Intestinal expression of TFF and related genes during postnatal development in a piglet probiotic trial.

Trefoil factor family (TFF) peptides provide protective and reparative effects by enhancing epithelial integrity and promoting mucosal restitution. TFF peptide expression is induced after mucosal damage. These processes are of central physiological relevance during the postnatal intestinal development and are strongly influenced during the weaning period. In piglets, weaning at early maturation stages frequently causes mucosal inflammation. The aim of this study was to evaluate postnatal intestinal TFF expression in a piglet probiotic trial. Low intestinal TFF2 expression was measured at early maturation stages. Weaning, however, was associated with a distinct response of increased TFF2 expression, indicating an important role in enhancing mucosal integrity. In the distal jejunum and ileum weaning could as well be associated with increased TFF3 mRNA levels. Differential TFF1 expression was not detected. Furthermore, TFF2 localization studies in different intestinal loci were performed by means of immunohistochemistry. Expression of selected genes (TGFA, EGFR, Cox-2) known to promote TFF signaling showed differential expression pattern as well, thereby providing further functional background. Furthermore, the expression patterns of EGFR observed in this study contribute to an advanced view of previous findings of EGFR regulation mainly obtained in rodents. An upregulated EGFR expression during early postnatal development suggests a local relevance to porcine intestinal maturation. However, a feed supplementation with the probiotic strain Enterococcus faecium did not influence TFF expression.

Concatameric cloning of porcine microRNA molecules after assembly PCR.

While the number of human or murine microRNAs (miRNAs) increases continuously, there are limited data available from other species. We report a novel identification method of small RNAs such as miRNAs, which allows simultaneous cloning of five RNA molecules within the same insert. First, RNA molecules <40nt were polyadenylated and five concatamerising 5' DNA adaptors were ligated to the molecules in independent reactions. Reverse transcription was carried out using oligo d(T)(18) primers with concatamerising 5' overhangs. The introduced complementary termini in the different reactions enabled the subsequent coupling of five purified antisense strands to one molecule by means of an assembly PCR. After cloning, small RNAs were identified by DNA sequencing. By means of this cloning approach, we identified 10 novel and one known porcine miRNAs. Furthermore, the endogenous expression of the cloned miRNAs was quantified in various tissues using a qRT-PCR approach.

miR-Q: a novel quantitative RT-PCR approach for the expression profiling of small RNA molecules such as miRNAs in a complex sample.

BACKGROUND: MicroRNAs (miRNAs) are small endogenous non-coding interfering RNA molecules regarded as major regulators in eukaryotic gene expression. Different methods are employed for miRNA expression profiling. For a better understanding of their role in essential biological processes, convenient methods for differential miRNA expression analysis are required. RESULTS: Here, we present the miR-Q assay as a highly sensitive quantitative reverse transcription PCR (qRT-PCR) for expression analysis of small RNAs such as miRNA molecules. It shows a high dynamic range of 6 to 8 orders of magnitude comprising a sensitivity of up to 0.2 fM miRNA, which corresponds to single copies per cell. There is nearly no cross reaction among closely-related miRNA family members, which points to the high specificity of the assays. Using this approach, we quantified the expression of let-7b in different human cell lines as well as miR-145 and miR-21 expression in porcine intestinal samples. CONCLUSION: miR-Q is a cost-effective and highly specific approach, which neither requires the use of fluorochromic probes, nor Locked Nucleic Acid (LNA)-modified oligonucleotides. Moreover, it provides a remarkable increase in specificity and simplified detection of small RNAs.