Calcium Signaling in Apoptosis
钙离子信号与细胞凋亡

What are the molecular mechanisms by which apoptosis is regulated by external or internal signals? This problem is under active investigation at present. As a major second messenger, Ca2 signal is known to be a key player in the regulation of many physiological and cellular processes. Does Ca2 signal also have a role in the regulation of apoptosis? Evidence implicating the involvement of Ca2 in apoptosis has been reported during the past decade from many studies. The detailed mechanisms concerning how Ca2 signals may interact with the apoptotic machinery, however, are still not very clearly understood yet. Results from different studies did not always give a consistent picture and sometimes might even be contradictory. In this review, the authors tried to summarize recent studies on Ca2 signaling in apoptosis to address two main questions: 1) Whether Ca2 signaling is involved in the commitment phase of apoptosis? 2) How may Ca2 signaling interact with the signaling pathway of apoptosis (including Bcl-2 family proteins)? They also discussed the roles of various pools of Ca2 stored in different subcellular compartments (including cytosolic Ca2 , ER Ca2 and mitochondrial Ca2 ) on the apoptotic process. Based on results from their own studies, they also tried to give a fair evaluation on the various proposed mechanisms suggested in the literatures. Finally, a model summarizing the possible pathways of Ca2 signaling in apoptosis was given in this review.