Cytoskeleton remodeling and alterations in smooth muscle contractility in the bovine jejunum during nematode infection

Abstract

Gastrointestinal nematodes of the genus Cooperia are arguably the most important parasites of cattle. The bovine jejunal transcriptome was characterized in response to Cooperia oncophora infection using RNA-seq technology. Approximately 71% of the 25,670 bovine genes were detected in the jejunal transcriptome. However, 16,552 genes were expressed in all samples tested, probably representing the core component of the transcriptome. Twenty of the most abundant genes accounted for 12.7% of the sequences from the transcriptome. A 164-h infection seemingly induced a minor change in the transcriptome (162 genes). Additionally, a total of 162,412 splice junctions were identified. Among them, 1,164 appeared unique to 1 of the 2 groups: 868 splice junctions were observed only in infected animals, while 278 were only present in all 4 control animals. Biological functions associated with muscle contraction were predominant Gene Ontology terms enriched in the genes differentially expressed by infection. The primary function of two of the four regulatory networks impacted was related to skeletal and muscular systems. A total of 34 pathways were significantly impacted by infection. Several pathways were directly related to host immune responses, such as acute phase response, leukocyte extravasation, and antigen presentation, consistent with previous findings. Calcium signaling and actin cytoskeleton signaling were among the pathways most significantly impacted by infection in the bovine jejunum. Together, these data suggest that smooth muscle hypercontractility may be initiated as a result of a primary C. oncophora infection, which may represent a mechanism for host responses in the jejunum during nematode infection.

Potential immunosuppressive effects of Escherichia coli O157:H7 experimental infection on the bovine host

“…A Fisher ‘s exact test was used for enrichment of certain GO terms. A multiple correction control (permutation to control false discovery rate, FDR) was implemented to set up the threshold to obtain the list of significantly over-represented GO-terms as previously described [21]. …”

Splice variants and regulatory networks associated with host resistance to the intestinal worm Cooperia oncophora in cattle

“…STAT6 knockout mice fail to expel N. brasiliensis (Urban et al, 1998). Our previous results show that smooth muscle hypercontractility plays a role in host responses to C. oncophora infection in cattle (Li and Schroeder, 2012). Indeed, enhanced intestinal smooth muscle contractility in parasite-infected mice is dependent on STAT6 and enteric nerves (Zhao et al, 2003).…”

“…Total RNA from 16 small intestine (jejunum) samples was extracted using Trizol (Invitrogen, Carlsbad, CA, USA) followed by DNase digestion and Qiagen RNeasy column purification (Qiagen, Valencia, CA, USA), as previously described (Li and Gasbarre, 2009;Baldwin et al, 2012;Li and Schroeder, 2012). The RNA integrity was verified using an Agilent Bioanalyzer 2100 (Agilent, Palo Alto, CA, USA).…”

“…High-quality RNA (RNA integrity number or RIN > 8.0) was processed using an Illumina TruSeq RNA sample prep kit following the manufacturer's instructions (Illumina, San Diego, CA, USA). Pooled RNAseq libraries were sequenced at 50 bp/sequence read using an Illumina HiSeq 2000 sequencer, as described previously (Li and Schroeder, 2012). Approximately, 36.7 million single-end sequence reads per sample (mean ± SD = 36,704,067 ± 12,717,940; N = 16) were generated.…”

“…Cuffdiff models the variance in fragment counts across replicates using the negative binomial distribution, as previously described (Anders and Huber, 2010). Differentially expressed genes in the transcriptome identified (cutoff: false discovery rate FDR ≤ 0.05) were further analyzed using gene ontology (GO) analysis as previously described (Li and Schroeder, 2012). Enrichment of certain GO terms was determined based on a Fisher's exact test.…”