Caspase effect mechanism

The characteristics of apoptotic cells include DNA fragmentation into fragments of about 200 bp, chromatin concentration, cell membrane activation, cell shrinkage, and finally the formation of apoptotic bodies wrapped in the cell membrane. Then, these apoptotic bodies are swallowed by other cells. This process takes about 30-60 minutes. The whole process of caspase induced changes related to the above apoptosis is not completely clear, but at least includes the following three mechanisms:

Inhibitor of apoptosis

Normal living cells do not break DNA because nuclease is inactive. This is because nuclease and inhibitor are combined. If the inhibitor is destroyed, nuclease can be activated, causing DNA fragmentation. It is known that caspase can cleave this inhibitor to activate nuclease, so this enzyme is called caspase activated deoxyribonuclease CAD, and its inhibitor is called ICAD. Therefore, under normal circumstances, CAD does not show activity because CAD-ICAD exists in the form of an inactive compound. Once ICAD is hydrolyzed by Caspase, CAD is endowed with nuclease activity, and DNA fragmentation is generated. It is significant that CAD can only be synthesized and show activity when ICAD exists, suggesting that CAD-ICAD exists in a co transcriptional manner, so it is necessary for ICAD to activate and inhibit CAD.