TJP1 and obesity due to melanocortin 4 receptor deficiency: A high-fat diet can reduce the expression of the intestinal epithelial tight junction proteins occludin and ZO-1, affect the integrity of the intestinal epithelium, cause changes in intestinal permeability and increase the level of circulating lipopolysaccharide, which contribute to increase the incidence of obesity (Cani et al., 2008).