PepT1-mediated epithelial transport of dipeptides and cephalexin is enhanced by luminal leptin in the small intestine
Marion Buyse, … , Claude Rozé, André Bado
Marion Buyse, … , Claude Rozé, André Bado
Published November 15, 2001
Citation Information: J Clin Invest. 2001;108(10):1483-1494. https://doi.org/10.1172/JCI13219.
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Article

PepT1-mediated epithelial transport of dipeptides and cephalexin is enhanced by luminal leptin in the small intestine

Abstract

Dietary proteins are mostly absorbed as di- and tripeptides by the intestinal proton-dependent transporter PepT1. We have examined the effects of leptin on PepT1 function in rat jejunum and in monolayers of the human enterocyte-like 2 cell Caco-2. Leptin is produced by the stomach and secreted in the gut lumen. We show here that PepT1 and leptin receptors are expressed in Caco-2 and rat intestinal mucosal cells. Apical (but not basolateral) leptin increased Caco-2 cell transport of cephalexin (CFX) and glycylsarcosine (Gly-Sar), an effect that was associated with increased Gly-Sar uptake, increased membrane PepT1 protein, decreased intracellular PepT1 content, and no change in PepT1 mRNA levels. The maximal velocity (Vmax) for Gly-Sar transport was significantly increased by leptin, whereas the apparent Michaelis-Menten constant (Km) did not change. Furthermore, leptin-stimulated Gly-Sar transport was completely suppressed by colchicine, which disrupts cellular translocation of proteins to plasma membranes. Intrajejunal leptin also induced a rapid twofold increase in plasma CFX after jejunal perfusion with CFX in the rat, indicating enhanced intestinal absorption of CFX. These data revealed an unexpected action of gastric leptin in controlling ingestion of dietary proteins.

Authors

Marion Buyse, Françoise Berlioz, Sandra Guilmeau, Annick Tsocas, Thierry Voisin, Gabriel Péranzi, Didier Merlin, Marc Laburthe, Miguel J.M. Lewin, Claude Rozé, André Bado

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Figure 1

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Expression of PepT1 and leptin receptors in Caco-2 cells. Three to seven...
Expression of PepT1 and leptin receptors in Caco-2 cells. Three to seventeen days after cell seeding, total RNA and total protein were extracted and subjected to RT-PCR and Western blot analysis, respectively. (a) RT-PCR of hPepT1 RNA. Lane 1, Caco-2 cells after 3 days of culture. Lane 2, negative control omitting reverse transcriptase. Lane 3, Caco-2 cells after 17 days of culture. Arrow indicates the expected size (498 bp) of the PCR product. (b) Western blot analysis of hPepT1 protein. A polyclonal anti-hPepT1 antibody was used. This representative immunoblot shows a ∼80-kDa protein that varies with the differentiation state of the Caco-2 cells (3 to 17 days of culture). (c) RT-PCR analysis of Ob-Rb RNA. Lane 1, Caco-2 cells after 3 days of culture. Lane 2, negative control omitting reverse transcriptase. Lane 3, Caco-2 cells after 17 days of culture. Arrow indicates the expected size (237 bp) of the PCR product. (d) Western blot analysis of leptin receptor protein. In this representative immunoblot, immunoreactive proteins of approximately 90 kDa, 130 kDa, and 170 kDa were detected in Caco-2 cells.