Aging researchers have long understood that human cells can only replicate themselves a finite number of times. Now a group of researchers at the Stowers Institute in Kansas City say they have identified a key protein that helps explain why that mechanism is limited, and what determines when an organism will die. And their study has implications both for aging as well as cancer research.
Rong Li, a cell biologist at the Stowers Institute, focused on multidrug resistant proteins (MDRs), which clear cells of material they identify as toxic, which can include drugs. They also bring in nutrients needed to keep the cell healthy. The "daughter" cells that are generated through replication are given new proteins while the mother cell retains the old proteins.
As the cell ages, the protein pumps start to break down, failing in their ability to repel toxic invaders while their machinery for drawing in new nutrients degenerates. And while cancer cells are known to be loaded with MDRs, the proteins also help prevent cancer by preventing damaged cells from dividing - complicating any move to fight aging by boosting levels of the proteins in cells.
"The question is what are they getting rid of and why is that relevant to aging? We don't know that yet," says Brian Kennedy, a biologist at the Buck Institute for Age Research.