Re: What are the aging-mechanisms in a gut cell, that lives only 2 days?

Date: Mon Sep 14 11:03:32 1998
Posted By: Kenneth Mitton, Post-doc/Fellow, Molecular Development Retina, Cataract, Dept Ophthalmology / U. Mich
Area of science: Cell Biology
ID: 897686633.Cb

Message:

There is no easy answer for you, but let us analyze in the Fermi way and find an answer,we can focus on two major events that determine any tissue population TURNOVER.

1) Cells form, from proliferation rate, new cells N (hr-1)
2) Cells are lost, from physical loss in gut (sloughed off) S (hr-1)
   or also die from apoptosis rate A (hr-1)

so a population change of intestinal epithelial cells may be modelled by:

change (hr-1) = (population*N) -(population*S)-(population*A)

Cells are often turned over at different rates in different tissues mosty 
dependent on the wear and tear that tissue experiences. IE. Red blood cells 
average two weeks, they eventually just wear out and will be cleaned up and 
recycled into the organism. Lens fiber cells, never turnover, they loose 
organelles and nucleus like RBC's, fill up with crystallins, lots of GSH 
and have saturated membranes that are resistive to oxidation. The center of 
our lenses have our fetal lens fiber cells and contain some proteins that 
have been modified but are the original item.

It seems that in the gut, cell death also regulates the turnover of cells in the intestinal mucosa to a significant extent. ie. The sloughing or wearing away of these cells is not the major way they are lost. There is much research into the nutritional effects on the rate of apoptosis (programmed cell shutdown) in the literature. I checked PubMed out (using turnover and intestinal) and found articles such as Surgery 1998 Aug;124(2):152-159 Glutamine deprivation induces apoptosis in intestinal epithelial cells , buy Papaconstantinou HT, Hwang KO, Rajaraman S, Hellmich MR, Townsend CM Jr, Ko TC.

If you go to this article you can ask PUBMED to show related articles on this topic. So the short anwser is proliferation and apoptosis and their relative balance control the turnover of this tissue as far as the literature indicates.

Kenneth Mitton, PhD Kellogg Eye Center University of Michigan

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