Expression of cysteine-rich intestinal protein in rat intestine and transfected cells is not zinc dependent.

The cysteine-rich intestinal protein (CRIP) is a member of a superfamily of proteins containing the LIM motif (a double zinc finger) that has been shown to bind zinc. The role of zinc in the regulation of CRIP was examined in adult rats, cultured intestinal epithelial cells and in a transient transfection system. When adult male rats were fed diets with various amounts of zinc, the amount of ileal CRIP mRNA was only 19% lower in rats fed a zinc-deficient diet (1 mg Zn/kg) and was not different in the zinc-supplemented group (180 mg Zn/kg) compared with the zinc-adequate group (30 mg Zn/kg). In contrast, metallothionein mRNA levels were 76% lower and 80% greater than control levels in the zinc-deficient and zinc-supplemented groups, respectively. Using the chloramphenicol acetyltransferase (CAT) reporter gene, 5'-deletion products of the CRIP genomic promoter were tested for basal and zinc-induced CAT activity in transiently transfected IEC-6 cells. Treatment of the cells with zinc did not alter CAT activity of any construct. These results suggest that CRIP is not directly regulated by zinc in the intestine of rats.