Figure 2

Schematic illustration of the involvement of death receptor pathway (right half) and mitochondrial pathway mediated (left half) apoptosis in nurse cell formation. Upon binding with TNF-α, TNF-RI recruits TRADD which functions as a platform adapter that recruits several signaling molecules. The recruitment of TRADD and FADD results in autocatalytic activation of procaspase 8. Activated caspase 8 cleaves effector procaspase 3 which plays a role in apoptosis in the basophilic cytoplasm of Trichinella infected muscle cells. On the other hand, the binding of TNF-α and TNF-RI induces the sequential recruitment of TRADD, TRAF2 and RIP, which leads to the activation of NF-kB. The activated NF-kB acts for anti-apoptosis in the basophilic cytoplasm. In mitochondrial pathway, Bax induces apoptosis by forming the membrane pore in mitochondria from which cytochrome c is released. Cytochrome c activates caspase 9 which in turn activates caspase 3 to induce apoptosis in infected muscle cells. As a co-factor, Apaf-1 plays a role with caspase 9 in apoptosis in the basophilic cytoplasm. On the other hand, Akt plays an anti-apoptosis role in the eosinophilic cytoplasm by inactivating proapoptotic proteins such as Bad and caspase 9. This figure referred the review by Gupta [35].