CD95/Fas/Apo-1-mediated signal transduction

The Fas/Apo-1/CD95 (Fas) receptor plays an important role in a variety of cellular systems via regulation of apoptotic cell death as, e.g., in lymphoid cells. Involvement of the Fas receptor in the pathogenesis of diseases such as AIDS, hepatitis and cancer has recently been postulated. The intracellular signal generated by the Fas receptor has been intensively studied during the past years and a wide variety of different molecules and signalling mechanisms have been implicated in the transduction of the death signal. However, there is evidence that triggering Fas does not only induce apoptosis but also stimulates mitogenic signals for cell activation and proliferation. Therefore, not all signalling components which have been detected after crosslinking the Fas receptor necessarily have to be related to the death signal. Furthermore, the recognition that apoptosis induced through activation of Fas is not protein synthesis dependent suggests that processes as the activation of transcription factors like NF-kappa B are most likely part of the stimulatory/mitogenic signal. Thus, signalling components of the Fas receptor are complex and have to be investigated carefully in terms of the outcome of the transmitted signal.