Fight Aging!

A variety of forms of cellular garbage accumulate with aging, and in some cases it is up for debate as to whether the garbage is a primary cause of aging or secondary effect of other damage that degrades cell maintenance. The origins of degenerative aging in single-celled organisms lie in the way in which they handle garbage when dividing: one option is for a mother cell to consistently retain garbage and split off pristine daughter cells. The mother cells is thus aging and will eventually die. This doesn't directly relate to the much more complex process of aging in multicellular organisms, however, but rather informs the cell dynamics of tissue maintenance over time. It is perhaps most relevant in long-lived cells, such as those of the central nervous system, that might be with us for our entire lifetime.

In this research scientists uncover a novel form of garbage in yeast cells, but for the reasons noted above much more work is needed to fully understand its relevance and role in mammalian tissues:

In two recently published studies, [researchers] reported that certain proteins stick around for the entire lifespan of cells, which could be the cause of cellular old age. Using baker's yeast, a single-celled fungus that shares certain characteristics with human stem cells, the scientists identified several ways these proteins could cause cellular aging, from changing the acidity of cells to creating stockpiles of molecular "garbage" that build up over time.

Long-lasting proteins in the eyes, brain and joints are unique because they exist outside of cells or inside cells that don't divide. Stem cells grow and divide over our lifetimes but eventually give out; one theory of human aging suggests that a dwindling pool of stem cells may drive old age as fewer cells are available to repair or regenerate failing body parts. Both stem cells and yeast divide asymmetrically, with aging "mother" cells giving birth to newborn "daughter" cells. Yeast mothers can generate 30 to 35 daughter cells before dying; their normal lifespan when dividing lasts less than two days. [The new] discoveries point to the reason mother cells age and die and how their daughter cells are able to start their life anew after budding.

To look for long-lived proteins in yeast, the scientists used a special protein-labeling technique to track molecules from a mother cell's birth to her death. They found a collection of 135 proteins present only in mother cells that don't turn over during the cell's lifespan. To the scientists' surprise, all but 21 of these proteins were non-functional fragments. Although the scientists don't yet understand what the individual protein fragments do in the cell or how they might initiate aging, these fragments are not good news. Because of the specific pieces present and their sheer number, they are likely to interfere with normal proteins and cellular functions. "With the number of different fragments, we think they're going to cause trouble in the cell."

Link: http://www.fredhutch.org/en/news/center-news/2014/09/hoarding-cellular-garbage-triggers-old-age.html