Exogenous nucleosides modulate expression and activity of transcription factors in Caco-2 cells

An Overlooked Prebiotic: Beneficial Effect of Dietary Nucleotide Supplementation on Gut Microbiota and Metabolites in Senescence-Accelerated Mouse Prone-8 Mice

Nucleotides (NTs) are regulatory factors in many biological processes and play important roles in the growth, development, and metabolism of living organisms. We used senescence-accelerated mouse prone-8 (SAMP8) to investigate the effects of NTs on the gut microbiota and metabolites. And the promoting effect of NTs on the growth of a probiotic (Lactobacillus casei) was explored through in vitro experiments. The results showed that the sequencing depth of 16S rDNA covered all microbial species in the feces of SAMP8. Supplementation with exogenous NTs to the diet enhanced the diversity of the gut microbiota, reduced the abundance of bacteria with negative effects on the body (such as Verrucomicrobia, Ruminococcaceae, Akkermansia and Helicobacter), and increased the abundance of the microbiota, which had beneficial effects on the mice (such as Lactobacillus, Candidatus saccharimonas and Lachnospiraceae_NK4A136_group). Metabonomic analysis showed that NT deficiency in the diet significantly affected metabolites in the mouse feces. The metabolites in mice supplemented with NTs tended to be normal (SAMR1). The differentially expressed metabolites caused by NT addition are involved in various pathways in the body, including linoleic acid metabolism, vitamin B6 metabolism, and histidine metabolism. Correlation analysis revealed a significant correlation between the gut microbiota and differentially expressed metabolites caused by the addition of NTs. In vitro experiments showed that NTs significantly promoted the growth, secretion of biofilm and extracellular polymeric substance of L. casei. NTs also promoted the ability of the crude extract of L. casei to resist the secretion of Shigella biofilm. Thus, NTs can regulate the abundance of the gut microbiota and alter the metabolic expression of the intestinal microbiome.

Effects of yeast hydrolysate supplementation on intestinal morphology, barrier, and anti-inflammatory functions of broilers

Objective

This study was conducted to evaluate the effects of dietary yeast hydrolysate (YH) supplementation on intestinal morphology, barrier, and anti-inflammatory functions of broilers.

Methods

A total of 320 one day old male broilers were randomly allocated into four groups with eight replicates of ten broilers each. The broilers were supplemented with a basal diet (the control group) or basal diets adding 50, 100, 150 mg/kg YH, respectively. This trial lasted for 42 days. The orthogonal polynomial contrasts were used to determine the linear and quadratic effects of increasing levels of YH.

Results

In our previous research, supplementing YH improved growth performance by enhancing body weight gain but decreased feed-to-gain ratio. In this study, compared with the control group, dietary YH addition linearly and quadratically decreased serum diamine oxidase activity (p<0.05). Additionally, supplementing YH linearly and/or quadratically decreased jejunal crypt depth (CD), tumor necrosis factor-alpha (TNF-α) concentration as well as mucin 2, interleukin-6 (IL-6), IL-1β, TNF-α, nuclear factor kappa B, and myeloid differentiation factor 88 gene expression levels (p<0.05). Whereas the jejunal villus height (VH), VH/CD, IL-10 concentration as well as zonula occludens-1 and IL-10 gene expression levels were linearly and/or quadratically increased by YH supplementation (p<0.05).

Conclusion

Dietary YH supplementation improved intestinal morphology, barrier and anti-inflammatory functions while decreased intestinal permeability of broilers, which might be related with altering pertinent genes expression. This study provides evidence of YH as a promising feed additive for broilers.

Effects of dietary Bacillus coagulans and yeast hydrolysate supplementation on growth performance, immune response and intestinal barrier function in weaned piglets

The present study investigated the effects of Bacillus coagulans and yeast hydrolysate supplementation on growth performance, immune response and intestinal barrier function of weaned piglets. Twenty-four weaned piglets with an average body weight (BW) of 6.89 ± 0.15 kg were divided into four diets for 28 days. The treatments were basal diet (control), basal diet supplemented with antibiotic (20 mg/kg colistin sulphate and 40 mg/kg bacitracin zinc, AT), probiotics (400 mg/kg Bacillus coagulans ≥5 × 109 CFU/g, BC) or yeast hydrolysate (5000 mg/kg yeast hydrolysate, YH). Average daily gain (ADG) and average daily feed intake (ADFI) were improved by AT and YH diets (p < 0.05), while BC diet only increased ADG (p < 0.05). The complement 3 (C3), lysozyme (LZM) and tumour necrosis factor-α (TNF-α) concentrations in serum were increased in BC diet (p < 0.05). Feeding AT and YH caused the increase of jejunal villus height (p < 0.05), and a higher ratio of villus height/crypt depth was observed in AT, BC and YH groups (p < 0.05). The mRNA expression of zonula occludens-1 (ZO-1) in jejunal mucosa was up-regulated by AT, BC and YH diets (p < 0.05). Dietary AT, BC or YH inclusion decreased the interleukin-1β (IL-1β) concentration and TNF-α mRNA expression (p < 0.05), and YH supplementation even down-regulated toll-like receptor 4 (TLR4) and CD14 expressions (p < 0.05). In summary, the dietary administration of BC or YH both improves growth performance through promoting the intestinal barrier function, indicating both of them can serve as potential alternatives to antibiotics growth promoters for the piglet production.

Nucleotide-mediated SPDEF modulates TFF3-mediated wound healing and intestinal barrier function during the weaning process

Most alterations during weaning involve physiological changes in intestinal structure and function. Here, we evaluated the molecular mechanisms regulating the effects of nucleotides on weaning. Nucleotide treatment induced Trefoil factor 3 (TFF3) expression and IPEC-J2 cell growth and reduced wound width. Treatment with nucleosides and TFF3 in lipopolysaccharide-challenged IPEC-J2 cells increased intestinal transepithelial electrical resistance and decreased intestinal permeability. Additionally, nucleosides improved intestinal barrier function through induction of TFF3-mediated phosphatidylinositol 3-kinase/Akt, extracellular signal-regulated kinase 1/2, p38, and Janus kinase/signal transducer and activator of transcription signaling pathways. Among selected differentially expressed genes, SAM pointed domain containing ETS transcription factor (SPDEF) expression was elevated by nucleotides in a concentration-dependent manner. Moreover, SPDEF directly regulated TFF3 expression via binding to the promoter. In vivo, nucleotide supplementation improved growth performance, serum stress levels, and intestinal morphology. Our findings provide insights into the molecular mechanisms of intestinal development during weaning in pigs.

Damage-inducible intragenic demethylation of the human TP53 tumor suppressor gene is associated with transcription from an alternative intronic promoter

Wild-type TP53 exons 5-8 contain CpG dinucleotides that are prone to methylation-dependent mutation during carcinogenesis, but the regulatory effects of methylation affecting these CpG sites are unclear. To clarify this, we first assessed site-specific TP53 CpG methylation in normal and transformed cells. Both DNA damage and cell ageing were associated with site-specific CpG demethylation in exon 5 accompanied by induction of a truncated TP53 isoform regulated by an adjacent intronic promoter (P2). We then synthesized novel synonymous TP53 alleles with divergent CpG content but stable encodement of the wild-type polypeptide. Expression of CpG-enriched TP53 constructs selectively reduced production of the full-length transcript (P1), consistent with a causal relationship between intragenic demethylation and transcription. 450K methylation comparison of normal (TP53-wildtype) and cancerous (TP53-mutant) human cells and tissues revealed focal cancer-associated declines in CpG methylation near the P1 transcription start site, accompanied by rises near the alternate exon 5 start site. These data confirm that site-specific changes of intragenic TP53 CpG methylation are extrinsically inducible, and suggest that human cancer progression is mediated in part by dysregulation of damage-inducible intragenic CpG demethylation that alters TP53 P1/P2 isoform expression. © 2015 The Authors. Molecular Carcinogenesis Published by Wiley Periodicals, Inc.

The role of the DNA damage response in zebrafish and cellular models of Diamond Blackfan anemia

Ribosomal biogenesis involves the processing of pre-ribosomal RNA. A deficiency of some ribosomal proteins (RPs) impairs processing and causes Diamond Blackfan anemia (DBA), which is associated with anemia, congenital malformations and cancer. p53 mediates many features of DBA, but the mechanism of p53 activation remains unclear. Another hallmark of DBA is the upregulation of adenosine deaminase (ADA), indicating changes in nucleotide metabolism. In RP-deficient zebrafish, we found activation of both nucleotide catabolism and biosynthesis, which is consistent with the need to break and replace the faulty ribosomal RNA. We also found upregulation of deoxynucleotide triphosphate (dNTP) synthesis - a typical response to replication stress and DNA damage. Both RP-deficient zebrafish and human hematopoietic cells showed activation of the ATR/ATM-CHK1/CHK2/p53 pathway. Other features of RP deficiency included an imbalanced dNTP pool, ATP depletion and AMPK activation. Replication stress and DNA damage in cultured cells in non-DBA models can be decreased by exogenous nucleosides. Therefore, we treated RP-deficient zebrafish embryos with exogenous nucleosides and observed decreased activation of p53 and AMPK, reduced apoptosis, and rescue of hematopoiesis. Our data suggest that the DNA damage response contributes to p53 activation in cellular and zebrafish models of DBA. Furthermore, the rescue of RP-deficient zebrafish with exogenous nucleosides suggests that nucleoside supplements could be beneficial in the treatment of DBA.

Dietary nucleotide improves markers of immune response to strenuous exercise under a cold environment

Background

Strenuous exercise has been classically associated to immune-suppression and consequently to an increased risk of infections, especially at the upper respiratory tract. The administration of dietary nucleotides has been demonstrated useful to maintain the immune function in situations of stress and thus could be an appropriate strategy to counteract the decline of the immune function associated to strenuous exercise. The aim of the present study was to asses the impact of a specific nucleotide formulation (Inmunactive®) on the markers of immune function of athletes after a heavy exercise bout under cold conditions.

Methods

Twenty elite male taekwondo athletes were randomly divided into two groups of 10 subjects that were supplemented with placebo (P) or Inmunactive (I) at 480 mg/day during 30 days. At baseline (day 0) and after 4 wk of supplementation (day 30) each subject undertook an exhaustion exercise test using a cycloergometer. Skin temperature, core temperature, heart rate, lactate concentration and rating of perceived exertion (RPE) were recorded during the test. Blood and saliva samples were obtained before and after each exercise test for determination of blood cell concentrations, PHA-stimulated lymphocyte proliferation (PHA-LP) and salivary immunoglobulin A (SIgA).

Results

Exercise tests induced neutrophilia and reduction in lymphocyte blood counts on day 0 and on day 30 in both groups. However, the I group exhibited a faster recovery from the lymphopenic response than the P group, so that lymphocyte levels were higher after 150 min (P < 0.0028). Furthermore, the lymphoproliferative response was modulated by nucleotide supplementation, since it was higher in the I group on day 30 despite an almost significant (P < 0.06) exercise-evoked decrease at baseline.

Conclusions

These findings suggest that supplementation with a nucleotide-based product for 4 weeks could counteract the impairment of immune function after heavy exercise.