ZIP7 is indispensable for proliferation of intestinal epithelial cells and maintenance of intestinal stem cells. Mus musculus

Intestinal epithelium are generated by intestinal stem cells, which are recognized morphologically as slender columnar cells at the base of the crypt. Stem cells produce transit-amplifying (TA) cells, which divide a number of times and the daughter cells differentiate into absorptive enterocytes as well as secretory-lineages. Intestinal stem cells highly express Lgr5 which is decreased in TA cells. Here, we show that the zinc transported SLC39A7/ZIP7 is essential for the proliferation of TA cells and maintenance of intestinal stem cells. Lgr5Med TA cells derived from Zip7-deficient mice upregulated the expression of unfold protein responses-related genes including pro-apoptotic genes, indicating of induction of ER stress in these cells. The same effect was seen in Lgr5Hi stem cells derived from Zip7-deficient mice. We conclude that ZIP7 is fundamental to the maintenance of crypt homeostasis by resolving ER stress. Overall design: Small intestinal crypts were isolated form tamoxifen-treated control (Zip7flox/+, Villin-CreERT2, Lgr5-EGFP-ires-CreERT2) and tamoxifen-treated Zip7∆IEC (Zip7flox/flox, Villin-CreERT2, Lgr5-EGFP-ires-CreERT2) mice. We FACS purified intestinal crypt cells according to their Lgr5 expression levels. RNA was isolated from four FACS sorted cell populations: Lgr5Hi cells and Lgr5Med cells derived from control mice, Lgr5Hi cells and Lgr5Med cells derived from Zip7∆IEC mice. Isolated RNA was analyzed using the Affymetrix platform.