Programmed cell death (PCD; sometimes referred to as cellular suicide) is the death of a cell in any form mediated by an intracellular program. PCD is carried out in a biological process, which usually confers advantage during an organism's life-cycle.For example, the differentiation of fingers and toes in a developing human embryo occurs because cells between the fingers apoptose; the result.
Autophagy and Cell Death Autophagy is known to be a cell survival mechanism, and has been shown to inhibit programmed cell death or apoptosis (a form of cellular suicide). However, certain experiments have demonstrated the induction of cell death by macroautophagy, thereby, suggesting it to be one of the mechanisms through which cells commit suicide.
Autophagy is actually a way for the cell to deal with stress. One signal that causes autophagy is a lack of nutrients, including protein, carbohydrates, and even oxygen.
In disease, autophagy has been seen as an adaptive response to stress, which promotes survival, whereas in other cases it appears to promote cell death and morbidity. In the extreme case of starvation, the breakdown of cellular components promotes cellular survival by maintaining cellular energy levels.
Autophagy is increasingly recognized for its active role in development and differentiation. In particular, its role in the differentiation of hematopoietic cells has been extensively studied, likely because blood cells are accessible, easy to identify and purify, and their progenitor tree is well defined.
Depending on the cellular context, autophagy can either serve as a cell survival pathway, suppressing apoptosis, or it can lead to death itself. Although most cells primarily use apoptosis as a mode of cell death it is often not an option in many types of cancers and thus it is important to explore how the cell regulates other forms of cell death.
AUTOPHAGY AND CELL DEATH As discussed above, autophagy plays a protective role in di-verse types of cellular stress. Paradoxically, autophagy can al-so lead to a form of non-apoptotic cell death known as “type 2 programmed cell death” (8-10) particularly when autophagy is excessive (11). Thus, the dual nature of autophagy can ei-.
The cell context-specific function of autophagy in cell death has been best described in Drosophila in which autophagic cell death is known to occur in multiple cell types. During larval salivary gland degradation, autophagy and caspases cooperate to efficiently clear dying cells. Therefore, impaired function of either autophagy or caspases.