New players in apoptosis

Researches on the area of apoptosis have achieved explosive progress over the past two decades. Two major regulating mechanisms of apoptosis have been uncovered in great details. One is called extrinsic apoptosis pathway, also known as the deathreceptor pathway. The extrinsic pathway is usually activated from outside the cell by TNF and other cytokines with their corresponding death receptors, such as TNF receptor, Fas, and TRAIL. The other is named intrinsic apoptosis pathway, also called as the mitochondrial pathway. The intrinsic pathway is activated responding to cell stresses or intracellular damage, such as DNA damage. So far, hundreds of proteins have been identified to be involved in the regulation of both extrinsic and intrinsic apoptosis pathways. And the collection of four research articles in this issue will provide new factors to this long list of apoptosis. In the first article, Dr Jiang and colleagues analyzed the pathogenesis of a new H1N1 influenzavirus strain, which was collected from China in 2009. Dr Jiang’s lab showed that viral infection by this H1N1 strain induced significant apoptotic cell death in two human carcinoma cell lines, and then concluded that the 2009 pandemic H1N1 strain can induce apoptosis in epithelial cells of the human respiratory tract. In the research area of infection diseases, people have established a link between apoptosis and virus infection, for