Intestinal Salmonella Typhimurium Infection Leads to miR-29a Induced Caveolin 2 Regulation

PLoS One. 2013 Jun 24;8(6):e67300. doi: 10.1371/journal.pone.0067300. Print 2013.

Abstract

Background: Salmonella are able to modulate host cell functions facilitating both uptake and resistance to cellular host defence mechanisms. While interactions between bacterial modulators and cellular proteins have been the main focus of Salmonella research, relatively little is known about mammalian gene regulation in response to Salmonella infection. A major class of mammalian gene modulators consists of microRNAs. For our study we examined interactions of microRNAs and regulated mRNAs in mammalian intestinal Salmonella infections using a piglet model.

Methodology/principal findings: After performing microRNA as well as mRNA specific microarray analysis of ileal samples from Salmonella infected as well as control piglets, we integrated expression analysis with target prediction identifying microRNAs that mainly regulate focal adhesion as well as actin cytoskeleton pathways. Particular attention was given to miR-29a, which was involved in most interactions including Caveolin 2. RT-qPCR experiments verified up-regulation of miR-29a after infection while its predicted target Caveolin 2 was significantly down-regulated as examined by transcript and protein detection. Reporter gene assays as well as RNAi experiments confirmed Caveolin 2 to be a miR-29a target. Knock-down of Caveolin 2 in intestinal epithelial cells resulted in retarded proliferation as well as increased bacterial uptake. In addition, our experiments showed that Caveolin 2 regulates the activation of the small Rho GTPase CDC42 but apparently not RAC1 in human intestinal cells.

Conclusions/significance: Our study outlines for the first time important regulation pathways in intestinal Salmonella infection pointing out that focal adhesion and organisation of actin cytoskeleton are regulated by microRNAs. Functional relevance is shown by miR-29a mediated Caveolin 2 regulation, modulating the activation state of CDC42. Further analysis of examined interactions may support the discovery of novel strategies impairing the uptake of intracellular pathogens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Animals
  • Blotting, Western
  • Caveolin 2 / genetics*
  • Caveolin 2 / metabolism
  • Cell Proliferation
  • Epithelial Cells / metabolism
  • Epithelial Cells / pathology
  • Focal Adhesions / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation*
  • Gene Knockdown Techniques
  • Gene Regulatory Networks / genetics
  • Genes, Reporter
  • Humans
  • Intestinal Mucosa / metabolism
  • Intestines / microbiology*
  • Intestines / pathology
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Oligonucleotide Array Sequence Analysis
  • RNA Interference
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Salmonella Infections, Animal / genetics*
  • Salmonella Infections, Animal / microbiology*
  • Salmonella Infections, Animal / pathology
  • Salmonella typhimurium / physiology*
  • Sus scrofa / genetics
  • Sus scrofa / microbiology
  • Up-Regulation / genetics
  • cdc42 GTP-Binding Protein / metabolism

Substances

  • Caveolin 2
  • MicroRNAs
  • RNA, Messenger
  • cdc42 GTP-Binding Protein

Grant support

This work was supported by the Deutsche Forschungsgemeinschaft (SH 465/1-1 and SFB 852 project B4.) The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.