The MAPK signaling cascade is a central hub in the regulation of cell cycle, apoptosis and cytoskeleton remodeling by tripeptidyl-peptidase II

Transcriptome Analysis Identifies Strategies Targeting Immune Response-Related Pathways to Control Enterotoxigenic Escherichia coli Infection in Porcine Intestinal Epithelial Cells

Enterotoxigenic Escherichia coli (ETEC) is an important cause of post-weaning diarrhea (PWD) worldwide, resulting in huge economic losses to the swine industry worldwide. In this study, to understand the pathogenesis, the transcriptomic analysis was performed to explore the biological processes (BP) in porcine intestinal epithelial J2 cells infected with an emerging ETEC strain isolated from weaned pigs with diarrhea. Under the criteria of |fold change| (FC) ≥ 2 and P < 0.05 with false discovery rate < 0.05, a total of 131 referenced and 19 novel differentially expressed genes (DEGs) were identified after ETEC infection, including 96 upregulated DEGs and 54 downregulated DEGs. The Gene Ontology (GO) analysis of DEGs showed that ETEC evoked BP specifically involved in response to lipopolysaccharide (LPS) and negative regulation of intracellular signal transduction. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that immune response-related pathways were mainly enriched in J2 cells after ETEC infection, in which tumor necrosis factor (TNF), interleukin 17, and mitogen-activated protein kinase (MAPK) signaling pathways possessed the highest rich factor, followed by nucleotide-binding and oligomerization domain-like receptor (NLRs), C-type lectin receptor (CLR), cytokine–cytokine receptor interaction, and Toll-like receptor (TLR), and nuclear factor kappa-B (NF-κB) signaling pathways. Furthermore, 30 of 131 referenced DEGs, especially the nuclear transcription factor AP-1 and NF-κB, participate in the immune response to infection through an integral signal cascade and can be target molecules for prevention and control of enteric ETEC infection by probiotic Lactobacillus reuteri. Our data provide a comprehensive insight into the immune response of porcine intestinal epithelial cells (IECs) to ETEC infection and advance the identification of targets for prevention and control of ETEC-related PWD.

Transcriptome analysis and identification of significantly differentially expressed genes in Holstein calves subjected to severe thermal stress

RNA-Seq analysis was used to characterize transcriptome response of Holstein calves to thermal stress. A total of eight animals aged between 2 and 3 months were randomly selected and subjected to thermal stress corresponding to a temperature humidity index of 95 in an environmentally controlled house for 12 h consecutively for 3 days. A set of 15,787 unigenes were found to be expressed and after a threshold of threefold change, and a Q value <0.05; 502, 394, and 376 genes were found to be differentially expressed on days 1, 2, and 3 out of which 343, 261 and 256 genes were upregulated and 159, 133, and 120 genes were downregulated. Only 356 genes out of these were expressed on all 3 days, and only they were considered as significantly differentially expressed. KEGG pathway analysis revealed that ten pathways were significantly enriched; the top two among them were protein processing in endoplasmic reticulum and MAPK signaling pathways. These results suggest that thermal stress triggered a complex response in Holstein calves and the animals adjusted their physiological and metabolic processes to survive. Many of the genes identified in this study have not been previously reported to be involved in thermal stress response. The results of this study extend our understanding of the animal's response to thermal stress and some of the identified genes may prove useful in the efforts to breed Holstein cattle with superior thermotolerance, which might help in minimizing production loss due to thermal stress.

Tripeptidyl Peptidase II Mediates Levels of Nuclear Phosphorylated ERK1 and ERK2

Tripeptidyl peptidase II (TPP2) is a serine peptidase involved in various biological processes, including antigen processing, cell growth, DNA repair, and neuropeptide mediated signaling. The underlying mechanisms of how a peptidase can influence this multitude of processes still remain unknown. We identified rapid proteomic changes in neuroblastoma cells following selective TPP2 inhibition using the known reversible inhibitor butabindide, as well as a new, more potent, and irreversible peptide phosphonate inhibitor. Our data show that TPP2 inhibition indirectly but rapidly decreases the levels of active, di-phosphorylated extracellular signal-regulated kinase 1 (ERK1) and ERK2 in the nucleus, thereby down-regulating signal transduction downstream of growth factors and mitogenic stimuli. We conclude that TPP2 mediates many important cellular functions by controlling ERK1 and ERK2 phosphorylation. For instance, we show that TPP2 inhibition of neurons in the hippocampus leads to an excessive strengthening of synapses, indicating that TPP2 activity is crucial for normal brain function.

Differential gene expression profiling of porcine epithelial cells infected with three enterotoxigenic Escherichia coli strains

Background

Enterotoxigenic Escherichia coli (ETEC) is one of the most important pathogenic bacteria causing severe diarrhoea in human and pigs. In ETEC strains, the fimbrial types F4 and F18 are commonly found differently colonized within the small intestine and cause huge economic losses in the swine industry annually worldwide. To address the underlying mechanism, we performed a transcriptome study of porcine intestinal epithelial cells (IPEC-J2) with and without infection of three representative ETEC strains.

Results

A total 2443, 3493 and 867 differentially expressed genes were found in IPEC-J2 cells infected with F4ab ETEC (C_F4ab), with F4ac ETEC (C_F4ac) and with F18ac ETEC (C_F18ac) compared to the cells without infection (control), respectively. The number of differentially expressed genes between C_F4ab and C_F4ac, C_F4ab and C_F18ac, and C_F4ac and C_F18ac were 77, 1446 and 1629, respectively. The gene ontology and pathway analysis showed that the differentially expressed genes in C_F4abvs control are significantly involved in cell-cycle progress and amino acid metabolism, while the clustered terms of the differentially expressed genes in C_F4acvs control comprise immune, inflammation and wounding response and apoptosis as well as cell cycle progress and proteolysis. Differentially expressed genes between C_F18acvs control are mainly involved in cell-cycle progression and immune response. Furthermore, fundamental differences were observed in expression levels of immune-related genes among the three ETEC treatments, especially for the important pro-inflammatory molecules, including IL-6, IL-8, TNF-α, CCL20, CXCL2 etc.

Conclusions

The discovery in this study provides insights into the interaction of porcine intestinal epithelial cells with F4 ETECs and F18 ETEC, respectively. The genes induced by ETECs with F4 versus F18 fimbriae suggest why ETEC with F4 may be more virulent compared to F18 which seems to elicit milder effects.