A Mouse Model of Acrodermatitis Enteropathica: Loss of Intestine Zinc Transporter ZIP4 (Slc39a4) Disrupts the Stem Cell Niche and Intestine Integrity
Figure 2
The intestine Zip4 gene controls growth and viability, but knockout mice can be partially rescued by nursing or excess dietary zinc.
(A) Neonatal mice homozygous for the floxed Zip4 gene and positive for the vil-CreERT2 gene (Zip4 intest KO) and littermates homozygous for the floxed Zip4 gene but negative for the vil-CreERT2 gene (Con) were injected for 5 consecutive days with tamoxifen beginning 5 days post-partum. After weaning on day 21 their body weights were measured daily (n = 5 to 8 mice per group). These mice were fed normal chow after weaning. Two representative mice from control and Zip4 intestine knock-out mice are shown but all these mice died by day 7 after weaning (see Figure S1A). (B) Zip4-intestine knockout and control neonatal mice were injected with tamoxifen as in A and at weaning these mice (n = 2) were provided access to drinking water containing excess zinc (ZnE). Their body weight was monitored daily for 2 weeks before removing excess zinc and continuing to feed normal chow (zinc adequate feed: ZnA). (Blot Inset) Northern blot hybridization was used to monitor Zip4, Zip5 and actin mRNAs in the neonatal intestine on day 12 post-partum, after the 5th injection of tamoxifen (n = 3 mice per group). (C, D, E) Recently weaned mice (Zip4 intest KO and Con) (n = 5 to 7 per group) were injected for 3 consecutive days or (F) injected once with tamoxifen and their body weight was measured daily. Two representative control and intestine knockout mice are shown. (D) A recently weaned (Con) control mouse (top: 16 g) and a Zip intest KO mouse (bottom: 9.8 g) were photographed 8 days after initiation of the knockout. Every Zip4-intestine knockout mouse examined died within 16 days of initiation of the knockout. (E) Recently weaned mice (n = 12) were provided excess zinc in the drinking water (ZnE) and normal chow beginning on day 1 after initiation of the knockout. Four weeks later excess zinc was replaced with deionized water and the body weights of the mice were monitored daily. (Blot Inserts) Northern blot hybridization of intestine RNA isolated on day 7 after initiation of the knockout (C) or on day 10 after removal from excess zinc (E). (F) Intestine RNA was isolated from uninjected mice (O), from mice on day 14 after a single injection of tamoxifen (1X) or day 21 (1XR) when the mice had recovered growth (n = 6 to 10 per group). For comparison intestine RNA from Zip4FX/FX:vil-CreERT2 mice injected twice with tamoxifen and harvested on day 4 is shown (2X). (G) Adult Zip4 intest KO and Control littermates (n = 2 per group; 7 weeks old) were injected for 3 consecutive days with tamoxifen and their body weights were measured daily thereafter. The adult Zip4- intestine knockout mice succumbed on day 9 after initiation of the knockout.