how notch heals a broken heart
From the December 22nd issue of the Journal of Experimental Medicine:
The Notch pathway helps a developing heart get into shape but also helps a damaged heart reshape itself and keep pumping. Weakened by a heart attack or the protracted stress of hypertension, the heart rebuilds itself as it struggles to maintain blood flow. Some studies suggest that heart stem cells begin proliferating to replace lost cardiomyocytes. Because the Notch pathway helps control self-renewal by other organs, it was hypothesized that it might also have a hand in heart remodeling.
In this study by Croquelois et al, when Notch1 was absent, mice with stressed hearts showed signs of over-exuberant repair including thicker ventricular walls and increased fibrosis–all signs of heart failure that are seen in humans after heart damage, for example after a heart attack. These mice and their heart muscle cells also had a higher-than-normal death rate. Loss of Notch also spurred more heart stem cells to differentiate. Notch might allow the heart to conserve these cells.
The Notch pathway triggers stem cell proliferation in skeletal muscle, and the pathway short-circuits as we age. The researchers say that it’s possible the same deterioration occurs in the older heart, explaining why elderly people are more vulnerable to heart failure.
