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 death for proliferative crypt cells subjected to radiation or chemotherapy. The Bcl-2 proto-oncogene is considered a major regulator of apoptosis. We investigated the relationship of enterocyte apoptosis and Bcl-2 expression in rat intestine and tissue culture cells. Fragmentation of DNA and levels of Bcl-2 transcripts were evaluated in rat enterocyte fractions of the crypt-to-villus axis of differentiation and in IEC tissue culture cells. A low percentage of isolated nuclei from each enterocyte fraction showed features of DNA fragmentation, including crypt cells. Detectable DNA fragmentation was seen in IEC cells only when cells were subjected to long-term confluent culture conditions. Bcl-2 mRNA was not detected in isolated rat intestinal cells but was detected in IEC cells where its level increased with serum deprivation and long-term culture. We conclude that increased Bcl-2 expression may be important in rescue of proliferative enterocytes subjected to stress.