New research from the Keck School of Medicine of the University of Southern California (USC) may help prevent damage to the liver caused by drugs like acetaminophen and other stressors.
Acetaminophen, more commonly known as Tylenol, helps relieve pain and reduce fever. The over-the-counter drug is a major ingredient in many cold and flu remedies as well as prescription painkillers like Percocet and Vicodin.
However, metabolized by the liver, acetaminophen is the most common cause of drug-induced liver disease and acute liver failure in the United States and United Kingdom. Tylenol's maker announced in July that it was lowering the maximum recommended daily dosage to 3,000 milligrams to help prevent accidental overdoses.
Doctors at the Keck School of Medicine of USC have identified a protein on the mitochondria of liver cells in mice that, when silenced, protects against liver toxicity usually associated with excess doses of acetaminophen.
They found that the protein Sab, or SH3-domain binding protein 5, binds with the enzyme JNK (c-Jun N-terminal kinase). JNK regulates cellular metabolism and survival in response to stress, protecting cells when activated for brief intervals. However, JNK also kills cells when activated for prolonged periods of time.
"Because the short-term activation of JNK is associated with cell survival, Sab is potentially a better target than inhibiting JNK, which could have adverse effects," said Neil Kaplowitz, M.D., the study's lead investigator and professor of medicine at the Keck School.
Researchers have long believed that acetaminophen was converted into toxic metabolites that, in excess, overwhelm liver cells, causing them to die. In a 2008 study, Kaplowitz, who holds the Keck School's Thomas H. Brem Chair in Medicine
and Veronica P. Budnick Chair in Liver Disease, and other USC colleagues turned that theory around they found that it was not the metabolite, but rather the sus
|Contact: Alison Trinidad|
University of Southern California