The regenerating gene (Reg) family genes in inflammatory bowel disease (IBD)

Regenerating gene (Reg) was first isolated in 1988 and proposed to be specifically expressed in rat regenerating pancreatic islets. Since then, many genes homologous to Reg have been discovered in other species, including humans, mice, hamsters, rabbits, sheep, dogs, cats, pigs, giant pandas, chickens, and frogs. Moreover, Reg and its related genes (Reg family genes) have been classified as types I, II, III, and IV. They are closely associated with cell and tissue regeneration, cell proliferation, and anti-apoptosis in various tissues and cells including pancreatic β cells. In particular, focusing on the digestive organs and tissues, there have been reports that they play important roles not only in stomach, colon, liver, and pancreatic duct cancer, but also in intestinal epithelial cells, especially inflammatory bowel diseases (IBD), such as Crohn’s disease (CD) and ulcerative colitis (UC). This review describes and discusses the expression of Reg family genes in intestinal epithelial cells of those affected by IBD and the molecular mechanisms underlying this expression.