Determination of mRNA Expression of Typical Proteins of Tight Junctions in the Intestinal Mucosa of Broilers (Gallus gallus domesticus)

Abstract

Tight junctions are mainly formed by two types of proteins; claudins and occludin, both of which are fundamental to maintain the integrity and barrier function of the intestinal epithelium. This barrier function allows for the absorption of nutrients, mainly by transcytosis; however, in birds, 90% of the substances are absorbed by paracellular mechanisms. Despite this, claudins present in the different parts of the intestinal tract of adult chickens are not known, much less their functional role. This study aimed to determine the presence of mRNA of claudins 1, 2, 3, 5, 10, 12, 16 and occludin, in the different regions of the intestine (duodenum, jejunum, ileum, cecum, and rectum) in chickens (Gallus gallus domesticus) through RT-PCR. To meet this goal, 7 weeks old roosters destined for slaughter and chicken embryos of 16 days of incubation (positive control) were used. For all the processed samples, amplicons of the expected size were obtained; claudin 1 (662 pb), claudin 2 (162 pb), claudin 3 (185 pb), claudin 5 (224 pb), claudin 10 (687 pb), claudin 12 (738 pb), claudin 16 (191 pb) and occludin (430 pb). To corroborate these findings, obtained amplicons were sequenced and, subsequently, a basic alignment was performed on the NCBI, obtaining a correlation of 100% with the original sequences in all analyzed samples. To our knowledge, the present work represents the first written report regarding the presence of mRNA of the main proteins involved in tight junction formation throughout the intestinal tract of domestic chickens of 7 weeks of age. These findings will allow elucidating the specific function of each of the reported proteins in the process of paracellular absorption in chickens.