A 12 year old boy receives radiation therapy for a malignant brain tumor. Two days later, a biopsy from nearby irradiated tissue shows shrunken eosinophilic cells with chromatin condensation and membrane bound apoptotic bodies but little surrounding inflammation. Which of the following molecular events most directly mediates this form of cell death through the intrinsic pathway?
- A)Inhibition of p53 at the G1 to S checkpoint
- B)Upregulation of selectins on endothelial cells
- C)Activation of phospholipase A2 leading to arachidonic acid production
- D)Activation of BAX with release of cytochrome c from mitochondriaGABARITO
- E)Deposition of immune complexes in vessel walls
Explicação
Radiation causes DNA damage that activates p53 and shifts the balance toward proapoptotic proteins such as BAX and BAK. This increases mitochondrial permeability, releases cytochrome c, and activates caspases, producing apoptosis with minimal inflammation. Ver explicação completa e trilha adaptativa →