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Am J Physiol Gastrointest Liver Physiol 267: G883-G891, 1994;
0193-1857/94 $5.00
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AJP - Gastrointestinal and Liver Physiology, Vol 267, Issue 5 883-G891, Copyright © 1994 by American Physiological Society

ARTICLES

Role of insulin and insulin-like growth factor receptors in regulation of T84 cell monolayer permeability

J. A. McRoberts and N. E. Riley
Department of Medicine, Harbor-UCLA Medical Center, Torrance 90502.

We previously showed that insulin and insulin-like growth factor (IGF)-I and IGF-II caused a dose-dependent increase in permeability through the paracellular pathway of T84 cell monolayers over 3-4 days. Here we have determined which cell surface receptors were involved in this response. Using radioligand binding studies and receptor cross-linking studies, we found that T84 cells possess insulin and IGF-I receptors. There were approximately 20 x 10(3) insulin receptors/cell with a dissociation constant (KD) of 0.5 nM and 29 x 10(3) IGF-I receptors with a KD of 0.6 nM for IGF-I. Cross-linking studies identified the alpha-subunit of insulin and IGF-I receptors with deduced molecular weights of 126 x 10(3) and 128 x 10(3), respectively. IGF-II bound to T84 cells with an apparent KD of approximately 2.0 nM. Radioreceptor cross-linking indicated that IGF-II interacted principally with the IGF-I receptor, although low levels of the IGF-II/mannose 6-phosphate receptor were also expressed on the cell surface. We then correlated the biological effect with the radioligand binding studies. It was first demonstrated that insulin and IGF-I were degraded in medium in the presence of cells. In addition, we showed that continuous exposure for 2-3 days to insulin or IGF-I was required to produce their biological effect on permeability. Taking into account the rate of degradation and the requirement for continuous exposure, we found a close correlation between radioligand binding and the half-maximal effective concentration for the hormonal effects on transepithelial permeability.(ABSTRACT TRUNCATED AT 250 WORDS)


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N. Chang, J. M. Uribe, S. J. Keely, S. Calandrella, and K. E. Barrett
Insulin and IGF-I inhibit calcium-dependent chloride secretion by T84 human colonic epithelial cells
Am J Physiol Gastrointest Liver Physiol, July 1, 2001; 281(1): G129 - G137.
[Abstract] [Full Text] [PDF]


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