October 7, 2006

Flipping the Aging Switch

Researchers at HU and NCU have found a gene in stem cells that actually "turns off" replication. They noticed a dramatic increase of expression from Ink4a in aging subjects - 10 to 100 times the expression of younger subjects.
Ink4a actively interferes with the ability of stem cells to divide in several different types of tissue, including the brain, the pancreas, and the blood-forming system of the bone marrow.

Under optimal circumstances, stem cells are able to copy themselves and differentiate into other cells, thus replenishing their numbers and acting as a repair system for the body. The Ink4a gene appears to be widely active in locations where stem cells regenerate new tissues.

Presumably as a regulator. Morrison, Sharpless and company suggest that synthesizing medicines to alter the expression of Ink4a could bolster our "defenses" (replication and neurotransmission) against aging.

One gene, one medicine?

Though mice with Ink4a deleted had more regenerative capacity in tissues like the brain and the pancreas as they aged, they started dying of a wide variety of cancers at one year of age. So it canÂ’t really be said that losing the gene helped them live longer.

"If you had a drug that could inhibit Ink4a function, youÂ’d potentially have a therapy against degenerative diseases," Morrison said. "But youÂ’d have to watch patients carefully for cancers. By the same token, drugs that mimic Ink4a function could be used to fight cancer." Ink4a was known to be a tumor suppressor gene that becomes more highly expressed with age, eventually triggering the cell to shut down replication.

*shrug* Every time I have read a statement like that from a geneticist (about medicines inhibiting or increasing expression of one gene) they usually turn out to be largely optimistic. These issues always tend to become more complicated.

The stem cells have a built in balance between replication inhibitors (Ink4a) and promoters (Bmi-1). Disrupting that balance doesn't sound like the best idea. Push too far one way and your body's regenerative ability slows; push too far the other way and your body turns into a tumor machine.

It would, however, be advantageous if the balance and rate of expression at a young age could be maintained into adulthood and beyond (which is probably what Morrison is talking about; he just worded it strangely).

I am hoping that classes/homework/newspaper will lighten a bit this week so I can update here more frequently. Today I have a slightly-less-than-blank Quark template waiting for me in the office. The newspaper calls.

No comments:

Post a Comment