Apoptosis plays an important role in homeostasis of intestinal epithelia and is also a stress response to toxic stimuli. Transgenic and knockout @entity19 have provided insights into the regulation of intestinal epithelial apoptosis that could not have been obtained by cell culture techniques. Two broad types of apoptosis have been characterized: spontaneous apoptosis, which occurs continuously at low levels in the normal, unstressed intestine, and stress-induced apoptosis, which occurs after genotoxic insult such as exposure to gamma radiation or DNA-damaging drugs. Spontaneous apoptosis occurs at the base of the crypt at or near the position of epithelial stem cells. Knockout studies have shown that spontaneous apoptosis is independent of @entity899 and @entity1380 in both small and large intestine, whereas @entity1379 only regulates spontaneous apoptosis in the colon. Little is known about the regulation of the specialized form of cell death at the villus tip. In contrast, knockout studies have demonstrated that both @entity899 and @entity1379 are important regulators of stress-induced apoptosis but that there are significant differences between early and late time points. @entity1380 plays only a minor role in the regulation of stress-induced apoptosis. The cumulative effect of stress-induced apoptosis on tissue architecture is not straightforward, and cell cycle arrest also plays a critical role. Nevertheless, @entity899 is an important determinant of the histopathological damage induced by @entity1487 in @entity19 intestinal epithelium. These studies have important implications for the development of more effective treatment for @entity29 and @entity5 .

Lessons from genetically engineered animal models. VII. Apoptosis in intestinal epithelium: lessons from transgenic and knockout XXXX .

@entity1380 :: ('12028(Tax:10090)', 'Gene') :: ['Bax'] @entity19 :: ('10090', 'Species') :: ['mice', 'murine'] @entity899 :: ('22060(Tax:10090)', 'Gene') :: ['p53'] @entity5 :: ('MESH:D009369', 'Disease') :: ['cancer'] @entity29 :: ('MESH:D015212', 'Disease') :: ['inflammatory bowel disease'] @entity1379 :: ('12043(Tax:10090)', 'Gene') :: ['Bcl2'] @entity1487 :: ('MESH:D005472', 'Chemical') :: ['5-fluorouracil']
@entity19 :: (10090,Species) :: ['mice']
