Cystathionine β-synthase-derived hydrogen sulfide regulates lipopolysaccharide-induced apoptosis of the BRL rat hepatic cell line in vitro

Hydrogen sulfide (H(2)S), is a member of the novel family of endogenous gaseous transmitters, termed "gasotransmitters exhibiting diverse physiological activities, and is generated in mammalian tissues mainly by cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3MST) in conjunction with cysteine (aspartate) aminotranferase (CAT). The distributions of these enzymes are species- and tissue-specific. The liver, as the main organ that generates H(2)S in vivo, functions in biotransformation and metabolism. However, the liver is vulnerable to damage from internal and external factors, including inflammatory mediators, drugs and poisons. The present study evaluated the endogenous CBS-H(2)S synthesis regulating lipopolysaccharide (LPS)-induced apoptosis of hepatic cells. The rat hepatic cell line, BRL, was incubated with LPS for various time periods to establish a cell-damage model. Incubation with LPS resulted in a significant increase in CBS expression and H(2)S production. It also stimulated apoptosis and decreased the mitochondrial membrane potential. Pretreatment with the CBS inhibitor aminooxyacetic acid (AOAA) or CBS small interfering RNA (siRNA) decreased LPS-enhanced H(2)S production. Notably, apoptosis increased for a short period and then decreased gradually, while the mitochondrial membrane potential demonstrated the opposite trend. These results showed that endogenous CBS-H(2)S synthesis demonstrated early anti-apoptotic activity and subsequent pro-apoptotic activity in LPS-induced apoptosis. These results suggest a new approach for developing novel drugs for this condition.