AJP - Cell Physiology, Vol 262, Issue 6 C1478-C1484, Copyright © 1992 by American Physiological Society
Gs and Gi protein subunits during cell differentiation in intestinal crypt-villus axis: regulation at the mRNA level
A. Couvineau, D. Darmoul, A. Blais, C. Rouyer-Fessard, D. Daviaud, T. Voisin, H. Paris, B. Rouot and M. Laburthe
Institut National de la Sante et de la Recherche Medicale (INSERM) U. 239, Faculte de Medecine X. Bichat, Paris, France.
The expression of subunits of the guanine nucleotide regulatory protein
that mediates hormonal stimulation of adenylyl cyclase (Gs) and of the
guanine nucleotide regulatory protein that mediates hormonal inhibition of
adenylyl cyclase (Gi) was studied during cell migration and differentiation
in the rat small intestine crypt-villus axis. Proliferative crypt cells
were separated from nonproliferative mature villus cells and the following
data were obtained: 1) alpha s subunits were more abundant in crypt cells
than in villus cells as evidenced by cholera toxin-catalyzed [32P]NAD
ribosylation and Western blotting of this relative molecular weight (M(r))
42,000 protein; 2) alpha i2- and alpha i3-subunits (M(r) 40,000 and M(r)
41,000, respectively) were preferentially expressed in villus cells as
evidenced by pertussis toxin-catalyzed [32P]NAD ribosylation and Western
blotting (alpha i1-subunit was not detectable in intestinal epithelium by
using these techniques); 3) Western blotting showed a higher expression of
the common beta- (M(r) 36,000) subunit of G proteins in villus cells than
in crypt cells; and 4) Northern blot analysis using an alpha s-subunit
oligonucleotide probe showed a 1.9-kb mRNA that was more abundant in crypt
cells than in villus cells. In contrast, alpha i2- and alpha i3-mRNA
species (2.3 and 3.5 kb, respectively), analyzed by using specific cDNA
probes, were much more abundant in villus cells than in crypt cells.
Finally, two beta-subunit mRNA species of 3.3 and 1.8 kb were detectable in
intestinal epithelial cells and were more abundant in villus cells than in
crypt cells.(ABSTRACT TRUNCATED AT 250 WORDS)
