P‐glycoprotein deficiency results in intestinal developmental delay in C. elegans

Inflammatory Bowel Disease (IBD) is a term used to group similar diseases characterized by the chronic inflammation of the digestive tract. IBD is an autoimmune reaction with an unknown cause. There is no known cure, only treatments to relieve symptoms. There are many genes linked to this disease, including MDR1. The MDR1 gene codes for a protein called P-glycoprotein (Pgp), which is known to be expressed in intestinal cells. The exact relationship between IBD and Pgp is unknown, but it has been observed that some patients with IBD have a mutation that causes a loss of function of Pgp. Our goal is to explore the use of Caenorhabditis elegans as a model for intestinal diseases. Because Pgp deficiency is associated with intestinal damage, we hypothesized to measure changes in the intestine and organism that indicate intestinal damage, particularly changes in tight junctions, which would lead to increased intestinal permeability leading to damage. Tight junctional analysis for using both immunohistochemistry and qRT-PCR shows a downregulation of the tight junctional protein LET-413 in Pgp1-/- C. elegans. These data support our hypothesis that Pgp deficiency impacts intestinal tight junctions in C. elegans, potentially leading to intestinal damage. This change in expression is similar to what is see in human inflammatory bowel disease, particularly those individuals who have Pgp polymorphisms. The downregulation of tight junctional genes (let41 and dlg1) was also seen in Pgp3-/- and Pgp1/3-/- C. elegans at the L1 stage. Interestingly, changes in gene expression were only observed in L1 stage C. elegans. Mid to old-aged larvae (L2-L4) and adult C. elegans displayed no change in gene expression. Additionally, Pgp deficient C. elegans also developed at a slower rate than the N2 control strain. This suggests that these changes are specific to early development. To explore this, gene expression analysis was also performed on several genes related to the development of the C .elegans intestine and pharynx. Pgp1-/- L1 C. elegans displayed significant increases in several genes (pal1, pha4, elt2, end1,and pie1), with all genes trending upwards. This might indicate that these worms have slower developing intestines, and are still undergoing the developmental process in the L1 stage, where the Pgp3-/- C. elegans has already completed the development of the intestine. Taken with the LET-413 staining which was also decreased in the Pgp1-/- samples, we conclude that the deficiency of Pgp1 impacts intestinal development, which leads to a change in tight junction expression.