Macronutrient regulation of PYY and DPPIV in human intestinal epithelial cells

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 649-675-Central Regulation of Appetite & Feeding/GI Regulatory Peptides
Bench to Bedside
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-667
M.Gulrez Zariwala*1, Anna Kosicka1 and Derek Renshaw2
1University of Westminster, London, United Kingdom, 2Univ of Westminster, London, United Kingdom
Increases in cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1) and PYY(3-36) and decreases in ghrelin secretion after meals are triggered by changes in the nutrient content of the intestine.The enzyme dipeptidyl peptidase-IV (DPP-IV) is expressed by gut epithelial cells and is involved in  deactivation of the incretin hormones GLP-1 and GIP, whereas conversely, by  cleaving PYY1-36 to PYY3-36 it allows specific activation of the Y2 receptors in the arcuate nucleus of the hypothalamus leading to hypophagia (1). Infused PYY3-36 has been shown to reduce food intake in healthy and obese humans by 30% (2). Furthermore, high protein meals have been shown to significantly increase plasma PYY3-36 levels compared to carbohydrate or fat (3). The role of DPPIV enzyme expression in intestinal cells or the role of individual amino acids on the up regulation of PYY has not been investigated.

Using the Caco-2 human intestinal epithelial cells we investigated the effect of specific macronutrients on PYY and DPPIV gene expression. Cells were stimulated for 24 hours with 1.59 mM L-Leucine, 2.39 mM L-Arginine, L-Leu+L-Arg, Non Essential Amino Acids (NEAA) x 10 concentration and 20 nM glucose. The expression of DPP-IV and PYY1-36 genes was determined by SYBR-green real time PCR. Cell culture supernatant PYY 3-36 protein was measured using a human enzyme immunoassay (EIA) kit. The protein concentration was standardised against total protein content quantified using bicinchoninic assay (BCA). Caco-2 cells were also incubated for 3 hours at varying concentrations (20, 50, 100, 200 and 500 nM) of exogenous PYY1-36. PYY3-36 protein was measured in cell culture supernatant.

Our results showed no significant change to the DPP-IV and PYY1-36 gene and PYY3-36 protein expression on stimulation with either L-Leu or L-Arg in isolation. However, addition of both L-Leu+L-Arg in combination resulted in a 1.5 fold induction of DPP-IV (P=0.017) gene and 1.8 fold up-regulation of PYY1-36 (P=0.019) gene expression. Similarly, the cellular PYY3-36 protein was significantly up-regulated when compared to control (P = 0.04) on stimulation with both L-Leu+L-Arg. Glucose treatment also caused a 1.4 up-regulation of DPPIV (P=0.041) and a 3.3 up-regulation of PYY1-36 (P<0.0001) genes. This gene induction was reflected in a significant increase in cellular PYY3-36 protein (P=0.01). Furthermore, incubation of Caco-2 cells with varying concentrations of exogenous PYY1-36 resulted in a linear increased concentration of PYY3-36 (R2=0.32, P<0.0001).These data show for the first time that PYY gene is expressed in the human gut epithelial cell line- Caco-2 and that stimulation with specific macronutrients leads to an increase in PYY3-36 gene expression and protein release as well as an up regulation of DPPIV gene.

(1) Batterham RL, Cowley MA, Small CJ, Herzog H, Cohen MA, Dakin CL, Wren AM, Brynes AE, Low MJ, Ghatei MA, Cone RD, Bloom SR. (2002) Gut hormone PYY(3-36) physiologically inhibits food intake. Nature. 418(6898),650-654. (2) Batterham RL, Cohen MA, Ellis SM, Le Roux CW, Withers DJ, Frost GS, Ghatei MA, Bloom SR. (2003). Inhibition of food intake in obese subjects by peptide YY3-36. N. Engl. J. Med. 349(10), 941-948. (3) Batterham RL, Heffron H, Kapoor S, Chivers JE, Chandarana K, Herzog H, Le Roux CW, Thomas EL, Bell JD, Withers DJ. (2006). Critical role for peptide YY in protein-mediated satiation and body-weight regulation. Cell Metabolism 4(3), 223-233.

Nothing to Disclose: MGZ, AK, DR

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Sources of Research Support: M.Gulrez Zariwala was supported by an Early career Grant from the Society for Endocrinology