These findings appear in the January 11, 2013 edition of The Journal of Biological Chemistry.
During periods of cellular stress, such as exposure to UV radiation, the number of highly reactive oxygen-containing molecules can increase in cells, resulting in serious damage. However, relatively little is known about the role played in this process by a number of stress-related enzymes.
In the new study, the TSRI team led by Professor Philip LoGrasso focused on an enzyme known as c-jun-N-terminal kinase (JNK). Under stress, JNK migrates to the mitochondria, the part of the cell that generates chemical energy and is involved in cell growth and death. That migration, coupled with JNK activation, is associated with a number of serious health issues, including mitochondrial dysfunction, which has long been known to contribute to neuronal death in Parkinson’s disease.
The new study showed for the first time that the interaction of JNK with a protein known as Sab is responsible for the initial JNK localization to the mitochondria in neurons. The scientists also found blocking JNK mitochondrial signaling by inhibiting JNK interaction with Sab can protect against neuronal damage in both cell culture and in the brain.
In addition, by treating JNK with a peptide inhibitor derived from a mitochondrial membrane protein, the team was able to induce a two-fold level of protection of neurons in the substantia nigra pars compacta, the brain region devastated by Parkinson’s disease.
The study noted that this inhibition leaves all other cell signaling intact, which could mean potentially fewer side effects in any future therapies.
“This may be a novel way to prevent neuron degeneration,” said LoGrasso. “Now we can try to make compounds that block that translocation and see if they’re therapeutically viable.”
The first author of the study, “Blocking c-jun-N-terminal Kinase (JNK) Translocation to the Mitochondria Prevents 6-hydroxydopamine-induced Toxicity in vitro and in vivo” is Jeremy W. Chambers, formerly of TSRI and currently at Florida International University. Other authors include Shannon Howard, also of TSRI. For more information on the paper, see http://www.jbc.org/content/early/2012/11/26/jbc.M112.421354.full.pdf
The work was supported by the National Institutes of Health (Grant Number U01NS057153-04) and by The Saul and Theresa Esman Foundation.
About The Scripps Research Institute
The Scripps Research Institute (TSRI) is one of the world’s largest independent, not-for-profit organizations focusing on research in the biomedical sciences. Over the past decades, TSRI has developed a lengthy track record of major contributions to science and health, including laying the foundation for new treatments for cancer, rheumatoid arthritis, hemophilia, and other diseases. The institute employs about 3,000 people on its campuses in La Jolla, CA, and Jupiter, FL, where its renowned scientists—including three Nobel laureates—work toward their next discoveries. The institute’s graduate program, which awards PhD degrees in biology and chemistry, ranks among the top ten of its kind in the nation. For more information, see www.scripps.edu.
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