J F Thompson1, M van den Berg, P C Stokkers. 1. Department of Pediatrics, New England Medical Center/Tufts University School of Medicine, Boston, Massachusetts.
Abstract
BACKGROUND/AIMS: Intraluminal epidermal growth factor (EGF) may regulate intestinal growth and function. The ontogeny, localization, and phosphorylation of the EGF receptor in rat small intestine were studied. METHODS: EGF-receptor phosphorylation was assayed by antiphosphotyrosine Western blot after EGF administration in vivo and EGF incubation to everted sacs in vitro. EGF-receptor abundance and localization were assayed by Western blot and immunofluorescence using anti-EGF-receptor antibodies. RESULTS: In vivo, orogastric EGF enhanced EGF-receptor phosphorylation in newborn rat jejunum and liver. However, intraluminal EGF had no effect on EGF-receptor phosphorylation in adult intestine or liver. In vitro, mucosal EGF stimulated a fourfold increase in EGF-receptor phosphorylation in suckling jejunum but not in weanling or adult jejunum. In Western blot, EGF-receptor abundance was similar in 22-day-old fetal, 8-day-old suckling, and adult jejunum. In both crypt and villus, EGF-receptor was localized to the basolateral membrane but not to the apical membrane in fetal, suckling, and adult jejunum. CONCLUSIONS: Mucosal EGF stimulates EGF-receptor phosphorylation in immature but not in mature intestine. These differences are not explained by EGF-receptor abundance or localization and suggest that the greater mucosal permeability of the immature gut may allow EGF to bind to the EGF-receptor in the basolateral membrane to mediate its effects in suckling rat intestine.
BACKGROUND/AIMS: Intraluminal epidermal growth factor (EGF) may regulate intestinal growth and function. The ontogeny, localization, and phosphorylation of the EGF receptor in rat small intestine were studied. METHODS: EGF-receptor phosphorylation was assayed by antiphosphotyrosine Western blot after EGF administration in vivo and EGF incubation to everted sacs in vitro. EGF-receptor abundance and localization were assayed by Western blot and immunofluorescence using anti-EGF-receptor antibodies. RESULTS: In vivo, orogastric EGF enhanced EGF-receptor phosphorylation in newborn rat jejunum and liver. However, intraluminal EGF had no effect on EGF-receptor phosphorylation in adult intestine or liver. In vitro, mucosal EGF stimulated a fourfold increase in EGF-receptor phosphorylation in suckling jejunum but not in weanling or adult jejunum. In Western blot, EGF-receptor abundance was similar in 22-day-old fetal, 8-day-old suckling, and adult jejunum. In both crypt and villus, EGF-receptor was localized to the basolateral membrane but not to the apical membrane in fetal, suckling, and adult jejunum. CONCLUSIONS: Mucosal EGF stimulates EGF-receptor phosphorylation in immature but not in mature intestine. These differences are not explained by EGF-receptor abundance or localization and suggest that the greater mucosal permeability of the immature gut may allow EGF to bind to the EGF-receptor in the basolateral membrane to mediate its effects in suckling rat intestine.
Authors: Jennifer C Miguel; Adrienne A Maxwell; Jonathan J Hsieh; Lukas C Harnisch; Denise Al Alam; D Brent Polk; Ching-Ling Lien; Alastair J M Watson; Mark R Frey Journal: J Cell Sci Date: 2016-03-29 Impact factor: 5.285