Pondering Aging Stem Cells in the Gut
From Science News: "Old age can hit animals in the gut. That's where elderly fruit flies experience a signaling imbalance that disrupts renewal of the gut wall, new research shows. The discovery could help scientists understand why the body's organs malfunction in old age, and why intestinal cancer is so common among older people. ... Normally, 'adult' stem cells in the intestinal wall churn out a steady stream of new cells to replenish the lining [but] in older animals, this balance seems to be breaking down ... The imbalance appears to be triggered by stress - not psychological stress, but the chemical stresses put on cells by free radicals or by chronic inflammation, both of which get worse as an animal ages. Cells in the gut lining respond to this stress by activating a protective gene [which] is part of a signaling pathway that spurs intestinal stem cells to grow and divide. In response, another signaling pathway - called the Delta/Notch pathway - ramps up to try to keep that growth in check. But too much Delta/Notch can also derail the natural conversion of these stem cells into mature gut cells, causing an abnormal accumulation of halfway converted cells. ... [This] malfunctioning of adult stem cells in old age [is] very similar to what happens in certain human stem cell populations."
Link: http://www.sciencenews.org/view/generic/id/37382/title/Old_age_causes_problems_for_gut_cells