Caspase-7 is a member of the caspase family of proteins, which are cysteine proteases playing a central role in the execution of apoptosis, or programmed cell death. Caspase-7, along with Caspase-3 and Caspase-6, is classified as an executioner caspase. These caspases are responsible for the demolition phase of apoptosis by directly degrading cellular structural and functional proteins, leading to the characteristic features of cell death. Caspase-7 is activated by initiator caspases such as Caspase-8 and Caspase-9 during death receptor and DNA damage-induced apoptosis, respectively. It is processed from its inactive zymogen form to its active form, which then cleaves a set of cellular substrates. Recent research indicates that Caspase-7 also plays a role in inflammation. Caspase-7 deficient mice are resistant to endotoxemia, suggesting that interfering with Caspase-7 activation may have therapeutic value for the treatment of inflammatory diseases. A novel function of Caspase-7 has been discovered in the repair of plasma membrane pores. Caspase-7 facilitates the repair of Gasdermin D and perforin pores by activating acid sphingomyelinase (ASM), which generates ceramide for membrane repair. This function is independent of Caspase-3 activity and is crucial for maintaining cell membrane integrity during inflammatory and apoptotic processes. Moreover, Caspase-7 has been implicated in the defense against intracellular pathogens. It can be activated by pyroptotic Caspase-1 in intestinal epithelial cells or act downstream of granzyme B in cells under attack by natural killer (NK) cells or cytotoxic T lymphocytes (CTLs).
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