P80 form of the human tumor necrosis factor receptor is involved in DNA fragmentation

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Abstract
Two different types of TNF receptors with molecular masses of 60 kDa (p60) and 80 kDa (p80) have been identified. TNF is known to cause DNA fragmentation in certain tumor cell lines but the role of p60 and p80 in this action is not understood. In the present study, we examined the role of these receptors in TNF‐induced DNA fragmentation. Treatment of U‐937 cells with phorbol ester caused downregulation of both types of TNF receptors and this was accompanied by disappearance of the TNF‐induced DNA fragmentation. The removal of phorbol ester led to two time‐dependent events: (1) the rapid regeneration of the p80 form but not the p60 form of the TNF receptor; and (2) the reappearance of TNF‐induced DNA fragmentation. These results suggest that the p80 receptor could mediate the TNF‐induced DNA fragmentation.