reply and query on cell death
rick at sjubiol.stjohns.edu
Mon Mar 7 23:36:59 EST 1994
To: ageing at net.bio.net
Reply to: uunet!reed.edu!tkim (Tae Hoon Kim)
Subject: STUDENT QUESTION: relationship between senescence and
From: richard a. lockshin
-->incidentally, I might as well ask here. Is there much
interest in trying to organize a cell death discussion group?
->be careful to distinguish, in the animal world, cell senescence
(limited lifespan of cells in culture), programmed cell death
(developmental, usually requiring gene activity), and apoptosis
(a particular type of morphology and non-lysosomal death seen in
many types of cells.
-->for aging and cell death, see Lockshin R. A. and Zakeri Z. F.,
Physiology and protein synthesis in programmed cell death. Early
synthesis and DNA degradation. in Franceschi C, Crepaldi G,
Cristofalo V. J., and Vijg, J, eds, Aging and Cellular Defense
Mechanisms, Annals N.Y. Acad. Sciences 663: 234-249, 1992.
1. Are there evidences that may implicate PKC in the pathwway of
-->not that I know of. There are some papers coming out on
metabolism of dying cells.
2. Are ultrastructural, morphological, behavior changes in ageing
similar to apoptotic cells?
-->in senescing cells, most people feel that the changes are not
like apoptosis. A few feel that they are. Cristofalo is working
on this now, and there will be a book out at the end of 94 in
which both subjects are treated. My understanding is that dying
plant cells do not have the morphology of apoptosis. I solicit
3. How is senescence regulated? Or is it regulated at all?
-->wow. Do you want a course, a Ph.D., or a Nobel prize?
4. How are ageing cells affected by environment?
-->again, senescence: nutrients, glucocorticoids, growth factors
play a large role. The environment in general (e.g., ecological
5. How much evidence are there to suggest that senescence is a
-->Please see C. Finchs book. Researchers primarily interested
in the genetics of senescence include George Martin (U Wash), Tom
Johnson (Boulder), Michael Rose (Irvine)
6. What is the relationship between senescence and cell cycle?
-->see articles by Judith Campisi, Eugenia Wang, James Smith and
Olivia Pereira-Smith, Tom Norwood. You can find these by a
literature search. The field is extensive.
7. Can this generalization hold?:
Senescence occurs in a terminally differentiated cells,
apoptosis occurs in relatively more neoplastic tissues.
-->no. The concepts at present are incommensurable. Interesting
thought though. Do you mean instead of neoplastic--a
Can I view apoptosis as a suicide and senescence as a natural
distinction seems to helpful in conceptualizing these ideas.
-->dont confuse cells and organisms. also, dont confuse
continuing mitosis and failure of same with cell death. phase
III cells in culture survive a very long time, without undergoing
mitosis. Unless you insist on a precise definition of cell
senescence, usually considered to refer to limited lifespan of
cells in culture, you will end up with total confusion.
--richard a. lockshin (rick at sjubiol.stjohns.edu)
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