells cultivated with a serum-free medium supplemented with selenite, selenomethionine, or selenocysteine, indicating that these selenium-containing compounds can not rescue the growth inhibition. These results suggest a physiological importance of SCL in normal cell function. Depletion of SCL may reduce the biosynthesis levels of selenoproteins which are essential for cell proliferation.