Related Experiment Video
Updated: May 25, 2026

Methods to Study Epithelial Transport Protein Function and Expression in Native Intestine and Caco-2 Cells Grown in 3D
Published on: March 16, 2017
Expression and functional analysis of intestinal organic cation/L-carnitine transporter (OCTN) in Crohn's disease
Marc Girardin1, Serge Dionne, Philippe Goyette
1DigestiveLab, Research Institute, McGill University Health Centre, Montreal, QC, Canada. marcgirardin@gmail.com
Background:
The IBD5 locus is a genetic risk factor for IBD, particularly Crohn's Disease, coding for the organic cation/carnitine transporters (OCTN1 and 2). Two variants of OCTN are associated with susceptibility to Crohn's Disease. Modified transport of carnitine in vitro has been reported for a polymorphism of OCTN1. The aim was to investigate the function of intestinal OCTNs in IBD in relation to genetic polymorphisms.
Methods:
Intestinal tissue was obtained from endoscopic biopsies and surgical resections from IBD patients (n=33 and 14, resp.) and controls (n=22 and 14, resp.). OCTN protein levels were measured in intestinal biopsies and carnitine transport was quantified in intestinal resections.
Results:
OCTN1 protein levels were significantly higher in ileal versus colonic tissue (2.95% ± 0.4 vs 0.66% ± 0.2, resp.; p<0.0002). OCTN1 expression was higher in Crohn's disease patients with mutant homozygous or heterozygous genotypes (0.6% ± 0.1 vs 3% ± 0.8, resp., p<0.02). Carnitine transport was very rapid and Na+ dependent (10s). It was not different comparing Crohn's Disease and control groups (0.45 ± 0.12 vs 0.51 ± 0.12 nM carnitine/mg prot/min, resp.). Carnitine transport tended to be higher in subjects with mutant homozygous and heterozygous OCTN1 and OCTN2 genotypes (0.19 vs 0.59 and 0.25 vs 0.6, respectively).
Conclusions:
The present data reveal that OCTN protein levels appear to be similar in intestinal tissue from Crohn's Disease patients and controls. Overall, ileal carnitine transport appears to as well equal in Crohn's Disease and control groups. However, there was a trend towards higher carnitine transport in subjects with OCTN1 and OCTN2 mutations.
Related Concept Videos
Carrier-Mediated Transport
Active transport involves two types of membrane-spanning transporters: uptake and efflux. Uptake transporters are expressed in the small...
Transcellular Transport of Solutes
Inflammatory Bowel Disease III: Crohn's Disease
Pharmacogenetics of Drug Transporters: P-Glycoprotein and Solute Carrier Transporters
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
ABC Transporters: Exporter

