apoptosis and necrosis
rick at sjubiol.stjohns.edu
Fri Apr 8 00:50:05 EST 1994
mzhou at bimcore.cc.emory.edu asks for the distinctions between apoptosis and
necrosis. start with the Tomei-Cope book (Cold Spring Harbor Press) and
Wyllie's review 2 years ago. Otherwise, see the review by Zakeri and
Lockshin in the Ann NY Acad Sci edited by Franceschi C et al last year.
Necrosis is usually described as an uncontrolled membrane-failure lysis,
resulting in swelling and rupture of the cell and organelles and (in
mammals) an inflammatory response. Apoptotic cells typically shrink,
apparently retaining membrane integrity (though one or a few authors
dispute the point) and show nuclear condensation and at least temporary
preservation of organelle structure. there are both lysosomal and non-
lysosomal forms of controlled cell death. the trypan blue staining is
typically for gross identification and is usually for macrophages that
are destroying these apoptotic bodies. in vivo, apoptotic bodies exist
for very short periods (Schulte-Hermann and Bursch, about 3 years ago,
or see the Cold Spring Harbor book for an article by Schulte-Hermann).
Apoptotic bodies can be identified by electron microscopy, H & E or
toluidine blue staining, or in situ end-labeling (tunnel technique,
Apoptag kit (Oncor)). Free-floating cells of reticulo-endothelial
origin may be recognized by fluorescence-sorting techniques, looking for
DNA content < 2N (numerous authors, including Wyllie and S. Umansky).
the programmed cell death paradigm, requiring synthesis of apparently
new proteins, is not easy to detect at present, since no unique protein
can be claimed to document apoptosis. (proteins such as TRPM-2 and
--correction, TRPM-2, alias clusterin or SGP-2--myc, fos, or ubiquitin)
are clearly NOT "cell death proteins". High levels of cross-linkage
may be useful but the technique is difficult. See also Zakeri et al,
FASEB J January 93; a follow-up is coming. If you have a specific instance
in mind, I can make a more effective suggestion.
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