Journal Club: Cell Death

Tuesday, April 16, 2013

Death is an essential part of the life cycle, at the level both of the organism and the cell. Cell death needs to occur during development to prevent webbed toes, for instance, or during an infection to prevent the spread of disease. Cells altruistically kill themselves to prevent further harm to the organism. Too much cell death, however, can lead to diabetes or neurodegenerative disease.  Too little can contribute to cancer.  Like many biological processes, death must be carefully regulated.

In order to treat diseases that result from deregulated death, we must understand the process. It turns out that the dying of a cell is pretty complicated.  Although the reality isn’t quite this clear-cut, we can separate cell death into three major categories:

  1. Apoptosis, or what we traditionally refer to by the term “programmed cell death,” is a neatly enclosed form of cellular suicide.  In response to irreparable damage or death signals, the cell “blebs” into pieces, and the DNA is cut up.  The pieces are then eaten by other healthy cells.
  2. Autophagy, or “self-eating,” often occurs if apoptosis is blocked.  Vacuoles, which can be compared to the garbage disposals of the cell, eat up the other components of the cell.
  3. Necrosis can occur if apoptosed cells don’t get engulfed.  This is frequently seen in large tumors.  Necrotic cells swell and burst and decompose, releasing the cellular innards.  This includes pro-inflammatory molecules that can harm the cells around them.