Cell Death

Definisi Cell Death

• Kegagalan sel untuk memelihara fungsi utamanya.

Cell death

• Apoptosis• Autofagi• Necrosis

Definisi Apoptosis• Apoptosis atau kematian cell terprogram,

adalah suatu komponen normal

1. Kerr JF, Wyllie AH, Currie AR. Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics. Br J Cancer. 1972;26:239–257

(http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2744427/)2. jkh

Apoptosis

• Apoptosis is accompanied by rounding-up of the cell, retraction of pseudopodes, reduction of cellular volume (pyknosis), chromatin condensation, nuclear fragmentation (karyorrhexis), classically little or no ultrastructural modifications of cytoplasmic organelles, plasma membrane blebbing (but maintenance of its integrity until the final stages of the process) and engulfment by resident phagocytes (in vivo). 1

• manifesting several among these morphological features.

• It is worth noting that it is not correct to assume that ‘programmed cell death’ (PCD)

• It occurs during physiological development,

http://www.ncbi.nlm.nih.gov/books/NBK26873/

• In multicellular organisms, cells that are no longer needed or are a threat to the organism are destroyed by a tightly regulated cell suicide process known as programmed cell death, or apoptosis.

• Apoptosis is mediated by proteolytic enzymes called caspases, which trigger cell death by cleaving specific proteins in the cytoplasm and nucleus.

• Caspases exist in all cells as inactive precursors, or procaspases, which are usually activated by cleavage by other caspases, producing a proteolytic caspase cascade.

• The activation process is initiated by either extracellular or intracellular death signals, which cause intracellular adaptor molecules to aggregate and activate procaspases.

• Caspase activation is regulated by members of the Bcl-2 and IAP protein families.

• The cell shrinks and condenses. The cytoskeleton collapses, the nuclear envelopedisassembles, and the nuclear DNA breaks up into fragments.

• Most importantly, the cell surface is altered, displaying properties that cause the dying cell to be rapidly phagocytosed, either by a neighboring cell or by amacrophage (a specialized phagocytic cell, discussed in Chapter 24), before any leakage of its contents occurs (Figure 17-37).