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98
The Regulation of Proline on Cell Proliferation Involved in Polyamine Metabolism in Porcine Enterocyte Ipec-J2.
J. Wang*, #, B. E. Tan*, 1, J. J. Li*, G. P. Guan*, X. Xiong*, and Y. L. Yin*, 1
* National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, Hunan, China;
# University of Chinese Academy of Sciences, Beijing 100008, China
1 Corresponding author: bietan@isa.ac.cn or yinyulong@isa.ac.cn
ABSTRACT: Increased levels of cellular polyamines are essential for stimulation of intestinal epithelial cell proliferation. Proline (Pro) is one of precursors of ornithine, which is converted into polyamines via ornithine decarboxylase (ODC). The aim of this study was to investigate the effect of Pro on the polyamine metabolism and cell proliferation in the porcine enterocyte IPEC-J2. Cells cultured with DMEM-H containing 10% FBS and were exposed to 400 μM L-Pro or 400 μM L-Pro + 10 mM α-difluoromethylornithine (DFMO) for 4 days. The results showed that the ODC protein level, spermidine and spermine contents was increased by L-Pro, but combined addition of L-Pro and DFMO prevented the expression of ODC protein and thus decreased the concentrations of putrescine, spermidine and spermine in the IPEC-J2 cells (P < 0.05). The percentage of cells in the S-phase was increased in response to L-Pro treatment and depletion of cellular polyamines by exposure to DFMO caused the G1-phase growth arrest (P < 0.05). Meanwhile, the mRNA expressions of c-fos and c-myc were elevated in the L-Pro treated IPEC-J2 cells, but significantly inhibited by DFMO; and inhibition of polyamine synthesis with DFMO increased p53 mRNA level (P < 0.05). Interestingly, compared with L-Pro supplementation, combination of L-Pro and DFMO decreased cell apoptosis and the levels of associated proteins, including Bax and cytochrome C (P < 0.05). These findings indicated that Pro promote the polyamines synthesis by mediating ODC expression and plays important role in cell-cycle progression and cell proliferation in the porcine enterocyte IPEC-J2, and polyamine-deficient IPEC-J2 cells may be protected from apoptosis, thereby provided useful information for dietary Pro or polyamines supplementation to improve the health and development of small intestinal mucosa in piglets.