Molecular cloning and expression profiling of excitatory amino acid carrier 1 in suckling Huanjiang mini-piglets with large or small body weight at birth

摘要

Dietary glutamate is extensively oxidized in enterocytes during its trans-cellular journey from the intestinal lumen to the blood. This corresponds to high energy requirement for the absorptive function and renewal of the epithelium. Excitatory aminoacid carrier 1 (EAAC1) is known to be the major transporter of glutamate in the intestine. The present study was conducted in Huanjiang mini-piglets which represent a valuable agronomical model for pig production and also extrapolation to human intestinal physiology in order: (i) to determine the amino acid sequence of EAAC1; (ii) to measure the ontogenic expression profiles of jejunal EAAC1 during the suckling period and (iii) to evaluate the influence of low body weight at birth on the expression of EAAC1. For such a purpose, we cloned EAAC1 from Huanjiang mini-pig and used real-time RT-PCR method and Western blotting analysis. Our results show that EAAC1 in the mini-pig encoded a predicted 524-AA protein with eight putative trans-membrane domains. The expression in mRNA and protein of EAAC1 in jejunum was increasing from birth up to 14 days of age and then decreased at 21 days. Piglets with small BW had lower jejunal EAAC1 protein content between birth and after 7 days suckling. These findings indicate that the expression of the EAAC1 in jejunum is much depending on the stage of piglet development and that low BW at birth is associated with lower expression of this carrier in the early suckling period. Then, it can be hypothesized that lower expression of the intestinal glutamate carrier may decrease the availability of glutamate to enterocytes, thus challenging the optimal absorptive function of the small intestine and normal mucosal growth.