Alteration of colonic epithelial cell differentiation in mice deficient for glucosaminyl N-deacetylase/N-sulfotransferase 4

Abstract

Glucosaminyl N-deacetylase/N-sulfotransferases (NDSTs) are the first enzymes that mediate the initiation of heparan sulfate sulfation. We previously identified NDST4 as a putative tumor suppressor in human colorectal cancer. In the study, we generated an Ndst4 knockout (Ndst4^−/−) mouse strain and explored its phenotypic characteristics, particularly in the development of colonic epithelial homeostasis. The Ndst4-deficient mice were viable and fertile, and their life spans were similar to those of wild-type littermates. No gross behavioral or morphological differences were observed between the Ndst4^−/− and wild-type mice, and no significant changes were determined in the hematological or serum biochemical parameters of the Ndst4^−/− mice. Ndst4 RNA transcripts were expressed in the brain, lung, gastrointestinal tract, pancreas, and ovary. However, Ndst4-null mice exhibited no gross or histological abnormalities in the studied organs, except for the colon. Although no alterations were observed in the crypt length or number of proliferating cells, the Ndst4^−/− mice exhibited an increased number of goblet cells and a decreased number of colonocytes in the proximal colon compared with the wild-type mice. Moreover, Ndst4 deficiency increased the basal level of apoptosis in the colonic epithelium. Taken together, we established, for the first time, an Ndst4^−/− mouse strain and revealed the involvement of Ndst4 in the development and homeostasis of colonic epithelium. Accordingly, NDST4 in human colon might direct the biosynthesis of specific heparan sulfate proteoglycans that are essential for the maintenance of colonic epithelial homeostasis. Thus, the loss of its function may result in the tumorigenesis and progression of colorectal cancer.