Apoptosis defined

It is well understood that caspases are critical for the process of apoptosis. Caspases are cysteinyl-containing active center proteases with specificity for protein cleavage after aspartyl residues. Thus the term caspase is derived from (ysteinyl-containing aij artate-specific proteinase. The caspases are responsible for many of the hallmarks of apoptosis defined in Table 18.1, mediated through their cleavage of specific polypeptide substrates. The caspases (e.g., caspase-2, -3, -6, -7, -8, -9, -10, and -12 in the mouse) are not the only proteases involved in PCD, as calpains have also been shown to play... 

Simon Yes, because there is no cell migration. If you want to construct a lobed leaf, for example, you have to define areas where cell divisions are still going on while in the adjacent areas they have stopped. We don t know how this is done. Apoptosis is a factor that is only occurring in a very few cases in plant development. It is controlled division that is important. 

Caspases are a family of evolutionary conserved cysteine proteases that cleave their substrates after an aspartic acid residue within a defined consensus sequence (Alnemri et al, 1996). They play a cracial role in the apoptotic program, as most of the characteristic features observed in apoptosis are attributable to their action (Eamshaw et al, 1999). They are... 

Apoptosis. Apoptosis— programmed cell death—involves elimination of damaged cells and maintenance of cell homeostasis. Homeostasis can be defined as the ability of living cells to regulate themselves in a dynamic manner. When apoptosis is deregulated, diseases such as cancers, immune... 

It is noteworthy that MHC class I downregulation is not the only escape mechanism available for tumors to avoid T cell responses other mechanisms such as downregulation of the tumor antigens, alterations of the apoptosis program, expression of inhibitory molecules, lack of expression of costimulatory molecules leading to immunological tolerance have been also described. The identification of defined immune escape mechanisms in human or mouse tumors point to the existence of active immunosurveillance which is important for the implementation T cell-based immunotherapy protocols. This information will further help to select patients suitable for such therapies. Furthermore, restoration of the tumor MHC class I phenotype to a normal MHC phenotype may be an other strategy to restore an efficient immune response in cancer patients. All these approaches are still hypothetical and no clinical procedures have been tested so far. 

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