[HTML][HTML] A role for c-FLIPL in the regulation of apoptosis, autophagy, and necroptosis in T lymphocytes

MX He, YW He - Cell Death & Differentiation, 2013 - nature.com
MX He, YW He
Cell Death & Differentiation, 2013nature.com
Caspase 8 plays a dual role in the survival of T lymphocytes. Although active caspase 8
mediates apoptosis upon death receptor signaling, the loss of caspase 8 activity leads to
receptor-interacting protein (RIP)-1/RIP-3-dependent necrotic cell death (necroptosis) upon
TCR activation. The anti-apoptotic protein c-FLIP (cellular caspase 8 (FLICE)-like inhibitory
protein) suppresses death receptor-induced caspase 8 activation. Moreover, recent findings
suggest that c-FLIP is also involved in inhibiting necroptosis and autophagy. It remains …
Abstract
Caspase 8 plays a dual role in the survival of T lymphocytes. Although active caspase 8 mediates apoptosis upon death receptor signaling, the loss of caspase 8 activity leads to receptor-interacting protein (RIP)-1/RIP-3-dependent necrotic cell death (necroptosis) upon TCR activation. The anti-apoptotic protein c-FLIP (cellular caspase 8 (FLICE)-like inhibitory protein) suppresses death receptor-induced caspase 8 activation. Moreover, recent findings suggest that c-FLIP is also involved in inhibiting necroptosis and autophagy. It remains unclear whether c-FLIP protects primary T lymphocytes from necroptosis or regulates the threshold at which autophagy occurs. Here, we used a c-FLIP isoform-specific conditional deletion model to show that c-FLIP L-deficient T cells underwent RIP-1-dependent necroptosis upon TCR stimulation. Interestingly, although previous studies have only described necroptosis in the absence of caspase 8 activity, we found that pro-apoptotic caspase 8 activity and apoptosis were also enhanced in c-FLIP L-deficient T lymphocytes. Furthermore, c-FLIP L-deficient T cells exhibited enhanced autophagy, which served a cytoprotective function. Together, these findings indicate that c-FLIP L plays an important antinecroptotic role and is a key regulator of apoptosis, autophagy, and necroptosis in T lymphocytes.
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