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. 2011 Jul;25(7):2492-9.
doi: 10.1096/fj.11-181990. Epub 2011 Apr 14.

Dietary Selenium Affects Host Selenoproteome Expression by Influencing the Gut Microbiota

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Free PMC article

Dietary Selenium Affects Host Selenoproteome Expression by Influencing the Gut Microbiota

Marina V Kasaikina et al. FASEB J. .
Free PMC article

Abstract

Colonization of the gastrointestinal tract and composition of the microbiota may be influenced by components of the diet, including trace elements. To understand how selenium regulates the intestinal microflora, we used high-throughput sequencing to examine the composition of gut microbiota of mice maintained on selenium-deficient, selenium-sufficient, and selenium-enriched diets. The microbiota diversity increased as a result of selenium in the diet. Specific phylotypes showed differential effects of selenium, even within a genus, implying that selenium had unique effects across microbial taxa. Conventionalized germ-free mice subjected to selenium diets gave similar results and showed an increased diversity of the bacterial population in animals fed with higher levels of selenium. Germ-free mice fed selenium diets modified their selenoproteome expression similar to control mice but showed higher levels and activity of glutathione peroxidase 1 and methionine-R-sulfoxide reductase 1 in the liver, suggesting partial sequestration of selenium by the gut microorganisms, limiting its availability for the host. These changes in the selenium status were independent of the levels of other trace elements. The data show that dietary selenium affects both composition of the intestinal microflora and colonization of the gastrointestinal tract, which, in turn, influence the host selenium status and selenoproteome expression.

Figures

Figure 1.
Figure 1.
Mouse models for examining the interrelationships between dietary Se, gut microbiota, and host Se status. A) Schematic illustration of selenoprotein expression in mice subjected to Se-deficient (0 ppm Se), Se-sufficient (0.1 ppm Se), and Se-enriched (0.4 ppm Se) diets. B, C) SelP expression was analyzed by Western blotting (WB) in plasma of conventional (B) and GF and CV (C) mice fed the indicated Se diets for 8 wk (B) or 6 wk (C; top panels); gels stained with Coomassie blue served as loading controls (bottom panels); 2 mice/group were analyzed.
Figure 2.
Figure 2.
Effect of dietary Se on gut microbiota. A) Rarefaction analysis was performed on pyrosequencing data from conventional and GF conventionalized animals. Sequences were pooled from animals of a similar feeding level and aligned using the complete linkage clustering at 97% cutoff available on the RDP pipeline, and clusters were subjected to rarefaction analysis. B) Box and whisker plots depict relative abundance of selected phylotypes showing statistically significant effects of dietary selenium (P<0.05). The taxonomic relationship of each phylotype is indicated above the relevant graph. Left panels: phylotypes from conventional animals (orange boxes). Right panels: phylotypes from GF conventionalized animals (light blue boxes). Vertical bars indicate range of proportions for each treatment group; boxes indicate upper and lower bounds of the 95% confidence intervals.
Figure 3.
Figure 3.
Selenoprotein expression in GF and CV mice. Expression (A) and specific GPx1 and MsrB1 activities (B) in livers and kidneys are shown; 3 mice/group were analyzed. A) Expression of GPx1 and MsrB1 was analyzed by Western blots in livers (top panels) and kidneys (bottom panels) of CV and GF mice fed 0-, 0.1-, and 0.4-ppm Se diets. B) GPx and MsrB activities in liver and kidney lysates of GF and CV mice fed 0-, 0.1-, and 0.4-ppm Se diets. Solid bars, CV mice; open bars, GF mice. *P < 0.05; Student's t test.
Figure 4.
Figure 4.
Regulation of SelP expression by dietary Se in CV and GF mice. A) SelP levels in plasma of CV and GF mice fed 0-, 0.1-, and 0.4-ppm Se diets, as analyzed by Western blots. B) Liver SelP mRNA expression analyzed by quantitative PCR. SelP mRNA expression in CV mice fed the 0-ppm Se diet was set to 1, and mRNA levels in other groups were calculated relative to this basal level. Significance was analyzed with Student's t test. C) Se levels in plasma in CV and GF mice fed 0-, 0.1-, and 0.4-ppm Se diets analyzed by ICP-MS. Values are expressed as means ± sd.
Figure 5.
Figure 5.
Trace elements in CV and GF mice maintained on Se diets. Trace elements were analyzed with ICP-MS in tissues from CV and GF mice fed 0-, 0.1-, and 0.4-ppm Se diets, as described in Materials and Methods. Values are means ± sd. Organs in which trace elements were analyzed are indicated at the bottom of each panel.

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