Role of tyrosine kinase and phosphotyrosine phosphatase in growth of the intestinal crypt cell (IEC-6) line.
The roles of gastrin and sodium vanadate in proliferation were examined in cultured IEC-6 cells that are mitotically active and derived originally from jejunal crypts of the rat intestine. Incubation of the cells in the presence of gastrin at a concentration of 250 ng/ml or of sodium vanadate at a concentration of 0.2 mM leads to a 60% increase in cell growth in 24 hr. The stimulated growth in both cases was inhibited by genistein, a tyrosine kinase inhibitor. Incubation in the presence of gastrin and sodium vanadate together produced a small, albeit significant, potentiation of growth of the cells. Gastrin as well as sodium vanadate also promoted the phosphorylation on tyrosine of a similar group of proteins with molecular masses of 42, 45, 52, 60, 78, and 120 kDa. The phosphorylations were rapidly occurring as early as 5 min and lasted for only 15 min. Several proteins were detected in normal IEC-6 cells, including GTPase activating protein, raf1 kinase, phospholipase C gamma-1, and phosphoinositide 3-kinase. The results suggest that gastrin and sodium vanadate induce growth of IEC-6 cells by stimulation of tyrosine kinase and/or inhibition of tyrosine phosphatase. The gastrin and sodium vanadate effects also involve the phosphorylation of a number of proteins, the identities of which are not known at present but may include some of the kinases that are frequently associated with cell growth, such as mitogen-activated protein kinase, raf1 kinase, phosphoinositide 3-kinase, and others.
Raid
A
A
Department of Medicine, Veterans Administration Medical Center, Newington, Connecticut 06111.
Oliver
B
B
Abdelrahman
A
A
Sha'afi
R I
RI
Hajjar
J J
JJ
D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D005755:Gastrins / Q000494:pharmacology*; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology; D007583:Jejunum / Q000166:cytology; D007700:Kinetics; D008970:Molecular Weight; D010750:Phosphoproteins / Q000096:biosynthesis / Q000302:isolation & purification; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D013997:Time Factors; D014638:Vanadates / Q000494:pharmacology*
D005755:Gastrins; D007529:Isoflavones; D010750:Phosphoproteins; D014638:Vanadates; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D017027:Protein Tyrosine Phosphatases