INTESTINAL-CELL APOPTOSIS AND BCL-2 EXPRESSION

Programmed cell death (apoptosis) is a normal characteristic of cells with a limited life span like the enterocyte and the usual mode of dea th for proliferative crypt cells subjected to radiation or chemotherap y. The Bcl-2 proto-oncogene is considered a major regulator of apoptos is. We investigated the relationship of enterocyte apoptosis and Bcl-2 expression in rat intestine and tissue culture cells. Fragmentation o f DNA and levels of Bcl-2 transcripts were evaluated in rat enterocyte fractions of the crypt-to-villus axis of differentiation and in IEC t issue culture cells. A low percentage of isolated nuclei from each ent erocyte fraction showed features of DNA fragmentation, including crypt cells. Detectable DNA fragmentation was seen in IEC cells only when c ells were subjected to long-term confluent culture conditions. Bcl-2 m RNA was not detected in isolated rat intestinal cells but was detected in IEC cells where its level increased with serum deprivation and lon g-term culture. We conclude that increased Bcl-2 expression may be imp ortant in rescue of proliferative enterocytes subjected to stress.