Distribution of Epidermal Growth Factor (Egf) Receptors(r) in the Fetal(f) Gastrointestinal Tract (Gi)

Sadiq, F; Gunn, Joseph; Cherhani, V; Devaskar, Uday

doi:10.1203/00006450-198404001-00706

Cited by 1 publication

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“…Similarly, the unlikelihood of the milk-derived factors reaching, in an active form, the mucosal surface of the lower digestive tract could theoretically account for the higher binding capacities in the distal gut compared to those in the proximal gut where EGF receptors are fully exposed to milk contents and, therefore, downregulated. This-in unlikely, however, since EGF binding was actually lower in the ileum than in the more proximal portion of the small intestine (18,23). Moreover, in the fetal rabbit gastrointestinal tract, where milk factors are not implicated, a 2-to 3-fold increase in EGF binding and receptor density was, nevertheless, observed in the colon compared to that in other regions of the small intestine (23).…”

Section: Discussionmentioning

confidence: 62%

“…This-in unlikely, however, since EGF binding was actually lower in the ileum than in the more proximal portion of the small intestine (18,23). Moreover, in the fetal rabbit gastrointestinal tract, where milk factors are not implicated, a 2-to 3-fold increase in EGF binding and receptor density was, nevertheless, observed in the colon compared to that in other regions of the small intestine (23).…”

Section: Discussionmentioning

confidence: 62%

“…Secondly, in all age groups studied, EGF binding in isolated colonic cells was markedly higher than that in corresponding intestinal cells. To our knowledge, the only other comparative study involving intestinal and colonic binding was reported in abstract form, in which plasma membrane-bound EGF receptors of the fetal rabbit stomach, intestine, and colon were isolated and characterized (23). Interestingly, the fetal colon displayed the highest specific binding and receptor density of all tissues studied.…”

Section: Discussionmentioning

confidence: 95%

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Epidermal Growth Factor Receptors during Postnatal Development of the Mouse Colon*

1987

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The present study was undertaken to establish the postnatal profile of specific epidermal growth factor (EGF) binding in the maturing mouse colon, with particular emphasis on possible regional differences between both proximal and distal colonic binding patterns vs. those of the small intestine. Binding studies using [125I]EGF were performed on isolated epithelial cells obtained from 2-, 5-, 9-, 16-, and 22-day-old mice as well as adults. At 2 days, cells isolated from the entire colon bound 4 times more [125I]EGF than did corresponding intestinal cells, whereas between the ages of 5 days to adult, colonic cells bound between 1.7-2.5 times more labeled EGF than their intestinal counterparts. The immature colon already exhibited maximal binding after birth as opposed to the small intestine where binding only reached maximal values by the third week of life. Comparison between the proximal and distal colon in 9-, 16-, and 22-day-old mice revealed a further 2-fold increase in EGF binding in the distal colon compared to that in the proximal colon. Scatchard plots of [125I]EGF displacement by native EGF in both proximal and distal colonic segments also revealed the presence of two classes of binding sites, with high affinity constants (K1) significantly greater in the distal colon. These results demonstrate for the first time not only the continued presence of EGF receptors in mouse colonic epithelium, but also significant regional differences in EGF-binding capacity within the digestive tract throughout the postnatal period.

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Section: Discussionmentioning

confidence: 62%