Enzyme That Plays Key in Aging Identified

by VR Sreeraman on Jul 12 2009 1:35 PM

Scientists from University of Pittsburgh School of Medicine have identified an enzyme that plays a crucial role in the process of aging.

Lead researcher Dr. Abbe de Vallejo, associate professor of Pediatrics and Immunology, has found that eliminating pregnancy-associated plasma protein A (PAPPA) enzyme increases the lifespan of study mice.

The researcher revealed that PAPPA enzyme has the ability to promote a robust immune system into old age, by maintaining the function of the thymus throughout life.

Thymus is the organ that produces T cells to fight disease and infection. It degenerates with age.

The study showed that PAPPA-knockout mice live at least 30 percent longer, and have significantly lower occurrence of spontaneous tumors than typical mice.

PAPPA controls the availability in tissues of a hormone known as insulin-like growth factor (IGF) that is a promoter of cell division. Hence, IGF is required for normal embryonic and postnatal growth.

IGF is associated with tumor growth, inflammation, and cardiovascular disease in adults.

By deleting PAPPA, the researchers were able to control the availability of IGF in tissues and dampen its many ill effects.

In the thymus, deletion of PAPPA maintained just enough IGF to sustain production of T cells without consuming precursor cells, thereby preventing the degeneration of the thymus.

"Controlling the availability of IGF in the thymus by targeted manipulation of PAPPA could be a way to maintain immune protection throughout life," de Vallejo said.

"This study has profound implications for the future study of healthy aging and longevity," de Vallejo added.

The study has been published in the Proceedings of the National Academy of Sciences.