Caspase-2 is activated at the CD95 death-inducing signaling complex in the course of CD95-induced apoptosis

Caspase-2 was reported to be involved in a number of apoptotic pathways triggered by various stimuli. However, the molecular mechanism of procaspase-2 activation in the course of apoptosis remains poorly defined. In this report, we demonstrate that procaspase-2 is recruited to the CD95 (Fas/APO-1) death-inducing signaling complex (DISC) in human T- and B-cell lines. We show that procaspase-2 is activated at the DISC on CD95 stimulation. Despite its presence at the DISC, caspase-2 does not initiate apoptosis on CD95 stimulation in caspase-8-deficient cell lines. Taken together, our data reveal that caspase-2 is activated at the DISC but does not play an initiating role in the CD95-induced apoptosis.